Plasmodium vivax ligand-receptor interaction: PvAMA-1 domain I contains the minimal regions for specific interaction with CD71+ reticulocytes

Abstract

The malarial parasite’s invasion is complex, active and coordinated, involving many low and high affinity interactions with receptors on target cell membrane. Proteomics analysis has described around 40 proteins in P. vivax which could be involved in reticulocyte invasion; few have been studied with the aim of elucidating how many of them establish specific interactions with their respective host cells. Given the importance of knowing which of the parasite’s protein regions are functionally important for invasion, minimum regions mediating specific interaction between Plasmodium vivax apical membrane antigen 1 (PvAMA-1) and its host cell were here elucidated. The region covering PvAMA-1 domains I and II (PvAMA-DI-II) specifically bound to the CD71+ red blood cell subpopulation. A 20 residue-long region (81EVENAKYRIPAGRCPVFGKG100) located in domain I was capable of inhibiting PvAMA-DI-II recombinant protein binding to young reticulocytes (CD71+CD45−) and rosette formation. This conserved peptide specifically interacted with high affinity with reticulocytes (CD71+) through a neuraminidase- and chymotrypsin-treatment sensitive receptor. Such results showed that, despite AMA-1 having universal functions during late Plasmodium invasion stages, PvAMA-1 had reticulocyte-preferring binding regions, suggesting that P. vivax target cell selection is not just restricted to initial interactions but maintained throughout the erythrocyte invasion cycle, having important implications for designing a specific anti-P. vivax vaccine.

Receptor-ligand and parasite protein-protein interactions inPlasmodium vivax: Analysing rhoptry neck proteins 2 and 4

“…When Pv RON4 binding to RBC ( m = 34 ± 2.7) was compared with binding to normocytes ( m = 11 ± 1.4), it was observed that the amount of rosettes compared with normocytes became significantly reduced, t test: t (10) = 18.68, p = .001 (Figure b,c). This suggested that Pv RON4 binding to RBC depends on a more immature RBC population, similar to that reported for other P. vivax antigens, such as Pv AMA1 (Arevalo‐Pinzon, Bermudez, Hernandez, Curtidor, & Patarroyo, ), Pv GAMA (Baquero et al, ), and EBP2 (Ntumngia et al, ), whereas Pv DBPRII bound to both RBC and normocytes (Figure c).…”

“…It has been reported (and also found here) that Pv DBP binding to DARC was susceptible to enzymatic treatment with chymotrypsin (Barnwell, Nichols, & Rubinstein, ), t test: t (4) = 24.4, p = .001 (Figure d). It has also been reported that Pv AMA1 binding was susceptible to neuraminidase and chymotrypsin action (Arevalo‐Pinzon et al, ). Interestingly, it was found here that Pv RON4 interacted with RBC membrane protein receptors susceptible to treatment with the three enzymes evaluated, ANOVA‐Tukey: F (3, 8) = 59, p = .001 (Figure d).…”

“…It has been reported that the Pf RON2 fragment involved in interaction with RBC is located in the carboxyl‐terminal region (Hossain et al, ), different to that found for Pv RON2 where, even though both regions bound, only the region located towards the protein's central portion (called Pv RON2‐RI here) specifically interacted with UCB RBC (Figure ). Such data, added to that available for P. vivax proteins (e.g., Pv MSP1 and Pv AMA1, Arevalo‐Pinzon et al, , and now Pv RON2), have shown that some P. vivax proteins having orthologues in P. falciparum fulfil the same functions but use different functional regions. This has important implications when designing effective control mechanisms against P. vivax malaria and could be partly responsible for the specificity of interaction with respective target cells.…”

“…Such HABPs have now been defined as immune protection‐inducing protein structures (IMPIPS), and some of them are strong candidates for a multiantigen, multistage, subunit‐based anti‐ P. falciparum vaccine (Patarroyo et al, ). The ~40 proteins identified in P. vivax could play important roles during reticulocyte invasion (Patarroyo et al, ); Pv DBP (Ocampo et al, ), Pv MSP1 (Rodriguez et al, ), Pv RBP1 (Urquiza et al, ), and Pv AMA1 (Arevalo‐Pinzon et al, ) HABPs had only been identified to date, but now Pv RON2 and Pv RON4 can be added to the list.…”

“…Recombinant plasmids encoding Pv AMA1 ectodomain, Domains I and II ( Pv AMA1‐DI‐II), Domains II and III ( Pv AMA‐DII‐III), and the C‐terminal fragment of Pv RON5 were taken from previous studies to express such fragments in E. coli (Arevalo‐Pinzon et al, ; Arevalo‐Pinzon et al, ). The pHVDR22 plasmid was used to express the Duffy‐binding Region II on COS‐7 cell membrane as positive control ( Pv DBP‐RII; Chitnis & Miller, ).…”