Detection of Virulent Gumboro Isolates of Euro-American Sublineage in Vietnam by Molecular Analysis of Gene VP2

Abstract

Genetic properties of Gumboro virus tend to divide the strains into two different groups, ie Asian and Euro-American sublineages. Using RT-PCR, cloning and sequencing, the entire VP2 (1359 bp) for virulent Gumboro isolates recently collected in Vietnam, viz. BDG23 (Binh Dương) and GPT (Phuc Tho), were obtained and genetically characterized with other Vietnamese (GHUT1; GSG4; GT1ST; BDG) and  foreign strains including SH92 (Korea), HK46 (Hong Kong), JD1 (China), OKYM (Japan), 52-70, D78, Gvx2512, GvxBL (USA). Based on the variation rule for antigen and virulence in the VP2 sequence, it was revealed that GPT was highly virulent, being grouped with other Vietnamese strains as members of the Asian sublineage. Meanwhile BDG23, analysed as a mild virulent strain, along with GSG4, belongs to the Euro-American sublineage. Phylogenetic analysis also confirmed the mixed, multi-lineaged origin of the Gumboro population in Vietnam.