Efficacy of Hemagglutinin Gene of Highly Pathogenic Avian Influenza as a Vaccine Candidate in Poultry: A Review

Abstract

The most prevalent fatal disease in poultry that can result in high morbidity and mortality is highly pathogenic avian influenza (HPAI), subtype H5N1. A vaccination program is the most frequent way to prevent HPAI cases in poultry, especially against the H5 subtype of HPAI. There are currently a number of avian influenza vaccines available, including recombinant and inactivated whole virus vaccines. The foundation of a recombinant vaccine is possible by the expression of an avian influenza gene of interest following insertion into a carrier vector (no pathogenic virus). A recombinant HPAI vaccine is required to further challenge avian influenza cases in poultry. As a recombinant vaccine inserted into a carrier vector, the hemagglutinin (HA) gene has proven effective. The recombinant Herpes Virus Turkey (rHVT) vector vaccine for avian influenza has been discovered and is commercially available. The rHVT vaccine was developed using a hemagglutinin insert from the HPAI virus clade 2.2. Overall, studies in this review aimed to determine the efficacy of any developed recombinant avian influenza vaccine that uses the HA gene from different clades challenged with any avian influenza virus (AIV) isolate. It was found that the efficacy of hemagglutinin as a recombinant vaccine could be promising for future HPAI vaccine development. In addition, it is possible to design a recombinant vaccine using local isolates to protect poultry farms, particularly in endemic regions.