E-Poster with pre-recorded video presentation Lorne Infection and Immunity 2021

Understanding Plasmodium vivax antigen diversity and identifying targets of immune selection  (#298)

Paolo Bareng 1 2 , Somya Mehra 1 2 , Myo Naung 1 2 3 4 , Alyssa Barry 1 2 3 4
  1. Institute for Mental Health and Physical Health and Clinical Translation (IMPACT), School of Medicine, Deakin University, Geelong, VIC, Australia
  2. Life Sciences Discipline, Burnet Institute, Melbourne, Victoria, Australia
  3. Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
  4. Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia

There has been limited attention on Plasmodium vivax infection and its impact on the global malaria control and elimination campaign. One of the major gaps in vivax research is the lack of information on the diversity of surface antigens, which could provide relevant details on the parasite population structure and vaccine development. Population genetic data can not only assess transmission intensity but also provide insights in detecting genes under immune selectionWe aimed to determine the global diversity of P. vivax vaccine candidates and serosurveillance antigens and identify gene regions under positive balancing selection. Global diversity and evidence of immune selection were measured from gene sequences extracted from whole genome sequences. Haplotype network diagrams were constructed to visualize the genetic relatedness of the analyzed sequences. Moreoverthe protein sequence of each antigen was mapped to predict B cell epitopes to identify immunodominant domainsInitial results showed varying levels of diversity in some of the major P. vivax antigens across different populations. The antigens’ RAMA, MSP119, FAM-a-1, MSP8, and S16 demonstrated remarkably conserved sequences while RBP2a, RBP2b, MSP3-a, MSP5 and DBP exhibited extensive genetic diversity. The haplotype network plot also showed distantly related sequences among highly diverse antigens reflecting their known extensive variation. Lastly, scanning the full-length antigen sequences revealed protein regions that are likely to be under immune selection and could be used as a guide in selecting domains to be included in a candidate vaccine. The data from this study will guide developers in designing widely effective vaccines and serological tools against P. vivax parasites.