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Highly pathogenic avian influenza (HPAI) viruses cause high mortality rates in wild birds and farmed poultry, and their potential for adaptation to humans remains a major pandemic threat (2). In [...]

Current poultry vaccines against influenza A viruses target the globular head region of the hemagglutinin (HA1), providing limited protection against antigenically divergent strains. Experimental subunit vaccines based on the conserved ectodomain of the matrix protein 2 (M2e) induce cross-reactive antibody responses, but fail to fully prevent virus shedding after low pathogenic avian influenza (LPAI) virus challenge, and are ineffective against highly pathogenic avian influenza (HPAI) viruses. This study assessed the benefits of combining nanoparticles bearing three tandem M2e repeats (NR-3M2e nanorings or NF-3M2e nanofilaments) with an HA1 subunit vaccine in protecting chickens against a heterologous HPAI H5N1 virus challenge. Chickens vaccinated with the combined formulations developed M2e and HA1-specific antibodies, were fully protected from clinical disease and mortality, and showed no histopathological lesions or virus shedding, unlike those given only HA1, NR-3M2e, or NF-3M2e. Thus, the combined vaccine formulations provided complete cross-protection against HPAI H5N1 virus, and prevented environmental virus shedding, crucial for controlling avian influenza outbreaks. [ABSTRACT FROM AUTHOR]

Background: On March 16th 2024, the first case of Human infection with avian influenza H10N3 since the end of the global COVID-19 Pandemic was reported in Kunming, China. To enhance comprehension of the source of infection and risk factors of the H10N3 virus infection, this case report summarizes the clinical features, epidemiological investigation, and laboratory test results. Provides recommendations for the prevention and control of Human infection with avian influenza H10N3. Case presentation: A 51-year-old male with a history of COVID-19 infection and a smoking habit of 30 years, worked in livestock breeding and was exposed to sick and dead poultry before falling ill with fever and chills on 28th February 2024. A week later, he was diagnosed with severe pneumonia, influenza, and respiratory failure by the Third People's Hospital of Kunming(KM-TPH). He was discharged on 17th April and none of his 6 close contacts showed any symptoms of illness. Environmental samples taken from the epidemic spot revealed that peacock feces tested positive for avian influenza sub-type H9 and waterfowl specimens showed positive results for avian influenza sub-type H5. Gene sequencing conducted on positive specimens from the patient's respiratory tract by the Chinese Centre for Disease Control and Prevention (CCDC) showed a high degree of similarity (98.6–99.5%) with the strain responsible for the second global case of human infected with H10N3 (reported from Zhejiang, China 2022). Conclusions: According to the available epidemiological information, there is limited evidence to suggest that H10N3 viruses are excessively lethal. However, adaptive site mutations have been observed in the H10N3 isoform of mammals. While it is unlikely that the H10N3 virus will spread among humans, the possibility of additional cases cannot be entirely ruled out. Symptoms of human infection with H10N3 avian influenza are similar to those of common respiratory infections, which may result in them being overlooked during initial clinical consultations. Therefore, it is essential to improve surveillance of the H10 sub-type of avian influenza and to increase the awareness of hospital-related workers of cases of pneumonia of unknown origin. [ABSTRACT FROM AUTHOR]

Until recent events, the Antarctic was the only major geographical region in which high pathogenicity avian influenza virus (HPAIV) had never previously been detected. Here we report on the detection of clade 2.3.4.4b H5N1 HPAIV in the Antarctic and sub-Antarctic regions of South Georgia and the Falkland Islands, respectively. We initially detected H5N1 HPAIV in samples collected from brown skuas at Bird Island, South Georgia on 8th October 2023. Since this detection, mortalities were observed in several avian and mammalian species at multiple sites across South Georgia. Subsequent testing confirmed H5N1 HPAIV across several sampling locations in multiple avian species and two seal species. Simultaneously, we also confirmed H5N1 HPAIV in southern fulmar and black-browed albatross in the Falkland Islands. Genetic assessment of the virus indicates spread from South America, likely through movement of migratory birds. Critically, genetic assessment of sequences from mammalian species demonstrates no increased risk to human populations above that observed in other instances of mammalian infections globally. Here we describe the detection, species impact and genetic composition of the virus and propose both introductory routes and potential long-term impact on avian and mammalian species across the Antarctic region. We also speculate on the threat to specific populations following recent reports in the area. High pathogenicity avian influenza virus has a wide host range and has been detected across a large geographic area. Here, the authors present evidence of spread to the Antarctic and sub-Antarctic regions, with signs of clinical infection and positive virus detection in birds and elephant seals. [ABSTRACT FROM AUTHOR]

The Gyrfalcon (Falco rusticolus) is a top avian predator, an Arctic specialist, and among the bird species most vulnerable to climate change. This vulnerability is driven by their narrow ecological niche, limited or lack of southward migration, and circumpolar distribution where the most rapid climatic changes are occurring. Climatic and habitat changes may alter Gyrfalcon disease ecology due to changes in vector distributions, host ranges, and pathogen life cycles. Warmer Arctic temperatures and accompanying landscape changes may also alter the Gyrfalcon's prey base, and dietary habits can influence transmission of pathogens. To better understand disease ecology in Gyrfalcons, we compared pathogen prevalence across varying time periods at three study sites in Alaska—the Seward Peninsula (2014–2022), the Alaska Peninsula (2021–2022), and the Yukon–Kuskokwim Delta (2008–2013). We collected Gyrfalcon whole blood, thin blood films, cloacal swabs, and fecal samples for serology, haemoparasite assays, microbiological cultures, and fecal tests for parasites. An aliquot of whole blood preserved on filter paper or in Longmire solution was kept for molecular diagnosis of haemoparasites. Serology revealed high exposure to Salmonella (77%), low seroprevalence of avian influenza antibodies (1.5%), exposure to falcon adenovirus type 1 in hatch-year Gyrfalcons (1.3%), and the first report of a Leucocytozoon spp. blood parasite in a Gyrfalcon. We found no antibodies indicative of prior exposure to avian paramyxovirus, West Nile virus, or Chlamydia. One nestling and one hatch-year bird sampled (2 of 12) on the Seward Peninsula exhibited oral plaques from capillarids (Eucoelus spp.) in contrast to those trapped in the Izembek National Wildlife Refuge on the Alaska Peninsula (0 of 6). [ABSTRACT FROM AUTHOR]

We isolated highly pathogenic avian influenza (HPAI) H5N5 and H5N1 viruses from crows in Hokkaido, Japan, during winter 2023–24. They shared genetic similarity with HPAI H5N5 viruses from northern Europe but differed from those in Asia. Continuous monitoring and rapid information sharing between countries are needed to prevent HPAI virus transmission. [ABSTRACT FROM AUTHOR]

