Detection of unusual G6 rotavirus strains in Italian children with diarrhoea during the 2011 surveillance season.

Two rare G6 rotavirus A (RVA) strains, designated as RVA/human-wt/ITA/CEC06/2011/G6P[6] and RVA/human-wt/ITA/PG05/2011/G6P[9], were identified in stool specimens from children hospitalized in Central Italy. After PCR genotyping, the samples CEC06 and PG05 gave G-UD-P[6] and G-UD-P[9] genotypes, respectively. To determine the G-type and to characterize further the two strains, sequencing of 8 of the 11 genomic segments was performed. CEC06 and PG05 strains were found to possess unusual genotype constellations: G6-P[6]-I2-A2-N2-T2-E2-H2 and G6-P[9]-I2-A3-N2-T3-E3-H3, respectively. This study reports the first detection of rare G6P[6] and G6P[9] RVA strains in peninsular Italy. Phylogenetic analysis of VP4 (VP8*), VP7, VP6, and NSP1-5 showed no evidence of zoonosis or inter-species reassortment, revealing for both strains constellations previously associated to human cases.