Long-term co-circulation of multiple influenza A viruses in pigs, Guangxi, China.

Influenza A viruses (IAVs) pose a persistent potential threat to human health because of the spillover from avian and swine infections. Extensive surveillance was performed in 12 cities of Guangxi, China, during 2018 and 2023. A total of 2540 samples (including 2353 nasal swabs and 187 lung tissues) were collected from 18 pig farms with outbreaks of respiratory disease. From these, 192 IAV-positive samples and 19 genomic sequences were obtained. We found that the H1 and H3 swine influenza A viruses (swIAVs) of multiple lineages and genotypes have continued to co-circulate during that time in this region. Genomic analysis revealed the Eurasian avian-like H1N1 swIAVs (G4) still remained predominant in pig populations. Strikingly, the novel multiple H3N2 genotypes were found to have been generated through the repeated introduction of the early H3N2 North American triple reassortant viruses (TR H3N2 lineage) that emerged in USA and Canada in 1998 and 2005, respectively. Notably, when the matrix gene segment derived from the H9N2 avian influenza virus was introduced into endemic swIAVs, this produced a novel quadruple reassortant H1N2 swIAV that could pose a potential risk for zoonotic infection.

Expression of recombinant Florida clade 2 hemagglutinin in baculovirus expression system: A step for subunit vaccine development against H3N8 equine influenza virus.

Background: Equine influenza (EI) is a transmissible viral respiratory sickness of the Equidae family. Two viruses, H7N7 and H3N8 caused EI; however, H7N7 has not been detected for decades. H3N8 has circulated and bifurcated into Eurasian and American lineages. The latter subsequently diversified into Kentucky, South America, and Florida sub-lineages. Florida clade 1 (FC1) and Florida clade 2 (FC2) strains are the only circulating EI viruses (EIVs) in the meantime. Immunization is considered the major means for the prevention and control of EI infection. Using disparate technologies and platforms, several vaccines have been developed and commercialized. According to the recommendations of the World Organization for Animal Health (WOAH), all commercial vaccines shall comprise representatives of both FC1 and FC2 strains. Unfortunately, most of the commercially available vaccines were not updated to incorporate a representative of FC2 strains. Aim: The purpose of this research was to develop a new EI vaccine candidate that incorporates the hemagglutinin (HA) antigen from the currently circulating FC2. Methods: In this study, we report the expression of the full-length recombinant HA gene of FC2 in the baculovirus expression system. Results: The HA recombinant protein has been proven to maintain its biological characteristics by hemadsorption (HAD) and hemagglutination tests. Moreover, using a reference-specific serum, the specificity of the HA has been confirmed through the implementation of immunoperoxidase and western immunoblotting assays. Conclusion: In conclusion, we report the expression of specific biologically active recombinant HA of FC2, which would act as a foundation for the generation of an updated EI subunit or virus vector vaccine candidates.

Analysis of H5N8 influenza virus infection in chicken with mApple reporter genes in vivo and in vitro.

H5N8 highly pathogenic avian influenza virus (HPAIV) has caused huge losses to the global poultry industry and critically threatens public health. Chickens are the important host for the transmission. However, the distribution of H5N8 avian influenza virus (AIV) in chicken and the infected cell types are limitedly studied. Therefore, in this study, we detected viral replication and infection by generating recombinant H5N8 AIV expressing an easily tracked mApple fluorescent reporter. The results showed that recombinant viruses passaged four times in chicken embryos successfully expressed mApple proteins detected by fluorescence microscopy and WB, which verified that the constructed recombinant viruses were stable. Compared to parental virus, although recombinant virus attenuated for replication in MDCK cells, it can still replicate effectively, and form visible plaques. Importantly, the experiments on infection of chicken PBMCs in vitro showed a strong correlation between mApple positivity rate and NP positivity rate (r = 0.7594, P =0.0176), demonstrating that mApple reporter could be used as an indicator to accurately reflect AIV infection. Then we infected monocytes/macrophages in PBMCs in vitro and detected the mApple positive percentage was 55.1%-80.4%, which confirmed the chicken primary monocytic/macrophages are important target cells for avian influenza virus infection. In chicken, compared with parental virus, the recombinant virus-infected chickens had lower viral titers in oropharyngeal cloacal and organs, but it can cause significant pathogenicity in chicken and the mortality rate was approximately 66%. In addition, the results of bioluminescent imaging showed that the fluorescence in the lungs was strongest at 5 days post-infection (DPI). Finally, we discovered the mApple positive expression in chicken lung immune cells (CD45+ cells), especially some T cells (CD4 and CD8 T cells) also carrying mApple, which indicates that the H5N8 AIV showed a tropism for immune cells including chicken T cells causing potentially aggressive against cellular immunity. We have provided a simple visualization for further exploration of H5N8 AIV infected chicken immune cells, which contributes to further understanding pathogenic mechanism of H5N8 AIV infection in chicken.

