Inactivated North American and European H5N2 avian influenza virus vaccines protect chickens from Asian H5N1 high pathogenicity avian influenza virus

Abstract

High-pathogenicity (HP) avian influenza (AI) virus of the H5N1 subtype has caused an unprecedented epizootic in birds within nine Asian countries/regions since it was first reported in 1996. Vaccination has emerged as a tool for use in managing the infection in view of future eradication. This study was undertaken to determine whether two divergent H5N2 commercial vaccine strains, one based on a European and the other a North American low-pathogenicity AI virus, could protect chickens against a recent Asian H5N1 HPAI virus. The North American and European vaccine viruses had 84 and 91% deduced amino acid sequence similarity to the HA1 segment of haemagglutinin protein of Indonesia H5N1 HPAI challenge virus, respectively. Both vaccine strains provided complete protection from clinical signs and death. The vaccines reduced the number of chickens infected and shedding virus from the respiratory and intestinal tracts at the peak of virus replication. In addition, the quantity of virus shed was reduced by 10 4 to 10 5 median embryo infectious doses. The use of specific neuraminidase inhibition tests allowed identification of infected chickens within the vaccinated groups. These data indicate that the currently available H5 vaccines of European and North American lineages will protect chickens against the Asian H5N1 HPAI virus and reduce environmental contamination by the H5N1 HPAI virus. They will be an adjunct to biosecurity measures to reduce virus transmission.

Evaluation of the protection induced by avian influenza vaccines containing a 1994 Mexican H5N2 LPAI seed strain against a 2008 Egyptian H5N1 HPAI virus belonging to clade 2.2.1 by means of serological andin vivotests

“…The results comply with previous work in which the ability of genetically distant vaccines against avian influenza in preventing infection, disease, and transmission in chickens and ducks was investigated (Swayne et al, 2006;Van der Goot et al, 2008). In these papers the authors showed that despite the low level of homology between the challenge viruses (Asian HPAI H5N1) and the vaccine strain (Mexican LPAI H5N2) transmission, the mortality and disease rate were markedly reduced after vaccination.…”

“…This system was developed to support the eradication programmes in the presence of several introductions of AI viruses (Capua & Alexander, 2004;. Previous studies have shown that vaccine containing the H5N2 A/chicken/Mexico/232/94/CPA strain is protective in chickens and ducks against H5N1 HPAI viruses of the Eurasian lineage despite the low haemagglutination (HA) homology between the vaccine strain and the field virus (Swayne et al, 2006;Van der Goot et al, 2008).…”

A consensus–hemagglutinin-based DNA vaccine that protects mice against divergent H5N1 influenza viruses

“…Influenza vaccines based on inactivated virions have been shown to confer protection against H5N1 infection in animals. For example, inactivated H5N2 vaccines adjuvanated with oil emulsion have been widely used in chickens to protect against H5N1 viruses (11). A similar approach using H5N3 viruses, however, induced only limited protection in mice (12).…”

Transmissibility of the highly pathogenic avian influenza virus, subtype H5N1 in domestic poultry: a spatio-temporal estimation at the global scale

“…Thus, the minimum vaccination coverage needed in the sub-district poultry population would be 21%, 51% and 32%, respectively, and the maximum value (51%) should be used as target to completely bring the epidemic under control. It should be acknowledged that vaccine efficacy is never 100% (van der Goot et al, 2005;Swayne et al, 2006;Webster et al, 2006), so an extra amount of vaccination coverage should always be added, e.g., 10% (van der Goot et al, 2005;Savill et al, 2006;Tiensin et al, 2007). Two issues must be stressed.…”