Genetic Polymorphism Of Plasmodium Vivax In Linzhi Region

In the world, Malaria is one of the most serious Mosquito-vectored parasitic diseases, especially brings great harm to Africa, South America and southeast Asia, so it is an important global public health problem. At present, about40%of the population worldwide are threated by this disease. According to the WHO’s report, there were225million malaria cases, and781,000people died from this disease in2009.Malaria is also an important parasitic disease in our country, it causes greatly damage to the people’s health and safety, and influences the social and economic development. To protect the people’s health and promote the economic and social harmonious development, and response to proposition of realizing the global malaria eradication which was raised in the UN millennium development goals high level meeting. In2010, the Chinese government has nationally launched the work of malaria elimination, and planed to realize the malaria elimination in most of the region in2015, achieving the national malaria elimination in2020.Linzhi Prefecture of Tibet is the only area where has malaria occurrence and prevalence, and Motuo County and Chayu County which both are administered to Linzhi constantly are malaria epidemic region, accumulatively2296malaria cases totally from1986to2008. In July2005, there was a malaria outbreak, in Linzhi. According to the results of the survey by the expert group appointed by the Ministry of Health of China, the Motuo County and Chayu County are tropical forest areas with low altitude, both the positive rate of blood test for Plasmodium spp. against residents and the population malaria antibody level were high, suggesting that this area is the epidemic region of Malaria, and its incidence of malaria headed the nation. According to the survey of every year’s cases reports and blood tests, the Plasmodium vivax is primarily spreaded in this area, but Plasmodium falciparum cann’t be ruled out. The different geographical strains of Plasmodium vivax may be different in the aspects such as the infectivity against vectors, immunogenicity to the host, especially there may be polymorphism of plasmodium spp. in Linzhi with the special geographic conditions and ecological environment. This study is to research the polymorphism of the Plasmodium vivax in Linzhi, with molecular biological methods, so as to provide the basis for formulating the local malaria control strategy.In the present study, the methods of PCR-RFLP and microsatellite genotyping were applied to analyze the polymorphism of the Plasmodium vivax collected from Muotuo county and Chayu county. There were35filter papers totally. Firstly, the sample DNA was extracted by Chelex-100boiled method. Secondly, the nested PCR based on the Plasmodium spp. genus-specific and species-specific primers was used to characterize the samples. In result, there were Plasmodium vivax only. Thirdly, the above plasmodium vivax positive samples were amplified by nested PCR based on the PvMSP-3α specific primers, and the PCR products were analyzed by RFLP with the restriction enzymes (Hha I and Alu I). As a result, there were type Ⅰ (1900bp,90.3%) and Ⅱ(1500bp,9.7%) in the PvMSP-3α gene, no type ⅢI identified. The amplified products of PvMSP-3α type Ⅰ and Ⅱ were digested by Hha I, resulting in clear band around1000bp, and6different genotypes under type Ⅰ with the most common bands around1000bp,400bp and200bp. But only1genotype under type Ⅱ. The amplified products of PvMSP-3α type Ⅰ and Ⅱ were digested by Alu I, resulting in clear band around500bp, and4different genotypes under type Ⅰ with the most common bands around500bp,200bp and150bp. But only1genotype under type Ⅱ too. Select the core of repeat units7base pairs in the chromosome8, design of microsatellite specific primer amplification and product analysis of the above P.vivax. The microsatellite loci design three primers, one of which is fluorescently labeled primers. The semi-nested PCR method for amplification of the microsatellite loci in the second round of PCR using fluorescently labeled primers, the PCR product GENESCAN detection. The detection of different fragment length, representing the different types of microsatellite allele. The microsatellite loci amplified fragment type analysis results showed that25homozygous and heterozygous7, expected heterozygosity was0.23±0.35. As the results showed, the genetic diversity of plasmodium vivax in Linzhi Prefecture of Tibet is low, without any obvious genetic differentiation. But due to the special geographic and ecological environment, and extremely inconvenient transportation in Tibet area, once it has local malaria infections or inported malaria cases, added to the weak disease control infrastructure, the faultiness professional team of disease control and prevention, which cause difficulties to local residents for seeking medical advice, what’s worse, there are high density of vector, it easily causes the malaria outbreak, so great attention should be paid.