Efficacy of two commercial inactivated h5 avian influenza vaccines against circulating HPAI Subtype H5N8 in Quails, 2018

Abstract EN

To investigate cross-protective efficacy of commercial inactivated H5 avian influenza vaccines against recent HPAI H5N8 virus in quails which was isolated in Egypt at the end of 2017 and causing high mortalities in the field of poultry industry and huge economic loss .

The efficacy of two inactivated commercial H5 AI vaccines (imported H5N1 vaccine containing (Re-6 strain) and local H5N1 vaccine), was evaluated using susceptible quails at one week of age.

The selection of these bird back to its a specific nature which characterized by presence of two types of avian influenza receptors giving a great chance for recombination of the different types of AIV emerging new mutant viruses can threat human health and poultry industry.

Susceptible quails used for potency assay were inoculated by one field dose and booster dose at 3 weeks post vaccination from each vaccine.

Blood samples were collected weekly from all vaccinated groups and AI, HI antibodies were measured individually of the collected sera by HI test using homologous H5N1 and heterologous H5N8 AI antigens containing 4 HA units.

Vaccinated quails with one dose and booster dose of vaccine were challenged by 100 LD50 of HPAI subtype H5N8 intranasal after 2, 4 and 8 weeks post vaccination, and 4 weeks post boostering, respectively.

It was found that HI antibody titer in sera of quails vaccinated by one or two doses of imported H5N1 AI vaccine containing RE-6 strain elicited higher immune response than that elicited by local commercial vaccine when examined against homologous H5N1AI antigen, but both vaccines exhibited antibody titer not optimal against heterologous H5N8AI antigens.

A challenge test with local H5N8 highly pathogenic influenza virus indicated unsatisfactory protection% for all groups of vaccinated quails.