Antarctica, the only continent without permanent human settlements, holds important messages for humanity. Recent studies of carbon dioxide concentrations in Antarctic ice cores reveal the impact of European colonization on the Western Hemisphere, leading to the abandonment of agricultural land and the regrowth of natural vegetation. The breaking off of iceberg A23a highlights the threat of melting ice shelves and the subsequent rise in global sea levels. Record-low levels of sea ice in Antarctica suggest a new state influenced by climate change. The International Association of Antarctic Tourism Operators (IAATO) plays a crucial role in preserving Antarctica's unique species and ecosystem. However, Antarctic tourism has environmental costs that need to be considered. Bird flu has reached Antarctica through migrating seabirds, posing a risk to penguins and marine mammals. Overfishing of krill, the base of the Antarctic food chain, could lead to an ecological catastrophe. Melting ice in Antarctica and Greenland has even affected the Earth's rotation. [Extracted from the article]

Since 2014, highly pathogenic avian influenza (HPAI) H5 viruses of clade 2.3.4.4 have been dominating the outbreaks across Europe, causing massive deaths among poultry and wild birds. However, the factors shaping these broad‐scale outbreak patterns, especially those related to waterbird community composition, remain unclear. In particular, we do not know whether these risk factors differ from those of other H5 clades. Addressing this knowledge gap is important for predicting and preventing future HPAI outbreaks. Using extensive waterbird survey datasets from about 6883 sites, we here explored the effect of waterbird community composition on HPAI H5Nx (clade 2.3.4.4) spatial patterns in the 2016/2017 and 2020/2021 epidemics in Europe, and compared it with the 2005/2006 HPAI H5N1 (clade 2.2) epidemic. We showed that HPAI H5 occurrences in wild birds in the three epidemics were strongly associated with very similar waterbird community attributes, which suggested that, in nature, similar interspecific transmission processes operate between the HPAI H5 subtypes or clades. Importantly, community phylogenetic diversity consistently showed a negative association with H5 occurrence in all three epidemics, suggesting a dilution effect of phylogenetic diversity. In contrast, waterbird community variables showed much weaker associations with HPAI H5Nx occurrence in poultry. Our results demonstrate that models based on previous epidemics can predict future HPAI H5 patterns in wild birds, implying that it is important to include waterbird community factors in future HPAI studies to predict outbreaks and improve surveillance activities. [ABSTRACT FROM AUTHOR]

This article was published open access under a CC BY-NC-ND licence: https://creativecommons.org/licenses/by-nc-nd/4.0/. [ABSTRACT FROM AUTHOR]

Background: The COVID-19 pandemic highlighted the need for timely, evidence-based rapid risk assessments (RRA) of infectious disease events to inform public health action during rapidly evolving situations with high uncertainty. In 2022, the Public Health Agency of Canada established a coordinated approach to public health risk assessment, including a methodology for qualitative RRA of infectious disease threats. Objective: To describe the RRA methodology and illustrate its use with examples from different infectious hazards of public health concern. Methods: The RRA methodology employs the risk pathway to describe the sequence of events leading from a hazard's source to the adverse event of concern and subsequent impacts; define specific questions to be addressed; and identify relevant knowledge gaps, limitations and recommendations. Qualitative likelihood and impact estimates are derived through integration of evidence review and expert opinion and are communicated together with corresponding levels of uncertainty. The impacts of the event are based on an assessment of the most likely spread scenario within Canada, considering individual-level impact on affected individuals, the impact on the general population and, if relevant, sub-groups at higher risk. Results: This RRA approach aligns with well-established international methods and provides flexibility to accommodate a broad range of risk questions. It has been implemented to estimate the risk of various threats of concern to Canada, including mpox, avian influenza A(H5N1) and measles. Conclusion: Given the broad range and complexity of public health hazards, RRAs provide a timely, coordinated and systematic process for characterizing and communicating the risk to inform risk mitigation and decision-making and to guide appropriate public health response. [ABSTRACT FROM AUTHOR]

This study examined the impact of the mad cow (BSE) and bird flu (HPAI) outbreaks on the demand for beef, pork, and broiler meat in the United States from 1997 to 2022. Using time‐varying elasticities obtained from the Rotterdam model extended to include animal disease outbreaks, we found that the BSE outbreaks significantly reduced beef consumption. These reactions were indeed time‐varying, ranging from 1.312% in 2003 to 1.212% in 2005. HPAI outbreaks had a delayed reaction, with a rebound in broiler meat consumption in the quarter following the start of the outbreak. In general, the magnitude of these reactions was proportional to the severity of an outbreak. [ABSTRACT FROM AUTHOR]

Persons who work in close contact with dairy cattle and poultry that are infected with highly pathogenic avian influenza (HPAI) A(H5N1) virus are at increased risk for infection. In July 2024, the Colorado Department of Public Health & Environment responded to two poultry facilities with HPAI A(H5N1) virus detections in poultry. Across the two facilities, 663 workers assisting with poultry depopulation (i.e., euthanasia) received screening for illness; 109 (16.4%) reported symptoms and consented to testing. Among those who received testing, nine (8.3%) received a positive influenza A(H5) virus test result, and 19 (17.4%) received a positive SARS-CoV-2 test result. All nine workers who received positive influenza A(H5) test results had conjunctivitis, experienced mild illness, and received oseltamivir. This poultry exposure–associated cluster of human cases of influenza A(H5) is the first reported in the United States. The identification of these cases highlights the ongoing risk to persons who work in close contact with infected animals. Early response to each facility using multidisciplinary, multilingual teams facilitated case-finding, worker screening, and treatment. As the prevalence of HPAI A(H5N1) virus clade 2.3.4.4b genotype B3.13 increases, U.S. public health agencies should prepare to rapidly investigate and respond to illness in agricultural workers, including workers with limited access to health care. [ABSTRACT FROM AUTHOR]

The global spread of H5 clade 2.3.4.4 highly pathogenic avian influenza (HPAI) viruses threatens poultry and public health. The continuous circulation of these viruses has led to their considerable genetic and antigenic evolution, resulting in the formation of eight subclades (2.3.4.4a–h). Here, we examined the antigenic sites that determine the antigenic differences between two H5 vaccine strains, H5-Re8 (clade 2.3.4.4g) and H5-Re11 (clade 2.3.4.4h). Epitope mapping data revealed that all eight identified antigenic sites were located within two classical antigenic regions, with five sites in region A (positions 115, 120, 124, 126, and 140) and three in region B (positions 151, 156, and 185). Through antigenic cartography analysis of mutants with varying numbers of substitutions, we confirmed that a combination of mutations in these eight sites reverses the antigenicity of H5-Re11 to that of H5-Re8, and vice versa. More importantly, our analyses identified H5-Re11_Q115L/R120S/A156T (H5-Re11 + 3) as a promising candidate for a broad-spectrum vaccine, positioned centrally in the antigenic map, and offering potential universal protection against all variants within the clade 2.3.4.4. H5-Re11 + 3 serum has better cross-reactivity than sera generated with other 2.3.4.4 vaccines, and H5-Re11 + 3 vaccine provided 100% protection of chickens against antigenically drifted H5 viruses from various 2.3.4.4 antigenic groups. Our findings suggest that antigenic regions A and B are immunodominant in H5 viruses, and that antigenic cartography-guided vaccine design is a promising strategy for selecting a broad-spectrum vaccine. [ABSTRACT FROM AUTHOR]

