Detection and genetic characterization of classic human astroviruses in Brazil, 2010-2012.

The aims of this study were to monitor human astrovirus (HAstV) infections in patients presenting with acute gastroenteritis in Brazil and to determine the HAstV genotypes of these viruses. From May 2010 to July 2012, a total of 140 samples that were negative for both rotaviruses and noroviruses were randomly selected and tested for the presence of HAstV using an RT-PCR assay specific for the ORF2 region. Viral genotypes were identified and genetic diversity was investigated by sequencing. HAstV infection was detected in 2.9% of samples (4/140). The viruses in three samples were shown by phylogenetic analysis to belong to HAstV-4 lineage "c", clustering together with strains detected in Europe and the Middle East. The virus in one sample was genotyped as HAstV-1 lineage "a", clustering with strains from Uruguay, Brazil and Russia. Our findings provide further evidence for a global distribution of HAstV-1a and suggest a possible emergent importance of the HAstV-4c lineage in this country. The present study does not suggest that HAstVs currently have a major epidemiological impact, even after the introduction of a rotavirus vaccine in 2006.