Human T cell leukemia virus type 1, the first human retrovirus ever identified, infects an estimated 5 to 10 million people worldwide, a figure extrapolated from surveys covering only about one-seventh of the global population. The virus inserts a DNA copy of its RNA genome into the chromosomes of host T cells, establishing a lifelong infection that can drive a spectrum of diseases, including adult T cell leukemia/lymphoma, HTLV-1-associated myelopathy, and HTLV-1-associated uveitis, a chronic inflammation inside the eye that is particularly common in endemic regions such as Japan. Despite the scale of the problem, coordinated global action has been slow; the World Health Organization only published technical reports aimed at reducing HTLV-1-related morbidity and mortality in 2021, and no broadly effective intervention has emerged in decades of research.

Current treatment for the ocular disease relies heavily on corticosteroids, delivered as topical drops, injections into the eye, or oral prednisone. This approach has serious shortcomings. Studies indicate that 30 to 60 percent of patients with HTLV-1-associated uveitis experience recurrent episodes, and long-term steroid exposure can trigger cataracts, glaucoma, macular edema, epiretinal membranes, retinal degeneration, optic nerve atrophy, and bullous keratopathy. Most importantly, corticosteroids suppress inflammation without reducing the number of virus-infected cells or halting disease progression. Newer molecular targeted agents, including the anti-CCR4 antibody mogamulizumab and the immunomodulatory drug lenalidomide, have been explored, but treatment-related inflammation and adverse effects remain significant obstacles. This therapeutic gap motivated a team led by Yaru Zou and Koju Kamoi of Tokyo Medical and Dental University to investigate whether an epigenetic drug already approved for blood cancer could address the root of the ocular inflammation.

The drug in question is valemetostat, marketed as EZHARMIA, a dual inhibitor of the enzymes EZH1 and EZH2 that was approved in 2022 for adult T cell leukemia/lymphoma. Both enzymes are the catalytic components of polycomb repressive complex 2, a molecular machine that silences genes by adding three methyl groups to lysine 27 on histone H3, producing the repressive chromatin mark known as H3K27me3. Previous work had shown that EZH1 and EZH2 are overexpressed, and H3K27me3 deposition increased, in ATL cells and in cells expressing the viral oncoprotein Tax. Dual EZH1/2 inhibitors have also been reported to curb the spontaneous proliferation and exaggerated immune responses of HTLV-1-infected cells in patients with HTLV-1-associated myelopathy. What remained unknown was whether such inhibition could benefit the inflamed eye.

To find out, the researchers built a series of laboratory models centered on ARPE-19 cells, a human retinal pigment epithelial cell line chosen because the retinal pigment epithelium forms the outer blood-retinal barrier and governs retinal immune homeostasis. They exposed these ocular cells to three kinds of T cells: MT-2 cells, which carry transcriptionally active HTLV-1 and express the viral protein Tax; TL-Om1 cells, an ATL-derived line in which the virus is largely silent and Tax is low or absent; and Jurkat cells, which are uninfected and served as controls. In parallel, they treated the T cell lines themselves. Western blotting and quantitative PCR revealed that HTLV-1 infection drove significant upregulation of both EZH1 and EZH2, along with elevated H3K27me3, in infected retinal pigment epithelial cells and in MT-2 cells, with EZH1 protein rising roughly 2.5-fold in infected ocular cells and six-fold in MT-2 cells. This was the first demonstration that HTLV-1 infection induces polycomb-mediated epigenetic changes in retinal cells.

The team then treated the models with valemetostat at 0.01, 0.1, and 1 micromolar for 96 hours, concentrations selected in preliminary experiments because they harmed infected T cells while leaving normal ocular cells, including primary human trabecular meshwork cells, unaffected below 10 micromolar. The results were strikingly dependent on the model. In co-cultures of retinal cells with Tax-positive MT-2 cells, and in retinal cells directly infected with HTLV-1, the drug produced modest but statistically significant reductions in cell viability at the highest dose, accompanied by small increases in late-stage apoptosis. No such effects appeared in co-cultures with TL-Om1 or Jurkat cells. Crucially, the absolute magnitude of apoptosis remained limited, typically only 1 to 3 percent above baseline, indicating that valemetostat is not broadly toxic to retinal cells, an important safety consideration given their role in maintaining vision.

The virological findings were equally nuanced. Valemetostat did not significantly reduce the HTLV-1 proviral load in co-culture systems or in directly infected retinal pigment epithelial cells. However, in MT-2 cells themselves, 1 micromolar valemetostat significantly lowered proviral load and suppressed the messenger RNA levels of both Tax and HBZ, the two hallmark transcripts of the virus. Because MT-2 cells represent the transcriptionally active, highly infectious state of HTLV-1, while TL-Om1 represents latency, the results suggest that the drug’s antiviral effect is gated by the transcriptional status of the infected cell. Within the four-day treatment window, the authors conclude, valemetostat’s benefit to the ocular environment is likely indirect, acting primarily by quieting the most virally active cells rather than by eradicating provirus everywhere.

The most clinically relevant effects emerged in the inflammatory readouts. HTLV-1-infected T cells recovered from the eyes of patients with uveitis are known to secrete copious interleukin-6, interleukin-8, and interleukin-10, all implicated in disease. In the new study, valemetostat produced a dose-dependent increase in the anti-inflammatory cytokine IL-10 in MT-2-containing conditions, significant at 1 micromolar in the co-culture system and across all doses in MT-2 cells. This fits a mechanistic expectation: blocking EZH1/2 removes H3K27me3 marks that repress the IL-10 gene, and prior genetic studies showed that loss of EZH2 directly activates IL-10 transcription in several CD4-positive T cell subsets. Meanwhile, pro-inflammatory signals fell in a context-dependent pattern. IL-12p70 and the chemokine CXCL-10 dropped in co-cultures, IL-6 and IL-8 declined mainly in MT-2 cells, and CCL-2 fell at low doses in the MT-2 co-culture, whereas the chemokine CCL-5 was unchanged in every model.

