|To, Thanh Long|
Submitted to: International Symposium on Avian Influenza
Publication Type: Abstract Only
Publication Acceptance Date: 1/28/2009
Publication Date: 4/5/2009
Citation: Pfeiffer, J., Suarez, D.L., Sarmento, L., To, T., Nguyen, T., Pantin Jackwood, M.J. 2009. Efficacy of commercial vaccines in chickens and ducks against H5N1 highly pathogenic avian influenza viruses from Vietnam [abstract]. 7th International Symposium on Avian Influenza, April 5-8, 2009, Athens, Georgia. p. 28. Interpretive Summary:
Technical Abstract: Highly pathogenic (HP) H5N1 avian influenza (AI) viruses continue to circulate in Asia and have spread to other regions of the world. Though attempts at eradication of the viruses during various outbreaks have been successful for short periods of time, new strains of H5N1 viruses continue to emerge and have become endemic throughout Asia. In countries like Vietnam, domestic ducks have been recognized as a primary factor in the spread of AI. Vaccination is a part of Vietnam’s AI control program and includes chickens and domestic ducks. Despite the use of vaccination, eradication of the disease has not been possible, due to the emergence and spread of new viruses. In this study we tested the abilities of three commercial inactivated avian influenza oil emulsion vaccines of different genetic origin to protect against disease and viral shedding in both two-week old white leghorn chickens and one-week-old Pekin ducks challenged with HPAI H5N1 viruses from Vietnam. Most vaccinated chickens were protected from clinical disease and had reduced oropharyngeal shedding of virus, compared to unvaccinated birds. All but one vaccinated duck were protected from mortality and disease, however, a different effect on viral shedding was observed between vaccines. While the current vaccines demonstrated to be effective, differences in hemagglutination inhibition antibody titers induced by the vaccines were observed in both chickens and ducks, suggesting it is time to consider using a more recent isolate as a seed for the vaccine to maintain optimal protection.