Protective efficacy of priming with recombinant vaccine in chickens challenged with Egyptian highly pathogenic H5N1 avian influenza virus
Protective efficacy of priming with recombinant vaccine in chickens challenged with Egyptian highly pathogenic H5N1 avian influenza virus
RehamM. El-Bakrey1, Shimaa M.G. Mansour2, Mohammed A. El Sisi1 AndAmal A.M. Eid1
ABSTRACT
Highly pathogenic avian influenza (HPAI) H5N1 virusesare now endemic in Egypt inducing economic losses in poultry industry and subsequent risk of human infection. Vaccination is an effective method for controlling avian influenza virus infections.This study was conducted to evaluate the efficacy of the commercially applied AI vaccine regimens against challenge with three H5N1 HPAI viruses isolated from chickens, Egypt during 2009-2011. Both inactivated and recombinant fowlpox virus expressing H5 (rFP-AI-H5) vaccines were measured. Vaccine efficacy was evaluated by percentage of protection from mortality, morbidity and reduction in virus shedding from respiratory and/orintestinal tracts. Despite the H5 antibody responses in vaccinated chickens with program I (rFP-AI-H5" vaccine then Re-5) being significantly lower prior to challenge, it provided good protection (73.3%) against the lethal A/chicken/Egypt/SHAH-1403/2011 (H5N1) AIV challenge, with no evidence of virus shedding. Keeping in mind that each bird was potentially challenged with 105 EID50, which may not be available to all birds under field condition. The foremost vaccine regimen can provide a safe, effective and considerable tool for the control of HPAIV in commercial chickens. Maximizing the beneficial role of recombinant and reassortant vaccines in single product could be utilized.
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