The hemagglutination inhibition (HI) assay is a traditional laboratory procedure for detection and quantitation of serum antibodies of hemagglutinating viruses containing the hemagglutinin (HA) gene. The current study aimed to investigate the novel use of virus like particles (VLP) as an antigen for the HI assay. VLPs were prepared from a strain of H5N1 using a baculovirus expression system. The VLPs were characterized using the hemagglutination test, Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting, and transmission electron microscopy. The comparative HI assay was performed using three different seed antigens: A/chicken/Mexico/232/94 (H5N2), A/chicken/Egypt/18-H/09(H5N1) and A/goose/Guangdong/1/1996(H5N1). The HI assay of serum antibody titrations using homologous antigens to these vaccinal seeds were compared to the VLP's antigens for the same serum. The HI titers were logically relevant to the similarity between VLP antigens and vaccinal seeds, indicating the VLPs behave similarly to the standard HI assay which uses inactivated whole virus as an antigen. VLPs could be considered as an alternative to the HI assay antigen as they show a relatedness between the similarity with vaccinal seed and serum antibodies. Compared to typical entire H5N1 viral antigen prepared in SPF eggs that require proper inactivation to avoid any public health risk, VLPs prepared in tissue culture, plants or insect cells are a safe, inexpensive and scalable alternative to inactivated whole virus antigen. [ABSTRACT FROM AUTHOR]

In 2004, the equine-origin H3N8 canine influenza virus (CIV) first caused an outbreak with lethal cases in racing greyhounds in Florida, USA, and then spread to domestic dogs nationwide. Although transmission of this canine virus to humans has not been reported, it is important to evaluate its zoonotic potential because of the high contact opportunities between companion dogs and humans. To gain insight into the interspecies transmissibility of H3N8 CIV, we tested its adaptability to human respiratory A549 cells through successive passages. We found that CIV acquired high growth properties in these cells mainly through mutations in surface glycoproteins, such as hemagglutinin (HA) and neuraminidase (NA). Our reverse genetics approach revealed that HA2-K82E, HA2-R163K, and NA-S18L mutations were responsible for the increased growth of CIV in human cells. Molecular analyses revealed that both HA2 mutations altered the optimum pH for HA membrane fusion activity and that the NA mutation changed the HA-NA functional balance. These findings suggest that H3N8 CIV could evolve into a human pathogen with pandemic potential through a small number of mutations, thereby posing a threat to public health in the future. [ABSTRACT FROM AUTHOR]

Introduction: The bar-headed goose (Anser indicus), one of the most well-known high-altitude birds, is renowned for its adaptation to high-altitude environments. Previous studies have shown that they can be infected with highly pathogenic avian influenza; however, there is currently limited research on other viruses in bar-headed geese. Methods: In this study, 10 fecal samples of healthy bar-headed geese were collected, and viral metagenomics method was conducted to identify novel picornaviruses. Results: Seven novel picornaviruses were identified in the fecal samples of bar-headed geese. Most of these picornaviruses were genetically different from other currently known viruses in the NCBI dataset. Among them, PICV4 was determined to be a new species belonging to the Anativirus genus, PICV5 and PICV13 were classified as novel species belonging to the Hepatovirus genus, and the remaining four picornaviruses (PICV1, PICV19, PICV21, and PICV22) were identified as part of the Megrivirus A species of the Megrivirus genus. Recombinant analysis indicates that PICV21 was a potential recombinant, and the major and minor parents were PICV1 and PICV22, respectively. Conclusion: The findings of this study increase our understanding of the diversity of picornaviruses in bar-headed geese and provide practical viral genome information for the prevention and treatment of potential viral diseases affecting this species. [ABSTRACT FROM AUTHOR]

This study reports on the immunogenicity and biodistribution of H5 hemagglutinin (HA)-based self-amplifying (sa) mRNA vaccines in mice. Four sa-mRNA vaccines encoding either a secreted full-length HA, a secreted HA head domain, a secreted HA stalk domain, or a full-length membrane-anchored HA were investigated. All vaccines elicited an adaptive immune response. However, the full-length HA sa-RNA vaccines demonstrated superior performance compared to head and stalk domain vaccines. The antibody titers positively correlated with the vaccine dose. Cellular immune responses and antigen-specific IgA antibodies in the lungs were also observed. The comparison of the sa-mRNA vaccines encoding the secreted and membrane-anchored full-length HA revealed that anchoring of the HA to the membrane significantly enhanced the antibody and cellular responses. In addition to the injection site, the intramuscularly injected sa-mRNA-LNPs were also detected in the draining lymph nodes, spleen, and to a lesser extent, in the lung, kidney, liver, and heart. [ABSTRACT FROM AUTHOR]

Avian influenza poses a severe threat to poultry production and global food security, prompting the development of vaccination programs in numerous countries. Modified live virus (MLV) vaccines, with their potential for mass application, offer a distinct advantage over existing options. However, concerns surrounding reversion, recombination, and unintended transmission have hindered the progress of MLV development for avian influenza in poultry. To address these concerns, we engineered reassortment-impaired, non-transmissible, safe, immunogenic, and protective MLVs through the rearrangement of internal gene segments and additional modifications to the surface gene segments HA and NA. The unique peptide marker aspartic acid-arginine-proline-alanine-valine-isoleucine-alanine-asparragine (DRPAVIAN) was incorporated into HA, while NA was modified to encode the chicken interleukin-18 (ckIL18) gene (MLV-H9N2-IL). In vitro, the MLV-H9N2 and MLV-H9N2-IL candidates demonstrated stability and virus titers comparable to the wild-type H9N2 strain. In chickens, the MLV-H9N2 and MLV-H9N2-IL candidates did not transmit via direct contact. Co-infection studies with wild-type virus confirmed that the altered HA and NA segments exhibited fitness disadvantages and did not reassort. Vaccinated chickens showed no clinical signs upon vaccination, all seroconverted, and the inclusion of ckIL18 in the MLV-H9N2-IL vaccine enhanced neutralizing antibody production. A significant decrease in viral loads post-challenge underscored the protective effect of the MLVs. The MLV-H9N2-IL vaccine, administered via drinking water, proved immunogenic in chickens in a dose-dependent manner, generating protective levels of neutralizing antibodies upon aggressive homologous virus challenge. In summary, this study lays the groundwork for safe MLVs against avian influenza suitable for mass vaccination efforts. [ABSTRACT FROM AUTHOR]