The drug’s influence on NF-kappaB, the central inflammatory pathway that Tax hijacks to drive both viral replication and cytokine production, was more subdued. Valemetostat modestly reduced NF-kappaB p65 phosphorylation in the MT-2 co-culture at the lowest dose and slightly decreased the nuclear-to-cytoplasmic ratio of p65 in retinal cells stimulated with TNF-alpha, but it did not abolish nuclear translocation. The authors attribute this to the overwhelming strength of Tax-driven NF-kappaB activation, which a 96-hour course of EZH1/2 inhibition may be insufficient to counteract, and to the fact that NF-kappaB and cytokine networks are regulated by many factors beyond polycomb complexes. Immunofluorescence confirmed that valemetostat significantly lowered H3K27me3 in retinal cells exposed to MT-2 cells or directly infected, but not in cells co-cultured with TL-Om1 or Jurkat cells, again underscoring the model dependence of the epigenetic response.

The study also carries a cautionary note about IL-10. Although the cytokine is anti-inflammatory, it can promote the survival of HTLV-1-infected T cells and facilitate immune evasion by impairing dendritic cell antigen presentation and downregulating MHC class I molecules, and patients with aggressive ATL often show abnormally elevated IL-10. The authors therefore suggest that combining EZH1/2 inhibition with IL-10 pathway blockade could prove more effective, noting evidence that IL-10 neutralization sensitizes ATL cells to standard therapies. In the TL-Om1 model of ATL-related ocular infiltration, valemetostat failed to reduce H3K27me3, proviral load, or NF-kappaB activation within the malignant cells, yet it suppressed TL-Om1-induced CXCL10 secretion and induced dose-dependent apoptosis, pointing to a benefit mediated through the inflammatory microenvironment rather than direct tumor killing.

The authors are candid about the limitations. The work relied entirely on in vitro co-cultures and established cell lines, which cannot reproduce the blood-retinal barrier, retinal architecture, or local immune regulation of a living eye, and the intraocular pharmacokinetics of valemetostat after systemic administration remain undefined. Sex as a biological variable could not be assessed because donor-defined primary cells were not used. Even so, the findings establish a proof of concept that an approved epigenetic therapy can counteract HTLV-1-induced chromatin changes in retinal cells, dampen viral transcription in the most active infected cells, and reshape the cytokine milieu that sustains uveitis. Longer treatment studies, in vivo models, and patient-derived systems will be needed to determine whether these modest, context-dependent effects can be translated into a genuine steroid-sparing therapy for one of the most burdensome manifestations of a virus that medicine has long neglected.

Subject of Research: EZH1/2-targeted epigenetic therapy with valemetostat for HTLV-1-associated uveitis

Article Title: Dual impact of EZH1/2-targeted therapy in HTLV-1-associated inflammation: Direct and indirect mechanisms

Article References: Zou, Y., Kamoi, K., Yang, M., Zong, Y., Zhang, J., & Ohno-Matsui, K. (2026). Dual impact of EZH1/2-targeted therapy in HTLV-1-associated inflammation: Direct and indirect mechanisms. iScience, 29(11), Article 117775. https://doi.org/10.1016/j.isci.2026.117775

Image Credits: AI Generated

DOI: 10.1016/j.isci.2026.117775

Keywords: HTLV-1, valemetostat, EZH1, EZH2, H3K27me3, uveitis, epigenetics, PRC2, Tax, IL-10, NF-kappaB, retinal pigment epithelium

Palliative care has long been framed as a specialist discipline reserved for hospices and oncology wards, but a growing body of evidence insists it belongs everywhere people approach the end of life, including nursing homes, where a large share of deaths in ageing societies now occur. A new qualitative study from Sweden, published in BMC Nursing, offers an unusually candid look at what happens inside care teams after they receive structured palliative care education, and the central finding is striking: training changes how staff think, but thinking alone does not change care. The researchers, Camilla Ekeblom, Carina Lundh Hagelin and Jane Österlind of Marie Cederschiöld University in Stockholm, found that the value of an educational intervention depends on an intricate alignment between individual emotions, relational dynamics and organisational realities, and that when any one of these dimensions falls out of step, the benefits of education can quietly dissolve.

The study set out to explore how nursing home staff reason about providing palliative care after participating in an interprofessional educational intervention, abbreviated in the literature as IPEI. Rather than measuring outcomes with questionnaires, the team chose a descriptive qualitative design, interviewing eighteen staff members drawn from five Swedish nursing homes. The participants represented the full spectrum of people who actually deliver and manage care: registered nurses, assistant nurses, a physician, first-line managers and designated palliative care champions. This breadth matters, because palliative care in nursing homes is not delivered by any single profession; it emerges, or fails to emerge, from the daily interplay of people with different training levels, responsibilities and emotional exposures to dying residents.

Data were collected through semi-structured individual interviews conducted between March and April 2024, and analysed using inductive qualitative content analysis, a method that allows themes to rise from the material itself rather than being forced into pre-existing theoretical boxes. From this analysis, three main categories emerged, and together they map the terrain on which palliative care is actually practised. The first concerns managing one’s own emotions, thoughts and attitudes. The second addresses the significance of relationships, communication and interactions in care. The third captures how staff navigate norms, assumptions and organisational structures in everyday palliative care. The categories correspond, respectively, to the individual, relational and organisational dimensions of the work, and the authors argue that it is the interplay among all three, not any single factor, that determines whether good palliative care becomes possible.

The individual dimension is perhaps the most human part of the findings. Staff described the ongoing internal work of confronting their own feelings about death, ageing and suffering, and of examining assumptions they carried about what palliative care even means. A recurring tension in the literature, echoed here, is the tendency to equate palliative care narrowly with end-of-life care, the final days and hours, rather than understanding it as an approach that can and should be integrated into everyday care over a longer trajectory. The interviews suggested that the educational intervention gave participants opportunities for personal as well as professional development, creating space to reflect on attitudes that had previously gone unexamined. In this sense, education functioned less like a knowledge transfer and more like a mirror, prompting staff to notice how their own emotional responses shaped their clinical decisions.

