Kafkas Üniversitesi Veteriner Fakültesi Dergisi 2017 , Vol 23 , Issue 6
Development of PPA-ELISA for Diagnosing Streptococcus suis Infection Using Recombinant Sao-M Protein As Diagnostic Antigen
Xiaojing XIA, Huihui ZHANG, Likun CHENG, Shouping ZHANG, Lei WANG, Shuguang LI, Zhiqiang SHEN, Gaiping ZHANG, Jianhe HU
1Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang 453003, P.R. CHINA
2Post-doctoral Research Station, Henan Agriculture University, Zhengzhou 450002, P.R. CHINA
3College of Animal Science and Veterinary Medicine, Henan Institute of Science and Technology, Xinxiang, 453003, P.R. CHINA
4Shandong Binzhou Animal Science &Veterinary Medicine Academy, Binzhou, 256600, P.R. CHINA
DOI : 10.9775/kvfd.2017.18110 Streptococcus suis, an important zoonotic agent, is responsible for outbreaks of human infections. The accurate and rapid detection of S. suis may help control the potential outbreak and ameliorate patient outcomes. In the present study, Sao-M was used to establish a horseradish peroxidase enzyme-linked staphylococcal protein A immunosorbent assay (PPA-ELISA) for the diagnosis of S. suis infection. Results of chessboard titration test showed that the optimal concentration of coating antigen and dilution of serum were 8 μg/ml and 1:80, respectively. The cut-off was confirmed as OD450≥0.351 for positive response. The specificity of test indicated that rSao-M had no cross-reaction with antisera against the other 6 species of pathogens. The variation coefficient of intra-batch and inter-batch in the repeating tests was less than 9.5%. Comparative analysis by using conventional ELISA kit and established GDH-based ELISA showed that the present PPA-ELISA has higher specificity and sensitivity than GDH-based ELISA. A total seroprevalence of 6.6% in 500 pig serum samples indicated the method"s applicability to detect S. suis infection. Cumulatively, the results suggested that the PPA-ELISA is a rapid, sensitive and specific diagnostic method and could be used as a new tool for large-scale epidemiological surveys and serological diagnosis of S. suis infection. Keywords : Streptococcus suis, PPA-ELISA, Sao-M, Diagnosis