Department of Veterinary Medicine

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    Challenge for One Health: Co-Circulation of Zoonotic H5N1 and H9N2 Avian Influenza Viruses in Egypt
    (MDPI, 2018-03-09) Kim, Shin-Hee
    Highly pathogenic avian influenza (HPAI) H5N1 viruses are currently endemic in poultry in Egypt. Eradication of the viruses has been unsuccessful due to improper application of vaccine-based control strategies among other preventive measures. The viruses have evolved rapidly with increased bird-to-human transmission efficacy, thus affecting both animal and public health. Subsequent spread of potentially zoonotic low pathogenic avian influenza (LPAI) H9N2 in poultry has also hindered efficient control of avian influenza. The H5N1 viruses acquired enhanced bird-to-human transmissibility by (1) altering amino acids in hemagglutinin (HA) that enable binding affinity to human-type receptors, (2) loss of the glycosylation site and 130 loop in the HA protein and (3) mutation of E627K in the PB2 protein to enhance viral replication in mammalian hosts. The receptor binding site of HA of Egyptian H9N2 viruses has been shown to contain the Q234L substitution along with a H191 mutation, which can increase human-like receptor specificity. Therefore, co-circulation of H5N1 and H9N2 viruses in poultry farming and live bird markets has increased the risk of human exposure, resulting in complication of the epidemiological situation and raising a concern for potential emergence of a new influenza A virus pandemic. For efficient control of infection and transmission, the efficacy of vaccine and vaccination needs to be improved with a comprehensive control strategy, including enhanced biosecurity, education, surveillance, rapid diagnosis and culling of infected poultry.
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    Improved hatchability and efficient protection after in ovo vaccination with live-attenuated H7N2 and H9N2 avian influenza viruses
    (2011-01-21) Cai, Yibin; Song, Haichen; Ye, Jianqiang; Shao, Hongxia; Padmanabhan, Rangarajan; Sutton, Troy C; Perez, Daniel R
    Mass in ovo vaccination with live attenuated viruses is widely used in the poultry industry to protect against various infectious diseases. The worldwide outbreaks of low pathogenic and highly pathogenic avian influenza highlight the pressing need for the development of similar mass vaccination strategies against avian influenza viruses. We have previously shown that a genetically modified live attenuated avian influenza virus (LAIV) was amenable for in ovo vaccination and provided optimal protection against H5 HPAI viruses. However, in ovo vaccination against other subtypes resulted in poor hatchability and, therefore, seemed impractical. In this study, we modified the H7 and H9 hemagglutinin (HA) proteins by substituting the amino acids at the cleavage site for those found in the H6 HA subtype. We found that with this modification, a single dose in ovo vaccination of 18- day old eggs provided complete protection against homologous challenge with low pathogenic virus in ≥70% of chickens at 2 or 6 weeks post-hatching. Further, inoculation of 19-day old egg embryos with 10 6 EID50 of LAIVs improved hatchability to ≥90% (equivalent to unvaccinated controls) with similar levels of protection. Our findings indicate that the strategy of modifying the HA cleavage site combined with the LAIV backbone could be used for in ovo vaccination against avian influenza. Importantly, with protection conferred as early as 2 weeks post-hatching, with this strategy birds would be protected prior to or at the time of delivery to a farm or commercial operation.