The relational dimension proved equally consequential. Palliative care in a nursing home is saturated with communication: conversations with residents about what matters to them, exchanges with distressed relatives, coordination between assistant nurses who know the residents intimately and nurses and physicians who carry clinical responsibility. The participants’ reasoning placed relationships and interactions at the heart of care provision, indicating that no amount of theoretical knowledge substitutes for the ability to build trust, listen and communicate across professional boundaries. This is where the interprofessional design of the intervention appears to have paid off. By bringing different professions into a shared educational space, the programme created a common language and, implicitly, a shared understanding of what the team was trying to achieve together, something that fragmented, profession-specific training often fails to produce.

The third dimension, the organisational, is where the study’s message becomes most uncomfortable for policymakers and care home leadership. Staff described navigating norms and assumptions embedded in their workplaces, along with structural conditions that could either support or obstruct a palliative approach. Staffing levels, routines, leadership priorities and workplace culture all shape what is practically possible on a shift where residents are dying, families are anxious and time is scarce. The authors’ conclusion is explicit on this point: providing palliative care was not solely a matter of enhancing staff knowledge. Knowledge and the conditions for care are shaped through the interplay between staff attitudes, their reasoning about care, relational dynamics and organisational conditions. When these dimensions align and mutually reinforce one another, favourable conditions for palliative care may be supported; when they do not, even well-trained staff may find their intentions frustrated.

Why does this matter on a societal scale? Nursing homes accommodate older people with complex needs and account for a large proportion of deaths, which makes palliative care a central component of care in these settings rather than an occasional emergency. Yet access to palliative care remains unequal, particularly for older people, and staff in long-term care often lack sufficient training. The demographic arithmetic is unforgiving: as populations age, the number of people who will die in nursing homes rises, and the quality of their final months depends heavily on the competence and confidence of the workforce that cares for them. Studies like this one move the conversation beyond the simplistic assumption that a training course fixes the problem, and toward a systems view in which education is necessary but insufficient on its own.

The study also carries a methodological lesson for how we evaluate educational interventions in care settings. Much of the existing research measures knowledge gains or self-reported confidence before and after training. Those metrics are useful, but they cannot reveal how staff actually reason about applying what they have learned in the messy reality of daily care. By using inductive content analysis of interviews, the Swedish team surfaced the texture of that reasoning: the hesitations, the emotional labour, the negotiations with colleagues and managers, the quiet adjustments between ideal practice and what the shift allows. The findings suggest that interprofessional educational initiatives work best when they combine theoretical knowledge with opportunities for reflection and practical application, allowing staff to translate concepts into their own working context rather than leaving translation to chance.

There are limits worth noting. The study involved eighteen participants in five Swedish nursing homes, interviewed at a single point in time after the intervention, and qualitative findings are not designed to be statistically generalised. The researchers themselves submitted the work for ethical review, receiving approval from the Swedish Ethical Review Authority, and obtained written informed consent from all participants, but the transferability of the results to other health systems will depend on how similar those systems’ nursing homes and educational programmes are to the Swedish context. Still, the three-dimensional framework that emerged, individual, relational and organisational, offers a portable lens that other teams can use to examine their own settings, and it aligns with a broader international consensus that palliative care competence must be built at every level of an organisation simultaneously.

The most durable insight from this research may be its refusal to locate the solution in any single place. Staff who completed the intervention perceived it as an opportunity for growth, and their reasoning showed genuine movement in how they understood palliative care as an ongoing approach rather than a final act. But their accounts also made clear that attitudes, relationships and structures must pull in the same direction for that understanding to reach residents’ bedsides. For nursing homes everywhere, the implication is a practical checklist of a different kind: train your staff together, give them room to reflect, examine the norms your workplace quietly enforces, and make sure the organisation’s daily conditions match what the education teaches. Where those elements align, palliative care stops being an aspiration and becomes, simply, the way care is done.

Subject of Research: Nursing home staff's reasoning about providing palliative care after an interprofessional educational intervention

Article Title: “Nursing home staff’s reasoning about providing palliative care following an educational intervention – a qualitative interview study”

Article References: Ekeblom, C., Lundh Hagelin, C., & Österlind, J. (2026). “Nursing home staff’s reasoning about providing palliative care following an educational intervention – a qualitative interview study”. BMC Nursing, 25(1), Article 956. https://doi.org/10.1186/s12912-026-05480-4

Image Credits: AI Generated

DOI: 10.1186/s12912-026-05480-4

Keywords: palliative care, nursing homes, older people, interprofessional education, qualitative research, nursing education, end-of-life care, care staff attitudes, organisational conditions, Sweden, BMC Nursing, healthcare workforce

Neutral mesons, the fleeting particles that endlessly oscillate between matter and antimatter forms, have just acquired a strikingly new mathematical lens. In a theoretical study published in The European Physical Journal C, physicist Swarup Sangiri of the Indian Institute of Technology Kharagpur has constructed a fresh class of geometric objects, called connected sequential Bargmann invariants, that encode how two different decay channels of an entangled meson pair relate to one another inside the projective geometry of quantum states. The work extends an earlier framework and shows that when decay-projected states are wired directly into a cyclic chain of quantum overlaps, the resulting quantities behave in a fundamentally different way near the boundary where CP violation switches off.

To appreciate why this matters, it helps to recall what makes neutral meson systems so special. Particles such as the neutral kaon, the D meson, and the two neutral B mesons are produced as flavor eigenstates but propagate as mixtures of heavy and light eigenstates, conventionally written as combinations of the meson and its antiparticle with coefficients p and q. When the magnitudes of p and q differ, the two propagation eigenstates are no longer orthogonal, and this nonorthogonality is the hallmark of indirect CP violation, the subtle asymmetry between matter and antimatter that was famously discovered in kaons in 1964. Because any physical observable must be independent of arbitrary phase conventions attached to quantum states, the natural language for describing interference in these systems is one of rephasing-invariant quantities.

