Evaluation of the immunogenic properties of the recombinant Histophilus somni outer membrane protein 40 kDa (rOMP40).

Abstract

BACKGROUND: Gram-negative bacterial infections are a serious problem in beef and dairy cattle. Bacterial outer membrane proteins (OMPs) play a pivotal role in cellular survival and the host-bacterium interaction. Histophilus somni OMP40 was identified as a porin with homology between its N-terminal amino acid sequence and the sequences of porins of other gram-negative bacteria The aim of this study was to produce recombinant H. somni OMP40 (rOMP40), optimize its production and evaluate its immunogenic properties in calves. The cross-reactivity of anti-rOMP40 antibodies were also checked. RESULTS: The highest overexpression of rOMP40 was demonstrated by Escherichia coli C41 using the autoinduction process. Double immunization of calves (20&#x2009;&#x3bc;g rOMP40 per animal) induced a significant increase of anti-rOMP40 antibodies in the IgG(P&#xa0;&#x2264;&#x2009;0.01) and IgG(P&#x2009;&#x2264;&#x2009;0.01, after first immunization only) subclasses, but not IgM. ELISA revealed increased reactivity of the IgG against surface antigens of E. coli and Pasteurella multocida after the second immunization (P&#xa0;<&#x2009;0.01). Cross reactivity of anti-rOMP40 antibodies with ~&#x2009;40&#x2009;kDa antigens of most common gram-negative pathogens was shown by Western blotting. CONCLUSION: Immunization with H. somni rOMP40 induced a humoral response in cattle with broad cross-reactivity with similar antigens of other species of Pasteurellaceae and Enterobacteriaceae families and the delayed-type hypersensitivity reaction. The obtained results encourage further study to evaluate the protective effect of the produced protein as a subunit vaccine in cattle.