Characterisation of influenza A H10N1 virus isolated from ducks in Lochinvar National Park Zambia

Abstract

The spectre of introduction of avian influenza in Zambia through migratory birds raises concerns for both human and animal health. Although avian influenza virus (AIV) surveillance has been on-going in wild waterfowl in Lochinvar national park (LNP) since 2006, little is known about the ecological drivers of AIV perpetuation in wild birds in Zambia. While several AIV subtypes have been isolated and characterized in Zambia, H10 viruses have not been studied. During routine AIV surveillance conducted in November 2014, of the 287 faecal samples collected from ducks, spur-winged geese and pelicans, four H10N1 viruses were isolated from ducks using embryonated eggs. In this study, the haemagglutinin (HA) and the neuraminidase (NA) genes of one of the isolates (designated A/duck/Zambia/36/2014 H10N1 (Dk-Zb14)) were amplified in a one-step reverse transcriptase polymerase chain reaction. Full length sequencing, phylogenetic and amino acid sequence analyses of the HA and NA genes was performed. The HA and NA gene phylogeny revealed that Dk-Zb14 belonged to the Eurasian-Avian lineage. The HA gene was closely related to that of A/Pekin duck/South Africa/AI1642/09 H10N7. In contrast, the NA gene was closely related to that of A/pelican/Zambia/13/09 H9N1 isolated in LNP. Dk-Zb14 had fewer glycosylation sites (3) than those reported for most AIVs. A glutamine to isoleucine substitution at the receptor biding site (position 226) was observed in the HA gene. The HA gene cleavage site had PEIMQGR?GLF amino acid motif, which is similar to previously described H10 isolates. Dk-Zb14 and Pel-Zb09 had ten amino acid differences within the NA gene. Additionally, the NA gene of Dk-Zb14 had a lysine at position 432 which formed a second neuraminic acid binding site. Surface glycoprotein phylogeny suggests interspecies transmission and maintenance of AIVs among wild and possibly domestic ducks within the Southern Africa ecosystem. These findings highlight the need for continued monitoring of AIVs in wild and domestic birds in the region.