Immunoinformatics Evaluation of a Fusion Protein Composed of LiHyV and Apyrase as a Vaccine Candidate against Visceral Leishmaniasis.

Background: Visceral leishmaniasis (VL) is a lethal parasitic disease, transmitted by sand fly vectors. Immunomodulatory properties of sand fly saliva proteins and their protective effects against infection in pre-exposed animals suggest that a combination of an antigenic salivary protein along with a antigen can be considered for designing a vaccine against leishmaniasis.

Methods: Three different fusion forms of hypothetical protein (LiHyV) in combination with salivary apyrase (PkanAp) were subjected to analyses. Major Histocompatibility Complex (MHC) class I and II epitopes in both humans and BALB/c mice were predicted. Antigenicity, immunogenicity, epitope conservancy, toxicity, and population coverage were also evaluated.

Results: Highly antigenic promiscuous epitopes consisting of truncated LiHyV (10-285) and full-length PkanAp (21-329) were identified in human and was named Model 1. This model contained 25 MHC-I and 141 MHC-II antigenic peptides which among them, MPANSDIRI and AQSLFDFSGLALDSN were fully conserved. LALDSNATV, RCSSALVSI, ALVSINVPL, SAVESGALF of MHC-I epitopes, and 28 MHC-II binding epitopes showed 60% conservancy among various clades. A population coverage with a rate of >75% in the Iranian population and >70% in the whole world was also identified.

Conclusion: Based on this approach, the predicted Model 1 could potentially be used as a vaccine candidate against VL.