Rapid Fire Presentation 8th International Conference on Plasmodium vivax Research 2022

P. vivax schizont transcriptomes reveal PvTRAg variation linked to band3-mediated invasion in invasion inhibition assays (#200)

Katlijn De Meulenaere 1 2 , Surendra K. Prajapati 1 3 , Johanna H. Kattenberg 1 , Bart Cuypers 2 , Elizabeth Villasis 4 , Bernadine Kasian 5 , Leanne J. Robinson 5 6 , Dionicia Gamboa 4 , Kris Laukens 2 , Anna Rosanas-Urgell 1
  1. Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp, Antwerp, Belgium
  2. Department of Computer Science, University of Antwerp, Antwerp, Belgium
  3. Uniformed Services University of the Health Sciences, Bethesda, USA
  4. Universidad Peruana Cayetano Heredia, Lima, Peru
  5. Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
  6. Burnet Institute, Melbourne, Australia

Plasmodium vivax (Pv) parasites invade reticulocytes in a multistep process that is still poorly understood, although identification of new receptor-ligand pairs of the invasion process is crucial to uncover vaccine candidates. Band3 is an interesting receptor candidate, as Pv infections are 50% reduced in Southeast Asian Ovalocytosis (SAO) red blood cells, which have a deletion in the band3 surface protein.

We performed invasion inhibition assays to investigate Pv invasion through the band3 receptor using SAO reticulocytes, band3 antibody blocking and competition with a PvTRAg38 peptide (ligand candidate). From those same isolates, we investigated the schizont transcriptome in association with invasion phenotypes.

Pv invasion of SAO reticulocytes was reduced by 34-87% compared to control reticulocytes. When blocking this newly identified band3 receptor with a polyclonal antibody, invasion efficiency again was highly variable between isolates (7%-65%) suggesting that some isolates heavily rely on band3, while others can invade independently of band3.

Based on the variable invasion inhibition levels in SAO reticulocytes, schizont stage transcriptomes of those same isolates were classified in groups of low, medium and high dependence on band3. We hypothesize that parasites with high band3 dependence highly express the band3 ligand(s) and vice versa. By comparing these groups with differential expression analysis, a list with band3 ligand candidates was obtained. The list is enriched in PvTRAg members including PvTRAg38, which was previously shown to bind to band3 in vitro. We confirmed PvTRAg38 as a band3 ligand with invasion inhibition assays, although results indicate that additional ligands can bind to band3.

In summary, we have identified a new band3-mediated pathway in Pv invasion and shown that linking invasion phenotypes with transcriptomes from the same parasites can inform host-parasite interactions involved in invasion. We constructed a list with band3 ligand candidates, among which the PvTRAg genes are the best candidates.