Efficacy of rHVT-AI Vector Vaccine in Broilers with Passive Immunity Against Challenge with Two Antigenically Divergent Egyptian Clade 2.2.1 HPAI H5N1 Strains

• DOI: 10.1637/10172-041012-reg.1
• Publication Date: 2013-01-03T05:29:21Z
• Authors: F. Rauw; V. Palya; Y. Gardin; T. Tatar-Kis; K. Moore Dorsey; B. Lambrecht; T. van den Berg
• Keywords: Inactivated vaccine; Viral Shedding; Highly pathogenic

In countries where avian influenza has become endemic, early vaccination of layer pullets or broilers with classical inactivated vaccines at the hatchery is no longer an option because interference passive immunity indirectly induced by necessary breeders. On other hand, injection thousands chicks from 7 to 10 days old on farms been determined be unreliable and, therefore, poorly efficacious. For these reasons, interest arisen regarding a newly developed live recombinant vector vaccine based turkey herpesvirus (HVT) expressing H5 gene clade 2.2 H5N1 highly pathogenic virus (HPAIV) strain (rHVT-H5), which in theory capable breakthrough both and insert (H5) consequently applicable hatchery. The objectives this trial were evaluate impact maternally derived antibodies (MDAs) specific efficacy (protection shedding) different programs including rHVT-H5 H5N2 applied alone combination. Therefore, carrying MDAs against HVT Asian HPAIV vaccinated first day age rHVT-H5, without boosting after days. groups challenged two antigenically divergent Egyptian dade 2.2.1 HPAIVs 4 wk age. Protection challenge was compared unvaccinated birds MDAs. Between 70% 90% clinical protection could observed possessing MDAs, indicating very low vaccination. Results protection, humoral, cell-mediated, mucosal immunity, as well re-excretion are presented discussed.