Avian influenza A(H5N1) viruses can infect humans and cause a range of illnesses, from mild respiratory infections to severe diseases that can be fatal. Human infections are typically acquired through direct contact with infected animals or contaminated environments. Recent outbreaks of avian influenza have been documented in various countries, including Cambodia, Australia, Vietnam, and the United States. While there have been cases of human infection from exposure to infected cows, genetic analysis suggests that the viruses have not yet specialized towards the human host. Continuous surveillance and monitoring are crucial to detect any genetic changes that may indicate a genuine spill-over event. [Extracted from the article]

Avian influenza virus continues to pose zoonotic, epizootic, and pandemic threats worldwide, as exemplified by the 2020–23 epizootics of re-emerging H5 genotype avian influenza viruses among birds and mammals and the fatal jump to humans of emerging A(H3N8) in early 2023. Future influenza pandemic threats are driven by extensive mutations and reassortments of avian influenza viruses rooted in frequent interspecies transmission and genetic mixing and underscore the urgent need for more effective actions. We examine the changing global epidemiology of human infections caused by avian influenza viruses over the past decade, including dramatic increases in both the number of reported infections in humans and the spectrum of avian influenza virus subtypes that have jumped to humans. We also discuss the use of advanced surveillance, diagnostic technologies, and state-of-the-art analysis methods for tracking emerging avian influenza viruses. We outline an avian influenza virus-specific application of the One Health approach, integrating enhanced surveillance, tightened biosecurity, targeted vaccination, timely precautions, and timely clinical management, and fostering global collaboration to control the threats of avian influenza viruses. [ABSTRACT FROM AUTHOR]

The quantitative real-time reverse polymerase chain reaction (RRT-PCR) is the preferred test method for the diagnosis of avian influenza (AI), but can be performed only in specialized laboratories. Different antigen detection methods for the diagnosis of AI were previously reported to be specific and sensitive in field outbreaks. These tests can be performed in basic countryside labs. Brain smears of domestic birds (n = 105) collected during AI field outbreaks were examined with immunocytochemistry (IC). The results were statistically analysed by comparing IC to brain histology (BH), and immunohistochemistry (IHC), to gross pathological examination (GP) (n = 105), and RRT-PCR (n = 91). AI was diagnosed with RRT-PCR in 66 cases. IC and IHC were positive in 59/66 (90%) and 60/66 (91%) cases, respectively. Lesions suspicious for AI were detected with GP and HP in 66/66 (100%) and 61/66 (92%) cases, respectively. An almost perfect agreement was found between RRT-PCR, IC, IHC, and HP. Substantial agreement was found between IC and GP, between IHC and GP, between HP and GP, and between RRT-PCR and GP. The chromogen-based IC test presented in this study produces durable staining, which can be evaluated using a simple brightfield microscope. The test is rapid (can be completed in 2 h), sensitive (90%), specific (100%), and cost-effective, which makes the method suitable for routine diagnostic tests in AI epidemics. RESEARCH HIGHLIGHTS Avian influenza virus (AIV) antigen detection was examined in field outbreaks. Bird brain smears were tested using immunocytochemistry (IC). IC results strongly correlated with real-time RT-PCR results. The IC method was rapid, specific, sensitive, and cost-effective in AIV field outbreaks. [ABSTRACT FROM AUTHOR]

Avian influenza virus has been long considered the main threat for a future pandemic. Among the possible avian influenza virus subtypes, A(H5N1) clade 2.3.4.4b is becoming enzootic in mammals, representing an alarming step towards a pandemic. In particular, genotype B3.13 has recently caused an outbreak in US dairy cattle. Since pandemic preparedness is largely based on the availability of prepandemic candidate vaccine viruses, in this review we will summarize the current status of the enzootics, and challenges for H5 vaccine manufacturing and delivery. [ABSTRACT FROM AUTHOR]

We report a natural infection with a Eurasian highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus in a free-ranging juvenile polar bear (Ursus maritimus) found dead in North Slope Borough, Alaska, USA. Continued community and hunter-based participation in wildlife health surveillance is key to detecting emerging pathogens in the Arctic. [ABSTRACT FROM AUTHOR]

Quantifying numbers of birds released for shooting is an important step towards understanding the ecological consequences of releasing. For Mallard, this has become urgent with the recent rise of Highly Pathogenic Avian Influenza (HPAI). By adapting a previous approach to generating UK-level estimates of numbers of huntable birds shot using the Game and Wildlife Conservation Trust's National Gamebag Census (Aebischer NJ (2019) Fifty-year trends in UK hunting bags of birds and mammals, and calibrated estimation of national bag size, using GWCT's National Gamebag Census. Eur J Wildl Res 65:64. https://doi.org/10.1007/s10344-019-1299-x), the number of Mallards released annually in the UK rose from 870,000 in 2004 to 1.3 million in 2022. Mallards were shot at just over half of NGC sites; of those a fifth released Mallards for shooting, accounting for 87% of the total Mallard bag in 2022. In that year, mean release size was 792 (median 300) and mean release density was 1.39 birds/ha (median 0.52). One fifth of release sites released over 1000 birds each, mostly in southern England and Scotland, corresponding to just 2% of UK shoots. The low percentage combined with low dispersal of released Mallards suggests that scope for them to spread disease is limited, and that any spread is more likely to occur by infection from and transmission to wild birds on passage than from dispersed released ducks. [ABSTRACT FROM AUTHOR]

This study aimed to establish an economical and rapid response system for carcass leachate leakage using a real-time groundwater monitoring system with sensors. In this work, four parameters, namely electrical conductivity (EC), chloride (Cl), nitrate nitrogen (NO3-N), and ammonia nitrogen (NH4-N), were monitored. Three actual livestock burial sites were selected as pilot areas and monitored for three years, from 2019 to 2021, using these four parameters. As a result of sensor quality control, the accuracy and precision range of the four parameters were found to be acceptable, within 75~125% and ±25%, respectively. When compared to the laboratory measurement value, the field measurement value recorded by the sensors was 1.1 times higher for EC, 1.6 times higher for Cl, and 2.5 times higher for NO3-N. The correlation analysis between the lab measurement and sensor measurement results showed that the EC had the highest correlation coefficient of 0.3837. Additionally, the factor extraction results showed that the EC showed a relatively significant correlation compared to the other parameters. In summary, based on the results of this study, EC may be considered a key sensor parameter for evaluating leachate leakage from groundwater near disposal sites. [ABSTRACT FROM AUTHOR]

