Prevalence and genetic diversities of hantaviruses in rodents in Beijing, China.

A total of 835 rodents captured in Beijing, China, were tested for hantavirus infection. Fifty-five (6.6%) were positive for viral RNA when lung tissue samples were examined by reverse transcriptase-polymerase chain reaction. Of 666 sera collected from the above rodents, 50 (7.5%) were positive for IgG antibody by ELISA. Among the 50 seropositive rodents, 37 were positive for viral RNA. In addition, five rodents were positive for viral RNA but negative for IgG antibody. The infection rates among study sites (chi(2) = 28.93, df = 8, P = 0.001) and habitats (chi(2) = 22.88,df = 7, P = 0.02) were significantly different. The sequences of partial M-segment of hantaviruses detected in 11 representative rodents had 0.1-8.2% divergence. Phylogenetic analysis showed that our hantavirus sequences fell into three different lineages regardless of geographical origin or rodent species. A strain detected from a trading center of agricultural products, which might be imported from other provinces, was genetically different from other strains of Beijing.

[Study on the association between hantavirus infection and Rattus norvegicus].

OBJECTIVE: To further understand the association of hantavirus (HV) harbored and transmitted in wild brown rats. METHODS: Rattus norvegicus (n = 570) were trapped in 10 sites in Beijing. RT-PCR was used to test rodent lung samples for hantavirus infection. Unconditional multivariate logistic regression analysis was performed, with PCR positive as the dependent variable and the characteristics of Rattus norvegicus population as independent variables. RESULTS: The overall HV prevalence in Rattus norvegicus was 9.1% (52/570). Significant association between HV infection in Rattus norvegicus and some biological characteristics of host population was observed. Adult Rattus norvegicus had a higher HV prevalence than juveniles. Males in the reproduction periods and rats with wounds were more likely to be infected with HV than others. CONCLUSION: It was further confirmed that there existed parallel transmission of HV in Rattus norvegicus hosts. Aggression might be the primary mode of HV transmission among male Rattus norvegicus.

[Investigation on hantaviruses infection in rodents from free markets in Beijing areas].

OBJECTIVE: In order to find out the factors related to hemorrhagic fever with renal syndrome (HFRS) infection, and to evaluate the probability of ecdemic hantaviruses (HV) infection in rodents in Beijing areas. METHODS: Rodents were collected in a large-scale railway station and a produce market with 'trap nights' method from April to May, 2004. The IgG reacting sera to HV antigen were detected using ELISA. The partial M and S segment of HV from captured rodent lung samples were amplified with RT-PCR. The PCR products were purified and sequenced. BLAST program was then used to perform on nucleotide pairwise alignment with all available sequence in GenBank. The alignment of the multiply nucleotide and the deduced amino acid sequences, together with phylogenetic analysis were completed with DNASTAR software. RESULTS: The average population density was 3.49% (24/690). The overall seroprevalence of HV infection was 8.3% (2/24). RT-PCR positive rates were 8.3% (2/24). The nucleotide sequences of 356 bp region (1958 - 2313) of M segment obtained from 2 samples were all identified to Seoul virus (SEOV), with 7.6% heterogeneity. The dc501 strain from railway station was closely related to SD227 and Hebei4 from Shandong and Hebei provinces respectively. BjFT01 strain from the farm product market had more special nucleotide transitional mutations than other known SEOV from Beijing in GenBank. This strain, together with known HN71 from Hainan province, K24-E7 from Zhejiang province, L99 from Jiangxi province and R22 from Henan province, represented a monophylogentic linkage. CONCLUSION: The higher HV prevalence of rodents in transportation center was the potential and important risk for HFRS epidemic in Beijing. The increasing prevalence of M. musculus should call for attention. It was possible that SEOV in Beijing was imported by infected rodents through vehicles from other provinces.