Epidemiological Study Of Neospora Caninum Infections In Abortion Dairy Cattle Of Xinjiang Region And Construction Of Prokaryotic Expression Plasmid Of NcSRS2 Gene

Neosporosis is a protozoan disease caused by Neospora caninum, an intracellular parasite that infects various species of livestock, which has brought serious detrimental effects on cattle. It is primarily causative agent of abortion, stillbirth and motor nervous system disease of nascent calves in cattle and has brought about huge economic loss to the livestock industry. Currently, there is no effective drug and vaccines for control of Neosporosis, so it is important to develop an early, accurate diagnostic method for controlling Neosporosis. The research on this field in China is relatively late, but has been studied deeply and systematically in recent years. The prevalence of Neosporosis in dairy cattle in Xinjiang of China was investigated. In total, 419 serum samples taken from aborting dairy cattle from 20 cattle farms of 15 regions in Xinjiang were examined for Neospora caninum infection by ELISA kit and rELISA methods by chahan B et al. Of the 419 samples, 43 samples were positive by ELISA kit and the serum antibody-positive rate was 10.26%. Neospora caninum serum antibody-positive rate in all cattle farms was 0 to 50% and there were no significant difference (P>0.05)in the antibody-positive rate between different ages of abortion dairy cattle sera, but there were significant difference(P<0.05)between different regions and different times of abortion dairy cattle sera. Of the 419 samples, 47 samples were positive by rELISA and the serum antibody-positive rate was 11.22%. Show that the existence of the Xinjiang region of Neospora infection.Based on the NcSRS2 gene sequence of Neospora caninum in the GenBank, the specific primers containing EcoRⅠenzyme digestion sites were designed. NcSRS2 gene was amplified by PCR using genomic DNA and inserted into pMD18-T Simple vector, then transformed into the competent E.coli DH5α. The positive recombinant pMD18-T-NcSRS2t and the expression vector pGEX-4T-3 were digested by restriction endonuclease digestion, then transformed into the competent E.coli BL21. Finally a recombinant plasmid named pGEX-4T-NcRSR2t was obtained, and was identified by restriction enzyme analysis and sequencing. Positive strains were induced with IPTG. The results of SDS-PAGE showed that the protein was 60.2kDa in size. The recombinant NcSRS2 protein will be used for further studies in diagnosis and immunity against Neospora caninum infection.