Phylogenetic Analysis of G and P Genotypes of Bovine Group A Rotavirus Strains Isolated from Diarrheic Vietnam Cows in 2017 and 2018

SIMPLE SUMMARY: Group A rotaviruses (RVAs) are thought to be the major cause of neonatal calf diarrhea worldwide. RVA-induced diarrhea in calves results in large economic losses to farmers in terms of treatment costs and reduced weight gain. Recent studies reveal that bovine RVA is caused predominantly by G6P[1] in China, G10P[11] in Japan, and G6P[5] in South Korea, Bangladesh, and Uruguay. In Vietnam, most RVA studies have been conducted in humans, with little information available for viruses in livestock. Therefore, for the first time, we performed a genetic analysis of RVAs prevalent in Vietnamese cows. ABSTRACT: This study aimed to investigate the genetic diversity of G- and P-type bovine RVAs (BoRVAs) prevalent in Vietnam. Between 2017 and 2018, the prevalence of BoRVAs detected in diarrhea samples from 8 regions was as low as 1.9% (11/582). The prevalence of the G-type was 45.5% for G6 and 18.2% for G10; however, 36.3% remain unidentified. Interestingly, all BoRVAs were investigated as P[11], and there was no diversity within this P-type. Geographically, the G6 and G10 types were not identified in any specific area; rather, they occurred in both Northern and Southern Vietnam. G6P[11] and G10P[11], which are combined G- and P-types, were identified in 71.4% and 28.6% of BoRVA-positive samples, respectively. Phylogenetic tree analysis revealed that the G6-type detected in Vietnamese cows is similar to strains derived from China, Japan, and Korea, whereas the G10 type is closely related to the Chinese strain. In addition, the P11 strain detected in Vietnamese cows is similar to the Spanish and Chinese strains. The BoRVA-positive rate was higher in cows aged less than 2 months (3.2%, 3/94) than in those aged 2 months or more (1.6%, 8/488). In summary, we detected the presence of G6P11 and G10P11 BoVRAs on Vietnamese cow farms, and found that they were more predominant in young calves than in older cows.