ABSTRACT
Objective To analyze the genetic characteristics of echovirus type 25( Echo25) strains isolated from patients with viral encephalitis in Longyan city. Methods Cerebrospinal fluid(CSF) specimens were collected from hospitalized patients with viral encephalitis or central nervous system infection in Longyan,2012. Enteroviruses(EV)were isolated from the specimens and then identified. Four strains of Echo25 were screened out by using serum neutralization test. Coding sequence of the VP1 region of the 4 Echo25 strains were amplified by RT-PCR and then sequenced. A phylogenetic tree was constructed to ana-lyze the nucleotide sequence homology between those sequences and the sequences of reference Echo25 strains available in the GenBank database. Results The VP1 nucleotide sequences of Echo25 strains isola-ted in Longyan were 498 bp in length,encoding 166 amino acid residues. The homology analysis showed that the VP1 nucleotide sequences of 3 strains were identical,sharing 97% homology in nucleotide with the rest strain. The Echo25 strains isolated in Longyan were highly similar to KJ957190( Beijing,2010)and HM031189(Henan,2008)strains. Phylogenetic analysis revealed that the Echo25 strains isolated in Longyan belonged to genotype B1. Conclusion Echo25 was one of the pathogens causing viral encephalitis in Longyan in 2012 and different transmission chains of Echo25 had emerged. This study indicates that it is necessary to strengthen the surveillance for EV and understand the genetic variation of the Echo25 for provi-ding better supportive evidences for the prevention and control of related diseases.
ABSTRACT
This study aimed to analyse the genetically characterize isolates of Echovirus 11 from Longyan City,Fujian Province,and to reveal their genetic relationships with other isolates from China and abroad. Cerebrospinal fluid specimens from patients diagnosed with viral encephalitis or central nervous system (CNS) infections were collected from Longyan First Hospital between January and December 2011. Seven Echo11 strains were isolated and identified using the RIMV serum panel. The entire VP1 coding regions of four strains were sequenced and typed as Echo11 by an online blast program and,subsequently, phylogenet- ic analyses of the VP1 sequences of these stains and others published on GenBank were conducted. There were 600 nucleotides (nt) in each complete VP1 coding region that encoded 200 amino acids (aa). Among those four Echo11 strains, the sequence identities of nt and aa were 100% and 99%-100% respectively. And phylogenetic analyses indicate belong to subtype DS, the homology compared with DS strain (GU393713) were 93% (nt) and 99% (aa). The sequence identities for the nt and aa were 75%-76% and 90%, respectively, between the current isolates from Longyan and the Gregory prototype strain found in 1953. The sequence identity of nt and aa between the Longyan virus strains and the domestic Shandong strains isolated in 2010 were lower, at 74% and 88%-89%, respectively. However,the highest level of ho- mology was found when the Longyan strains were compared with the Netherlands strain (GU393773) found in 2007 (nt and aa identity: 94%-95% and 98%-99%, respectively). The relatively low levels of similarity between domestic isolates suggest that different transmission routes exist for Echo11 in mainland China.