First detection of a reassortant G3P[8] rotavirus A strain in Italy: a case report in an 8-year-old child.

Background: Acute gastroenteritis (AGE) due to group A rotavirus (RVA) agent is one of the major causes of hospitalization in paediatric age. The G3P[8] RVA genotype has been usually considered as one of the major human genotypes, largely circulating in Asia, but showing low detection rates in the European countries. In recent years, the G3P[8] RVAs emerged also in Europe as a predominant genotype and the viral strains detected revealed high similarities with equine-like G3P[8] RVA strains, resulting in a new variant circulating in humans and able to cause AGE in the paediatric population.

Case Presentation: An 8-year-old boy was admitted to the Emergency Room because he had suffered from severe diarrhoea, vomiting, and high fever over the previous two days. Severe dehydration was evident based on low serum concentrations of potassium and sodium, low glycaemia, and pre-renal failure (creatinine 2.48 mg/dL, urea 133 mg/dL). Immunological tests were within normal range. Enzyme immunoassay for the detection of RV was positive, and a sample of faeces was collected in order to perform the molecular characterization of the viral strain. The phylogenetic trees revealed relatedness between the VP7 and VP4 genes of the G3P[8] RVA Italian strain (namely PG2) and those belonging to recent G3P[8] RVAs detected worldwide. The G3 VP7 belonged to the G3-I lineage and shared the highest nucleotide sequence identity (99.8%) with the equine-like G3 previously identified in other countries. The P [8] VP4 revealed a similar clustering pattern to that observed for the VP7. In addition, the molecular characterization of the 11 gene segments of strain PG2 revealed a G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 genomic constellation.

Conclusions: This case shows the first detection in Italy of a reassortant G3P[8] RVA associated with a severe AGE, which is unusual in a school-age child without any known severe underlying problems. The findings reported in this paper highlight the importance of continuously monitoring the RVA strains circulating in paediatric age in order to detect novel viral variants able to spread in the general population.