Modulation of infectious Salmon Anaemia virus infection by clathrin-mediated endocytosis and macropinocytosis inhibitors.

Infectious salmon anaemia virus (ISAV) is a pathogen that causes disease and large mortality in farm-raised Salmo salar L., being considered as a major problem in the salmon industry. However, despite its relevance, there are still numerous knowledge gaps on virus entry and early stages of infection. Previous studies suggested that virus entry into cells occurs via endocytosis, with no description of specific mechanisms. However, it remains unknown if the endocytosis induced by ISAV is a clathrin-dependent or clathrin-independent process. This study aimed to identify cellular mechanisms allowing ISAV entry into Atlantic Salmon head kidney (ASK) cells. Our results showed that ISAV can be found in coated pits and membrane ruffles, the latter being induced by a rearrangement of actin filaments promoted by ISAV infection. Additionally, it was determined that ISAV stimulate the uptake of extracellular fluid in a multiplicity of infection (MOI)-dependent manner. When the clathrin-mediated endocytic pathway was pharmacologically inhibited, ISAV infection was significantly reduced but not entirely inhibited. Similarly, when the Na+/H+ exchanger (NHE), a key component of macropinocytosis, was inhibited, ISAV infection was negatively affected. Our results suggest that ISAV enters cells via both clathrin-mediated endocytosis and most likely macropinocytosis.

Novel influenza A viruses in pigs with zoonotic potential, Chile.

Novel H1N2 and H3N2 swine influenza A viruses (IAVs) have recently been identified in Chile. The objective of this study was to evaluate their zoonotic potential. We perform phylogenetic analyses to determine the genetic origin and evolution of these viruses, and a serological analysis to determine the level of cross-protective antibodies in the human population. Eight genotypes were identified, all with pandemic H1N1 2009-like internal genes. H1N1 and H1N2 were the subtypes more commonly detected. Swine H1N2 and H3N2 IAVs had hemagglutinin and neuraminidase lineages genetically divergent from IAVs reported worldwide, including human vaccine strains. These genes originated from human seasonal viruses were introduced into the swine population since the mid-1980s. Serological data indicate that the general population is susceptible to the H3N2 virus and that elderly and young children also lack protective antibodies against the H1N2 strains, suggesting that these viruses could be potential zoonotic threats. Continuous IAV surveillance and monitoring of the swine and human populations is strongly recommended.IMPORTANCEIn the global context, where swine serve as crucial intermediate hosts for influenza A viruses (IAVs), this study addresses the pressing concern of the zoonotic potential of novel reassortant strains. Conducted on a large scale in Chile, it presents a comprehensive account of swine influenza A virus diversity, covering 93.8% of the country's industrialized swine farms. The findings reveal eight distinct swine IAV genotypes, all carrying a complete internal gene cassette of pandemic H1N1 2009 origin, emphasizing potential increased replication and transmission fitness. Genetic divergence of H1N2 and H3N2 IAVs from globally reported strains raises alarms, with evidence suggesting introductions from human seasonal viruses since the mid-1980s. A detailed serological analysis underscores the zoonotic threat, indicating susceptibility in the general population to swine H3N2 and a lack of protective antibodies in vulnerable demographics. These data highlight the importance of continuous surveillance, providing crucial insights for global health organizations.

Genomic characterization of equine influenza A subtype H3N8 viruses by long read sequencing and functional analyses of the PB1-F2 virulence factor of A/equine/Paris/1/2018.