The evolution of the H5 highly pathogenic avian influenza (HPAI) viruses has led to the emergence of distinct groups with genetically similar clusters of hemagglutinin (HA) sequences. In this study, a consensus H5 HA sequence was cloned into the baculovirus expression system. The HA protein was expressed in baculovirus-infected insect cells and utilized as the antigen for the production of an oil emulsion-based H5 avian influenza vaccine (rBacH5Con5Mut). Twenty-one-day-old SPF chickens were immunized with this vaccine and then challenged at 21 days post-vaccination with clade 2.3.2.1, clade 2.3.4.4, and clade 7.2 of H5 HPAI viruses. The sera of vaccinated chickens exhibited high hemagglutination inhibition (HI) titers against the rBacH5 vaccine antigen, while lower HI titers were observed against the different challenge virus H5 hemagglutinins. Furthermore, the rBacH5Con5Mut vaccine provided 100% protection from mortality and clinical signs. Virus isolation results showed that oropharyngeal and cloacal shedding was prevented in 100% of the vaccinated chickens when challenged with clade 2.3.2.1 and clade 2.3.4.4 H5 viruses. When the rBacH5Con5Mut vaccine candidate was administrated at one day of age, 100% protection was demonstrated against the challenge of clade 2.3.4.4 virus at three weeks of age, indicating the potential of this vaccine for hatchery vaccination. Overall, A single immunization of rBacH5Con5Mut vaccine candidate with a consensus HA antigen can protect chickens against different clades of H5 HPAI viruses throughout the rearing period of broiler chickens without a boost, thus fulfilling the criteria for an efficacious broad-spectrum H5 avian influenza vaccine. [ABSTRACT FROM AUTHOR]

The enormous effects of avian influenza on poultry production and the possible health risks to humans have drawn much attention to this disease. The H9N2 subtype of avian influenza virus is widely prevalent among poultry, posing a direct threat to humans through infection or by contributing internal genes to various zoonotic strains of avian influenza. Despite the widespread use of H9N2 subtype vaccines, outbreaks of the virus persist due to the rapid antigenic drift and shifts in the influenza virus. As a result, it is critical to develop a broader spectrum of H9N2 subtype avian influenza vaccines and evaluate their effectiveness. In this study, a recombinant baculovirus expressing the broad-spectrum HA protein was obtained via bioinformatics analysis and a baculovirus expression system (BES). This recombinant hemagglutinin (HA) protein displayed cross-reactivity to positive sera against several subbranch H9 subtype AIVs. An adjuvant and purified HA protein were then used to create an rHA vaccine candidate. Evaluation of the vaccine demonstrated that subcutaneous immunization of the neck with the rHA vaccine candidate stimulated a robust immune response, providing complete clinical protection against various H9N2 virus challenges. Additionally, virus shedding was more effectively inhibited by rHA than by the commercial vaccine. Thus, our findings illustrate the efficacy of the rHA vaccine candidate in shielding chickens against the H9N2 virus challenge, underscoring its potential as an alternative to conventional vaccines. [ABSTRACT FROM AUTHOR]

This article deals with Central Nervous System (CNS) disorders of marine mammals as putative neuropathology and neuropathogenesis models for their human and, to some extent, their animal "counterparts" in a dual "One Health" and "Translational Medicine" perspective. Within this challenging context, special emphasis is placed upon Alzheimer's disease (AD), provided that AD-like pathological changes have been reported in the brain tissue of stranded cetacean specimens belonging to different Odontocete species. Further examples of potential comparative pathology interest are represented by viral infections and, in particular, by "Subacute Sclerosing Panencephalitis" (SSPE), a rare neurologic sequela in patients infected with Measles virus (MeV). Indeed, Cetacean morbillivirus (CeMV)-infected striped dolphins (Stenella coeruleoalba) may also develop a "brain-only" form of CeMV infection, sharing neuropathological similarities with SSPE. Within this framework, the global threat of the A(H5N1) avian influenza virus is another major concern issue, with a severe meningoencephalitis occurring in affected pinnipeds and cetaceans, similarly to what is seen in human beings. Finally, the role of Brucella ceti-infected, neurobrucellosis-affected cetaceans as putative neuropathology and neuropathogenesis models for their human disease counterparts is also analyzed and discussed. Notwithstanding the above, much more work is needed before drawing the conclusion marine mammal CNS disorders mirror their human "analogues". [ABSTRACT FROM AUTHOR]

The avian influenza virus is an infectious agent that may cause global health problems in poultry and is potentially zoonotic. In the recent decades, bacterial-derived sialidases have been extensively studied for their ability to inhibit avian influenza virus infections. In this study, the antiviral activity of NanB sialidase from Pasteurella multocida was investigated through in vitro analysis using Madin-Darby canine kidney (MDCK) cells. NanB sialidase was purified from P. multocida to test its toxicity and its ability to hydrolyse its sialic acid receptors on MDCK cells. The H9N2 challenge virus was propagated in MDCK cells until cytopathic effects appeared. Antiviral activity of NanB sialidase was tested using MDCK cells, and then observed based on cell morphology, viral copy number, and expression of apoptosis-mediating genes. NanB sialidase effectively hydrolysed Neu5Acα(2,6)-Gal sialic acid at a dose of 129 mU/ml, while at 258 mU/ml, it caused toxicity to MDCK cells. Antiviral activity of sialidase was evident based on the significant decrease in viral copy number at all doses administered. The increase of p53 and caspase-3 expression was observed in infected cells without sialidase. Our study demonstrates the ability of NanB sialidase to inhibit H9N2 virus replication based on observations of sialic acid hydrolysis, reduction in viral copy number, and expression of apoptosis-related genes. The future application of sialidase may be considered as an antiviral strategy against avian influenza H9N2 virus infections. RESEARCH HIGHLIGHTSNanB sialidase effectively hydrolyses Neu5Acα(2,6)-Gal at a dose of 129 mU/ml.NanB sialidase from Pasteurella multocida can inhibit the entry of H9N2 virus into cells.NanB sialidase of Pasteurella multocida prevents infection-induced cell apoptosis.NanB sialidase reduces the H9N2 viral copy number in MDCK cells.NanB sialidase effectively hydrolyses Neu5Acα(2,6)-Gal at a dose of 129 mU/ml.NanB sialidase from Pasteurella multocida can inhibit the entry of H9N2 virus into cells.NanB sialidase of Pasteurella multocida prevents infection-induced cell apoptosis.NanB sialidase reduces the H9N2 viral copy number in MDCK cells. [ABSTRACT FROM AUTHOR]

