Molecular epidemiology of SARS-associated coronavirus, Beijing.

Single nucleotide variations (SNVs) at 5 loci (17564, 21721, 22222, 23823, and 27827) were used to define the molecular epidemiologic characteristics of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) from Beijing patients. Five fragments targeted at the SNV loci were amplified directly from clinical samples by using reverse transcription-polymerase chain reaction (RT-PCR), before sequencing the amplified products. Analyses of 45 sequences obtained from 29 patients showed that the GGCTC motif dominated among samples collected from March to early April 2003; the TGTTT motif predominanted afterwards. The switch from GGCTC to TGTTT was observed among patients belonging to the same cluster, which ruled out the possibility of the coincidental superposition of 2 epidemics running in parallel in Beijing. The Beijing isolates underwent the same change pattern reported from Guangdong Province. The same series of mutations occurring in separate geographic locations and at different times suggests a dominant process of viral adaptation to the host.

[A case-control study on the mxA polymorphisms and susceptibility to severe acute respiratory syndromes].

OBJECTIVE: To investigate the association between the genetic polymorphisms of myxovirus resistance 1 (MxA) gene and susceptibility to severe acute respiratory syndromes (SARS). METHODS: A case-control study was conducted and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to detect the T/G polymorphism at position-88 in the mxA gene promoter. Information on related factors of SARS was collected using a pre-testing questionnaire. Univariate and multivariate logistic analyses were conducted with SPSS software package. RESULTS: Sixty-six cases and sixty-four controls were selected for the study. Comparing with GG genotype, the proportion of GT genotype were significantly higher in the case group (81.3%) than that in the control group (62.5%)) with an OR (95% CI) of 2.700 (1.208-6.037). Multivariate logistic regression analysis revealed that the significant association remained after factors as wearing masks, protection gowns and eye-protection when contacting with SARS patient etc. were adjusted with an OR (95 % CI) of 2.911 (1.027-8.250). CONCLUSION: mxA promoter-88G/T SNP might be confered to host genetic susceptibility to SARS in Chinese Han population.