Efficacy of Avian influenza vaccines testing in chicken against A/H5N6 clade 2.3.4.4B virus

Abstract

In order to assess the efficacy of some vaccines against the newly- occurred avian influenza
A/H5N6 virus in Viet Nam, this study was conducted on the chickens with locally-made NavetVifluvac vaccine, the Re-5 vaccine and the Re-6 vaccine imported from China. The result of
testing chicken serum after vaccination using HI test with the antigen homologous with that in
vaccines showed that these vaccines induced the experimental chickens in antibody production
with a titre of 4.3log2 for Navet vifluvac vaccine; 7.8log2 for Re-5 vaccine and 5.3log2 for Re-6
vaccine. The result of virulent challenge with A/H5N6 clade 2.3.4.4B showed that the protective
rate of the vaccinated chickens for all three vaccines Navet-Vifluvac, Re-5 and Re-6 vaccines
was 70%. The vaccinated chickens with three vaccines discharged virus within 10 days after
challenge, but the vaccinated chickens with Navet-Vifluvac significantly reduced viral shedding
in 10 days, post-challenge. The vaccinated chickens with Re-5 vaccine excreted virus with high
level in 10 days, post-challenge