Cloning And Analysis Of CD4 And IL-6 In The Wild And Laboratory Tree Shrews

Tree shrews are small squirrel-like mammals, belonging to the order Scandentia, which have a wide distribution in tropical and subtropical regions especially in Southeast Asia. And owing to a variety of unique characteristics for example, small adult body size, easily tamed, short reproductive cycle and life span, low cost of feeding and management, and most importantly, a claimed close affinity to primates, the tree shrew has been proposed as a viable human infectious disease animal model for example HBV, HCV and HFMD, in biomedical research.However, there is a lack of immune related molecular genetic genes in tree shrews. And few studies examine CD4 and interleukin-6 (IL-6), important cellular immunity related factors in disease model evaluation. And in the process of virus infection, CD4 molecule recognizes antigen-antibody complexes as a T cell receptor, play an important role in anti-infection immunity. And IL-6, as the Th2 cytokines, is a major proinflammatory cytokine in the process of anti-infection. It can stimulate proliferation, differentiation of a variety of cells, and plays an important role in immune response, bone marrow hematopoiesis, autoimmunity, and organism defense. Therefore, we cloned and analyzed the polymorphism and important function sites of CD4 and IL-6 nucleotide and amino acid sequence in the wild tree shrew, and the first-generation, the second-generation of the laboratory tree shrews. Comparing the nucleotide and amino acid sites of CD4 and IL-6 of the wild type with the laboratory tree shrews, will provide the basic parameters for establishing closed colony tree shrew and animal model of human infectious diseases.In this study, a 1365 bp and 627 bp of the full-length CD4 and IL-6 cDNA encoding sequence was cloned from the RNA of tree shrew peripheral blood lymphocytes, which were then cultivated and stimulated with phytohemagglutinin (PHA) after 24 hours. Sequence analysis of CD4 and IL-6 molecules in tree shrews showed that different individuals have different degrees of mutation in the nucleic acid and amino acid sites, and there are 35% and 26.7% of base mutations is synonymous mutations respectively. And non-synonymous mutation loci of CD4 and IL-6 molecules in tree shrews don’t affect the function of the important sites. Therefore, the important amino acid sites are conservative and stable in the wild tree shrew. Synonymous mutation frequencies of CD4 molecules is 40.7%, and IL-6 molecules is 41.2% in the first-generation of laboratory tree shrews. Synonymous mutation frequencies of CD4 molecules is 50.0%, and IL-6 molecules is 27.3% in the second-generation of laboratory tree shrews. So, synonymous mutation frequencies of CD4 and IL-6 molecules in the laboratory tree shrews are relatively higher than wild type in tree shrews. It showed that the encoded amino acid remains the same, and do not produce effect of mutation. Therefore, artificial breeding tree shrews will reduce the differences between individuals effectivly. And the important amino acid sites are conservative and stable in the wild tree shrew and laboratory tree shrew.The study will provide a fundamental basis for the preparation of CD4 and IL-6 monoclonal antibodies and establishment of tree shrew animal model.