Molecular Characterization and Genetic Diversity of Isolated Foot-and-Mouth Disease Viruses Circulating in Cattle in The Mekong Delta Provinces, Vietnam.

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-footed livestock caused by foot-and-mouth disease virus (FMDV). FMD has significant impacts on farmers and national economies. The evolution and mutation of FMDV have contributed to the emergence of new strains of FMDV. Sequences of VP1 from 11 FMDV isolates in the Mekong Delta Provinces were obtained by Sanger sequencing technology. The phylogenetic analysis of VP1 sequence elucidated that 8 FMDV isolates including O-VN-CTU-VL01 (PP897837), O-VN-CTU-VL02 (PP897838), O-VN-CTU-TV01 (PP897840), O-VN-CTU-TV02 (PP897841), O-VN-CTU-TV03 (PP897842), O-VN-CTU-TV04 (PP897844), O-VN-CTU-BT04 (PP897847), and O-VN-CTU-BT05 (PP897847) were clustered into Group 1. On the other hand, 3 FMDV isolates including O-VN-CTU-BT01 (PP897844), O-VN-CTU-BT02 (PP897844), and O-VN-CTU-BT03 (PP897844) were clustered into Group 2. In addition, the nucleotide and deduced amino acid sequences of VP1 in Group 1 were closely related to lineage Mya-98, topotype SEA, and Type O (89%-93% nucleotide identity and 91%-99% amino acid identity). The similarity of FMDV isolates in Group 2 was closely related to lineage Pan Asia, topotype ME-SA, Type O (91.13%-94.53% and 96%-99.44% nucleotide and amino acid similarities, respectively). Analysis of amino acid sequences of VP1 illustrated several substitution mutations detected at amino acid positions 133-158 (the main antigenic site) in lineages Mya-98 (O/SEA) and Pan Asia, (O/ME-SA). Notably, a substitution mutation at position M144V was detected in FMDVs O-VN-CTU-VL1 (PP897837) and FMDV O-VN-CTU-TV1 (PP897840). No recombinant events were detected at VP1 sequences. In brief, genetic analysis of VP1 nucleotide and amino acid sequences of isolated FMDVs contributed to detecting the mutation which was able to cause the emergence of new strains as well as to elucidate the evolution of FMDVs circulating in the Mekong Delta Provinces.