First influenza D virus full-genome sequence retrieved from livestock in Namibia, Africa

Influenza D virus (IDV) was first isolated in 2011 in the USA and has since been shown to circulate in cattle, pigs, sheep, wild boar, and camels. In Africa, there is limited data on the epidemiology of IDV and, so, we investigated the presence of IDV among domestic ruminants and wild animals in Namibia by screening nasal swabs using an IDV-specific molecular assay. IDV RNA was detected in bovines (n=2), giraffes (n=2) and wildebeest (n=1). The hemagglutinin-esterase-fusion (HEF) gene from one of the bovine and the wildebeest samples was successfully sequenced as well as the full genome for the second bovine sample. Phylogenetic analysis of the HEF gene positioned the African virus variants within the D/OK lineage but with a long branch. The African variant had an amino acid diversity of 2.41% and most likely represents a distinct genotype within the lineage. Notably, the polymerase acidic protein gene (PA) was more closely related to a different lineage (D/660), indicative of potential reassortment. This is the first genetic characterization of IDV in Africa and it adds important data to our understanding of the global IDV distribution.