Survival Competition Of Two Clones Of Plasmodium Yoelii And Molecular Systematic Of Different Species Of Plasmodium Based On Coxâ…¢

It is an extremely common phenomenon of mixed infection in malaria.When the mixed infection happens,the host-parasite system will induce a series of more complex interactions which could have an important impact on the evolution of virulence of the parasite.On the other hand,the existence of mixed infection may have significant effects on the host immune response.In order to thoroughly clarify the mechanism of host immune response post infection,and give a better guide to develop vaccine for malaria,it is very necessary to carry out research on the response of host immune system.We used RTQ-PCR technology in our experiment so as to rapidly distinguish and accurately quantify genetically distinct parasites clones of the same species present in a mixed infection.In our research,we successfully found suitable molecular markers for identification of two clones of Plasmodium yoelii17XNL, 265BY.And then,we made use of RTQ-PCR to monitor the composition proportion of two clones in the process of mixed infection.The results showed that the compositon proportion of a more virulent clone in mixed infection would increase regardless of its initial proportion during the process of infection.When the initial ratio was 17XNL:265BY=5:5,the clone of 265BY comprised 81%in population byD12.Combination with the data of host survival and parasitemia,we got a fully understanding of the competition between two clones of different virulence and characterization of the host immune response when mixed infection occurred.Change of population number is not simply the addition of two clones in two separate infection,however,regardless of the strength of its virulence,or the proportion of its inoculation,each of clone is subject to varied degrees of inhibition.Take a example, When the initial ratio was 17XNL:265BY=1:9,the clone of 17XNL was suppressed by 98%.Whatever,When the ratio was 9:1,the clone of 265BY was suppressed by 60%.Although it is still not clear the relations between occurrence of dynamic changes and the impact of host immune system,our experiment lay down a foundation for exploring the changes of cytokines of host immune response,which can finally explain mechanism of the dynamic balance of protective and pathological immune responses.In this paper,we use the blood sample from a patient who is naturally infected of Plasmodium vivax as our genome resource.We extracted genomic DNA,amplified coxâ…¢gene and constructed phylogenetic tree.We wanted to explore that it was suitable of coxâ…¢as a molecular marker for our study of molecular systematic between different species of Plasmodium.We selected 13 species of Plasmodium,as well as Plasmodium vivax in our experiment.Then we established a phylogenetic tree which could well reflect the genetic relationship between different Plasmodium species.We believe that we can use coxâ…¢gene as an effective tool to carry out taxonomic and phylogenetic relationships research in our future work.