Emerging Microbes & Infections

MERS-CoV poses a constant pandemic risk, as its viral lineages continue evolving, and zoonotic spillover events could lead to random viral polymorphisms that might lead to human adapted variants. Currently, no small animal model reliably recapitulates both disease progression and transmission dynamics, which are critical aspects for counter-viral measures like vaccine development. Although the Syrian hamster is an optimal animal model for SARS-CoV-2 infection and transmission, it is naturally resistant to MERS-CoV infection. Dipeptidyl peptidase-4 (DPP4) is the functional receptor for MERS-CoV infection, and is highly expressed in human kidney, intestine, liver, and lung tissues. Here, we evaluated the suitability of a human DPP4 (hDPP4) transgenic Syrian hamster model for MERS-CoV research. We used two different MERS-CoV strains (EMC/2012 and D10540/2023) for intranasal inoculation of hamsters. Both strains replicated efficiently, led to comparable severe clinical outcomes, and had similar viral transmission efficiencies. MERS-CoV RNA and nucleoprotein antigen were mainly detected in the brain and the respiratory tract. In summary, we validated a novel hDPP4-transgenic hamster as a suitable model for MERS-CoV infection enabling vaccine and transmission research.

Currently circulating swine influenza viruses (SIVs) mainly include H1N1, H1N2, and H3N2 subtypes. In this study, two G4 genotype Eurasian avian-like (EA) H1N1 SIVs were isolated from 556 samples collected between 2023 and 2026. A systematic analysis was conducted on the two EA H1N1 isolates (FYD30 and YZF69) to assess their pandemic potential. The hemagglutinin (HA) proteins of both H1N1 viruses possessed residues 225E and 228S, indicating enhanced affinity for human-like -2,6-linked sialic acid receptors, which was confirmed by receptor-binding assays. Polymerase activity tests demonstrated that the two SIVs exhibited significantly higher activity in mammalian cells, relative to avian cells, which is consistent with the efficient replication in mammalian cells. Challenge experiments revealed that both H1N1 caused significant pathogenicity in mice and pigs, with YZF69 exhibited higher virulence than FYD30. The higher virulence of YZF69 may be attributed to its molecular features, including the NP Q357K mutation, and an additional glycosylation site in HA. In conclusion, currently circulating EA H1N1 SIVs have acquired key molecular signatures of mammalian adaptation, exhibit enhanced virulence in mammals, and continue to undergo extensive reassortment driven by international swine trade. These findings highlight the potential pandemic risk of SIVs and underscore the urgent need for strengthened surveillance.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a global health concern due to a high fatality rate associated with human infections and no approved vaccines or therapeutics. While Syrian hamsters are a value animal model for coronavirus research, including SARS-CoV-2, MERS-CoV does not infect wild-type hamsters. Here, we generated transgenic Syrian hamsters expressing human dipeptidyl peptidase-4 (hDPP4), the cellular receptor for MERS-CoV., MERS-CoV replicated efficiently in the respiratory tract tissues of hDPP4 hamsters, causing lethal disease. Treatment with the 3CLpro inhibitor nirmatrelvir significantly reduced viral titers in the lower respiratory tract of infected hDPP4 hamsters. While airborne transmission was not observed, direct contact transmission was observed in all contact hDPP4 hamsters cohoused with infected cage mates. Immunization with purified MERS receptor-binding domain protein reduced virus replication and disease severity but did not prevent direct contact transmission. Collectively, our findings demonstrate that hDPP4 transgenic Syrian hamsters are useful for studying MERS-CoV pathogenesis, transmission, and countermeasure efficacy.

The panzootic caused by high pathogenicity avian influenza (HPAI) H5N1 clade 2.3.4.4b has been devastating for animals, globally. Despite global spread, the virus remains absent in Oceania. Herein we report the results of our fourth year of enhanced migratory bird surveillance, coinciding with the spring migration of wild birds in 2025; none of the 847 migratory wild birds or 38 marine mammals were positive for HPAI H5N1, although we did detect LPAI. Surveillance remains a critical tool for HPAI H5N1 response, with early detection and rapid response being critical to mitigate the impacts of this virus on animal, environment and human health.

