Immunogenicity and efficacy of fowlpox-vectored and inactivated avian influenza vaccines alone or in a prime-boost schedule in chickens with maternal antibodies.

Inactivated and fowlpox virus (FP)-vectored vaccines have been used to control H5 avian influenza (AI) in poultry. In H5 AI endemic countries, breeder flocks are vaccinated and therefore, maternally-derived antibodies (MDA) are transferred to their progeny. Results of three immunogenicity and one efficacy studies performed in birds with or without MDA indicated that the immunogenicity of an inactivated vaccine based on a H5N9 AI isolate (inH5N9) was severely impaired in chicks hatched from inH5N9-vaccinated breeders.

Compatibility of turkey herpesvirus-infectious bursal disease vector vaccine with Marek's disease rispens vaccine injected into day-old pullets.

Mixtures of turkey herpesvirus (HVT) and Rispens poultry vaccines have been used worldwide for over 20 yr, mainly for vaccination of future layers and breeders. With increasing virulence of Marek's disease (MD) virus strains, vaccination strategies are evolving toward the use of vaccines combining HVT and Rispens. A single vaccination either in ovo or at 1 day of age with the HVT + infectious bursal disease (IBD) vector vaccine is efficient against IBD.

Immunogenicity of poxvirus vector avian influenza vaccines in Muscovy and Pekin ducks.

Fowlpox (FP)-vectored avian influenza (FP-AI) vaccines are used in 1-day-old chickens, but they have also recently been shown to be immunogenic in ducks. The objectives of this work were 1) to evaluate safety and to compare the immunogenicity in ducks of three poxvirus vectors (fowlpox, canarypox, and vaccinia) expressing the same hemagglutinin gene from an H5N1 isolate, 2) to study the effect of the dose of the FP-AI and the presence of an adjuvant in 1-day-old Pekin ducks on antibody response after a boost with inactivated vaccine given 3 wk later, and 3) to confirm the immunogenicity of such a heterologous prime-boost vaccination scheme in 1-day-old Muscovy ducks. Immunogenicity induced by the three poxvirus vectors was comparable, and the FP vector was selected for the other studies.

Efficacy of two H5N9-inactivated vaccines against challenge with a recent H5N1 highly pathogenic avian influenza isolate from a chicken in Thailand.

The objective of this study was to compare the efficacy of two avian influenza (AI) H5-inactivated vaccines containing either an American (A/turkey/Wisconsin/68 H5N9; H5N9-WI) or a Eurasian isolate (A/chicken/Italy/22A/98 H5N9; H5N9-It). Three-week-old specific pathogen-free chickens were vaccinated once and challenged 3 wk later with a H5N1 highly pathogenic AI (HPAI) virus isolated from a chicken in Thailand in 2004. All unvaccinated challenged birds died within 2 days, whereas 90% and 100% of chickens vaccinated with H5N9-WI and H5N9-It, respectively, were protected against morbidity and mortality.