Abstract: This study was aimed to investigate the prevalence of bovine astrovirus (BoAstV) in buffalo from Guangxi,a total of 297 fecal samples were collected from 15 different scale buffalo farms in five regions including Nanning,Guigang,Beihai,Hengxian and Lingshan in Guangxi,the RNA was extracted by Trizol and the nest RT-PCR was used to detect the BoAstV.The positive samples were connected to pMD18-T vector for sequencing.Homology analysis of sequencing results was carried out,and phylogenetic tree was constructed.The results showed that the positive rate of BoAstV in buffalo farms was 40.00% (6/15),the positive rate of samples was 11.11% (33/297), and the buffalo calves which under 180 days old were more sensitve to infected BoAstV 18.75% (27/144).Total 19 BoAstV ORF1b sequences from positive samples were cloned and uploaded to NCBI BLAST.The nucleotide homology and amino acid sequence homology of the 19 BoAstV strains were 53.9% to 99.3% and 12.1% to 98.5%,respectively.Based on the phylogenetic analysis of these sequences and reference sequences,4 clusters could be classified.The first subgroup included NNC-286,HX-3,HX-4 and NNA-14,and these sequences were closed with novel nervous tropism BoAstV like BoAstV NeuroS1 and BoAstV BH89/14 which belonged with Mamastrovirus 13.The second subgroup included NNA-12,NNA-13,NNA-17 and NNA-11,and these sequences were closed with buffalo astrovirus,and belonged to the branch of buffalo astrovirus.The third subgroup included HX-1,HX-5,HX-6 and BH-C22,and these sequences were closed with classic BoAstV like BoAstV B170-HK.The last subgroup included NNA-7,NNA-15,NNA-6,NND-S2,NND-S16,NNC-296 and BH-C14,and these sequences were closely related to the local endemic strains of bovine stellavirus in Guangxi.The different genotype of BoAstV were infected buffalo herds in different regions from Guangxi.This study found that the neurophilic BoAstV strain infected buffalo in Guangxi,and provided reference for further understanding of the epidemiology and biological characteristics of the virus.

Key words: bovine astrovirus(BoAstV); ORF1b gene; diarrhea; semi-nest RT-PCR; phylogenetic analysis