Study On The Ability Of The Family Of Variable Surface Protein Of Mycoplasma Hyorhinis To Mediate Adhesion To The Host Cell

Mycoplasma hyorhinis (M. hyorhinis) is a swine pathogen that can cause multiple chronic inflammation including polyserositis, pneumonia, arthritis and otitis media. It is also a potential pathogen for human beings, associated with various human cancers. In previous study, vlp family has been revealed to play a role in mediating cytoadhesion of M.hyorhinis. Herein, we furtherly studied the cytoadhesion function of vlp, particularly the cytoadhesion functional domain and how the repeat time of repetitive unit impact the function. According to the sequence published on GenBank, the gene of vlpX was amplified from bacterial genome. Furthermore, vlpXn genes containing 0,3,6,9 and 12 times of repetitive unit in region Ⅲ was artificially synthesized. The genes were inserted into pET-32(a) and expressed in Escherichia coli. At the same time, seven peptide of the repetitive unit of vlpX were artificially synthesized. All the recombinant proteins, as well as the peptide were detected for their adherence to STEC and PK-15 cell by using the indirect immunofluorescence assay or microtiter plate adherence assay. All the recombinant proteins has been successfully induced for expression and purified by affinity chromatography. Adherence of vlpmix to STEC and PK-15 cell has been observed in the indirect immunofluorescence assay. The result of microtiter plate adherence assay indicated that all region Ⅱ of vlp (vlpX0) and region Ⅲ of vlpB,vlpG contains cytoadhesion sites.The adhesion capability was associated with the number of repeat time. As the repeat time increased, the adherence significantly decreased.The results of this study laid the foundation for further study on the pathogenic mechanism of M.hyorhinis.