Eurasian avian like H1N1 (EAavH1N1) and influenza D viruses (IDV) with their ongoing evolution and zoonotic potential are a serious threat to animal and human health. Using experimental infection of pigs, we characterized and compared their pathogenesis, and immune responses. EAavH1N1 induced rapid viral clearance, early immune activation, including robust systemic and mucosal antibody responses and increased IFN{gamma} and TNF production. This heightened immune response was associated with more severe pathology of the upper and lower respiratory tract. In contrast, IDV infection resulted in prolonged viral shedding and higher viral titres, with delayed and attenuated cellular immune responses. Single cell transcriptomic analysis of lung further indicated early and persistent suppression of antiviral and innate immune pathways during IDV infection. These findings demonstrate that EAavH1N1 and IDV exhibit distinct viral kinetics, immune activation profiles, and lung responses, providing insight into differences in transmission dynamics, disease severity, and immune control among influenza virus types in swine.

The emergence of the panzootic clade of highly pathogenic avian influenza H5N1 (2.3.4.4b) in 2020 marked a major expansion in the host range of influenza A viruses (IAVs), raising concerns about further cross-species transmission events and zoonotic spillover. Introduction of 2.3.4.4b viruses into U.S. dairy herds has resulted in widespread circulation, accompanied by reduced milk yield, mastitis, and high viral loads in milk. Notably, virus circulation in dairy cattle represents a novel route for mammalian adaptation and transmission that has already led to more than 40 human cases in the U.S. since 2024. Here, we investigated whether avian clade 2.3.4.4b viruses could infect mammary tissue from Aberdeen Angus, Holstein Friesian, and Limousin cattle, three breeds commonly farmed in Europe, the Americas, and Oceania. Using mammary gland explants, we inoculated tissues with attenuated reassortant viruses expressing the haemagglutinin and neuraminidase glycoproteins of three 2.3.4.4b viruses that predated the emergence of H5N1 in US cattle: A/chicken/England/053052/2021 (AIV07), A/chicken/Scotland/054477/2021 (AIV09), and A/chicken/England/085598/2022 (AIV48). Infected epithelial cells were identified using immunohistochemistry in explants from both the teat and gland cistern for all three breeds following infection with AIV09 and AIV48, indicating that mammary tissue from each of the three tested cattle breeds cattle is permissive to H5N1 infection. Lectin staining showed expression of both 2,3-linked and 2,6-linked sialic acids in the mammary tissue of all donors showing that all three breeds have the potential to support infection with both avian-adapted and mammalian adapted IAVs. Together, these findings demonstrate that mammary glands from both beef and dairy cattle breeds are permissive to infection with avian-adapted and mammalian-adapted H5N1 viruses and highlight the potential for this tissue to act as a mixing vessel for IAV reassortment, underscoring the need to include cattle in ongoing H5N1 surveillance and risk-assessment frameworks. Impact StatementThe emergence of highly pathogenic avian influenza H5N1 in dairy cattle has expanded the recognised host range of influenza A viruses. Further, the ability of the virus to infect the mammary gland and transmit via milk revealed a novel interface for transmission to humans and animals. Although sustained circulation in US dairy herds has been reported, the susceptibility of mammary tissue from other breeds (including beef cattle) commonly used in different countries has been largely unexplored. Here, we show that avian-origin H5N1 viruses can infect tissues derived from the mammary gland of three common cattle breeds (Aberdeen Angus, Holstein Friesian, and Limousin). Virus was detected in epithelial cells from both dairy and beef breeds, indicating that H5N1 can infect multiple breeds. Receptor profiling showed abundant 2,3-linked and 2,6-linked sialic acids, consistent with a tissue environment that may support infection with both avian-adapted and mammalian-adapted viruses. These findings demonstrate that multiple cattle breeds are permissive to H5N1 infection and strengthens the evidence base for including cattle in H5N1 surveillance and risk-assessment frameworks.

