Pigs are capable of generating reassortant influenza viruses of pandemic potential, as both the avian and mammalian influenza viruses can infect pig epithelial cells in the respiratory tract. The source of the current influenza pandemic is H1N1 influenza A virus, possibly of swine origin. This study was conducted to understand better the pathogenesis of H1N1 influenza virus and associated host mucosal immune responses during acute infection in humans. Therefore, we chose a H1N1 swine influenza virus, Sw/OH/24366/07 (SwIV), which has a history of transmission to humans. Clinically, inoculated pigs had nasal discharge and fever and shed virus through nasal secretions. Like pandemic H1N1, SwIV also replicated extensively in both the upper and lower respiratory tracts, and lung lesions were typical of H1N1 infection. We detected innate, proinflammatory, Th1, Th2, and Th3 cytokines, as well as SwIV-specific IgA antibody in lungs of the virus-inoculated pigs. Production of IFN-γ by lymphocytes of the tracheobronchial lymph nodes was also detected. Higher frequencies of cytotoxic T lymphocytes, γδ T cells, dendritic cells, activated T cells, and CD4⁺and CD8⁺T cells were detected in SwIV-infected pig lungs. Concomitantly, higher frequencies of the immunosuppressive T regulatory cells were also detected in the virus-infected pig lungs. The findings of this study have relevance to pathogenesis of the pandemic H1N1 influenza virus in humans; thus, pigs may serve as a useful animal model to design and test effective mucosal vaccines and therapeutics against influenza virus.

In this study, respiratory viral pathogens were screened using real-time RT-PCR in 86 broiler chicken flocks suffering from respiratory diseases problems in 4 Egyptian governorates between January 2012 and February 2014. The mortality rates in the investigated flocks ranged from 1 to 47%. Results showed that mixed infection represented 66.3% of the examined flocks. Mixed infectious bronchitis (IBV) and avian influenza (AI)-H9N2 viruses were the most common infection (41.7%). Lack of AI-H9N2 vaccination and high rates of mixed infections in which AI-H9N2 is involved indicate an early AI-H9N2 infection with a potential immunosuppressive effect that predisposes for other viral infections. High pathogenic AI-H5N1 and virulent Newcastle disease virus (vNDV) infections were also detected (26.7% and 8.1%, respectively). Interestingly, co-infection of AI-H9N2 with either AIV-H5N1 or vNDV rarely resulted in high mortality. Partial cell-mediated immunity against similar internal AI genes, as well as virus interference between AI and vNDV, could be an explanation for this. Highly prevalent IBV and AI-H9N2 were isolated and were molecularly characterized based on S1 gene hypervariable region 3 ( HVR3: ) and hemagglutinin gene (HA) sequences, respectively. IBV strains were related to the variant group of IBV with multiple mutations in HVR3. Though AI-H9N2 viruses showed low rate of evolution in comparison to recent strains, few amino acid substitutions indicative of antibody selection pressure were observed in the HA gene. In conclusion, mixed viral infections, especially with IBV and AI-H9N2 viruses, are the predominant etiology of respiratory disease problems in broiler chickens in Egypt. Further investigations of the role of AI, IBV, and ND viruses' co-infections and interference in terms of altering the severity of clinical signs and lesions and/or generating novel reassortants within each virus are needed.

Avian influenza virus (AIV) variants emerge frequently, which challenges rapid diagnosis. Appropriate diagnosis reaching the sub- and pathotype level is the basis of combatting notifiable AIV infections. Real-time RT-PCR (RT-qPCR) has become a standard diagnostic tool. Here, a total of 24 arrayed RT-qPCRs is introduced for full subtyping of 16 hemagglutinin and nine neuraminidase subtypes of AIV. This array, designated Riems Influenza A Typing Array version 2 (RITA-2), represents an updated and economized version of the RITA-1 array previously published by Hoffmann et al. RITA-2 provides improved integration of assays (24 instead of 32 parallel reactions) and reduced assay volume (12.5 µL). The technique also adds RT-qPCRs to detect Newcastle Disease (NDV) and Infectious Bronchitis viruses (IBV). In addition, it maximizes inclusivity (all sequences within one subtype) and exclusivity (no intersubtypic cross-reactions) as shown in validation runs using a panel of 428 AIV reference isolates, 15 reference samples each of NDV and IBV, and 122 clinical samples. The open format of RITA-2 is particularly tailored to subtyping influenza A virus of avian hosts and Eurasian geographic origin. Decoupling and re-arranging selected RT-qPCRs to detect specific AIV variants causing epizootic outbreaks with a temporal and/or geographic restriction is possible.

Domestic cats have several features that make them ideal vehicles for interspecies transmission of influenza viruses; however, they have been largely overlooked as potential reservoirs or bridging hosts. In this study, we conducted serological surveillance to assess the prevalence of novel pandemic H1N1 as well as seasonal human influenza virus infections in domestic cats in Ohio. Four hundred serum samples collected from domestic cats (September 2009 to September 2010) were tested using a hemagglutination inhibition (HI) test. The seroprevalences of pandemic H1N1, seasonal H1N1, and H3N2 were 22.5%, 33%, and 43.5%, respectively. In addition, a significant association between clinical feline respiratory disease and influenza virus infection was documented. In this sample of cats, the prevalence of pandemic H1N1 did not follow the seasonality pattern of seasonal H1N1 or H3N2 influenza, similar to observations in humans. Pandemic H1N1 seroprevalence did not vary in relation to ambient temperature changes, while the seroprevalence of seasonal H3N2 and H1N1 influenza viruses increased with the decline of ambient temperature. Our results highlight the high prevalence of influenza virus infection in domestic cats, a seasonality pattern of influenza virus infection comparable to that in humans, and an association of infection with clinical respiratory disease.