Cloning And Expression Of IgG Binding Protein Gene Of Rhipicephalus Haemaphysaloide

Ticks are obligate haematophagous ectoparasites, they distribute widely and are the significant vectors transmitting a great number of pathogens of human and animals, such as arboriruses, rickettsiae, spirochetes and parasitic protozoa. At present, there are about 820 kinds of tick in the world and more than 110 kinds of ticks are found in China, Rhipicephalus haemaphysaloides tick is a predominate kind of ticks in south of china, which transmit Babesia bovis, B.equi and B.gibsoni and so on.The economic loss caused by ticks and tick-borne pathogens is quite great and immunological protection is deemed as the most potential measure at present, which makes the searching for the sensitive, long-term effective, safe antigen genes be the base for immunological protection. IgG binding protein is an significant kind of protein in ticks mainly existing in haemolymph and salivary which are able to bind host IgG that entering the haemolymph of ticks, thus avoiding the damage to the their internal organs. Some kinds of IGBPs are male specific which is essential for the male helping the female to have a successful meal.Firstly, we obtained the full-length sequence from rapid amplification of cDNA ends protocol, the gene had 683bp edcoding 178 amino acid residues with 19.5kDa predicted molecular weight and showed a rather high homology (92% cDNA identities) with Rhipicephalus appendiculatus IGBP-MB. Secondly, the expression feature of male specific , in the different organs and phages were analysised by the reverse transcription polymerase chain reaction method (RT-PCR), the results suggested the expression of IGBP gene had no male specific characteristic, and IGBP gene were expressed in the salivary, shell, eggs, unfed larva, unfed nymphae and adult, but not expressed in the gut. Thirdly, the recombinant proteins of GST-IGBP were expressed by pGEX-4T-1 vector in E.coli and the fused protein were purified by GST Sepharose. The result indicated that it can be expressed in high level in E.coli. Lastly, the biological activity of IGBP was assayed by ELISA(Enzyme-linked immunosorbent assay).In a word, the study cloned and expressed a IGBP gene of Rhipicephalus haemaphysaloides for the first time and researched the function in a pilot study, this will be the foundation to the further study.