Introduction: The increasing geographical spread of highly pathogenic avian influenza viruses (HPAIVs) is of global concern due to the underlying zoonotic and pandemic potential of the virus and its economic impact. An integrated One Health model was developed to estimate the likelihood of Avian Influenza (AI) introduction and transmission in Cuba, which will help inform and strengthen risk-based surveillance activities. Materials and methods: The spatial resolution used for the model was the smallest administrative district (“Consejo Popular”). The model was parameterised for transmission from wild birds to poultry and pigs (commercial and backyard) and then to humans. The model includes parameters such as risk factors for the introduction and transmission of AI into Cuba, animal and human population densities; contact intensity and a transmission parameter (β). Results: Areas with a higher risk of AI transmission were identified for each species and type of production system. Some variability was observed in the distribution of areas estimated to have a higher probability of AI introduction and transmission. In particular, the south-western and eastern regions of Cuba were highlighted as areas with the highest risk of transmission. Discussion: These results are potentially useful for refining existing criteria for the selection of farms for active surveillance, which could improve the ability to detect positive cases. The model results could contribute to the design of an integrated One Health risk-based surveillance system for AI in Cuba. In addition, the model identified geographical regions of particular importance where resources could be targeted to strengthen biosecurity and early warning surveillance. [ABSTRACT FROM AUTHOR]

This study reviews chronologically the international scientific and health management literature and resources relating to impacts of highly pathogenic avian influenza (HPAI) viruses on pinnipeds in order to reinforce strategies for the conservation of the endangered Caspian seal (Pusa caspica), currently under threat from the HPAI H5N1 subtype transmitted from infected avifauna which share its haul-out habitats. Many cases of mass pinniped deaths globally have occurred from HPAI spill-overs, and are attributed to infected sympatric aquatic avifauna. As the seasonal migrations of Caspian seals provide occasions for contact with viruses from infected migratory aquatic birds in many locations around the Caspian Sea, this poses a great challenge to seal conservation. These are thus critical locations for the surveillance of highly pathogenic influenza A viruses, whose future reassortments may present a pandemic threat to humans. [ABSTRACT FROM AUTHOR]

High and low pathogenicity avian influenza viruses (HPAIV, LPAIV) are the primary causes of poultry diseases worldwide. HPAIV and LPAIV constitute a major threat to the global poultry industry. Therefore, early detection and well-adapted surveillance strategies are of the utmost importance to control the spread of these viruses. Volatile Organic Compounds (VOCs) released from living organisms have been investigated over the last decades as a diagnostic strategy. Mass spectrometry instruments can analyze VOCs emitted upon viral infection. Selected ion flow tube mass spectrometry (SIFT-MS) enables direct analysis of cell headspace in less than 20 min. As a proof-of-concept study, we investigated the ability of a SIFT-MS coupled sparse Partial Least Square-Discriminant Analysis analytical workflow to discriminate IAV-infected cells. Supernatants of HPAIV, LPAIV, and control cells were collected from 1 to 72 h post-infection and analyzed using our analytical workflow. At each collection point, VOCs' signatures were first identified based on four independent experiments and then used to discriminate the infectious status of external samples. Our results indicate that the identified VOCs signatures successfully discriminate, as early as 1-h post-infection, infected cells from the control cells and differentiated the HPAIV from the LPAIV infection. These results suggest a virus-dependent VOCs signature. Overall, the external samples' status was identified with 96.67% sensitivity, 100% specificity, and 97.78% general accuracy. [ABSTRACT FROM AUTHOR]

Animal movement and population connectivity are key areas of uncertainty in efforts to understand and predict the spread of infectious disease. The emergence of highly pathogenic avian influenza (HPAI) in South America poses a significant threat to globally significant populations of colonial breeding marine predators in the South Atlantic. Yet, there is a poor understanding of which species or migratory pathways may facilitate disease spread. Compiling one of the largest available animal tracking datasets in the South Atlantic, we examine connectivity and inter‐population mixing for colonial breeding marine predators tagged at the Falkland Islands. We reveal extensive connectivity for three regionally dominant and gregarious species over the Patagonian Shelf. Black‐browed albatrosses (BBA), South American fur seals (SAFS) and Magellanic penguins (MAG) used coastal waters along the Atlantic coast of South America (Argentina and Uruguay). These behaviours were recorded at or in close proximity to breeding colonies and haul‐out areas with dense aggregations of marine predators. Transit times to and from the Falkland Islands to the continental coast ranged from 0.2–70 days, with 84% of animals making this transit within 4 days ‐ a conservative estimate for HPAI infectious period. Our findings demonstrate BBA, SAFS and MAG connectivity between the Falkland Islands and mainland South America over an expansive spatial network and numerous pathways, which has implications for infectious disease persistence, transmission and spread. This information is vital in supporting HPAI disease surveillance, risk assessment and marine management efforts across the region. [ABSTRACT FROM AUTHOR]

Background: Acinetobacter baumannii (AB) has emerged as one of the most challenging pathogens worldwide, causing invasive infections in the critically ill patients due to their ability to rapidly acquire resistance to antibiotics. This study aimed to analyze antibiotic resistance genes harbored in AB and non-baumannii Acinetobacter calcoaceticus-baumannii (NB-ACB) complex causing invasive diseases in Korean children. Methods: ACB complexes isolated from sterile body fluid of children in three referral hospitals were prospectively collected. Colistin susceptibility was additionally tested via broth microdilution. Whole genome sequencing was performed and antibiotic resistance genes were analyzed. Results: During January 2015 to December 2020, a total of 67 ACB complexes were isolated from sterile body fluid of children in three referral hospitals. The median age of the patients was 0.6 (interquartile range, 0.1-7.2) years old. Among all the isolates, 73.1% (n=49) were confirmed as AB and others as NBACB complex by whole genome sequencing. Among the AB isolates, only 22.4% susceptible to carbapenem. In particular, all clonal complex (CC) 92 AB (n=33) showed multi-drug resistance, whereas 31.3% in non-CC92 AB (n=16) (P<0.001). NB-ACB showed 100% susceptibility to all classes of antibiotics except 3rd generation cephalosporin (72.2%). The main mechanism of carbapenem resistance in AB was the blaoxa23 gene with ISAba1 insertion sequence upstream. Presence of pmr gene and/or mutation of lpxA/C gene were not correlated with the phenotype of colistin resistance of ACB. All AB and NB-ACB isolates carried the abe and ade multidrug efflux pumps. Conclusions: In conclusion, monitoring and research for resistome in ACB complex is needed to identify and manage drug-resistant AB, particularly CC92 AB carrying the blaoxa23 gene. [ABSTRACT FROM AUTHOR]

