Abstract
Background
Orthohantavirus infection is a neglected global health problem affecting approximately 200,000 people/year, spread by rodent hosts and associated to fatal human diseases, such as hemorrhagic fever with renal syndrome (HFRS) and orthohantavirus cardiopulmonary syndrome (HCPS). Circulation of HFRS-associated orthohantaviruses, such as Seoul, Gou, Amur, Dobrava and Hantaan, are supposed to be restricted to Eurasian countries even though their hosts can be a worldwide distribution. Few confirmed HFRS orthohantavirus infections in humans have been reported in American countries, but due to lower medical awareness of the symptoms of this zoonosis, it could be associated to viral underreporting or to misdiagnosis with several tropical hemorrhagic diseases. Serological evidence of orthohantavirus infections, using enzyme-linked immunosorbent assay for the presence of immunoglobulin M and G against recombinant nucleoprotein protein, remains as an essential assay for viral surveillance. In this study, we aimed to identify in silico immunogenic B-cell linear epitopes present on orthohantavirus nucleoprotein that are exclusive to HFRS-related species.
Methodology/Principal findings
In silico analysis were performed using Seoul orthohantavirus nucleoprotein (SHNP) sequence as a model. Linear B-cell-epitopes on SHNP and its immunogenicity were predicted by BepiPred-2.0 and Vaxijen algorithms, respectively. The conservancy of predicted epitopes was compared with the most clinically relevant HFRS or HCPS-associated orthohantavirus, aiming to identify specific sequences from HFRS-orthohantavirus. Peptide validation was carried out by ELISA using Balb/c mice sera immunized with purified recombinant rSHNP. Peptides cross-reactivity against HCPS orthohantavirus were evaluated using immunized sera from mice injected with recombinant Juquitiba orthohantavirus nucleoprotein (rJHNP).
Conclusion/Significance
In silico analysis revealed nine potential immunogenic linear B-cell epitopes from SHNP; among them, SHNP(G72-D110) and SHNP(P251-D264) showed a high degree of sequence conservation among HFRS-related orthohantavirus and were experimentally validated against rSHNP-IMS and negatively validated against rJHNP-IMS. Taken together, we identified and validated two potential antigenic B-cell epitopes on SHNP, which were conserved among HFRS-associated orthohantavirus and could be applied to the development of novel immunodiagnostic tools for orthohantavirus surveillance.
Orthohantaviruses are the etiological agents of serious rodent-borne neglected human diseases named as hemorrhagic fever with renal syndrome (HFRS) and orthohantavirus cardiopulmonary syndrome (HCPS). These distinct clinical manifestations of disease are related to specific orthohantavirus species and it is believed that HFRS-associated orthohantavirus mainly circulate into Old World (Asia and Europe) whereas HCPS-associated orthohantaviruses are predominant into New World countries (Americas). However, since Seoul orthohantavirus, associated with HFRS, was isolated in America and its natural host (Rattus norvegicus) are widely distributed around the world, it raised the question if the viral underreporting is associated to lower medical awareness of the symptoms or if it is associated to misdiagnosis with other tropical hemorrhagic diseases (leptospirosis, yellow fever). In this context, considering that the HFRS are clinically indistinguishable from order hemorrhagic diseases, and that serological tests are predominantly based on serology tests against nucleoprotein, a highly conserved protein among different orthohantavirus, we hypothesize that current available tests do not detect all HFRS-associated orthohantavirus. In this sense; we aimed to identify B-cell linear epitopes exclusively conserved on HFRS-associated orthohantavirus nucleoprotein, using a combination of in silico and experimental approaches, to identify targets that could be applied in the development of novel immunodiagnostic tools able to identify different HFRS orthohantavirus species.
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