Unusual G3P[10] bat-like rotavirus strains detected in children with acute gastroenteritis in Thailand

Rotavirus A (RVA) is the main cause of acute gastroenteritis among children under the age of five globally. The unusual bat-like human RVA strains G3P[10] (RVA/Human-wt/THA/CMH079/05/2005/G3P[10] and RVA/Human-wt/THA/CMH-S015-19/2019/G3P[10]) were detected in children with acute gastroenteritis in 2005 and 2019, respectively, in the same geographical area of Northern Thailand. To elucidate the genetic backgrounds of these unusual or bat-like human RVA strains, the complete genome of these RVA strains was sequenced and phylogenetically analyzed. All eleven genome segments of these G3P[10] strains were genotyped as G3-P[10]-I8-R3-C3-M3-A9-N3-T3-E3-H6, which is closely related to bat G3P[10] RVA strain (RVA/Bat-tc/CHN/MYAS33/2013/G3P[10]) and bat-like human RVA strain (RVA/Human-wt/THA/MS2015-1-0001/2015/G3P[10]). The findings indicate that human G3P[10] RVA strains detected in this study (RVA/Human-wt/THA/CMH079/05/2005/G3P[10] and RVA/Human-wt/THA/CMH-S015-19/2019/G3P[10]) contained all eleven genome segments similar to those of bat RVA strains and appeared to be human RVA strains of bat origin. Phylogenetic analysis revealed that several genome segments of these two RVA strains were also closely related with those of other species in addition to bats and had a zoonotic transmission history. The results of this study supported the roles of interspecies transmission of RVA strains among bats and humans in the natural environment and provided convincing evidence that the evolution of human RVAs was closely interrelated with those of animal RVAs. Continuing surveillance of RVAs in humans and animals is imperative to gain a better understanding of the origin and the evolution of these viruses.