Whole genome characterization of feline-like G3P[8] reassortant rotavirus A strains bearing the DS-1-like backbone genes detected in Vietnam, 2016

While conducting rotavirus gastroenteritis surveillance in Vietnam, two G3P[8] rotavirus A specimens possessing an identical short RNA electropherotype were detected. They were RVA/Human-wt/VNM/0232/2016/G3P[8] and RVA/Human-wt/VNM/0248/2016/G3P[8], and recovered from 9 and 23 months old boys, respectively. The patients developed diarrhoea within one-week interval in March 2016 but in places >100 km apart in northern Vietnam. Whole genome sequencing of the two G3P[8] rotavirus A strains revealed that their genomic RNA sequences were identical across the 11 genome segments, suggesting that they derived from a single clone. The backbone gene constellation was I2-R2-C2-M2-A2-N2-T2-E2-H2. The backbone genes and the VP4 gene had a virtually identical nucleotide sequences with identities ranging from 99.2 to 100% to the corresponding genes of RVA/Human-wt/VNM/1149/2014/G8P[8]; the prototype of recently-emerging bovine-like G8P[8] reassortant strains in Vietnam. On the other hand, the VP7 gene was 98.8% identical with that of RVA/Human-wt/CHN/E2451/2011/G3P[9], and they were clustered together in the lineage represented by RVA/Cat-tc/JPN/FRV-1/1986/G3P[9]. The observations led us to hypothesise that one of the bovine-like G8P[8] strains bearing the DS-1-like backbone genes reassorted with a locally circulating FRV-1-like strain to gain the G3 VP7 gene and to emerge as a thus-far undescribed feline-like G3P[8] reassortant strain. The identification of feline-like G3P[8] strains bearing the DS-1-like backbone genes exemplifies the strength and necessity of the whole genome sequencing approach in monitoring, describing and understanding the evolutionary changes that are occurring in emerging strains and their interactions with co-circulating strains.