SFTSV is an emerging tick-borne pathogen associated with high case fatality rates, particularly in elderly patients. While severe pathogenicity has been reported in aged ferrets, lethal or clinically significant infection in younger animals and genotype-dependent differences in pathogenicity remain insufficiently defined. In this study, we established a ferret infection model using two Korean clinical isolates representing genotypes B and F and systematically compared disease progression between one-year-old and three-year-old ferrets. Three-year-old ferrets exhibited rapid fever onset, marked body weight loss, early clinical deterioration, severe thrombocytopenia and leukopenia, significant elevations in AST and ALT levels, and earlier peak viremia with higher tissue viral loads, indicating impaired early viral control and accelerated systemic dissemination. Notably, one-year-old ferrets also developed measurable pathogenic manifestations, including febrile responses, progressive weight loss, detectable viremia, and multiorgan viral distribution, although disease progression was delayed and less severe compared with older animals. Within the same age group, differences in pathogenicity between genotypes B and F were limited. These findings demonstrate that host age is a major determinant of SFTSV disease severity and support the use of an age-stratified ferret model for preclinical evaluation of vaccines and antiviral therapeutics. ImportanceSFTS is an emerging tick-borne disease that can cause high fever, thrombocytopenia, and multi-organ failure, with particularly severe outcomes in older adults. Currently, no approved vaccines or specific antiviral treatments are available. Reliable animal models that recapitulate human disease are therefore essential for the development of effective countermeasures. Ferrets have recently been proposed as a useful model for SFTS, especially in aged animals, but the susceptibility of younger ferrets and the impact of viral strain differences remain unclear. Here we show that host age strongly determines disease severity in ferrets infected with two genetically distinct SFTS virus strains, establishing a flexible animal model for evaluating vaccines and antiviral therapies.

Climate change and ecosystem collapse promote geographic expansion of vector-borne diseases, as witnessed by the recent incursions into Spain of the virus responsible for Crimean-Congo hemorrhagic fever (CCHFV). CCHFV is maintained in a tick-vertebrate cycle, principally involving ticks of the genus Hyalomma. Faced with the spread of Hyalomma ticks, and therefore the threat of a natural introduction of CCHFV into Western Europe, appropriate surveillance tools and control measures need to be implemented. It is both within and by the tick that CCHFV is maintained and spread in the environment. Despite prolonged portage of the virus, the tick is not overtly affected by CHFV infection. One of the prerequisites in conceiving control strategies is to understand the molecular mechanisms that intimately link the virus to its arthropod host. Despite the central role of the tick in the biology of CCHFV, these mechanisms are ill-defined, owing in part to the constraints associated with handling CCHFV-infected ticks in biosafety level 4 containment. In this study, we established the network of interactions between the S segment of the RNA genome Hazara virus (HAZV), a BSL-2 model of CCHFV, and Hyalomma proteins using ChIRP-MS technique. We identified 166 tick proteins, 21 of which have been described as RNA-binding proteins. Gene ontology and pathway enrichment analyses revealed that the S segment RNA interacts predominantly with mitochondrial proteins that belong to various mitochondrial metabolic pathways.

Influenza viruses present a significant public health risk, causing substantial illness and death in humans each year. Seasonal flu vaccines must be updated regularly, and their effectiveness often decreases due to mismatches with circulating strains. Furthermore, inactivated vaccines do not provide protection against shifted influenza viruses that have the potential to cause a pandemic. The highly pathogenic avian influenza H5N1 clade 2.3.4.4b is prevalent among wild birds worldwide and is causing a multi-state outbreak affecting poultry and dairy cows in the United States (US) since March 2024. In this study, we have generated a NS1 deficient mutant of a low pathogenic version of the cattle-origin human influenza A/Texas/37/2024 H5N1, namely LPhTXdNS1, and validated its safety, immunogenicity, and protection efficacy in a prime vaccination regimen against wild-type (WT) A/Texas/37/2024 H5N1. The attenuation of LPhTXdNS1 in vitro was confirmed by its reduced replication in cultured cells and inability to control IFN{beta} promoter activation. In C57BL/6J mice, LPhTXdNS1 has reduced viral replication and pathogenicity compared to WT A/Texas/37/2024 H5N1. Notably, LPhTXdNS1 vaccinated mice exhibited high immunogenicity that reach its peak at weeks 3 and 4 post-immunization, leading to robust protection against subsequent lethal challenge with WT A/Texas/37/2024 H5N1. Altogether, we demonstrate that a single dose vaccination with LPhTXdNS1 is safe and able to induce protective immune responses against H5N1. Both safety profile and protection immunity suggest that LPhTXdNS1 holds promise as a potential solution to address the urgent need for an effective vaccine in the event of a pandemic for the treatment of infected animals and humans.