Bargmann invariants provide exactly that language. For a closed sequence of quantum states, the nth-order Bargmann invariant is the product of overlaps taken around the cycle, and it remains unchanged under independent phase redefinitions of each state. Its phase is a geometric phase, the kind of holonomy familiar from the Berry phase, accumulated along a closed loop in the space of rays. Earlier work had applied this machinery to correlated neutral meson decays, constructing third-order invariants that probe single-channel interference and fourth-order invariants that correlate two decay channels through the heavy and light propagation eigenstates. Those constructions linked the geometric picture to conventional flavor observables, including Jarlskog-type structures, without introducing any new phenomenological parameters.

The new study asks a deceptively simple question: what happens if the two decay-projected states themselves are connected directly inside the cyclic overlap chain? When one meson of an entangled pair, produced for example in the decay of a phi or Upsilon resonance, decays into a channel f, its partner is projected into a conditional state determined by the decay amplitudes. A second channel g prepares a different conditional state. The connected sequential fourth-order Bargmann invariant follows the loop from the heavy eigenstate to the f-conditioned state, then directly to the g-conditioned state through their mutual overlap, then to the light eigenstate, and finally back to the heavy one. The crucial new ingredient is the overlap between the two conditional states, a quantity built purely from the decay amplitudes that measures how similar the two post-selected meson states are in projective Hilbert space.

This change in connectivity has dramatic consequences for how the geometric quantities scale as CP violation becomes small. The previously studied disconnected fourth-order invariant, when normalized by the product of two third-order invariants, produced a ratio that blows up quadratically, scaling as the inverse square of the mixing asymmetry, the difference between the squared magnitudes of p and q. The connected sequential ratio, by contrast, carries only a single factor of that asymmetry in its denominator, so its enhancement near the CP-conserving limit is merely linear. Physically, replacing one propagation-mediated link with a direct overlap between the projected states removes one power of the heavy-light suppression, placing the two classes of geometric correlation in distinct scaling classes.

A second new ratio compares the sequential invariant directly with the disconnected one. This comparison ratio behaves in the opposite manner: it is proportional to the mixing asymmetry itself, vanishing in the exact CP-symmetric limit. Its behavior is governed by a competition between two effects, the shrinking of the heavy-light overlap on one side and the possible alignment of interference phases between the two decay channels on the other. When the conditional states prepared by the two channels become geometrically aligned, the suppression can be weakened, revealing that the connected structure is sensitive not only to mixing asymmetry but also to the relative coherence of the decay projections.

To make these statements precise, the analysis is carried out in terms of the standard rephasing-invariant interference parameters lambda, the products of the mixing ratio q over p and the ratios of decay amplitudes to their CP-conjugates. A systematic small-asymmetry expansion, with the squared magnitudes of p and q written as one half plus or minus a small parameter, shows that the sequential ratio depends explicitly on the phase difference between the two channels through the numerator structure. This dependence has no analogue in the disconnected construction, where the channels communicate only through the propagation eigenstates. It means the connected sequential geometry probes the relative orientation of the decay-conditioned rays themselves, a piece of interference information that conventional observables do not isolate on their own.

The geometric interpretation is perhaps the most elegant part of the story. Both the disconnected and the sequential fourth-order invariants involve the same four rays, the heavy and light propagation eigenstates and the two decay-projected states, yet they define different closed paths through projective Hilbert space. A Bargmann invariant depends not just on which states participate but on how they are stitched together, so rewiring the cycle produces a genuinely different geometric correlation. In the CP-conserving limit the heavy and light eigenstates become orthogonal, one link of every cycle collapses, and the entire cyclic structure degenerates, which is why the invariants vanish there. The formalism thus ties the very existence of these CP-sensitive geometric objects to the nonorthogonality of the propagation eigenstates.

Crucially for experiment, none of this requires new physics inputs. The sequential invariant and both ratios can be written entirely in terms of the mixing parameters and decay amplitudes already extracted from time-dependent flavor analyses at flavor factories such as the KLOE experiment with entangled kaons and the BABAR and Belle measurements with entangled B mesons. The framework simply reorganizes the same accessible information into cyclic geometric quantities. The neutral kaon system, with its small indirect CP violation and long-lived interference phenomena, is flagged as a particularly natural arena where the linear enhancement of the sequential ratio could be pronounced, with candidate channels including two-pion, semileptonic, and multi-pion final states. The B meson systems, including channels like B decays to J/psi kaons and to pion pairs, offer rich phase-dependent interference structures, while the D system, where both mixing and CP violation remain tiny in the Standard Model, could serve as a sensitive testing ground for small deviations from exact symmetry.

The study stops short of claiming a new dynamical observable. The author is careful to note that the sequential construction does not add an extra propagation stage in the manner of conventional cascade CP analyses; it is a reorganization of overlap geometry within a single meson system. Even so, the result establishes a hierarchy of Bargmann invariant structures, from single-channel triangles through disconnected quadrilaterals to directly connected sequential cycles, each capturing a different layer of CP-sensitive interference. As precision flavor physics continues to squeeze ever tighter constraints on the origins of matter-antimatter asymmetry, geometric tools of this kind may reveal correlation patterns hiding in plain sight within data that experiments already collect.

