| Objective To explore virulence of enterovirus 71 from infected children in neonatal mouse. Methods Three strains of EV71 were isolated from the mild, severe and dead patients. Symptoms, weight and death of mice were registered throughout 14 days. A group of mice were sacrificed on the first, third, fifth, seventh and nith day post infection to gain tissue like liver, spleen, lung, intestine, brain and muscle tissue which were used to detect the virus tilter by real-time RT-QPCR, and pathological lesions by HE staining. Results As to the severity of symptoms, no significant difference existed between the severe and mild group (P = 0.693), which were more serious than that of the fatal group. (P = 0.000<0.05/6, P = 0.000 <0.05/6).The survival rate of the mice infected with mild, severe and fatal virus was 77.2%, 81.7% and 97.8%, respectively and there was significant difference between the three groups (P = 0.0010 <0.05, P = 0.001 <0.05, P = 0.0004 <0.05). Lung hemorrhage of the mild group was the most serious, and there were no significant differences of brain, muscle, spleen and intestine in pathological lesions. Virus tilter in liver and muscle was higher than the other tissues and that in mild group of different tissues tended to be more than the other two groups. Conclusions Neonatal mouse infected with the mild strains presented the heaviest symptoms, which were not consistent with outcomes of human. It was considered to be related to the virus gene, host and other factors. |