Equine influenza virus (EIV) remains a threat to horses, despite the availability of vaccines. Strategies to monitor the virus and prevent potential vaccine failure revolve around serological assays, RT-qPCR amplification, and sequencing the viral hemagglutinin (HA) and neuraminidase (NA) genes. These approaches overlook the contribution of other viral proteins in driving virulence. This study assesses the potential of long-read nanopore sequencing for fast and precise sequencing of circulating equine influenza viruses. Therefore, two French Florida Clade 1 strains, including the one circulating in winter 2018-2019 exhibiting more pronounced pathogenicity than usual, as well as the two currently OIE-recommended vaccine strains, were sequenced. Our results demonstrated the reliability of this sequencing method in generating accurate sequences. Sequence analysis of HA revealed a subtle antigenic drift in the French EIV strains, with specific substitutions, such as T163I in A/equine/Paris/1/2018 and the N188T mutation in post-2015 strains; both substitutions were in antigenic site B. Antigenic site E exhibited modifications in post-2018 strains, with the N63D substitution. Segment 2 sequencing also revealed that the A/equine/Paris/1/2018 strain encodes a longer variant of the PB1-F2 protein when compared to other Florida clade 1 strains (90 amino acids long versus 81 amino acids long). Further biological and biochemistry assays demonstrated that this PB1-F2 variant has enhanced abilities to abolish the mitochondrial membrane potential ΔΨm and permeabilize synthetic membranes. Altogether, our results highlight the interest in rapidly characterizing the complete genome of circulating strains with next-generation sequencing technologies to adapt vaccines and identify specific virulence markers of EIV.

Bacillus subtilis-597 induces changes in lung pathology and inflammation during influenza A virus infection in pigs.

In recent years, it has become apparent that imbalances in the gastrointestinal system can impact organs beyond the intestine such as the lungs. Given the established ability of probiotics to modulate the immune system by interacting with gastrointestinal cells, our research aimed to investigate whether administering the probiotic strain Bacillus subtilis-597 could mitigate the outcome of influenza virus infection in pigs. Pigs were fed a diet either with or without the probiotic strain B. subtilis-597 for 14 days before being intranasally inoculated with a swine influenza A H1N2 strain (1 C.2 lineage). Throughout the study, we collected fecal samples, blood samples, and nasal swabs to examine viral shedding and immune gene expression. After seven days of infection, the pigs were euthanized, and lung and ileum tissues were collected for gene expression analysis and pathological examination. Our findings indicate that the administration of B. subtilis-597 exhibit potential in reducing lung lesions, possibly attributable to a general suppression of the immune system as indicated by reduced C-reactive protein (CRP) levels in serum, decreased expression of interferon-stimulated genes (ISGs), and localized reduction of the inflammatory marker serum amyloid A (SAA) in ileum tissue. Notably, the immune-modulatory effects of B. subtilis-597 appeared to be unrelated to the gastrointestinal microbiota, as the composition remained unaltered by both the influenza infection and the administration of B. subtilis-597.

Nucleoprotein reassortment enhanced transmissibility of H3 1990.4.a clade influenza A virus in swine.

