Dataset Information

Modulation of the severity of highly pathogenic H5N1 influenza in chickens previously inoculated with Israeli H9N2 influenza viruses.

ABSTRACT: The continued evolution of H9N2 and H5N1 viruses and their spread and re-emergence across Eurasia raise concern that prior H9N2 virus infection may limit the detection of subsequent H5N1 infection in gallinaceous poultry by attenuating the severity of disease. We show that H9N2 viruses isolated from Israeli turkeys during 2000-2004 were antigenically and genetically distinguishable. These three H9N2 viruses caused no overt signs of disease in chickens. The 2004 isolate replicated and spread most efficiently, and chickens previously inoculated with this H9N2 virus showed 90%-100% survival after inoculation 1 to 35 days later with lethal H5N1 virus. Chickens that survived did not show signs of disease but did shed lethal H5N1 virus from the cloaca. The modulation of survivability was time-dependent; the effect was maximal 5 days after H9N2 inoculation. These findings suggest that co-circulation of H9N2 viruses can contribute to the spread of lethal H5N1 viruses.

SUBMITTER: Khalenkov A

PROVIDER: S-EPMC2632966 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Modulation of the severity of highly pathogenic H5N1 influenza in chickens previously inoculated with Israeli H9N2 influenza viruses.

Khalenkov Alexey A Perk Shimon S Panshin Alexander A Golender Natalia N Webster Robert G RG

Virology 20081107 1

The continued evolution of H9N2 and H5N1 viruses and their spread and re-emergence across Eurasia raise concern that prior H9N2 virus infection may limit the detection of subsequent H5N1 infection in gallinaceous poultry by attenuating the severity of disease. We show that H9N2 viruses isolated from Israeli turkeys during 2000-2004 were antigenically and genetically distinguishable. These three H9N2 viruses caused no overt signs of disease in chickens. The 2004 isolate replicated and spread most ...[more]

PMID: 18992907

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Project description:The cocirculation of zoonotic highly pathogenic avian influenza virus (HPAIV) of subtype H5N1 and avian influenza virus (AIV) of subtype H9N2 among poultry in Egypt for at least 6 years should render that country a hypothetical hot spot for the emergence of reassortant, phenotypically altered viruses, yet no reassortants have been detected in Egypt. The present investigations proved that reassortants of the Egyptian H5N1 clade 2.2.1.2 virus and H9N2 virus of the G1-B lineage can be generated by coamplification in embryonated chicken eggs. Reassortants were restricted to the H5N1 subtype and acquired between two and all six of the internal segments of the H9N2 virus. Five selected plaque-purified reassortant clones expressed a broad phenotypic spectrum both in vitro and in vivo Two groups of reassortants were characterized to have retarded growth characteristics in vitro compared to the H5N1 parent virus. One clone provoked reduced mortality in inoculated chickens, although the characteristics of a highly pathogenic phenotype were retained. Enhanced zoonotic properties were not predicted for any of these clones, and this prediction was confirmed by ferret inoculation experiments: neither the H5N1 parent virus nor two selected clones induced severe clinical symptoms or were transmitted to sentinel ferrets by contact. While the emergence of reassortants of Egyptian HPAIV of subtype H5N1 with internal gene segments of cocirculating H9N2 viruses is possible in principle, the spread of such viruses is expected to be governed by their fitness to outcompete the parental viruses in the field. The eventual spread of attenuated phenotypes, however, would negatively impact syndrome surveillance on poultry farms and might foster enzootic virus circulation.IMPORTANCE Despite almost 6 years of the continuous cocirculation of highly pathogenic avian influenza virus H5N1 and avian influenza virus H9N2 in poultry in Egypt, no reassortants of the two subtypes have been reported. Here, the principal compatibility of the two subtypes is shown by forcing the reassortment between copassaged H5N1 und H9N2 viruses in embryonated chicken eggs. The resulting reassortant viruses displayed a wide range of pathogenicity including attenuated phenotypes in chickens, but did not show enhanced zoonotic propensities in the ferret model.

Dataset Information

Modulation of the severity of highly pathogenic H5N1 influenza in chickens previously inoculated with Israeli H9N2 influenza viruses.

Publications

Modulation of the severity of highly pathogenic H5N1 influenza in chickens previously inoculated with Israeli H9N2 influenza viruses.

Similar Datasets

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