# Whole‐Genome Characterization of Rare Artiodactyl‐Like G10P [14] and G8P [14] Rotavirus a Strains Detected in Pediatric Gastroenteritis Cases in Hokkaido Prefecture, Japan

## TL;DR

This study identifies rare rotavirus strains in children in Japan, which resemble those found in artiodactyl animals and may not be fully covered by current vaccines.

## Contribution

The study reports the whole-genome characterization of rare artiodactyl-like RVA strains with potential implications for vaccine effectiveness.

## Key findings

- Three artiodactyl-like RVA strains (G10P[14] and G8P[14]) were identified in pediatric cases in Japan.
- The strains showed low nucleotide identity with each other and previously reported artiodactyl RVA strains.
- A detected strain showed significant antigenic differences from the Rotarix vaccine strain.

## Abstract

Rotavirus alphagastroenteritidis (RVA) is the leading cause of acute gastroenteritis in young children worldwide, as well as in a wide range of animal species. In 2020 and 2022, we identified three unusual RVA strains in pediatric gastroenteritis patients in Hokkaido Prefecture, Japan, using next‐generation sequencing: one G10P[14] strain (Ni20‐23) and two G8P[14] strains (Ni20‐37 and To22‐1). All three strains possessed the genotype constellation G10/G8‐P[14]‐I2‐R2‐C2‐M2‐A3‐N2‐T6‐E2‐H3. Phylogenetic analyses of these 11 genome segments indicated that the strains were artiodactyl‐like RVAs. However, no genome segment exhibited > 98% nucleotide identity among the three strains, suggesting that they originated from distinct artiodactyl RVA strains. Furthermore, no previously reported artiodactyl RVA strain showed > 90% nucleotide identity across all 11 segments; thus, the direct animal origins of these strains remain unclear. As observed in these strains, nearly all artiodactyl‐like RVAs previously detected in humans have carried the VP4 genotype P[14], indicating a potential role of P[14] in facilitating cross‐species transmission. One strain (To22‐1/G8P[14]) was detected in a child who had received two doses of Rotarix (G1P[8] monovalent vaccine). Comparative amino acid analysis of VP4 between the To22‐1/G8P[14] strain and the P[8] Rotarix vaccine strain revealed substitutions at 18 of 37 (48.6%) known antigenic epitope sites, suggesting a potential antigenic mismatch. Continued surveillance and further studies are warranted to elucidate the mechanisms underlying interspecies transmission of artiodactyl‐like P[14] RVAs and to assess the effectiveness of current vaccines against such strains.