Background
Edwardsiellosis & Columnaris are the two important infectious diseases occurring in fish caused by bacterial pathogens Edwardsiella tarda and Flavobacterium columnare. Since efficient vaccinations are still not in place for the disease outbreaks, we carried out an in silico, immunoinformatic approach to identify T cell epitopes that can be used as potential peptide vaccine candidates. Determination of T cell epitopes and their binding and interaction with major histocompatibility complex (MHC) proteins play a very important role in the activation of T cells. Upon activation, the T cell receptors invade the pathogens by inducing apoptosis.
Results
We have identified potential T cell epitopes that bind with MHC from the outer membrane proteins of the pathogens. The sequences of the outer membrane proteins (OMPs) were analyzed owing to the fact that they are increasingly recognized as potential targets for inducing immune responses. OMPs were selected based on their antigenic and immunogenic properties. The OMPs of genes TolC and FCOL_04620 from E.tarda and F.columnare were taken for study. We identified 4 cytotoxic T cell epitopes from the OMP of E. tarda. Out of four, two epitopes exhibited excellent protein-peptide interaction. Eighteen cyctotoxic T cell epitopes were identified from the OMP of F.columnare. Out of eighteen, five epitopes bound well with MHC class I alleles and had good protein-peptide interaction.
Conclusion
Activation of T cell receptors plays a very important role in the destruction of the invading foreign pathogens. Cytotoxic T cells bound with MHC class I and class II alleles activate the T cells and convert them to T cell receptors. This study identified potential peptides from the OMPs of the fish pathogens that bound well with MHC class I alleles. There is ample scope for further in vitro studies to develop potential peptide vaccines using the peptides mentioned above.