The increased detection of H3 C-IVA (1990.4.a) clade influenza A viruses (IAVs) in US swine in 2019 was associated with a reassortment event to acquire an H1N1pdm09 lineage nucleoprotein (pdmNP) gene, replacing a TRIG lineage NP (trigNP). We hypothesized that acquiring the pdmNP conferred a selective advantage over prior circulating H3 viruses with a trigNP. To investigate the role of NP reassortment in transmission, we identified two contemporary 1990.4.a representative strains (NC/19 and MN/18) with different evolutionary origins of the NP gene. A reverse genetics system was used to generate wild-type (wt) strains and swap the pdm and TRIG lineage NP genes, generating four viruses: wtNC/19-pdmNP, NC/19-trigNP, wtMN/18-trigNP, and MN/18-pdmNP. The pathogenicity and transmission of the four viruses were compared in pigs. All four viruses infected 10 primary pigs and transmitted to five indirect contact pigs per group. Pigs infected via contact with MN/18-pdmNP shed virus 2 days earlier than pigs infected with wtMN/18-trigNP. The inverse did not occur for wtNC/19-pdmNP and NC/19-trigNP. This suggests that pdmNP reassortment resulted in a combination of genes that improved transmission efficiency when paired with the 1990.4.a hemagglutinin (HA). This is likely a multigenic trait, as replacing the trigNP gene did not diminish the transmission of a wild-type IAV in swine. This study demonstrates how reassortment and evolutionary change of internal genes can result in more transmissible viruses that influence HA clade detection frequency. Thus, rapidly identifying novel reassortants paired with dominant hemagglutinin/neuraminidase may improve the prediction of strains to include in vaccines.IMPORTANCEInfluenza A viruses (IAVs) are composed of eight non-continuous gene segments that can reassort during coinfection of a host, creating new combinations. Some gene combinations may convey a selective advantage and be paired together preferentially. A reassortment event was detected in swine in the United States that involved the exchange of two lineages of nucleoprotein (NP) genes (trigNP to pdmNP) that became a predominant genotype detected in surveillance. Using a transmission study, we demonstrated that exchanging the trigNP for a pdmNP caused the virus to shed from the nose at higher levels and transmit to other pigs more rapidly. Replacing a pdmNP with a trigNP did not hinder transmission, suggesting that transmission efficiency depends on interactions between multiple genes. This demonstrates how reassortment alters IAV transmission and that reassortment events can provide an explanation for why genetically related viruses with different internal gene combinations experience rapid fluxes in detection frequency.

Isolation and characterization of genotype 4 Eurasian avian-like H1N1 influenza virus in pigs suffering from pneumonia.

Swine influenza viruses pose ongoing threat to pork industry throughout the world. In 2023, fattening pigs from a swine farm in Inner Mongolia of China experienced influenza-like symptoms. Co-infection of influenza A virus with Pasteurella multocida was diagnosed in lung tissues of diseased pigs and a genotype 4 (G4) Eurasian avian-like (EA) H1N1 virus was isolated, which was named as A/swine/Neimenggu/0326/2023. We demonstrated the virus preferentially bound human-like SAα2,6Gal receptor. It was noteworthy that the virus possessed multiple genetic markers for mammalian adaptation in the internal genes. Animal studies showed that compared with genotype 1 (G1) EA H1N1 virus and early prevalent G4 EA H1N1 virus, A/swine/Neimenggu/0326/2023 virus exhibited increased virus shedding, enhanced replication in lungs, and caused more severe lung lesions in pigs. These findings indicate that the G4 EA H1N1 virus poses increased threat to pork industry, controlling the prevailing viruses in pigs should be promptly implemented.

Characteristics of two zoonotic swine influenza A(H1N1) viruses isolated in Germany from diseased patients.

Interspecies transmission of influenza A viruses (IAV) from pigs to humans is a concerning event as porcine IAV represent a reservoir of potentially pandemic IAV. We conducted a comprehensive analysis of two porcine A(H1N1)v viruses isolated from human cases by evaluating their genetic, antigenic and virological characteristics. The HA genes of those human isolates belonged to clades 1C.2.1 and 1C.2.2, respectively, of the A(H1N1) Eurasian avian-like swine influenza lineage. Antigenic profiling revealed substantial cross-reactivity between the two zoonotic H1N1 viruses and human A(H1N1)pdm09 virus and some swine viruses, but did not reveal cross-reactivity to H1N2 and earlier human seasonal A(H1N1) viruses. The solid-phase direct receptor binding assay analysis of both A(H1N1)v showed a predominant binding to α2-6-sialylated glycans similar to human-adapted IAV. Investigation of the replicative potential revealed that both A(H1N1)v viruses grow in human bronchial epithelial cells to similar high titers as the human A(H1N1)pdm09 virus. Cytokine induction was studied in human alveolar epithelial cells A549 and showed that both swine viruses isolated from human cases induced higher amounts of type I and type III IFN, as well as IL6 compared to a seasonal A(H1N1) or a A(H1N1)pdm09 virus. In summary, we demonstrate a remarkable adaptation of both zoonotic viruses to propagate in human cells. Our data emphasize the needs for continuous monitoring of people and regions at increased risk of such trans-species transmissions, as well as systematic studies to quantify the frequency of these events and to identify viral molecular determinants enhancing the zoonotic potential of porcine IAV.