Sarbecoviruses, including SARS-CoV and SARS-CoV-2, are frequently linked to Rhinolophus bats as their putative natural reservoirs. Angiotensin-converting enzyme 2 (ACE2), a host carboxypeptidase widely expressed in mammalian tissues, plays a critical role in sarbecovirus infection by serving as the cellular receptor for the viral spike (S) protein. Given recent human outbreaks and pandemics caused by members of sarbecoviruses, and the wide distribution of Rhinolophus bats, it is essential to maintain surveillance of these viruses while improving our understanding of their interactions with bat hosts, particularly the ACE2 receptor. However, while Rhinolophus bats from Asia have been relatively well studied, African Rhinolophus bats remain underrepresented and require further investigation. In this study, five Rhinolophus bat lung samples were obtained from Zambia, and ACE2 genes from these individuals were cloned and sequenced. We further evaluated the susceptibility of ACE2 variants to a panel of sarbecoviruses, revealing key residues that influence viral infectivity. ACE2 polymorphism was observed among Rhinolophus simulator individuals, revealing multiple ACE2 genotypes within the sampled population. However, R. simulator ACE2s did not permit infection by the clade 3 Afro-Eurasian sarbecoviruses tested in this study. Notably, RhGB01 and BM48-31 virus utilized only Rhinolophus blasii ACE2. Mutational analyses further suggested that ACE2 residues 31 and 41 play important roles in modulating spike-ACE2 interactions. This study reports 4 unique ACE2 sequences of R. simulator and R. blasii, and provides new insights into the molecular interactions between African Rhinolophus species ACE2s and the S protein of sarbecoviruses circulating in Africa and Europe. ImportanceAs putative natural reservoirs of sarbecoviruses, including SARS-CoV and SARS-CoV-2, Rhinolophus bats play a critical role in the emergence of zoonotic coronaviruses, making it essential to understand their interactions with these viruses for future pandemic preparedness. While Asian Rhinolophus bats have been relatively well studied, African species remain underrepresented, highlighting the need for further investigation. In this study, we cloned and sequenced ACE2 genes of five Rhinolophus bats collected in Zambia, Africa. We identified ACE2 polymorphism among Rhinolophus simulator individuals, although this variation was not associated with susceptibility to the clade 3 Afro-Eurasian sarbecoviruses examined. In addition, we identified key ACE2 residues that govern SARS-CoV-2 spike-ACE2 interactions and contribute to distinct infectivity patterns across species. These findings expand our understanding of the molecular determinants of sarbecovirus host range and support improved surveillance and risk assessment of emerging coronaviruses.

Orthohantaviruses cause severe human diseases including hemorrhagic fever with renal syndrome (HFRS) and hantavirus cardiopulmonary syndrome (HCPS), with case fatality rates up to 40%. No FDA-approved therapeutics are currently available, highlighting urgent need for drug development following recent outbreak events. We systematically examined host protease dependencies in hantavirus replication, focusing on Signal Peptidase (SP) and Signal Peptide Peptidase (SPP) essential for viral glycoprotein maturation. Through comprehensive database mining and molecular docking analysis, we identified six potential protease inhibitors, with Compound E achieving the highest binding confidence score (-0.28) against SPP. Our analysis reveals that targeting host ER proteases represents a viable antiviral strategy, providing a systematic framework for protease-targeted antihantavirus drug development and identifying specific lead compounds for experimental validation.

