Speaker
Description
According to the definition of the OIE, highly pathogenic (HP) avian influenza viruses (AIVs) are any AIV with an intravenous pathogenicity index (IVPI) ≥1.2, or H5 and H7 viruses with a polybasic cleavage site (CS) in the hemagglutinin (HA). However, according to this definition non-H5/H7 viruses with a polybasic CS, which were rarely reported from nature, are classified as low pathogenic (LP). In 2012, an H4N2 virus with a polybasic CS (322PEKRRTR/G329) and IVPI of 0 was isolated from quails in California. Here, we investigated the virulence of this virus after (1) insertion of point mutations in the CS, (2) reassortment with HPAIVs and (3) passaging in embryonated chicken eggs. All gene segments of H4N2 virus were cloned and threonine at position 327 in the CS was changed either to arginine (R327) or lysine (K327). Beside the wild-type (wt) virus, a mutant possessing the CS of a HP H5N2-strain and viruses carrying R327 or K327 in the CS with or without gene segments from HPAIVs A/swan/Germany/R65/2006(H5N1) or A/chicken/Germany/AR1385/2015(H7N7) were generated. Chickens were inoculated via intravenous (IV) or oculonasal (ON) routes. HPAIV H5N1 carrying either the wildtype H4 HA or variants at position 327, and the wt virus after 20 egg passages exhibited IVPI > 2.0. The IVPI values of the other viruses ranged from 0 to 0.6 indicating low virulence. Together, the H4N2 virus with a polybasic CS may shift to high virulence, resembling H5/H7 viruses after few genetic changes in the HA or serial passages.
| Choose primary session | Pathogenesis |
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| Choose secondary Session | Evolution and Emerging viruses |
