Study on the pathological and molecular characteristics of viral meningitis outbreaks in Linhai county, Zhejiang province, 2004 / 中华流行病学杂志

ABSTRACT

Objective In order to confirm the causes of viral meningitis outbreaks in Linhai county,Zhejiang province in 2004,and to analyze the relationship between hereditary variation and evolution of the pathogen.Methods 60 cerebrospinal fluid(CSF)specimens were collected from the suspected patients.Virus strains from the specimens were isolated with RD and Hep-2 cell lines,and identified through neutralization test.VP1 and VP4/VP2 genes of the isolated viruses were sequenced.Both phylogcnetic and homological trees were also constructed.Results 19 Echovirus type 30(E30)strains were isolated from 60 CSFs,in which E30 accounted for 31.7％.All of the complete VP1 genes in 4 sequenced virus isolates of E30 were composed of 876 nt,encoding 292 amino acids(aa).The identity of nucleotide and amino acid in VP1 gene were 82.4％-84.1％ and 93.5％-94.2％ between the 4 Linhai strains and the prototype strain Bastianni of E30,were 87.1％-99.9％ and 97.9％-100.0％ among the 4 virus strains of E30 from Linhai,respectively.The 4 Linhai strains could be classified into two classes.The diversity of nt and aa was minimal in the same class but obvious between the two classes,with the range of diversities as 12.9％ and 2.1％,respectively.The Linhai E30 strains had maximum similarity with the Zhejiang E30 strains in 2002-2003.The 4 Linhai strains of E30 in the phylogenetic tree of the VP1 gene were attributed into two branches of the G and H genotype,respectively.The G branch also included the E30 strains from Zhejiang,Jiangsu and Shangdong in 2003,while the H branch including E30 strains from Zhuji,Zhejiang in 2002.The phylogenetic tree of VP4/VP2 genes was similar to that of VP1 gene.Conclusion The outbreak of viral meningitis in Linhai county in 2004 was caused by the two classes of E30 strains with G and H genotype existed simultaneously.The Linhai E30 strains had maximum genetic relations to the Zhejiang,Jiangsu and Shangdong strains of E30.The H genotype was inferred to be a new variant strain,which was first isolated in Zhejiang province in 2002.