Effectiveness Evaluation of Recombinant Antigen rCPI For iELISA Detection of Camel Parabronemiasis

Parabronemiasis is a serious parasitic disease in ruminants and a major parasitic nematode in camels. There is still no ideal method for diagnosing the disease when the hosts are alive. In order to screen the antigen of P. skrjabini for establishing a serological diagnostic method for camel parabronemiasis, in this study, we amplified and cloned the gene encoding cysteine protease inhibitor (cpi) of P. skrjabini by RT-PCR and constructed the expression plasmid pET-cpi, which was then transferred into Escherichia coli BL21 (DE3) to obtain the recombinant protein rCPI. The purified recombinant protein was used as the coating antigen to establish an indirect ELISA diagnostic method for parabronemiasis. A total of 140 sera collected from camels in Inner Mongolia were tested. A recombinant cpi protein rCPI with a size of 20.2 kDa was obtained, which can specifically bind to IgG in the serum of camels infected with P. skrjabini. An iELISA method for the detection of parabronemiasis was established with good specificity. The positive rate of 140 camel sera was 84.3% (118/140), indicating that rCPI iELISA can be used as a serological diagnostic method for camel parabronemiasis.