Antibody Response After Vaccination Of Broiler Chickens With VAXXITEK® HVT+IBD Under Field Conditions

Grogan K. 

A field study examining seroconversion following vaccination with VAXXITEK HVT+IBD was conducted in Brazil in a large integrated broiler operation. Broiler flocks were monitored for VAXXITEK HVT+IBD uptake, field infectious bursal disease virus (IBDV) and chicken anemia virus (CAV) exposure via antibody response and virus detection. The aim of the study was to examine the effects of concurrent CAV exposure, if CAV exposure affects the antibody response to vaccine or alter the protection against IBDV. Early seroconversion was detected in all flocks to IBDV in response to vaccination. CAV antibodies were detected between 30-34 days & 37-41 days of age. Serology and histology demonstrated IBDV infection after 30 days of age for molecular groups 3 and 15 IBDVs. In this study, CAV infection did not impact seroconversion to vaccination. Immunosuppression is a constant battle in commercial poultry flocks. Many factors in the rearing environment, not limited to viruses and bacteria, can alter the birds immune response to pathogens and the vaccines we administer to improve health. Two viral agents are particularly notable for their immunosuppressive abilities, IBDV and CAV. Both viruses can create a lymphocytolytic infection that is capable of suppressing both humoral and cell-mediated immune functions [1]. To examine the potential effects of these two immunosuppressive agents in Brazilian broilers, a field study was conducted to determine if CAV exposure was affecting antibody response and protection to a recombinant IBDV vaccine administered in ovo. In addition, the study allowed better characterization of the antibody response after vaccination with VAXXITEK HVT+IBD in field conditions.