Genetic and evolutionary characterization of norovirus from sewage and surface waters in Córdoba City, Argentina

FERNÁNDEZ BLANCO, M.D.; TORRES, C.; MARTÍNEZ, L.C.; GIORDANO, M.O.; MASACHESSI, G.; BARRIL, P.A.; ISA, M.B.; CAMPOS, R.H.; NATES, S.V.; MBAYED, V.A.

Infection, Genetics and Evolution

ELSEVIER SCIENCE BV

Año: 2011 p. 1631 - 1637

1567-1348

Noroviruses (NoVs) are among the most common viral agents that cause gastroenteritis in humans of all ages from all over the world. They are excreted in the feces and introduced into environmental waters as raw or treated sewage. In this work, sewage and environmental samples from the Suquía River in the city of Córdoba, Argentina, were evaluated for NoV contamination as a reflection of the true circulation of this virus in the population, not restricted to the symptomatic cases. The phylogenetic analysis demonstrated that the main genotype detected was GII.4, belonging to the widely-distributed 2006b variant, followed by isolates related to the putative recombinant GII.g virus. Those isolates were more phylogenetically related with recent viruses from other countries than with previous local sequences, suggesting a rapid and wide spread of viral strains that prevents a geographically structured phylogeny. A Bayesian coalescent analysis demonstrated that variants isolated in this work have a most recent common ancestor placed in 2007-2008 with estimated substitution rates of 3.7-5.8 x 10-3 s/s/y. Environmental samples showed a mixture of both viral types, pointing up to the co-circulation and the risk of mixed infections and recombination. There are few reports regarding NoV epidemiology in our country and this is the first surveillance report in environmental waters and sewage with a genetic and evolutionary characterization.