Serological diagnosis of Parabronema skrjabini infection using a recombinant antigen in bactrian camels

In order to find out an effective method for the in vivo diagnosis of parabronemosis and on the basis of results of histological analysis obtained in the laboratory, the serine threonine protein kinase (STPK) gene, an immune-related secretory gene of P. skrjabini, was screened. A total of 140 Bactrian camel sera samples from different regions of Inner Mongolia were screened. The results of bioinformatics analysis showed that the nucleic acid sequence of STPK gene was 579 bp, contained a complete open reading frame encoding 199 amino acids, had no signal peptide, was atypical secretory protein and had 8 antigenic epitopes. The total RNA of P. skrjabini was extracted and the STPK gene was obtained by RT-PCR amplification. The recombinant expression plasmid was constructed and expressed in Escherichia coli BL21 (DE3). A recombinant protein, rSTPK, 28 kDa in size, that was primarily expressed in inclusion bodies, was obtained. An indirect enzyme-linked immunosorbent assay (iELISA) using rSTPK as an antigen was established using recombinant protein. We observed a positive detection rate of 85.7% (120/140), indicating that rSTPK-iELISA can be used as a serological method to diagnose parabronemiasis in camels.