RESUMO
The protective properties of an inactivated bluetongue virus serotype 2 (BTV-2) vaccine were evaluated in sheep. Sheep (two groups of seven), vaccinated with either one or two doses of the vaccine, were monitored for antibody response over one year. All sheep developed high titres of neutralizing antibodies by 35 days after first vaccination and titres were maintained over one year. Control sheep (n=7) remained seronegative until challenge. One year after vaccination, all sheep were inoculated with a virulent BTV-2. All controls developed pyrexia, clinical signs and viraemia. In contrast, the sheep vaccinated with one or two doses of inactivated BTV-2 vaccine were protected from clinical disease and viraemia was completely prevented. These data show that a single dose of the BTV-2 vaccine given to sheep induces a strong immunity which confers protection for at least one year.
Assuntos
Vírus Bluetongue/imunologia , Vírus Bluetongue/patogenicidade , Bluetongue/imunologia , Bluetongue/prevenção & controle , Ovinos/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Vírus Bluetongue/classificação , Temperatura Corporal , Feminino , Fatores de Tempo , Titulometria , Vacinas de Produtos Inativados/efeitos adversos , Vacinas de Produtos Inativados/imunologia , Vacinas Virais/efeitos adversos , VirulênciaRESUMO
The efficacy of different vaccination schedules was evaluated in 17-day-old Pekin ducks using an experimental inactivated whole virus vaccine based on the H5N9 A/chicken/Italy/22A/98 isolate (H5N9-It) and/or a fowlpox recombinant (vFP-H5) expressing a synthetic HA gene from an Asian H5N1 isolate (A/chicken/Indonesia/7/2003). Full protection against clinical signs and shedding was induced by the different vaccination schemes. However, the broadest antibody response and the lowest antibody increase after challenge were observed in the group of ducks whose immune system was primed with the fowlpox vectored vaccine and boosted with the inactivated vaccine, suggesting that this prime-boost strategy induced optimal immunity against H5N1 and minimal viral replication after challenge in ducks. In addition, this prime-boost vaccination scheme was shown to be immunogenic in 1-day-old ducklings.
