Sporozoite glycoprotein antigen (SGA) of Cryptosporidium parvum is a promising vaccine target for prevention of cryptosporidiosis In silico analysis of C. parvum SGA protein

Abstract

Cryptosporidiosis is a zoonotic parasitic infection causing diarrhea in humans and farm animals. The present study was done to computationally analyze the Cryptosporidium parvum sporozoite glycoprotein antigen (SGA) regarding immunogenic epitopes, as a potential vaccine candidate. Physico-chemical properties, solubility, antigenicity, allergenicity, signal peptide, transmembrane domain and post-translational modifications (PTMs) along with secondary and tertiary structure analyses were predicted. Also, linear B-cell epitopes, cytotoxic T-lymphocyte (CTL; human, cattle) and helper T-lymphocyte (HTL; human) epitopes were forecasted. The molecular weight of this 265-residue protein was 27.14 kDa, with hydrophilicity (GRAVY: 0.700), high solubility (0.892), and aliphatic index (46.83). No signal peptide and transmembrane domain was predicted, and the most abundant PTMs were phosphorylation (n = 68) and O-glycosylation (n = 53). Coils were dominant in secondary structure analysis, and the tertiary model refinement showed enhancement in the refined than crude model. Only 4 shared B-cell epitopes among three web servers (ABCpred, BepiPred 2.0, and SVMTriP) were shown to be antigenic, non-allergenic, with good water solubility. Also, five potent CTL epitopes in humans and two in cattle were predicted. Notably, four HTL epitopes were found as inducers of IFN-γ, IL-4 or both. In conclusion, our results demonstrated several immunogenic epitopes in this protein, which could be directed towards multi-epitope vaccine design.