Journal of Infectious Diseases & Therapy
Open Access

Abstract

Avian influenza viruses (AIV) are classified as either low pathogenic (LP) or highly pathogenic (HP) due to their virulence in chickens. Highly pathogenic avian influenza viruses (HPAIV) exhibit a polybasic cleavage site (PCS) within the hemagglutinin (HA) protein and therefore the HA can be cleaved and activated by ubiquitous proteases causing severe systemic disease with high lethality. Naturally occurring HPAIV have always been of subtype H5 or H7 with very rare exceptions. Recently we showed that HPAIV can be created with other HA subtypes exhibiting an artificial PCS in a H5 HPAIV background and the introduction of a PCS within the HA in the parental background was not sufficient. Therefore, the objective of the study was to investigate the minimal requirement for exhibiting a highly pathogenic phenotype of non-H5/H7 LPAI viruses. Reverse genetics systems were established for LPAIV strains H4N6 and H8N4. Reassortants of LPAIV HA with artificial PCS and gene segments of a H5N1 HPAIV were generated and the virulence was ascertained in SPF chickens. In summary, the HPAIV H5N1 nucleoprotein (NP), neuraminidase (NA) and the matrix protein (M) segments conferred increased virulence. Whereas the impact on virulence of the NA and M gene segments differed, the NP gene of H5 HPAIV increased virulence in both H4 and H8 backgrounds. Furthermore, the impact of single NP amino acids was assessed.

Biography

Email: jutta.veits@fli.bund.de