Phylogenetic analysis of the nucleoprotein genome of rabies viruses in Yunnan province, China from 2006 to 2015 / 中华实验和临床病毒学杂志

ABSTRACT

Objective@#To understand the molecular evolution characteristics of the nucleoprotein (N) genes and epidemiological feature of 118 rabies virus (RABV) strains isolated in Yunnan province, China from 2006 to 2015.@*Methods@#The brain tissue samples from mad dogs, suspicious sick dogs, sick cow, and human brain tissue, saliva and CSF samples from rabies patients were collected in Yunnan province to detect the viral antigen by direct immunofluorescence assay (DFA). The viral RNA from positive samples was extracted. Coding region of N gene was amplified by RT-PCR and sequenced. The phylogenetic tree was constructed by Neighbor-Joining method of MEGA5.0 software.@*Results@#The sequences of N genes of 91 RABV strains in Yunnan from 2012 to 2015 were obtained. With the sequences of N genes of 27 RABV strains in Yunnan from 2006 to 2011 and 29 RABV strains from Southeast Asian Countries, the phylogenetic analysis was performed. RABV strains in Yunnan were divided into clades YN-A (105 strains), YN-B (6 strains), YN-C (7 strains), which belonged to clades China-I, China-VI, China-II respectively. Clade YN-A was epidemic every year from 2006 to 2015, of them, 14 strains from 2006 to 2011 and 91 strains from 2012 to 2015 were distributed in 13 prefectures (cities) of Yunnan. Clades YN-B and YN-C were epidemic only from 2006 to 2010 and from 2008 to 2011 respectively. The regional distribution of clades YN-B and YN-C was limited. The strains of YN-A and YN-C were closely related to the strains of clades China-I and China-II from neighboring Sichuan, Guizhou, Guangxi and Hunan provinces. The strains of YN-B were closely related to the strains from Myanmar, Laos, Vietnam and Cambodia.@*Conclusions@#Three RABV clades with multiple transmission sources were identified in Yunnan. Clade YN-A was widely distributed in rabies endemic area in Yunnan from 2006 to 2015, and it has strong ability to spread as principal clade in Yunnan. Since 2012, clades YN-B and YN-C were not found again in Yunnan.