Influenza A virus antibodies in dogs, hunting dogs, and backyard pigs in Campeche, Mexico.

AIMS: This study aimed to identify exposure to human, swine, and avian influenza A virus subtypes in rural companion and hunting dogs, backyard pigs, and feral pigs. METHODS AND RESULTS: The study took place in a region of southeastern Mexico where the sampled individuals were part of backyard production systems in which different domestic and wild species coexist and interact with humans. We collected blood samples from pigs and dogs at each of the sites. We used a nucleoprotein enzyme-linked immunosorbent assay to determine the exposure of individuals to influenza A virus. Haemagglutination inhibition was performed on the positive samples to determine the subtypes to which they were exposed. For data analysis, a binomial logistic regression model was generated to determine the predictor variables for the seropositivity of the individuals in the study. We identified 11 positive individuals: three backyard pigs, four companion dogs, and four hunting dogs. The pigs tested positive for H1N1 and H1N2. The dogs were positive for H1N1, H1N2, and H3N2. The model showed that dogs in contact with backyard chickens are more likely to be seropositive for influenza A viruses. CONCLUSIONS: We demonstrated the essential role hunting dogs could play as intermediate hosts and potential mixing vessel hosts when exposed to human and swine-origin viral subtypes. These results are relevant because these dogs interact with domestic hosts and humans in backyard systems, which are risk scenarios in the transmission of influenza A viruses. Therefore, it is of utmost importance to implement epidemiological surveillance of influenza A viruses in backyard animals, particularly in key animals in the transmission of these viruses, such as dogs and pigs.

An experimental universal swine influenza a virus (IAV) vaccine candidate based on the M2 ectodomain (M2e) peptide does not provide protection against H1N1 IAV challenge in pigs.

Swine flu is a common disease problem in North American pig populations and swine influenza A viruses (IAV) are extremely diverse and the lack of cross protection between heterologous strains is impacting vaccine efficacy in the field. The objective of this study was to design and test a novel swine flu vaccine targeting the M2 ectodomain (M2e) of IAV, a highly conserved region within the IAV proteome. In brief, an M2e peptide was designed to match the predominant swine IAV M2 sequence based on global analysis of sequences from pigs and humans. The resulting sequence was used to synthesize the M2e peptide coupled to a carrier protein. The final vaccine concentration was 200 µg per dose, and a commercial, microemulsion-based aqueous adjuvant was added. Nine 3-week-old IAV negative piglets were randomly assigned to three groups and rooms including non-vaccinated pigs (NEG-CONTROLs) and vaccinated pigs using the intramuscular (M2e-IM) or the intranasal route (M2e-IN). Vaccinations were done at weaning and again at 2 weeks later. An in-house enzyme-linked immunosorbent assay (ELISA) was developed and validated to study the M2e IgG antibody response and demonstrated M2e-IM pigs had a higher systemic antibody response compared to M2e-IN pigs. Subsequently, an IAV challenge study was conducted. The results indicated that M2e-IM vaccinated pigs were not protected from H1N1 (US pandemic clade, global clade 1A.3.3.2) challenge despite having a strong humoral anti-M2e immune response. In conclusion, while the experimental IAV vaccine was able to induce anti-M2e antibodies, when challenged with H1N1, the vaccinated pigs were not protected, perhaps indicating that reactivity to the M2e antigen alone is not sufficient to reduce clinical signs, lesions or shedding associated with experimental IAV challenge.

Understanding if the reward is worth the influenza risk: The true cost of showing pigs.

