In silico analyses and experimental validation of the MHC class-I restricted epitopes of Ebolavirus GP.

Ebolavirus (EBOV) causes an extremely high mortality and prevalence disease called Ebola virus disease (EVD). There is only one glycoprotein (GP) on the virus particle surface, which mediates entry into the host cell. Major histocompatibility complex (MHC) class-I restricted cluster of differentiation 8 (CD8+) T cell responses are important antiviral immune responses. Therefore, it is of great importance to understand EBOV GP-specific MHC class-I restricted epitopes within immunogenicity. In this study, computational approaches were employed to predict the dominant MHC class-I molecule epitopes of EBOV GP for mouse H2 and major alleles of human leukocyte antigen (HLA) class-I supertypes. Our results yielded 42 dominant epitopes in H2 haplotypes and 301 dominant epitopes in HLA class-I haplotypes. After validation by enzyme-linked immunospot (ELISpot) assay, in-depth analyses to ascertain their nature of conservation, immunogenicity, and docking with the corresponding MHC class-I molecules were undertaken. Our study predicted MHC class-I restricted epitopes that may aid the advancement of anti-EBOV immune responses. An integrated strategy of epitope prediction, validation and comparative analyses was postulated, which is promising for epitope-based immunotherapy development and application to viral epidemics.

Integrative Analysis of HTNV Glycoprotein Derived MHC II Epitopes by In Silico Prediction and Experimental Validation.

Hantaan virus (HTNV), the causative pathogen of hemorrhagic fever with renal syndrome (HFRS), is a negative RNA virus belonging to the Orthohantaviridae family. HTNV envelope glycoprotein (GP), encoded by the genomic medium segment, is immunogenic and is therefore a promising vaccine candidate. Major histocompatibility complex class I (MHC-I) epitopes derived from HTNV has been extensively studied, but little is known of MHC-II epitopes. In silico predictions based on four databases indicated that the full-length HTNV GP has 1121 15-mer epitopes, of which 289 had a high score for binding to the human and murine MHC-II superfamily. It found that epitope ILTVLKFIANIFHTS could potentially bind most MHC-II molecules covering human and murine haplotypes. Dominant epitopes were validated by enzyme-linked immunospot assay of splenocytes from immunized mice; 6 of 10 epitopes supported the predictions including TATYSIVGPANAKVP, TKTLVIGQCIYTITS, FSLLPGVAHSIAVEL, CETYKELKAHGVSCP, CGLYLDRLKPVGSAY, and NLGENPCKIGLQTSS. Conservation analysis of dominant epitopes revealed host-virus interactions without geographic stratification, thus meeting the requirements of candidate vaccines for large-population prophylaxis. These findings provide insight into hantavirus antigenicity and suggest that vaccines targeting MHC-II could provide immune protection in large population to complement symptomatic therapies for the treatment of HFRS.

Construction and evaluation of DNA vaccine encoding Ebola virus glycoprotein fused with lysosome-associated membrane protein.

Ebola virus (EBOV) of the genus Ebolavirus belongs to the family Filoviridae, which cause disease in both humans and non-human primates. Zaire Ebola virus accounts for the highest fatality rate, reaching 90%. Considering that EBOV has a high infection and fatality rate, the development of a highly effective vaccine has become a top public health priority. Glycoprotein (GP) plays a critical role during infection and protective immune responses. Herein, we developed an EBOV GP recombinant DNA vaccine that targets the major histocompatibility complex (MHC) class II compartment by fusing with lysosomal-associated membrane protein 1 (LAMP1). Through lysosome trafficking and antigen presentation transferring, the LAMP1 targeting strategy successfully improved both humoral and cellular EBOV-GP-specific immune responses. After three consecutive immunizations, the serum antibody titers, especially the neutralizing activity of mice immunized with the pVAX-LAMP/GPEBO vaccine were significantly higher than those of the other groups. Antigen-specific T cells showed positive activity against three dominant peptides, EAAVSHLTTLATIST, IGEWAFWETKKNLTR, and ELRTFSILNRKAIDF, with high affinity for MHC class II molecules predicted by IEDB-recommended. Preliminary safety observation denied histological alterations. DNA vaccine candidate pVAX-LAMP/GPEBO shows promise against Ebola epidemic and further evaluation is guaranteed.