Molecular analyses of G3A/G3B and G14 equine group A rotaviruses detected between 2012 and 2018 in Japan.

This research investigates the genotypes of Equine group A rotaviruses, which cause diarrhea in foals, from samples gathered between 2012 and 2018 in Japan. The study identified a genetic reassortment in specific genotypes, marking an emergence in G3A genotypes from 2016.

Objective and Methodology

• The researchers aimed to investigate the G genotypes of the equine group A rotaviruses (RVAs), primarily responsible for causing diarrhea in foals.
• Their investigation was based on 360 RVA-positive samples obtained from diarrheic foals in the Hidaka district of Hokkaido, Japan, over six years (2012 – 2018).
• The method used for the investigation was sequence analysis of VP7, a significant surface protein of the rotavirus that determines its G (glycoprotein) type.

Major Findings

• The samples collected were all classified into genotypes G3A, G3B, and G14.
• G3B RVAs were detected up until 2016, while G3A RVAs were identified from 2016 to 2018. G14 RVAs were detected throughout the entire period from 2012 to 2018.
• The researchers noticed a significant shift in the prevalence of the genotypes. G3B RVAs, which had been previously circulating in Japan for long, were suddenly replaced by the emergence of G3A RVAs in 2016.
• The molecular analyses of VP7 and VP4 showed a close relationship between these Japanese G3A RVAs and G3A RVAs found in North America in 2017. This suggests a potential intercontinental transmission of the virus.

Reassortments and Implications

• The research also involved an entire genome analysis that suggested genetic reassortments have occurred between G3A and G14 RVAs in NSP1, NSP2, NSP4, and NSP5.
• This finding is of vital importance as genetic reassortment often leads to the emergence of a new strain of viruses.
• The sudden emergence of G3A RVAs replacing G3B RVAs from 2017 may have been a result of such reassortments. Further research in this direction could inform new strategies for rotavirus vaccines in equines.