The A(H1N1)pdm09 virus remains a major global health threat. This study examined the burden of ICU admission, mortality, and associated predictors among patients with A(H1N1)pdm09 pneumonia in a leading center for infectious diseases in Vietnam. Information on demographic, clinical, and laboratory characteristics, and outcomes was retrieved from medical records of adults admitted with influenza A(H1N1)pdm09 during 2009-2019. Among 729 cases, 21.7% (158/729) developed pneumonia. Among 158 pneumonia cases, 36.7% (58/158) developed moderate-to-severe acute respiratory distress syndrome (ARDS), and 15.2% (24/158) received invasive ventilation. ICU admission and mortality rates were 48.7% (77/158, 95%CI 41.1-56.5%) and 8.2% (13/158, 95%CI 4.9-13.6%), respectively. Predictors of ICU admission included being >60 years old (adjusted OR [AOR] 13.864, 95%CI 2.185-87.956, P=0.005), comorbidities (AOR 6.527, 95%CI 1.710-24.915, P=0.006), AST (AOR 1.013, 95%CI 1.001-1.025, P=0.029), and moderate-to-severe ARDS (AOR 14.027, 95%CI 4.220-46.627, P<0.001). Predictors of mortality were invasive ventilation (AOR 55.355, 95%CI 1.486-2062.375, P=0.030) and double-dose oseltamivir or combination therapy (AOR 32.625, 95%CI 1.594-667.661, P=0.024). In conclusion, mortality is not rare in A(H1N1)pdm09 infection. Monitoring of older patients and those with comorbidities, liver enzyme elevation, or moderate-to-severe ARDS is essential for the timely detection of complications requiring intensive care.

Influenza A virus (IAV) circulates widely in European pig populations and continues to diversify through frequent introductions from humans, followed by reassortment within swine. Spain represents a particularly dynamic ecological setting due to the coexistence of intensive whitepig production, extensive Iberianpig systems, and abundant wild boar populations. This study provides an integrated analysis of IAV evolution and genomic diversity in swine in Spain between 2019 and 2022, expanding on previous surveillance from 2016 to 2019. Sampling across 24 provinces yielded 66 new wholegenome sequences from Iberian and white pigs. We identified 18 genotypes, including 11 novel reassortants not detected in our previous survey. Several genotypes, such as H1huN2 G21 and G22, H3N2 G23, and the unusual H3N1 G12, were exclusive to the country. Some genotypes were detected across white pigs, Iberian pigs, and wild boar in Toledo and Badajoz, suggesting viral flow among swine populations. Phylogenetic analyses revealed ongoing introductions of H1N1pdm09 from humans into pigs, generating at least five reassortant genotypes (G10, G16-G19). These lineages incorporated pandemic internal cassettes and, in some cases, humanseasonal N2 segments, highlighting the continued role of humans as a source of viral incursions. Conversely, four zoonotic infections (H1N1v) detected in Spain between 2022 and 2026 were linked to genotypes circulating in white pigs, underscoring the bidirectional nature of IAV transmission at the human swine interface. Overall, this study demonstrates that Spain provides ecological conditions conducive to IAV diversification, reassortment, and zoonotic risk. The findings reinforce the need for sustained One Health surveillance. HighlightsO_LINovel swine influenza virus (SIV) genotypes exclusive to Spain C_LIO_LIPhylogenetic analysis of genomic segments of zoonotic variants of swine origin detected in Spain since 2022 C_LIO_LIShared circulation of influenza A compatible with interbreed transmission among domestic pigs and wild boar C_LI

African swine fever virus (ASFV) causes a lethal haemorrhagic fever in pigs and spread of this disease threatens many pig species (Suidae) globally. By contrast, ASFV infections in the natural evolved hosts, the warthog and bushpig, are subclinical. The macrophage (M{varphi}) is the primary target of ASFV and species-dependent responses in M{varphi}s are presumed to influence disease susceptibility. In an attempt to model these differences in vitro, we generated transgene-regulated induced pluripotent stem cells (iPSCs) from domestic pig, wild boar, red river hog and warthog, and confirmed that their corresponding iPSC-derived M{varphi}s (iPSCdMs) supported infection and replication of ASFV. In contrast to the other species, however, warthog iPSCdMs did not induce interferon upon infection by either virulent or attenuated ASFV. iPSCdMs may therefore represent an experimental system to understand how ASFV infection of M{varphi}s contributes to disease and aid development of strategies to combat this economically and environmentally devastating pathogen.