Subject of Research: Geometric Bargmann invariant structures and CP-sensitive interference in correlated neutral meson systems

Article Title: Connected sequential Bargmann invariants and (\mathcal CP~)-sensitive geometric correlation structures in neutral meson systems

Article References: Sangiri, S. (2026). Connected sequential Bargmann invariants and $$\mathcal CP~$$-sensitive geometric correlation structures in neutral meson systems. The European Physical Journal C, 86(9), Article 1056. https://doi.org/10.1140/epjc/s10052-026-16308-5

Image Credits: AI Generated

DOI: 10.1140/epjc/s10052-026-16308-5

Keywords: Bargmann invariants, neutral mesons, CP violation, geometric phase, quantum interference, meson mixing, projective Hilbert space, kaons, B mesons, rephasing invariance, entangled meson pairs, flavor physics

The viruses that gave rise to SARS-CoV-2 have been circulating in horseshoe bats and related mammals across Asia for millennia, and most of them have never spilled over into people. Yet a small number of these bat sarbecoviruses clearly can infect humans, as the COVID-19 pandemic demonstrated. A central question for pandemic preparedness has therefore been whether scientists can look at the properties of a newly discovered bat coronavirus and make an evidence-based judgement about how dangerous it might be. A new study published in PLOS Biology suggests that one measurable property, the breadth of species whose ACE2 receptor a virus can use, may be a surprisingly informative signal, predicting not only which animals a virus can infect but also how closely related it is to SARS-CoV-2 in the eyes of the human immune system.

Sarbecoviruses, the subgenus of coronaviruses that includes SARS-CoV and SARS-CoV-2, attach to their host cells through the receptor-binding domain, or RBD, of the Spike protein. This domain grips the angiotensin-converting enzyme 2 receptor, ACE2, on the surface of host cells, and it is also the principal target of neutralising antibodies. That dual role creates an intimate link between host range and antigenicity: the same molecular surface that determines which species’ receptors a virus can engage also determines how well antibodies raised against one virus recognise another. The research team, led by scientists at The Pirbright Institute together with collaborators including researchers at King’s College London, set out to map that relationship systematically across a diverse collection of bat sarbecoviruses.

The experimental strategy combined three complementary approaches. First, the researchers used binding assays to test whether the Spike proteins of different sarbecoviruses could attach to ACE2 proteins from a wide panel of mammalian species. Second, they used pseudotype-entry assays, in which harmless lentiviral particles are decorated with each coronavirus Spike protein, to test whether receptor binding actually translates into cell entry. Third, they measured how sera from SARS-CoV-2 convalescent individuals and monoclonal antibodies from vaccinated people who had experienced breakthrough infections neutralised the different viruses. By running the same viruses through all three assays, the team could directly correlate receptor usage with antigenic behaviour.

The results revealed a striking pattern. Sarbecoviruses in clade 1, the group that contains SARS-CoV-2 itself and the BANAL viruses isolated from bats in Laos, tended to be generalists. Their Spike proteins could productively engage ACE2 receptors from many different bat species, indicating that they are not finely tuned to a single host. In contrast, viruses from clade 3, exemplified by RhGB07, and clade 5, exemplified by Rc-o319, behaved as specialists, using a much narrower range of ACE2 receptors. Rc-o319, which was previously known to be unable to use human ACE2 efficiently, fits this specialist profile, whereas the BANAL viruses, which can use human ACE2, sit firmly in the generalist camp alongside SARS-CoV-2.

To understand the structural basis of this specialism, the team solved a novel structure of the RhGB07 Spike protein. The structure allowed them to identify specific residues within the RBD that are associated with the restricted receptor usage of this clade 3 virus. These residues presumably shape the receptor-binding interface in ways that favour particular bat ACE2 variants while excluding others. Such structural insights are valuable because they point to the molecular features that distinguish viruses capable of flexible receptor engagement from those locked into narrow host ranges, and they may help predict the properties of newly discovered sarbecoviruses from sequence data alone.

When the researchers extended their receptor panel beyond bats to include more diverse mammalian ACE2 proteins, the generalist phenotype largely held. Clade 1 viruses could bind and enter cells expressing ACE2 from humans, non-human primates, livestock, and rodents, as well as from species considered potential intermediate reservoir hosts, such as civets, raccoon dogs, and pangolins. This is significant because intermediate hosts are thought to have played a role in previous coronavirus spillovers, including the emergence of SARS-CoV in 2002. A virus that can already use the receptors of many species faces fewer barriers on the path from bat to human. The specialist viruses, by contrast, showed wider phenotypic diversity across this expanded panel, with RhGB07 exhibiting a more idiosyncratic pattern of receptor usage that did not simply mirror its bat-host profile.

The study also examined how SARS-CoV-2’s ongoing evolution in humans has changed its receptor preferences. Comparing variants that have emerged during the pandemic, the researchers found an expanding and, in some cases, shifting pattern of generalism, particularly for Omicron and its many sub-lineages. Omicron’s Spike has accumulated numerous mutations in the RBD, and these changes appear to have broadened or reconfigured the range of ACE2 molecules the virus can engage. This observation underscores that receptor usage is not a fixed property of a virus but a dynamic trait that can evolve under immune pressure and changing transmission landscapes, with potential consequences for which animal species might serve as new reservoirs for human-derived variants.

The antigenic side of the analysis produced equally important findings. When convalescent sera from people who had recovered from COVID-19 were tested against the panel of bat sarbecoviruses, clade 1 viruses, being phylogenetically closest to SARS-CoV-2, were antigenically the most similar. There was robust evidence for cross-neutralisation of these viruses, meaning that immunity generated against SARS-CoV-2 offers meaningful protection against its closest bat relatives. Importantly, however, the team also found evidence for limited cross-neutralisation across the entire subgenus, suggesting that even the more distantly related specialist viruses are not completely invisible to immunity primed by SARS-CoV-2 infection. This graded pattern of cross-reactivity maps closely onto the phylogenetic and receptor-usage relationships the researchers had established.

Using monoclonal antibodies derived from COVID-19 vaccinees who subsequently experienced breakthrough infections, the researchers were able to pinpoint which classes of antibody epitopes are responsible for the broader neutralisation observed across the sarbecovirus panel. Because antibodies recognise specific structural features of the RBD, identifying the epitope classes that mediate cross-neutralisation provides a rational basis for designing vaccines and therapeutics with deliberately broad coverage. Antibodies directed against more conserved features of the receptor-binding interface, rather than those specific to SARS-CoV-2’s particular configuration, appear to underpin the wider neutralising activity.

Taken together, the study delivers a unifying message: generalist ACE2 usage, phylogenetic proximity to SARS-CoV-2, and antigenic similarity travel together. A bat sarbecovirus that can flexibly use receptors from many mammalian species is likely to be a close relative of SARS-CoV-2 and likely to be partially neutralised by existing human immunity. This constellation of traits offers surveillance teams a practical framework for triage. When a new sarbecovirus is discovered, characterising its receptor-binding breadth through binding and pseudotype assays could provide an early, laboratory-based assessment of both its zoonotic potential and the degree to which current vaccines and antibodies might protect against it. As bat habitats are disturbed and human-wildlife interfaces expand, such tools for distinguishing the generalists from the specialists among the thousands of circulating bat coronaviruses could prove essential for anticipating, and perhaps preventing, the next spillover.

Subject of Research: ACE2 receptor usage breadth as a predictor of host range and antigenic relatedness across bat sarbecoviruses

Article Title: Breadth of ACE2 receptor usage predicts host range and antigenic relatedness across bat sarbecoviruses

Article References: Thakur, N., Newman, J., Ni, D., Seow, J., Hay, A. L., Lee, Y., Upadhyay, A., Ekundayo, B. E., Hammond, J. A., Peacock, T. P., Lau, K., Doores, K. J., & Bailey, D. (2026). Breadth of ACE2 receptor usage predicts host range and antigenic relatedness across bat sarbecoviruses. PLOS Biology, 24(10), e3003944. https://doi.org/10.1371/journal.pbio.3003944

Image Credits: AI Generated

DOI: 10.1371/journal.pbio.3003944

Keywords: sarbecoviruses, ACE2, SARS-CoV-2, host range, receptor-binding domain, antigenicity, cross-neutralisation, bat coronaviruses, zoonotic spillover, Omicron, monoclonal antibodies, pseudotype assays

Where is the line between firm discipline and child abuse? For millions of families in the United States, the answer depends on where they grew up, what their parents did, and how their culture defines good parenting. A new study published in the Journal of Child and Family Studies tackles this thorny question with an ambitious goal: building a scientific instrument that can measure how people from different backgrounds judge parenting practices that are accepted in some communities but condemned in others. The Parenting Practices and Discipline Scale, or PPDS, developed by Kevin Ortiz Diaz, Maureen C. Kenny, and Helia Baez at Florida International University, is one of the first tools designed specifically to capture culturally situated discipline practices that existing measures simply ignore.

The stakes are enormous. Child abuse is recognized as a global health issue, and in the United States it occurs at what researchers describe as epidemic proportions. Federal data show 546,159 victims of child abuse and neglect in 2023 alone, and the vast majority of these cases, roughly 89 percent, are committed by one or both parents. Children from minority groups are often the most affected, with Black or African American children among the most likely to experience abuse, second only to American Indian or Alaska Native children. Yet the definitions of what constitutes abuse vary dramatically across countries and cultures, creating a legal and ethical minefield for immigrant families who may not realize that practices considered normal at home are illegal in their new country.

The problem is particularly acute for Hispanic families, who make up 19 percent of the American population and represent the largest share of recent immigrants. Hispanic culture is far from monolithic, encompassing communities from South and Central America and the Caribbean with distinct traditions, but certain common threads run through the research. The concept of familismo, a cultural orientation and sense of obligation to family, has been linked to greater parental warmth in some studies. At the same time, physical violence as a disciplinary method remains common in many Hispanic cultures, and the chances that such behaviors are carried over by families immigrating to the United States are high. The result is a potential collision between generations of cultural practice and a legal system, anchored by the Child Abuse Prevention and Treatment Act of 1974, that defines abuse in terms of serious physical or emotional harm.

What makes the new study distinctive is its grounding in intersectionality theory, a framework rooted in feminist scholarship that examines how multiple categories of identity, such as race, ethnicity, gender, and nativity, interact to shape experience. Rather than treating demographic characteristics as independent variables, the researchers designed their analyses to test whether these dimensions jointly predict how individuals classify discipline practices as culturally acceptable or abusive. The framework has practical urgency: racial and ethnic disparities exist in both the reporting and substantiation of child maltreatment, and current child protection policies can disproportionately affect women of color who use social services and face heightened surveillance and risk of reports to child protective services.

The scale itself emerged from a careful two-stage piloting process. First, four experienced mental health clinicians specializing in child abuse, with 10 to 20 years of experience each, reviewed a draft pool of 54 items describing parenting behaviors and case vignettes. Then ten first-generation Hispanic immigrants from a range of nationalities, including Puerto Rican, Cuban, Colombian, Mexican, Dominican, and Nicaraguan participants, examined the refined items and identified which behaviors they would associate with parents in their own cultures and whether they would label those behaviors abusive or acceptable. Consensus required agreement from at least 70 percent of the pilot group. Eighteen items survived, ten identified as culturally acceptable behaviors such as yelling, using the chancla, the slipper famously wielded in many Latino households, or letting a child sleep with parents, and eight identified as abusive behaviors such as spanking, leaving a child alone in a car, or forcing a child to bathe with an adult.

The main study recruited 1,477 undergraduates at a large Hispanic-Serving Institution in Miami, ultimately yielding an analytic sample of 1,089 participants after exclusions for failed attention checks, missing data, and groups too small for meaningful analysis. The final sample was 72.2 percent Hispanic, 16.3 percent non-Hispanic Black, and 11.6 percent non-Hispanic White, nearly 70 percent U.S.-born, and predominantly female at 88.8 percent. Participants rated each of the 18 behaviors on a three-point scale: not abusive, inappropriate but not abusive, or abusive. The choice of a college population was deliberate, since emerging adults are on the cusp of parenthood, attitudes at this life stage predict later parenting intentions, and parenting practices tend to be transmitted intergenerationally.

