DEVELOPMENT OF A BIVALENT INACTIVATED OIL ADJUVANTED VACCINE USING LOCAL ISOLATES OF LOW AND HIGH PATHOGENIC AVIAN INFLUENZA VIRUSES AND COMPARISON OF ITS IMMUNOGENIC RESPONSE WITH MONOVALENT VACCINES OF BOTH STRAINS.

Highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI) viruses pose a serious economic threat to the poultry industry both in terms of high mortality and productivity losses. Currently, majority of the industry relies on imported vaccines and small-scale vaccine manufacturing is carried out from locally isolated strains. Vaccine development using locally isolated strains and preventing inoculation stress using bivalent vaccines is highly desirable. In the present study, we compared the efficacy of monovalent vaccines prepared from local LPAI (H9N2) and HPAI (H5N8) isolates with a bivalent vaccine containing both isolates. Immunogenic response of bivalent and monovalent vaccines was checked in 3-week-old layer chickens. The hemagglutination inhibition (HI) antibody titers were measured on day14, 28, 42, 56, and 70 post-booster. Monovalent vaccines were inoculated at 0.3 ml/bird, whereas bivalent vaccine was administered at 0.3 ml/bird and 0.5 ml/bird. Both monovalent and bivalent vaccines at both dose rates induced protective titers. However, higher titers were observed in chicks inoculated with 0.5 ml/bird dose. No antigen dominance was observed among both strains. All the vaccines remained stable for a period of 1 year. Our findings suggest that bivalent vaccine containing H9 and H5 strains is equally effective and can be a good replacement of monovalent vaccines in order to minimize the inoculation stress to the birds and cost of production.