Title

Implications from predicted B-cell and T-cell epitopes of Plasmodium falciparum merozoite
proteins EBA175-RII and Rh5

Authors

Kevin Kariuki Wamae1,2, & Lynette Isabella Ochola-Oyier*1,2

Affiliation

1Centre for Biotechnology and Bioinformatics, University of Nairobi, Kenya; 2KEMRI-Wellcome Trust Collaborative Programme, Kilifi, Kenya; P.O. Box 230, Kilifi – 80108, Kenya

Email

Email: kwamae@kemri-wellcome.org; Fax:+ 254 20 2711673; *Corresponding
author

Article Type

Hypothesis

Date

Received February 05, 2016; Revised March 21, 2016; Accepted March 25, 2016; Published June 15, 2016

The leading circumsporozoite protein (CSP) based malaria vaccine, RTS,S, though promising, has shown limited efficacy in field studies. There is therefore, still a need to identify other malaria vaccine targets. Merozoite antigens are potential vaccine candidates, since naturally acquired antibodies generated against them inhibit erythrocyte invasion and in some cases result in the
clinical protection from disease. We thus used in silico tools (BCPreds, NetMHCcons and NetMHCIIpan 3.0) to predict B-cell epitopes (BCEs) and T-cell epitopes (TCEs) in two merozoite invasion proteins, EBA175-RII and Rh5. Initially, we validated these tools using CSP to determine whether the algorithms could predict the epitopes in the RTS,S vaccine. In EBA175-RII, we prioritised three BCEs 15REKRKGMKWDCKKKNDRSNY34, 420SNRKLVGKINTNSNYVHRNKQ440 and 528WISKKKEEYNKQAKQYQEYQ547, a CD8+ epitope 553KMYSEFKSI561 and a CD4+ epitope 440QNDKLFRDEWWK VIKKD456. Three Rh5 epitopes were prioritised, a BCE 344SCYNNNFCNTNGIRYHYDEY363, a CD8+ epitope 198STYGKCIAV206 and a Rh5 CD4+ epitope
180TFLDYYKHLSYNSIYHKSSTY200. All these epitopes are in the region involved in the proteins’ interaction with their erythrocyte receptors, thus enabling erythrocyte invasion. Therefore, upon validation of their immunogenicity, by ELISA using serum from a malaria endemic population, antibodies to these epitopes may inhibit erythrocyte invasion. All the epitopes we predicted in
EBA175-RII and Rh5 are novel. We also identified polymorphic epitopes that may escape host immunity, as some variants were not predicted as epitopes, suggesting that they may not be immunogenic regions. We present a set of epitopes that following in vitro validation provide a set of molecules to screen as potential vaccine candidates.

Citation

Wamae et al. Bioinformation 12(3): 82-91 (2016)

Edited by

P Kangueane

ISSN

0973-2063

Publisher

Biomedical Informatics

License

This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. This is distributed under the terms of theCreative Commons Attribution License.