Molecular analysis of group A rotaviruses detected in adults and adolescents with severe acute gastroenteritis in Italy in 2012

Hospital-based surveillance of acute gastroenteritis caused by rotavirus has produced ample knowledge on the infection in children, whereas little is known on rotavirus infection among adults. The Italian surveillance program RotaNet-Italia collected 1,595 samples from patients admitted to hospital with gastroenteritis in 2012. All patients presented with vomiting, diarrhea, fever, and/or abdominal pain. Forty-two samples obtained by the RotaNet-Italia (2.6%) were from adolescents or adults (10-89 years). The study compared the genotypes and gene sequences of the rotavirus strains identified in adults with strains obtained from children worldwide. All 42 Italian strains were genotyped by the EuroRotaNet RT-nested-PCR protocols, and 12 rotaviruses from patients >13-year-old were subjected to nucleotide sequencing of their VP7 and/or VP4 genes. All strains analyzed belonged to the common human genotypes G1P[8], G2P[4], G4P[8], and G9P[8], except an uncommon G3P[19] genotype detected in a single patient. Phylogenetic analysis of the 12 strains showed that within each genotype they clustered in RVA lineages reported worldwide. The amino acid sequences of the VP7 and the VP8* hypervariable regions were highly conserved between the RVA strains collected from adults and children, in each lineage. Genotyping, phylogenetic analysis, and the study of viral epitopes revealed that rotaviruses circulating in adults in Italy are closely similar to the strains circulating in children, with high nucleotide identity particularly with strains reported in Europe and Asia. The circulation of the same rotavirus strains in both children and adults suggests that adults may contribute to sustain the circulation of rotaviruses through the population.