ABSTRACPorcine respiratory diseases caused by extraintestinal pathogenic Escherichia coli (ExPEC) pose a severe threat to swine production and public health; however, research on respiratory tract-isolated ExPEC remains limited. This study comprehensively analyzed the genomic characteristics and antibiotic resistance gene (ARG) transfer potential of 441 ExPEC strains isolated from porcine lungs across 21 Chinese provinces (including 53 newly isolated strains from 2022-2024 and 388 NCBI-deposited strains). Phylogenetic analysis revealed that 84% of the isolates belonged to phylogroups A, B1, and C, with ST410, ST101, and ST88 as the predominant STs. The strains exhibited extensive ARG diversity, harboring 111 distinct ARG subtypes, with sul2 (81.4%), floR (73.5%), and tet (A) (68.0%) being the most prevalent. Importantly, critical "last-resort" antibiotic resistance genes (e.g., blaNDM-1/5, the mcr family, and tet (X4)) were also detected. Notably, 77.2% of the ARGs presented horizontal transfer potential, with plasmids (especially IncF family replicons) serving as core vectors, followed by integrons and transposons. Cooccurrence network analysis identified aph (3)-Ib, aph (6)-Id, sul2, and floR as core subnetworks driving multidrug resistance dissemination. Pangenomic analysis confirmed an open genome architecture, with core genes accounting for only 6%, reflecting the strains capacity to acquire exogenous genetic material via horizontal transfer. From the One Health perspective, these transferable ARGs can spread to the environment and humans through fecal discharge and the food chain. These findings underscore the importance of monitoring and controlling ExPEC infections in swine, as such strains can as reservoirs of ARGs, pose potential risks to human health, and may even act as sources of pathogenic agents responsible for human infections. IMPORTANCEPorcine respiratory ExPEC-induced diseases threaten swine production and public health, yet respiratory tract-isolated ExPEC research remains scarce. This study comprehensively analyzed 441 porcine lung ExPEC strains across 21 Chinese provinces, uncovering their dominant phylogroups, high ARG diversity (111 subtypes) and the presence of "last-resort" antibiotic resistance genes. We identified 77.2% of ARGs with horizontal transfer potential, plasmids (especially IncF family) as core vectors, and a core ARG subnetwork driving multidrug resistance. The open pangenome (6% core genes) highlights ExPECs strong capacity to acquire exogenous genes. These findings fill the research gap of respiratory ExPEC, clarify ARG transmission mechanisms in swine ExPEC, and provide critical genomic data for One Health-based AMR surveillance and control, guiding targeted strategies to mitigate ARG spread from swine to humans and the environment.

Horseshoe bats are known as the natural reservoir of sarbecoviruses. To understand how horseshoe bats coexist with sarbecoviruses in nature, experimental infection can provide direct evidence. However, in vivo infection studies using horseshoe bats have been lacking because of the difficulty of maintaining insectivorous bats in a laboratory setting. Here, we established a stable husbandry system for greater horseshoe bats (Rhinolophus ferrumequinum) and performed experimental infection with SARS-CoV-2. In contrast to Syrian hamsters which showed substantial viral replication, infected horseshoe bats exhibited low-level but persistent viral replication in the lung without overt disease. Histological analyses revealed that inflammatory lesions in the bat lungs were spatially restricted and temporally delayed compared with those in hamsters. Transcriptomic analyses further showed preferential activation of tissue repair pathways but limited inflammatory responses following infection. Notably, bats expressed several interferon-stimulated genes prior to infection. Our results suggest that a host strategy combining constitutive antiviral state, limited inflammation and enhanced tissue repair may result in controlled viral replication without overt disease, likely enabling horseshoe bats to coexist with sarbecoviruses.

Foot-and-mouth disease (FMD) virus is one of the most feared and most consequential pathogens of livestock worldwide. It can be spread rapidly by the transboundary movement of animals, animal products and byproducts. In January 2025, Germany detected its first FMD outbreak since 1988 in extensively reared water buffalo on a small farm in the state of Brandenburg, directly outside Berlin, the federal capital. Immediate control measures including a standstill for movements of susceptible animals and pre-emptive culling were implemented by the veterinary authorities. Whole-genome sequencing identified the virus as serotype O, topotype ME-SA, lineage SA-2018 and revealed extensive recombination, but cross-neutralization assays suggested good heterologous protection by an O/PanAsia-2 vaccine strain. Epidemiological back-calculation placed the time of virus introduction in late December 2024. Although the entry route remains unresolved, human-associated introduction is most likely. Network analysis revealed minimal farm connectivity, and simulations predicted low potential for onward transmission, which is consistent with the outbreak being ultimately restricted to a single herd. This event underscores the constant and unpredictable risk of introduction of the virus. Early detection through increased awareness and comprehensive differential diagnostics as well as the international collaboration of veterinary services, laboratories and experts are essential in the face of the global presence of FMD.

