Molecular Epidemiology Of Echovirus9in Aseptic Meningitis In Kunming

Enteroviruses (EVs) are the most important cause of aseptic meningitis in children, which is the most commonly encountered serious illness. Echovirus9(ECHO9) is one of the most common EV genotypes detected from patients with aseptic meningitis, often appearing in the form of an epidemic or endemic.The objective of this study is to carry out a comprehensive molecular epidemiology survey of ECHO9in hospitalized aseptic meningitis children under5years old in Kunming. In order to explore the molecular epidemiology of aseptic meningitis, clinical cases information and stool specimens were collected. By using statistics, molecular biology and cell culture, the VP1gene was analyzed and the pathogen was confirmed as ECHO9virus. The genotype and variation of ECHO9was detected by sequencing VP1. It will be benefit to prevention, control and research of aseptic meningitis.Viral RNA of510samples was extracted directly from specimen, and the VP1gene was analyzed by using RT-PCR and sequencing. Sequences were analyzed using Omiga and Mega5.05software.The statastics of clinical characteristics were analyzed using SPSS17.0. According to protocols in reference book "Manual for the Virological Investigation of Poliomyelitis", virus was isolated.The results of clinical characteristics analysis showed that there was no significant difference between patients with or without ECHO9infection in age, sex distribution, symptoms and clinical checks, which suggested that the clinical characteristics analysis can not be directly used to identify ECHO9infection. The results of sequence analysis showed that (1) ECHO9positive detection rate was8.82%. But in comparison to the prototype strain (DM strain), part of the VP1region of the collected samples existed nucleotide variation. Phylogenetic tree showed that A236, A238, F50and Yunnan strains formed a branch. The other samples formed another new branches.(2) The results from VP1BC-loop amino acids sequence alignment show that there were obvious substitution among BC-loop, excludingUSA-10606,ES23-Bb-ED-07,France258066-05,IS02-ns-EW-04,GB24-Br-E A-08,E9-TS-1482-kras-RU-2008,183YN-CHN-2000-00-A271, compared with the prototype strains of ECHO9(DM strains).The results of the cell separation showed that one ECHO9virus strains was isolated from45specimens identified as ECHO9.The results indicated that there was no significant correlation between children with or without ECHO9infection and clinical manifestations. ECH09in China showed the significant difference on geographical distribution, and also showed variation among different strains isolated from same area, which may indicated the existence of different routes of transmission. Sequence analysis indicated that ECH09has relative large variation. PCR was more sensitive than cell culture in identification of virus. Further study need to be done to verify whether these variations affect its immunogenicity and other features.