Psychometrically, the study unfolded in two parts. Study 1 established the scale’s initial properties using exploratory factor analysis with principal axis factoring and oblique rotation on a polychoric correlation matrix, an approach suited to the ordinal, non-normally distributed responses. The analysis supported a two-factor structure: Factor 1 captured discipline and psychological aggression, including spanking, yelling, the chancla, cursing, ignoring, comparing, fighting, and religion, while Factor 2 reflected neglect and physical endangerment, such as using drugs in front of a child, refusing treatment for illness, and allowing smoking. The two factors accounted for 29.5 percent of the variance and were moderately correlated. Internal consistency for the full 18-item measure was acceptable at a Cronbach’s alpha of 0.71, though the abusive subscale showed weaker reliability, a limitation the authors acknowledge candidly.

Study 2 then deployed regression models to test how demographic identities shaped perceptions, and the results were revealing. Gender and parental status emerged as the strongest and most consistent predictors: women and parents were significantly more likely to classify culturally acceptable practices as abusive. Among Hispanic participants, those not born in the United States were more likely than U.S.-born Hispanics to view behaviors like spanking as abusive, a finding that ran counter to the researchers’ hypothesis and suggests that acculturation may shift parenting beliefs toward American child protection norms. Across racial and ethnic groups, Hispanic participants were more likely than Black participants to classify culturally acceptable practices as abusive. Notably, for the more overtly harmful behaviors in Factor 2, parental status was the only significant predictor, suggesting broad agreement that neglecting a sick child or encouraging substance use transcends cultural and gendered expectations.

The effect sizes were small, with the models explaining roughly 1 to 6 percent of the variance, a reminder that unmeasured cultural and contextual factors account for most of the variation in how people judge discipline. Still, the patterns carry real implications for prevention. The authors suggest that father-focused education programs may be valuable, since men were less likely to identify physical discipline as harmful and may therefore be at greater risk of normalizing such practices. Culturally adapted interventions have already shown promise, from brief summer parent training programs benefiting Hispanic children to the multinational Triple P Positive Parenting Program, and the PPDS could help practitioners identify which disciplinary practices are perceived as acceptable within specific communities, allowing messaging to be tailored rather than uniform.

The researchers are careful to frame their findings as preliminary. The sample was heavily female and drawn from a single Miami institution in a minority-majority city, socioeconomic status was not assessed, and social desirability bias may have influenced responses to questions about parenting. The abusive subscale needs refinement, and future work should apply confirmatory factor analysis and measurement invariance testing across cultural groups. Yet the core contribution stands: a novel measure that captures culturally situated discipline practices invisible to existing tools like the Alabama Parenting Questionnaire or the Child Abuse Potential Inventory. As parenting practices pass from generation to generation and families cross borders into legal systems with different rules, understanding exactly how culture shapes perceptions of abuse may be the first step toward protecting children without criminalizing the traditions their parents brought with them.

Subject of Research: Development and validation of a scale measuring cultural perceptions of parenting and discipline practices

Article Title: Development and Validation of the Parenting Practices and Discipline Scale in an Ethnically Diverse Sample

Article References: Ortiz Diaz, K., Kenny, M. C., & Baez, H. (2026). Development and Validation of the Parenting Practices and Discipline Scale in an Ethnically Diverse Sample. Journal of Child and Family Studies. https://doi.org/10.1007/s10826-026-03370-6

Image Credits: AI Generated

DOI: 10.1007/s10826-026-03370-6

Keywords: child abuse, parenting practices, discipline, Hispanic families, intersectionality, psychometrics, scale development, cultural perceptions, child welfare, corporal punishment, acculturation, exploratory factor analysis

Metal ions are everywhere in biology and the environment, and telling them apart quickly and cheaply has long been a challenge for chemists. A new open-access review published in Discover Chemistry by M. S. Ajay Kumar, Pradeep Bhaskar, and B. Anindita of Presidency University in Bengaluru takes a fresh look at one of the most versatile tools in the detection toolbox: organic fluorescent probes. Rather than simply cataloguing probes and their detection limits, the review argues that the real key to building better sensors lies in understanding why different metal ions produce fundamentally different fluorescence responses, from brilliant turn-on emission to complete quenching.

The stakes are high. Essential ions such as copper, zinc, and iron participate in enzymatic catalysis, cellular signaling, redox regulation, and gene expression, but when their balance is disrupted they can contribute to oxidative stress, metabolic disorders, and neurodegenerative diseases. Toxic heavy metals such as mercury and lead offer no biological benefit at all and are hazardous even at trace levels because of their persistence, bioaccumulation, and long biological half-lives. Conventional analytical techniques like atomic absorption spectroscopy and inductively coupled plasma mass spectrometry deliver excellent accuracy, but they demand expensive instruments, trained personnel, and complex sample preparation, making them poorly suited for real-time or on-site detection. Fluorescent probes, which convert metal-ligand interactions into measurable optical signals, promise something different: fast, simple, and biologically compatible sensing.

The central insight of the review is that probe performance depends not only on the fluorophore but on the compatibility between the target ion and the sensing mechanism. Paramagnetic ions such as Cu2+ and Fe3+ usually promote fluorescence quenching through non-radiative decay, intersystem crossing, and charge-transfer pathways. Diamagnetic Zn2+, by contrast, more readily supports turn-on emission through suppression of photoinduced electron transfer, known as PET, and chelation-induced rigidification of the molecular framework. Soft heavy metals such as Hg2+ and Pb2+ occupy a middle ground: they bind strongly to carefully selected donor atoms, yet their heavy-atom character can trigger spin-orbit coupling that quenches emission, so designers must balance strong binding against signal reliability.

