Unexpected predominance of rotavirus G9P[8] strain in Tunisian adult diarrheal patients.

Introduction. Group A Rotavirus (RVA) is known to be a major cause of acute gastroenteritis (AGE) in children but its role as a potential pathogen in immunocompetent adults is probably underestimated. Aim. To compare RVA infections in patients from different age groups. Methodology. Fecal samples were collected from patients aged from birth to 65 years, hospitalized or consulting for AGE between 2015 and 2017. All samples were screened by RT-PCR for the detection of VP6 gene specific of RVA. RVA-positive samples were VP7 and VP4 genotyped using multiplex semi-nested RT-PCR. Full-length VP7 gene of G9-positive strains were sequenced and submitted for phylogenetic analysis. Results. Of 1371 stool specimens collected from children (<5 years; n=454), older children (5 to <15 years; n=316) and adults (15-65 years; n=601), 165 (12.0%) were RVA-positive. RVA detection rates were significantly higher in children and adults than in older children (15.8% and 12.1 Vs 6.3%, respectively; P<0.001). While RVA infections were mostly detected during the coldest months in children, they were observed all year-round in patients aged >5 years. Although G1P[8] remained the most prevalent combination (41.7%) detected in children, G9P[8] strains widely predominated in adults (58.1 %), followed by G2P[4] (12.9%). All characterized G9 strains clustered in the modern lineage III. Conclusion. RVA play an important role in AGE not only in children but also in adults. The findings of a wide G9 predominance in patients >5 years highlights the need for continuing surveillance in both pediatric and mature populations.