Genetic Diversity of Astrovirus in Children From a Birth Cohort in Nepal

This study describes the types of Human astroviruses detected in stool samples collected from a birth cohort of children in Nepal. Using a commercial kit (ProSpecT), a total of 5,224 diarrheal and non-diarrheal stool samples were screened for Human astrovirus by ELISA. RT-PCR was performed on ELISA positive samples (2.8%) for further confirmation. The primary RT-PCR assay used targets the ORF2 region and detects human astrovirus type 1-8. Samples that were negative in this assay were further analyzed using primers that target the ORF1b region of human astrovirus which detect both classical type (HAstV 1-8) and novel types (MLB1-5, VA 1-5). PCR positive samples were analyzed by Sanger sequencing to determine the genotype. A total of 148 available ELISA positive stool samples were analyzed by RT-PCR and further genotyped. RT-PCR analysis of these samples using the ORF2 and ORF1b assay revealed that 124 (84%) were positive for classical human types (HAstV 1-8). Seven different classical HAstV genotypes based on ORF2 and ORF1a were identified (HAstV 1- HAstV 8) with the greatest prevalence of HAstV 5 genotype (42.2%), followed by HAstV 1 (34.7%), HAstV 2 and HAstV 8 (7.4%), HAstV 4 (4.1%), HAstV 3 (3.3%), and HAstV 6 (0.8%). Non-classical types were not detected in our study. A high diversity of circulating Astrovirus strains were detected in young children, both with and without symptoms of gastroenteritis. HAstV 5 and HAstV 1 were the most common genotypes in young children in Nepal.