The authors walk through the major photophysical mechanisms one by one. PET-based probes contain an electron-rich donor unit that quenches the excited fluorophore in the free state; when a metal ion coordinates to the donor, the electron-transfer pathway is blocked and fluorescence returns. This OFF-ON switching works beautifully for closed-shell d10 ions like Zn2+ but often fails for paramagnetic targets, where suppressing PET merely opens the door to stronger quenching routes such as ligand-to-metal charge transfer. Intramolecular charge transfer, or ICT, systems integrate the binding site directly into the conjugated framework, producing wavelength shifts that enable ratiometric sensing, a more reliable readout than simple intensity changes because it reduces dependence on probe concentration and excitation conditions. Twisted intramolecular charge transfer adds a conformational dimension: metal coordination can restrict torsional motion, suppressing non-emissive twisted states and boosting emission.

Chelation-enhanced fluorescence and its counterpart, chelation-enhanced quenching, are presented not as separate mechanisms but as opposite outcomes of the same coordination event. When metal binding locks a flexible ligand into a rigid, planar geometry, non-radiative decay is suppressed and brightness increases; when the bound ion instead introduces intersystem crossing or electron transfer, the same binding event extinguishes the signal. Excited-state intramolecular proton transfer, or ESIPT, offers another elegant route: photoexcitation drives a proton from a donor group to a nearby acceptor, generating a keto tautomer with a much larger Stokes shift. Metal ions can either disrupt the hydrogen bond required for this process or stabilize it, giving designers a tunable switch between enol and keto emission bands.

The review also highlights through-bond energy transfer, an emerging mechanism in which excitation energy moves along a covalently linked donor-acceptor backbone rather than through space as in FRET. Because TBET does not require strict spectral overlap or precise donor-acceptor distances, it can generate large pseudo-Stokes shifts and support ratiometric, multi-channel detection. A representative Hg2+-responsive cassette shows weak emission in the OFF state but strong acceptor fluorescence once metal binding enhances electronic communication between the chromophores. The authors caution, however, that TBET systems demand precise molecular architecture and often struggle with aggregation-induced quenching in water.

Computational chemistry receives a notably critical treatment. Density functional theory and time-dependent DFT are now standard in probe studies, but the authors argue their value is frequently squandered on decorative HOMO-LUMO diagrams. Used properly, ground-state DFT can confirm binding sites, coordination geometry, and structural rearrangements such as rigidification or ring opening, while TD-DFT can assign whether an observed transition is locally excited, charge-transfer, or ligand-to-metal in character. The review stresses that a smaller HOMO-LUMO gap alone proves nothing; orbital localization, charge-transfer direction, and experimental fluorescence output must all be correlated. Method choice matters too: hybrid functionals like B3LYP suit organic fluorophores, while effective core potential basis sets such as LANL2DZ are needed for heavy metals, and long-range corrected functionals like CAM-B3LYP or omega-B97XD better describe charge-transfer states.

Metal-by-metal, the review distills design lessons from dozens of representative probes. For Cu2+, quenching dominates because of its paramagnetic d9 configuration, with peptide-based probes reaching detection limits as low as 1.5 nanomolar, while rhodamine ring-opening and ratiometric platforms offer turn-on and quantitative alternatives. Iron sensing is even harder because Fe3+ is a hard, highly charged, paramagnetic d5 ion that promotes ligand-to-metal charge transfer, so most probes are turn-off or colorimetric. Zn2+ is the friendliest target: ratiometric and turn-on probes routinely achieve low-nanomolar detection in seconds, though discriminating Zn2+ from its fellow d10 ion Cd2+ remains the field’s stubborn challenge. For Hg2+ and Pb2+, the standout performers combine aggregation-induced emission, near-infrared output, and ratiometric readout, with some systems reporting detection limits down to the picomolar range in water, food, and living cells.

The application landscape is shifting rapidly from bench-top demonstrations to real-world deployment. Recent probes have been validated in tap water, groundwater, river water, milk, soil, fruit juice, and plant tissues, with recovery values typically between 90 and 102 percent. Smartphone-assisted detection, 3D-printed sensing devices, and paper test strips are turning molecular recognition into field-ready tools. In bioimaging, ratiometric probes have tracked intracellular Cu2+ in HeLa cells, an AIE probe with a 130-nanometer Stokes shift visualized Hg2+ in A549 cells and in the roots of rice plants, and a peptide-based self-assembling system detected Pb2+ in groundwater and living cells below 10 nanomolar. Nitrogen and sulfur co-doped carbon dots have even combined metal sensing with logic-gate behavior in a single platform.

Significant hurdles remain before fluorescent probes fulfill their promise. Absolute selectivity in complex matrices is still elusive, because borderline and soft ions such as Pb2+, Hg2+, and Cd2+ exhibit overlapping coordination behavior. Quantitative accuracy inside cells is compromised by probe distribution, intracellular heterogeneity, and interference from endogenous biomolecules like glutathione. Many probes lack reversibility, subcellular targeting, or the long-term stability needed for continuous monitoring. The review’s closing message is clear and likely to shape the next generation of research: successful probes must be mechanism-guided rather than structure-driven, matching the electronic personality of each metal ion with the right signal-transduction pathway, and validated not under ideal laboratory conditions but in the messy, competitive environments where metal ions actually matter.

Subject of Research: Organic fluorescent probes for detecting metal ions through mechanism-guided photophysical design and bioimaging

Article Title: Organic fluorescent metal ion probes for understanding design rules photophysical mechanisms and bioimaging applications

Article References: Ajay Kumar, M. S., Bhaskar, P., & Anindita, B. (2026). Organic fluorescent metal ion probes for understanding design rules photophysical mechanisms and bioimaging applications. Discover Chemistry, 3(1), Article 472. https://doi.org/10.1007/s44371-026-00857-5

Image Credits: AI Generated

DOI: 10.1007/s44371-026-00857-5

Keywords: fluorescent probes, metal ion sensing, photoinduced electron transfer, intramolecular charge transfer, ESIPT, chelation-enhanced fluorescence, aggregation-induced emission, DFT calculations, zinc detection, mercury detection, lead detection, bioimaging

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