Norovirus molecular detection in Uruguayan sewage samples reveals a high genetic diversity and GII.4 variant replacement along time

AimsTo determine the prevalence and molecular epidemiology of norovirus (NoV) genogroup I (GI) and GII in Uruguay. Methods and ResultsOne hundred and sixteen sewage samples were collected in six cities (Bella Union, Salto, Paysandu, Fray Bentos, Melo and Treinta y Tres) from March 2011 to April 2013, viruses were concentrated by ultracentrifugation and NoV studies were performed by semi-nested RT-PCR (partial capsid region). NoV were detected in samples from all the cities and detected in 72% (84/116) of the samples with nine of them belonging to GI, 48 to GII and 27 to both genogroups. Remarkably, a high genetic diversity was identified: GII.2 (n=13), GII.4 (n=13), GI.1 (n=5), GI.4 (n=5), GI.8 (n=4), GII.13 (n=4), GII.1 (n=3), GII.6 (n=3), GI.3 (n=1), GI.5 (n=1), GI.6 (n=1), GII.3 (n=1), GII.17 (n=1). Interestingly, a complete replacement of GII.4 New Orleans 2009 by GII.4 Sydney 2012 variants during 2012 was evidenced. ConclusionThis study reveals a high circulation of different NoV GI and GII genotypes in sewage evidencing a replacement of GII.4 variants. Significance and Impact of StudyThis approach can be used as an indicator of the presence of a new GII.4 variant which can originate an increase in acute gastroenteritis outbreaks worldwide.