Full genome-based characterization of G4P[6] rotavirus strains from diarrheic patients in Thailand: Evidence for independent porcine-to-human interspecies transmission events.

The exact evolutionary patterns of human G4P[6] rotavirus strains remain to be elucidated. Such strains possess unique and strain-specific genotype constellations, raising the question of whether G4P[6] strains are primarily transmitted via independent interspecies transmission or human-to-human transmission after interspecies transmission. Two G4P[6] rotavirus strains were identified in fecal specimens from hospitalized patients with severe diarrhea in Thailand, namely, DU2014-259 (RVA/Human-wt/THA/DU2014-259/2014/G4P[6]) and PK2015-1-0001 (RVA/Human-wt/THA/PK2015-1-0001/2015/G4P[6]). Here, we analyzed the full genomes of the two human G4P[6] strains, which provided the opportunity to study and confirm their evolutionary origin. On whole genome analysis, both strains exhibited a unique Wa-like genotype constellation of G4-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1. The NSP1 genotype A8 is commonly found in porcine rotavirus strains. Furthermore, on phylogenetic analysis, each of the 11 genes of strains DU2014-259 and PK2015-1-0001 appeared to be of porcine origin. On the other hand, the two study strains consistently formed distinct clusters for nine of the 11 gene segments (VP4, VP6, VP1-VP3, and NSP2-NSP5), strongly indicating the occurrence of independent porcine-to-human interspecies transmission events. Our observations provide important insights into the origin of zoonotic G4P[6] strains, and into the dynamic interaction between porcine and human rotavirus strains.

Genomic characterization of a novel G3P[10] rotavirus strain from a diarrheic child in Thailand: Evidence for bat-to-human zoonotic transmission.

An unusual rotavirus strain with the G3P[10] genotype (RVA/Human-wt/THA/MS2015-1-0001/2015/G3P[10]) was identified in a stool sample from a hospitalized child aged 11 months with severe gastroenteritis in Thailand. In the current study, we sequenced and characterized the full genome of strain MS2015-1-0001. On full-genomic analysis, strain MS2015-1-0001 exhibited the following genotype configuration: G3-P[10]-I8-R3-C3-M3-A9-N3-T3-E3-H6, which is identical or closely related to those of bat and bat-like rotavirus strains (MYAS33-like). Furthermore, phylogenetic analysis revealed that all 11 genes of strain MS2015-1-0001 appeared to be of bat origin. Our findings provide evidence for bat-to-human interspecies transmission of rotaviruses and important insights into dynamic interactions between human and bat rotavirus strains.