Molecular epidemiology of avian rotavirus in fecal samples of broiler chickens in Amazon Region, Brazil, from August 2008 to May 2011

Enteric viruses cause avian diseases that result in economic losses. Avian Rotavirus (AvRV) is the most important virus associated with enteritis in poultry. The main goals of this study were to determine the prevalence of AvRV using molecular tests in broiler chickens (Gallus gallus) from the metropolitan mesoregion of Belm (Par State, Brazil), to provide epidemiological information, and to compare the rotaviruses detected in this study with reference to strains by phylogenetic analysis. Pooled fecal samples were collected from 37 poultry farms. The samples were tested for the NSP4 gene using reverse transcription polymerase chain reaction (RT-PCR). In total, 35 (41.2%) of the 85 fecal samples were positive for NSP4. There were 19 (51.4%) farms with at least one poultry house positive for AvRV. Considering the distribution of positive samples by age, the chicks aged 31-45 days comprised 18 (51.4%) of the 35 rotavirus-positive samples. Analyzing the data by density population, the houses with more than 9 birds/m 2 had 25 (86.2%) positive samples, showing that higher infection rates occurred in higher density houses. To confirm the RT-PCR results and perform phylogenetic analysis, 20 positive samples were selected for sequencing. The rotaviruses detected in our study were clustered in a single group and had 93.5 to 100% sequence identity at the nucleotide level. The most affected age group included broiler chickens older than 15 days. Climatic conditions and high population densities favored the spread of AvRV and supported its uniform maintenance between seasons.