Genotyping of duck hepatitis virus type 3 isolated in Vietnam during 2009-2013

The entire sequences for VP1 gene of ten DHAV samples isolated during 2009-2013 from six provinces in Vietnam were obtained. Based on high identity (91-100%) for nulcleotide and amino acid, DHAV strains of Vietnam belonged to genotype 3 (DHAV-3) and have a “hyper variable region” at C-terminal of VP1. Notably, 6/10 strains of Vietnam showed four consistent differences within this group but distinct from all other DHAV-3 global strains (The positions are T184M, Q200H, K207N, K214R). Phylogenetic analysis indicated that DHAV-3 strains divided into three main clades, of which four of ten Vietnamese isolates were clustered in the same clade with the Chinese strains (Clade 1). Six of others belonged to clade 3 close to the Chinese B63 strain. Four Korean strains formed a separate clade (Clade 2).