Influenza A virus transmission between pigs and humans has been reported periodically worldwide, and spillover events across the animal-human species barrier could lead to the next influenza pandemic. Swine exhibitions serve as a unique interface conducive to zoonotic disease transmission due to extensive commingling of pigs and humans for prolonged periods of time. The majority of zoonotic influenza A virus transmission in the United States has been linked to swine exhibitions, leading some to suggest additional controls for influenza A virus at the swine-human interface. Determining the value of the exhibition swine industry and gauging the financial impacts influenza A virus outbreaks could have on society, helps to inform adoption decisions of mitigation recommendations. This study estimates the total value of the exhibition swine industry in the United States and calculates the predicted costs of the most extreme mitigation strategy, cancelling swine exhibitions to reduce zoonotic influenza A virus transmission. Mixed methods, including a survey, were used to collect data and inform the study model. We estimated that the direct economic impact of the exhibition swine sector in 2018 was $1.2 billion. If pig shows were to be cancelled for one year, the estimated direct economic impact would be $357.1 million. A permanent, > 3-year ban on swine exhibitions would result in a $665 million economic impact, which is a 45% reduction from baseline. The direct economic impact of cancelling the swine show circuit could not be determined, as youth exhibitors may pursue alternative activities that cannot be precisely accounted for. However, the estimated loss to the swine industry justifies seeking enhanced mitigation to prevent disease transmission. Moreover, economic losses secondary to exhibition cancellations may explain hesitancy to participate in active influenza A virus surveillance efforts.

Evolution of influenza A viruses in exhibition swine and transmission to humans, 2013-2015.

AIMS: Swine are a mixing vessel for the emergence of novel reassortant influenza A viruses (IAV). Interspecies transmission of swine-origin IAV poses a public health and pandemic risk. In the United States, the majority of zoonotic IAV transmission events have occurred in association with swine exposure at agricultural fairs. Accordingly, this human-animal interface necessitates mitigation strategies informed by understanding of interspecies transmission mechanisms in exhibition swine. Likewise, the diversity of IAV in swine can be a source for novel reassortant or mutated viruses that pose a risk to both swine and human health. METHODS AND RESULTS: In an effort to better understand those risks, here we investigated the epidemiology of IAV in exhibition swine and subsequent transmission to humans by performing phylogenetic analyses using full genome sequences from 272 IAV isolates collected from exhibition swine and 23 A(H3N2)v viruses from human hosts during 2013-2015. Sixty-seven fairs (24.2%) had at least one pig test positive for IAV with an overall estimated prevalence of 8.9% (95% CI: 8.3-9.6, Clopper-Pearson). Of the 19 genotypes found in swine, 5 were also identified in humans. There was a positive correlation between the number of human cases of a genotype and its prevalence in exhibition swine. Additionally, we demonstrated that A(H3N2)v viruses clustered tightly with exhibition swine viruses that were prevalent in the same year. CONCLUSIONS: These data indicate that multiple genotypes of swine-lineage IAV have infected humans, and highly prevalent IAV genotypes in exhibition swine during a given year are also the strains detected most frequently in human cases of variant IAV. Continued surveillance and rapid characterization of IAVs in exhibition swine can facilitate timely phenotypic evaluation and matching of candidate vaccine strains to those viruses present at the human-animal interface which are most likely to spillover into humans.

Reassortant H9N2 canine influenza viruses containing the pandemic H1N1/2009 ribonucleoprotein complex circulating in pigs acquired enhanced virulence in mice.

The reassortment between avian H9N2 and Eurasian avian-like (EA) H1N1 viruses may have potentially changed from avian-to-mammals adaptation. This study generated 20 reassortant viruses with the introduction of H1N1/2009 internal genes from EA H1N1 virus into H9N2 virus. 12 of these recovered the replication capability both in the lungs and turbinate samples. 10 of 12 obtained PA gene segments from the ribonucleoprotein (RNP) complexes of the EA H1N1 virus, and 3 exhibited extreme virulence. Specially, the combination of PB2, PA and NP genes could overcome the species-specific restriction in human cells. Analysis of the polymerase activities found that introduction of the PA gene resulted in increased polymerase activity. These findings indicated that RNP complexes from EA H1N1 virus could confer an adaptation advantage and high compatibility to avian H9N2 virus. This raises new concerns for public health due to the possible coexistence of H9N2 and EA H1N1 viruses in dogs.

Rescue of Infectious Salmon Anemia Virus (ISAV) from Cloned cDNA.

