Submitted to: Avian Influenza Symposium International Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2006
Publication Date: 4/3/2006
Citation: Bublot, M., Pritchard, N., Cruz, J., Mickle, T.R., Selleck, P., Swayne, D.E. 2006. Efficacy of the fowlpox vectored vaccine Trovac-AIV H5 against highly pathogenic Asian H5N1 avian influenza challenge [abstract]. Abstracts of the 6th International Symposium on Avian Influenza, April 3-6, 2006, Cambridge, United Kingdom. p. 35. Interpretive Summary:
Technical Abstract: TROVAC-AIV H5 (TROVAC) is a licensed avian influenza (AI) vaccine that contains a fowlpox recombinant expressing the hemagglutinin of the A/turkey/Ireland/1378/83 H5N8 isolate. TROVAC vaccine was shown to be protective against a panel of HPAI H5 isolated from 1959 to 1997. Recently, Swayne (2004)* showed that TROVAC protected against a recent H5N1 isolate (A/chicken/SouthKorea/03, SK03). Here, we evaluate the efficacy of TROVAC (1) against escalating doses of SK03 and (2) against a 2004 Vietnam H5N1 isolate. In both studies, one-day old SPF chickens were vaccinated by SC route with a field dose of TROVAC and challenged 3 weeks later by the oro-nasal route. In the first study, mortality in the control groups reached 80% and 100% after challenge with 3.5-8.0 log10 EID50 of SK03, respectively. Full and 80% protection against mortality/morbidity was induced by TROVAC after challenge with 3.5-6.5 and 8.0 log10 EID50 of SK03, respectively. A 2-4 log10 and >4 log10 reduction of oral and cloacal shedding were observed in TROVAC vaccinated birds, respectively. TROVAC vaccination induced HI antibodies (7-8 log2) detectable with the homologous H5N8 antigen; the boost in HI titers after challenge was challenge dose-dependent. In the second study, TROVAC-vaccinated chicks were fully protected against morbidity and mortality after challenge with A/chicken/Vietnam/04, whereas unvaccinated chickens died within 2 days after challenge. Altogether, these results confirm the excellent level of protection induced by TROVAC against recent Asian HPAI H5N1 isolates. *Swayne (2004) In “Control of Infectious Animal Diseases by Vaccination” Schudel and Lombard (eds) Dev Biol Basel Karter, 119, pp219-228.