Journal of Medical Virology 79:530–538 (2007) Prevalence of Human Astrovirus Genotypes Associated With Acute Gastroenteritis Among Children in Bele ´ m, Brazil Yvone B. Gabbay, 1 * Alexandre C. Linhares, 1 Elielma L. Cavalcante-Pepino, 1 Liliany S. Nakamura, 1 Darleise S. Oliveira, 1 Luciana Damascena da Silva, 1 Joana D’Arc P. Mascarenhas, 1 Consuelo S. Oliveira, 1 Talita Anto ˆ nia F. Monteiro, 1 and Jose ´ Paulo G. Leite 2 1 Virology Section, Instituto Evandro Chagas, Secretaria de Vigilaˆncia em Sau ´de, Ministe´rio daSau ´de, Ananindeua, Para´, Brazil 2 Department of Virology, Instituto Oswaldo Cruz, Fundac ¸a˜o Oswaldo Cruz, Rio de Janeiro, Brazil Worldwide human astroviruses (HAstV) have increasingly been recognized as causative agents of viral gastroenteritis, mainly in infants and young children. The aim of this study was to assess the epidemiology and genotype diversity of HAstVs detected in children who participated in a trial in Bele ´m, Brazil with the rhesus human reassortant rotavirus vaccine tetravalent (RRV- TV). From April/1990 to August/1992, 624 diarrheic stool samples were tested by enzyme immuno- assay (EIA) for HAstV, with a positive rate of 4.0%. Reverse transcription-polymerase chain reaction (RT-PCR) was done in 129 samples (25 positive and 104 with twice the optical density (OD) value of negative control by EIA) being 33 positive. The overall positivity yielded by both methods was 5.4% (34/624). Genotyping of the 33 positive samples was done by type-specific RT-PCR and confirmed by sequence analysis. Phylogenetic analysis was performed using a 348-bp fragment of the ORF2 region of the capsid gene. HAstV-1 was the most prevalent, accounting for 45.5% of the isolates, followed by HAstV-2 (27.3%), HAstV-3 (12.1%), HAstV-4 (12.1%), and HAstV-6 (3.0%). The monthly distribution showed that HAstV-1 was predominant in the first year of study (May/1990 to May/1991) with highest prevalence in January/ 1991. HAstV-2 was predominant from July to November/1991 and HAstV-4 from September to October/1990. At 24 months of age, 30.6% of children had been infected by HAstV. The clinical symptoms registered during HAstV associated- diarrhea were usually mild. These data highlight the circulation of the different HAstV genotypes in Bele ´m during the study period. J. Med. Virol. 79:530–538, 2007. ß 2007 Wiley-Liss, Inc. KEY WORDS: astroviruses; PCR-genotyping; sequencing; infants; diarrhea INTRODUCTION Human astroviruses (HAstVs) were first detected in 1975 in stool samples from children with acute gastro- enteritis examined by electron microscopy [Appleton and Higgins, 1975; Madeley and Cosgrove, 1975]. With the improvement of the diagnostic methods, including the use of enzyme immunoassay (EIA) [Herrmann et al., 1991; Lew et al., 1991], and the recently developed molecular techniques [Noel et al., 1995; Sakamoto et al., 2000; Schnagl et al., 2002], a significant amount of data has been gathered highlighting the role of HAstV in the etiology of acute infantile gastroenteritis [Jakab et al., 2004]. Epidemiological studies conducted worldwide, have reported the occurrence of HAstVs infection among children hospitalized with diarrhea and in the context of community-based studies. Overall, prevalence rates have ranged from 2% to 16% in hospital-based studies and from 5% to 17% in community-acquired gastroenteritis [Polombo and Bishop, 1996; Walter and Mitchell, 2000; Me ´ndez-Toss et al., 2004]. HAstVs have also been associated with outbreaks of diarrhea in children [Mitchell et al., 1999] and adults [Belliot et al., 1997]. HAstVs have also been recognized as a common cause of nosocomial diarrhea [Unicomb et al., 1998; Rodriguez-Baez et al., 2002] and was shown to be more severe among patients with HIV infection [Cunliffe et al., 2002]. HAstVs belong to the Astroviridae family, genera Mamastrovirus, and their genome is composed of a single-stranded positive sense RNA molecule containing *Correspondence to: Yvone B. Gabbay, Virology Section, Instituto Evandro Chagas, Secretaria de Vigila ˆncia em Sau ´ de, Rodovia BR 316, Km 07, S/N, Levila ˆ ndia, 67.030-000, Ananin- deua, Para ´ , Brasil. E-mail: yvonegabbay@iec.pa.gov.br Accepted 22 December 2006 DOI 10.1002/jmv.20813 Published online in Wiley InterScience (www.interscience.wiley.com) ß 2007 WILEY-LISS, INC.