Identification of a novel intra-genotype reassortant G1P[8] rotavirus in Italy, 2021

Objectives: Rotaviruses G1P[8] are epidemiologically relevant and are targeted by vaccines. The introduction of vaccines has altered rotavirus epidemiology. Hospital -based surveillance conducted in Sicily, Italy, showed a progressive decline in rotavirus prevalence since 2014, along with an increasing vaccine coverage (63.8% in 2020), and a marked decrease in circulation of G1P[8] strains. Surprisingly in 2021, G1P[8] viruses accounted for 90.5% (19/21) of rotavirus infections. This study aimed to understand if the increased activity of G1P[8]'s was related to virus -related peculiarities. Design: In 2021, 266 patients < 15 years of age were hospitalized with acute gastroenteritis (AGE) and included in rotavirus surveillance. Viral proteins (VP7 and VP4) genotyping and sequence data were generated from all rotavirus-positive samples. The genetic makeup of G1P[8] rotaviruses was investigated by full-genome sequencing. Results: Peculiar G1P[8] rotaviruses, with VP7 and VP4 belonging to novel sub -lineages, circulated in 2021, accounting for 76.2% (16/21) of all rotavirus infections. On full-genome analysis, the novel G1P[8] variant displayed an intra-genotype (Wa-like) reassortant constellation, involving G12 and G1 strains, into a unique arrangement never observed before. The novel G1P[8] variant showed peculiar amino acid substitutions in 8-1 and 8-3 epitopes of the VP4 with respect to the Rotarix strain. Conclusions: Prompt identification of virus variants circulating in the human population is pivotal to understanding epidemiological trends and assessing vaccine efficacy. (c) 2024 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY -NC -ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )