Vaccinomic Approach for Multi Epitopes Vaccine from Glycoprotein D of Virulent Strains of Avian Infectious Laryngotracheitis Virus

Abstract

Avian infectious laryngotracheitis virus (ILTV) is an alphaherpesvirus that causes an economically important respiratory chicken disease. The disease mainly controlled by vaccination. However conventional vaccinations increased the spread of the virus by latency. Therefore the aim of this study was to design multi epitopes vaccine against glycoprotein D of ILTV using immunoinformatics tools. The envelope glycoprotein D sequences were retrieved from the National Center for Biotechnology Information (NCBI) and aligned using Bioedit software for conservancy. The prediction of B and T cell epitopes were performed using Immune Epitope Database (IEDB) analysis resources. Homology modeling and docking were also performed to predict the binding affinity of the predicted epitopes to the chicken alleles. B cell prediction methods proposed nineteen linear epitopes, among them twelve epitopes were on surface and eleven antigenic epitopes using Bepipred, Emini surface accessibility and kolaskar antigenicity methods, respectively. However, only seven epitopes fulfilled the B cell prediction methods. Among these seven epitopes, two epitopes namely 256PRPDSVPQEIPAVTKK271 and 226 RHADDVY 232 were proposed as the top B cell epitopes. For T cells, three epitopes namely 24STAAVTYDY32, 20FASQSTAAV28 and 353FAAFVACAV361 were proposed as cytotoxic T cells (CTL) epitopes due to their great allele’s linkage to MHC class I alleles. MHC class II alleles extensively interacted with multiple epitopes. The best predicted epitopes were 88FEASVVWFY96, 212FQGEHLYPI220, 353FAAFVACAV361 and 137VDYVPSTLV145. Moreover, molecular docking revealed high binding affinity between chicken MHCI BF alleles and MHC1 docked epitopes (20FASQSTAAV28, 24STAAVTYDY32 and 353FAAFVACAV361) that indicated by the lower global energy scores. The In-silico analysis of ILTV glycoprotein D in this study suggested eight epitopes that could be a better choice as worldwide multi epitopes vaccine. These epitopes may effectively elicit both humoral and cell-mediated immunity. Furthermore in vitro and in vivo studies are required to support the effectiveness of these epitopes as vaccine candidates.