Objective To study heredity characteristics and stability of NSP4 gene of rotavirus(RV) vaccine strain LLR and provide a basis for the quality control of vaccine.Methods Rotavirus strain LLR was subcultured in primary bovine kidney cells from passage 38(LLR38) to passage 49,and the viral RNAs of passages 38,43,44 and 49 were extracted for amplification of NSP4 gene by RT-PCR.The amplified gene fragment were cloned into plasmid pGEM-T for sequencing.Results The NSP4 gene of LLR strain,with a full-length of 7...