The Construction Of CDNA Expression Library Of Haemaphysalis Qinghaiensis Tick And Screening, Cloning & Expression Of "Concealed Antigen" Gene

Haemaphysalis qinghaiensis ticks and the protozoal disease they transmitted are major economic burden to animal husbandry in China. Currently the principal tick control method is the application of acaricides. This approach is, however, associated with a number of disadvantages such as chemical pollution of the food chain and the environment as well as the quick development of resistance against acaricides by ticks. These limitations have necessitated the search for alternative tick control measures. Among the several alternative tick control measures only host vaccination against ticks appears promising. In this research, sheep ani\-H.qinghaiensis tick salivary gland protein and saliva protein sera were generated respectively by two different methods. By comparison to sheep anti-H.qinghaiensis tick saliva protein serum, more differential protein bands were detected by sheep and-H.qinghaiensis tick salivary gland protein surem on Western blots of tick salivary gland extracts. The molecular weights of those differential proteins were 49kDa, 35.8kDa, 31kDa and 23.5kDa respectively. Rabbit anli-Haemaphysalis qinghaiensis tick differential proteins serum was then generated by immunization rabbit with those differential protein bands cut from SDS-PAGE gel; A primary cDNA library with a size of 2.0x106PFU was constructed from organs such as salivary glands, Malpighian tubules, ovaries dissected from partially fed H. qinghaiensis ticks and was immunoscreened with rabbit &n\\-Haemaphysalis qinghaiensis tick differential proteins serum. Thus 5 new genes of H. qinghaiensis tick were obtained and designated Hq02, Hq03, Hq04, HqOS and Hq06. The sizes of those new genes were 1085bp, 726bp, 617bp, 847bp and 1178bp respectively. Fusion proteins with different molecular weights were expressed by Hq02, Hq04, and Hq05 genes and used to immunize sheep. The expressed products were proved to be immunogenic and immundreactive by hybridizing anti-sera of the immunized sheep with tick salivary gland extracts by Western blot analysis. All those would be a good foundation for the development of snti-H.qinghaiensis vaccine.