The piscine orthomyxovirus called infectious salmon anemia virus (ISAV) is one of the most important emerging pathogens affecting the salmon industry worldwide. The first reverse genetics system for ISAV, which allows the generation of recombinant ISA virus (rISAV), is an important tool for the characterization and study of this virus. The plasmid-based reverse genetics system for ISAV includes the use of a novel fish promoter, the Atlantic salmon internal transcribed spacer region 1 (ITS-1). The salmon, viral, and mammalian genetic elements included in the pSS-URG vectors allow the expression of the eight viral RNA segments. In addition to four cytomegalovirus (CMV)-based vectors that express the four proteins of the ISAV ribonucleoprotein complex, the eight pSS-URG vectors allowed the generation of infectious rISAV in salmon cells.

Equine influenza outbreak in Eastern of Algeria in 2021: The first introduction of Florida Clade 1 to Maghreb area.

We have performed an equine influenza (EI) serological study of the equine population in Algeria by testing 298 serum samples collected between February and August 2021 from 5 provinces. The results were obtained performing an NP-ELISA. Our results revealed that 49.3% (147/298) samples positive for antibodies to EI (H3N8). During this study and after a gap of one decade an outbreak of EI was reported in Algeria in the first week of March 2021. The disease was confirmed by virus detection from the nasal swabs (n = 39) by qRT-PCR and by identifying 5 EI seroconversion. The virus sequences were identified as H3N8 by sequencing the haemagglutinin (HA) and neuraminidase (NA) genes. Alignment of HA1 amino acid sequence confirmed that viruses belong to Clade 1 of the Florida sublineage in the American lineage. This study indicate the first detection of FC1 strain of EIV in Maghreb area.

Description of spatiotemporal patterns of infectious salmon anemia virus (ISAV) detections in marine Atlantic Salmon farms in Newfoundland and Labrador.

OBJECTIVE: The objectives of this study were to describe spatiotemporal patterns of infectious salmon anemia virus (ISAV) detections in marine salmonid production sites in the province of Newfoundland and Labrador in Canada. METHODS: Infectious salmon anemia virus surveillance data between 2012 and 2020 from the province of Newfoundland and Labrador were used. Data comprised a total of 94 sampling events from 20 Atlantic Salmon Salmo salar production sites in which ISAV was detected. Using linear regression models, factors influencing time to detection (days from stocking to first ISAV detection) and time to depopulation (days from first detection to production site depopulation) were investigated. RESULT: Based on 28 unique cases, site-level annual incidence risk of ISAV detection ranged from 3% to 29%. The proportion of ISAV detection by PCR in fish samples ranged from 2% to 45% annually. Overall, ISAV variants from the European clade were more common than variants from the North American clade. The type of ISAV clade, detections of ISAV in nearest production sites based on seaway distances, and year of infectious salmon anemia cases were not associated with time to first ISAV detection. Time to depopulation for sites infected with the ISAV-HPRΔ variant was not associated with ISAV North American or European clades. CONCLUSION: Our results contribute to the further understanding of the changing dynamics of infectious salmon anemia detections in Newfoundland and Labrador since its first detection in 2012 and will likely assist in the design of improved disease surveillance and control programs in the province.

Influenza D in Domestic and Wild Animals.

Influenza D virus (IDV) infections have been observed in animals worldwide, confirmed through both serological and molecular tests, as well as virus isolation. IDV possesses unique properties that distinguish it from other influenza viruses, primarily attributed to the hemagglutinin-esterase fusion (HEF) surface glycoprotein, which determines the virus' tropism and wide host range. Cattle are postulated to be the reservoir of IDV, and the virus is identified as one of the causative agents of bovine respiratory disease (BRD) syndrome. Animals associated with humans and susceptible to IDV infection include camels, pigs, small ruminants, and horses. Notably, high seroprevalence towards IDV, apart from cattle, is also observed in camels, potentially constituting a reservoir of the virus. Among wild and captive animals, IDV infections have been confirmed in feral pigs, wild boars, deer, hedgehogs, giraffes, wildebeests, kangaroos, wallabies, and llamas. The transmission potential and host range of IDV may contribute to future viral differentiation. It has been confirmed that influenza D may pose a threat to humans as a zoonosis, with seroprevalence noted in people with professional contact with cattle.