The outbreak of clade 2.3.4.4b H5 highly pathogenic avian influenza (HPAI) in North America that started in 2021 has increased interest in applying vaccination as a strategy to help control and prevent the disease in poultry. Two commercially available vaccines based on the recombinant herpes virus of turkeys (rHVT) vector were tested against a recent North American clade 2.3.4.4b H5 HPAI virus isolate: A/turkey/Indiana/22-003707-003/2022 H5N1 in specific pathogen free white leghorn (WL) chickens and commercial broiler chickens. One rHVT-H5 vaccine encodes a hemagglutinin (HA) gene designed by the computationally optimized broadly reactive antigen method (COBRA-HVT vaccine). The other encodes an HA gene of a clade 2.2 virus (2.2-HVT vaccine). There was 100% survival of both chicken types COBRA-HVT vaccinated groups and in the 2.2-HVT vaccinated groups there was 94.8% and 90% survival of the WL and broilers respectively. Compared to the 2.2-HVT vaccinated groups, WL in the COBRA-HVT vaccinated group shed significantly lower mean viral titers by the cloacal route and broilers shed significantly lower titers by the oropharyngeal route than broilers. Virus titers detected in oral and cloacal swabs were otherwise similar among both vaccine groups and chicken types. To assess antibody-based tests to identify birds that have been infected after vaccination (DIVA-VI), sera collected after the challenge were tested with enzyme-linked lectin assay-neuraminidase inhibition (ELLA-NI) for N1 neuraminidase antibody detection and by commercial ELISA for detection of antibodies to the NP protein. As early as 7 days post challenge (DPC) 100% of the chickens were positive by ELLA-NI. ELISA was less sensitive with a maximum of 75% positive at 10DPC in broilers vaccinated with 2.2-HVT. Both vaccines provided protection from challenge to both types of chickens and ELLA-NI was sensitive at identifying antibodies to the challenge virus therefore should be evaluated further for DIVA-VI. [ABSTRACT FROM AUTHOR]

A Newcastle disease virus (NDV)-vectored vaccine expressing clade 2.3.4.4b H5 Hemagglutinin was developed and assessed for efficacy against H5N1 highly pathogenic avian influenza (HPAI) in specific pathogen-free (SPF) chickens, broilers, and domestic ducks. In SPF chickens, the live recombinant NDV-vectored vaccine, rK148/22-H5, achieved complete survival against HPAI and NDV challenges and significantly reduced viral shedding. Notably, the live rK148/22-H5 vaccine conferred good clinical protection in broilers despite the presence of maternally derived antibodies. Good clinical protection was observed in domestic ducks, with decreased viral shedding. It demonstrated complete survival and reduced cloacal viral shedding when used as an inactivated vaccine from SPF chickens. The rK148/22-H5 vaccine is potentially a viable and supportive option for biosecurity measure, effectively protecting in chickens against the deadly clade 2.3.4.4b H5 HPAI and NDV infections. Furthermore, it aligns with the strategy of Differentiating Infected from Vaccinated Animals (DIVA). [ABSTRACT FROM AUTHOR]

In recent years, the complex evolution of the highly pathogenic avian influenza (HPAI) situation reflects a change in the eco-epidemiology of the causative agent which, among other demands, renews the need for better understanding of the connectivity between countries through the main virus reservoirs to improve prevention, early warning and mitigate the associated risks. Our objective was to determine migratory connectivity of Blue-winged Teal and evaluate the risk of AIV introduction to Cuba by this species. The stable hydrogen isotope (d2H) value in flight feathers was analyzed. Individuals were sampled during the migratory season of 2021 (N=126) and winter residence of 2020 (N=152), in western and central Cuba, respectively. Based on banding records from 1955 to 2018, the transition probabilities from 3 breeding areas in North America to 9 wintering areas was estimated with a Burnham's live-recapture dead-recovery modeling framework. A map of likely origin in North America of the individuals sampled for each season was generated, combining the isotopic information and transition probabilities. Evidence of an age-related and phenological pattern in migratory origins was identified. Individuals harvested in the migratory season in western Cuba were most likely from molt or natal areas in the prairies and forest regions from United States and southern Canada. Alternatively, individuals harvested in winter in the center of Cuba had the most likely origin in the U.S. prairie region. The spatial-temporal pattern of AIV prevalence in the estimated region was analyzed and suggestions are made to assist the Cuban system of active AIV surveillance of wild birds. [ABSTRACT FROM AUTHOR]

Recent outbreaks of highly pathogenic avian influenza have devastated poultry production across the United States, with more than 77 million birds culled in 2022–2024 alone. Wild waterfowl, including various invasive species, host numerous pathogens, including highly pathogenic avian influenza virus (HPAIV), and have been implicated as catalysts of disease outbreaks among native fauna and domestic birds. In major poultry‐producing states like Arkansas, USA, where the poultry sector is responsible for significant economic activity (>$4 billion USD in 2022), understanding the risk of invasive waterfowl interactions with domestic poultry is critical. Here, we assessed the risk of invasive waterfowl‐poultry interaction in Arkansas by comparing the density of poultry production sites (chicken houses) to areas of high habitat suitability for two invasive waterfowl species, (Egyptian Goose [Alopochen aegyptiaca] and Mute Swan [Cygnus olor]), known to host significant pathogens, including avian influenza viruses. The percentage of urban land cover was the most important habitat characteristic for both invasive waterfowl species. At the 95% confidence interval, chicken house densities in areas highly suitable for both species (Egyptian Goose = 0.91 ± 0.11 chicken houses/km2; Mute Swan = 0.61 ± 0.03 chicken houses/km2) were three to five times higher than chicken house densities across the state (0.17 ± 0.01 chicken houses/km2). We show that northwestern and western Arkansas, both areas of high importance for poultry production, are also at high risk of invasive waterfowl presence. Our results suggest that targeted monitoring efforts for waterfowl‐poultry contact in these areas could help mitigate the risk of avian pathogen exposure in Arkansas and similar regions with high poultry production. [ABSTRACT FROM AUTHOR]

In January 2020, increased mortality was reported in a small broiler breeder flock in County Fermanagh, Northern Ireland. Gross pathological findings included coelomitis, oophoritis, salpingitis, visceral gout, splenomegaly, and renomegaly. Clinical presentation included inappetence, pronounced diarrhoea, and increased egg deformation. These signs, in combination with increased mortality, triggered a notifiable avian disease investigation. High pathogenicity avian influenza virus (HPAIV) was not suspected, as mortality levels and clinical signs were not consistent with HPAIV. Laboratory investigation demonstrated the causative agent to be a low-pathogenicity avian influenza virus (LPAIV), subtype H6N1, resulting in an outbreak that affected 15 premises in Northern Ireland. The H6N1 virus was also associated with infection on 13 premises in the Republic of Ireland and six in Great Britain. The close genetic relationship between the viruses in Ireland and Northern Ireland suggested a direct causal link whereas those in Great Britain were associated with exposure to a common ancestral virus. Overall, this rapidly spreading outbreak required the culling of over 2 million birds across the United Kingdom and the Republic of Ireland to stamp out the incursion. This report demonstrates the importance of investigating LPAIV outbreaks promptly, given their substantial economic impacts. [ABSTRACT FROM AUTHOR]