West Nile virus (WNV) and Usutu virus (USUV) are neurotropic Orthoflaviviruses sharing a similar enzootic transmission cycle primarily involving Culex pipiens mosquitoes as vectors and birds as amplifying hosts. First identified in Africa, both viruses established endemicity across Europe over the past two decades, most likely introduced and spread by migratory bird species along Mediterranean flyways. In avian species, infection outcomes range from subclinical to fatal neuroinvasive disease, varying by viral strain, host immunity, and species susceptibility. Southern France emerges as a key hotspot for the circulation of these viruses, supported by diverse avian habitats conducive to year-round viral maintenance. This study investigated the prevalence of WNV and USUV in more than 2500 sedentary and migratory wild birds from these regions during 2024-2025 using molecular surveillance. Samples were collected using mist net and bird boxes, across multiple passerine and non-passerine taxa, spanning wetlands, urban fringes, and agricultural zones. Our analyses revealed widespread viral circulation across diverse species, mainly among passerines such as great tits, house sparrows, and barn swallows with USUV detected at higher rates than WNV in both study years. Overall prevalence was markedly higher in 2024 than in 2025, potentially reflecting climatic or ecological drivers. Migratory individuals likely seed viral introductions during seasonal passages, whereas resident populations sustain local enzootic cycles, facilitating overwintering persistence. These results highlight the pivotal role of mixed avifauna in arbovirus dynamics within Mediterranean Europe and emphasize the necessity for integrated, year-round surveillance targeting high-risk species and habitats. Enhanced monitoring will aid in predicting spillover risks and informing vector control strategies to mitigate zoonotic threats.

Hantavirids, specifically the members within the genus Orthohantavirus, represent a significant global public health threat, with bat-associated lineages challenging traditional reservoir paradigms. To investigate the genetic diversity of hantavirids in Southeast Asia, we conducted an expanded surveillance program in Lao PDR from May 2023 to October 2025 in bat populations and wild animals from local wet markets. Using molecular screening and deep sequencing to characterize hantavirids from bat populations and wild animals from local wet markets, we identified 20 positive samples across four bat species, recovering coding-complete genomes for multiple novel variants. Phylogenetic analysis confirmed that these viruses form a monophyletic group within Mobatvirus, resolving into two major subclades. The first subclade clustered with Quezon and Robina viruses found in fruit-eating bats. The second subclade further split into two lineages corresponding to Thakrong and Xuan Son viruses, which are associated with trident and leaf-nosed bats, respectively. Despite the strong host specificity observed, the detection of these viruses in a wet market, a critical interface for human-wildlife contact, indicates a potential zoonotic risk. These findings significantly expand the known diversity of mobatviruses in Laos and highlight the urgent need for serological surveillance in at-risk human populations to assess the potential for spillover.

Plasmodium vivax is the second most prevalent Plasmodium species, with 2.5 billion people at risk of infection worldwide and around 10 million cases of clinical vivax malaria every year. Despite the clinical importance of this pathogen, very little is known about the P. vivax proteins recognized by the host immune system, which hinders our ability to select vaccine candidates or develop efficient serological markers. To comprehensively characterize immunogenic P. vivax proteins, we designed a high-density peptide array containing 4.2 million peptides covering the entire protein sequence of all P. vivax genes and analyzed antibody responses of infected and malaria-naive individuals. We identified a total of 283 proteins that are commonly immunogenic in symptomatic individuals. These proteins included most proteins known to be involved in erythrocyte invasion, a putative new invasion protein, several nucleoporins, and many uncharacterized proteins that should be further investigated for their roles during blood-stage infections. These analyses also revealed a unique pattern of antibody response against PIR proteins in asymptomatic individuals, that could be associated with protection against clinical vivax malaria. Overall, these data provide an agnostic and comprehensive perspective on immunogenic P. vivax proteins and constitute an important resource for the malaria community to develop new tools for better detecting and eliminating this important human pathogen.