Whole-genome sequence analysis of G3 and G14 equine group A rotaviruses isolated in the late 1990s and 2009-2010.

The research article presents a detailed analysis of whole-genome sequences of G3 and G14 equine rotavirus strains, isolated during the late 1990s and 2009-2010 in Japan, to understand their evolutionary patterns.

Study Background

• The study focuses on group A rotavirus strains G3P[12] and G14P[12], commonly found in horses, responsible for causing gastroenteritis in foals globally. Strains of G3P[12] and G14P[12] have been co-circulating in Japan since the latter emerged in the late the 1990s.
• With limited whole-genome sequence data on these recent Japanese strains of equine rotaviruses, there is a need to comprehend their evolutionary development better. This comprehension is vital in developing effective prevention strategies.

Methodology

• A whole-genome analysis of 23 equine rotavirus isolates from the late 1990s and 2009-10 and a vaccine strain RVA/Horse-tc/JPN/HO-5/1982/G3P[12] (HO-5) was conducted in the study.

Findings

• It was observed that the genome of G3 strains (including strain HO-5) had a genotype constellation of G3-P[12]-I6-R2-C2-M3-A10-N2-T3-E2-H7, with all 11 gene segments highly conserved, regardless of the time of isolation.
• The G14 strains portrayed the same genotype constellation but branched out into two lineages within the VP7-G14 and NSP4-E2 genotypes when viewed from a phylogenetic perspective.
• G14 strains were found to be closely related to G3 strains in their VP4, VP1-3, NSP1-3 and NSP5 gene segments.
• A unique observation was that the NSP4 gene of all G3 and G14 strains isolated in the late 1990s branched into a bovine-rotavirus-like NSP4 gene cluster.

Conclusion

• The findings suggest that, while the VP7, VP6, and NSP4 genes varied, the Japanese equine rotavirus strains shared a highly conserved genetic backbone.
• Additionally, it was noted that strains carrying a bovine-rotavirus-like NSP4 gene were dominant in the late 1990s in Japan. Knowledge of such conserved genes and evolving gene patterns can help in the development in effective vaccination strategies.