The avian influenza virus, particularly the H5N1 strain, poses a significant and ongoing threat to both human and animal health. Recent outbreaks have affected domestic and wild birds on a massive scale, raising concerns about the virus' spread to mammals. This review focuses on the critical role of microRNAs (miRNAs) in modulating pro-inflammatory signaling pathways during the pathogenesis of influenza A virus (IAV), with an emphasis on highly pathogenic avian influenza (HPAI) H5 viral infections. Current research indicates that miRNAs play a significant role in HPAI H5 infections, influencing various aspects of the disease process. This review aims to synthesize recent findings on the impact of different miRNAs on immune function, viral cytopathogenicity, and respiratory viral replication. Understanding these mechanisms is essential for developing new therapeutic strategies to combat avian influenza and mitigate its effects on both human and animal populations. [ABSTRACT FROM AUTHOR]

Between 16 March and 14 June 2024, 42 highly pathogenic avian influenza (HPAI) A(H5) virus detections were reported in domestic (15) and wild (27) birds across 13 countries in Europe. Although the overall number of detections in Europe has not been this low since the 2019–2020 epidemiological year, HPAI viruses continue to circulate at a very low level. Most detections in poultry were due to indirect contact with wild birds, but there was also secondary spread. Outside Europe, the HPAI situation intensified particularly in the USA, where a new A(H5N1) virus genotype (B3.13) has been identified in >130 dairy herds in 12 states. Infection in cattle appears to be centred on the udder, with milk from infected animals showing high viral loads and representing a new vehicle of transmission. Apart from cattle, HPAI viruses were identified in two other mammal species (alpaca and walrus) for the first time. Between 13 March and 20 June 2024, 14 new human cases with avian influenza virus infection were reported from Vietnam (one A(H5N1), one A(H9N2)), Australia (with travel history to India, one A(H5N1)), USA (three A(H5N1)), China (two A(H5N6), three A(H9N2), one A(H10N3)), India (one A(H9N2)), and Mexico (one fatal A(H5N2) case). The latter case was the first laboratory‐confirmed human infection with avian influenza virus subtype A(H5N2). Most of the human cases had reported exposure to poultry, live poultry markets, or dairy cattle prior to avian influenza virus detection or onset of illness. Human infections with avian influenza viruses remain rare and no human‐to‐human transmission has been observed. The risk of infection with currently circulating avian A(H5) influenza viruses of clade 2.3.4.4b in Europe remains low for the general public in the EU/EEA. The risk of infection remains low‐to‐moderate for those occupationally or otherwise exposed to infected animals or contaminated environments. [ABSTRACT FROM AUTHOR]

The article focuses on the emergence of clade 2.3.4.4b avian influenza A(H5N1) in North America and its potential impact on mammalian hosts, including humans, contrasting with the susceptibility of cattle primarily to influenza D virus. Topics include the investigation into influenza virus infections among dairy cattle in Texas, where veterinary diagnostic laboratories initially explored other pathogens before considering influenza A virus as a possible cause.

The article focuses on the epidemiology and pandemic potential of clade 2.3.4.4b highly pathogenic avian influenza A(H5N1) viruses, emphasizing their widespread host expansion, reassortment with other influenza A viruses, and ability to cause severe disease in mammals, including humans and ferrets. Topics include the transmission dynamics observed in a human case in Chile, severe and fatal outcomes in ferrets following intranasal inoculation.

The article focuses on the threat posed by highly pathogenic avian influenza (HPAI) H5N1 viruses, particularly the Eurasian strain (clade 2.3.4.4b), which has caused outbreaks in North America and raised concerns due to spillover into mammals and severe human cases in Ecuador and Chile. Topics include the syndrome observed in lactating dairy cattle in Texas and neighboring regions in early 2024, characterized by reduced milk production and nonspecific clinical signs.

Background: In response to China’s ban on medicinal feed additives with growth-promoting functions in livestock and poultry feed, there is an urgent need in modern animal husbandry for alternatives to antibiotics to sustain livestock health and improve feed conversion efficiency. Allicin, known for its safety, efficiency, lack of drug resistance and absence of residue, regulates the intestinal flora structure; inhibits the growth of harmful bacteria; improves intestinal health, immunity and stress resistance; and improves animal production. Methods: To investigate the impact of allicin on immune performance and immune-related gene expression in Muchuan black-bone chickens, diets were supplemented with varying allicin levels (50, 100, 200 mg/kg), designated as test groups A, B and C, respectively. Initially, growth performance was assessed. Subsequently, immunoglobulins were measured via enzyme-linked immunosorbent assay (ELISA) and colorimetry; immune titers for avian influenza and Newcastle disease were evaluated using hemagglutination and hemagglutination inhibition tests and the expression of immune genes was analyzed via real-time quantitative PCR. Finally, serum biochemical indices in each group were determined. Result: Compared to the control group, allicin supplementation resulted in increased average fasting body weight in the experimental group and significantly (P<0.05) higher thymus and musogastric indices in groups A and C, respectively. Serum levels of immunoglobulin M in groups A and B and immunoglobulin G levels were significantly higher in all experimental groups than in controls. Antibody titers against avian influenza H5 and H7 strains were higher in all test groups, with Newcastle disease antibody titers in groups B and C significantly higher than those in controls. The mRNA expression levels of IFN-γ were lower across all experimental groups, whereas the expression levels of TLR3 in groups B and C and TLR15 in group B were higher. Serum levels of triglycerides in group A were significantly higher and blood urea nitrogen levels were significantly lower in groups B and C than in controls. These findings indicate that dietary allicin (50-200 mg/kg) significantly improves growth performance, immunity and protein and lipid metabolism in Muchuan black-bone chickens, offering valuable data for the development and use of allicin as an antibiotic alternative. [ABSTRACT FROM AUTHOR]

Clade 2.3.4.4b highly pathogenic avian influenza (HPAI) H5N1 virus was detected in the South American sea lions found dead in Santa Catarina, Brazil, in October 2023. Whole genome sequencing and comparative phylogenetic analysis were conducted to investigate the origin, genetic diversity, and zoonotic potentials of the H5N1 viruses. The H5N1 viruses belonged to the genotype B3.2 of clade 2.3.4.4b H5N1 virus, which was identified in North America and disseminated to South America. They have acquired new amino acid substitutions related to mammalian host affinity. Our study provides insights into the genetic landscape of HPAI H5N1 viruses in Brazil, highlighting the continuous evolutionary processes contributing to their possible adaptation to mammalian hosts. [ABSTRACT FROM AUTHOR]