BIOINFORMATICS BASED PREDICTION OF B-CELL EPITOPES ON SURFACE GLYCOPROTEINS OF THE ANDES VIRUS

SCHIERLOH P; MARTINEZ V; LANDONI V; GARCÍA M; BALBOA L; SASIAIN MC; PADULA P

Los Cocos

Congreso; LXI Reunión Anual de la Sociedad Argentina de Inmunología; 2013

Sociedad Argentina de Inmunología (SAI)

Hantavirus pulmonary syndrome (HPS) is an endemic deadly disease which lack of specific treatment or vaccine. Andes virus (ANDV) is the predominant etiologic agent of HPS in Argentina. Through interaction with host beta 3 integrin, the viral glycoproteins mediate the entrance into microvascular endothelium. Given that in HPS patients the titer of neutralizing antibodies correlates with good prognostic, in the present study we apply computational methods in order to predict antigenic determinants on Gn and Gc proteins which are exposed at surface of the virion and the infected cells. Then predictions were faced with experimental measurements. From selected primary sequences of Gn and Gc ectodomains of ANDV (n=20), we identified five conserved linear B-cell epitopes candidates based on combined propensity scores computed by 8 different immunoinformatics algorithms. Given that conformational epitope prediction required 3D coordinates structure data and given that Gn and Gc were not yet crystallized, we performed homology modeling using all the available 3D structures of RNA-virus glycoproteins as templates (n=10, computing time ≈20hs). Discontinuous epitopes were then predicted on the most likely 3D models using two different algorithms. Interestingly, three of the best-rated linear epitopes were also overlapped with predicted conformational epitopes. Furthermore, double predicted epitopes also matches with previously reported serological data. Finally, in order to experimentally contrast our predictions, 13-mer peptides (n=3) were synthesized, covalently linked to carrier proteins (BSA, HSA) and used to immunize rabbits and as coating Ag in indirect ELISA assays for testing local patients sera (n=20). Peptide-specific humoral response was observed in animals after single dose immunization. Besides, 20% of patients? sera gave positive reaction with at least one peptide. Taken together these results argue in favor for the application of immunoinformatical approaches in HPS.