High prevalence of DS-1-like rotavirus infection in Thai adults between 2016 and 2019

Rotavirus infection is the most common cause of viral diarrhea in infants and young children but uncommon and usually asymptomatic in adults. In the winter of 2017-2018, a large-scale outbreak of rotavirus in both children and adults was reported in Thailand. The current study focused on the prevalence, genotyping, and molecular characterization of rotavirus infections in Thai adults from July 2016 to December 2019. In 2,598 stool samples collected from adult residents of Bangkok (aged #x2265; 15 years) with acute gastroenteritis, rotavirus was detected via real-time RT-PCR analysis of theVP6gene.G,PandIgenotypes were determined by direct sequencing ofVP7,VP4, andVP6genes, respectively. Our results showed 8.7% (226/2,598) of stool samples were positive for rotavirus. The incidence of rotavirus was high during the winter season of 2017-2018 (17.7%) compared to another studied periods (4.5% between July 2016- October 2017 and 2.8% between March 2018- December 2019). Nucleotide sequencing ofVP7andVP4revealedG3P[8]as the predominant strain (33.2%,75/226), followed byG9P[8](17.3%,39/226), andG2P[4](15.0%,34/226). Uncommon G and P combinations were additionally detected at low frequencies.VP6sequencing was conducted to discriminateIgenotype between the Wa and DS-1 genogroup. The unusual DS-1-likeG3P[8]strain was most prevalent amomg rotavirus strains detected in this study (29.6%, 67/226), and the correspondingVP7sequences showed high nucleotide identity with unusual DS-1-like globally circulating strains. Our study demonstrates that rotavirus outbreaks in adults are attributable not only to high prevalence of RV infection but also the unusual DS-like genogroup. The collective findings reinforce the importance of investigating rotavirus diagnosis in adults suffering from acute gastroenteritis and taking appropriate preventive measures.