Immunoprofiling of the Tryptophan-Rich Antigen Family in Plasmodium vivax

Abstract

h Tryptophan-rich antigens (TRAgs) are an antigen family that has been identified in human and rodent malaria parasites. TRAgs have been proposed as candidate antigens for potential vaccines. The Plasmodium vivax TRAg (PvTRAg) family includes 36 members. Each PvTRAg contains a tryptophan-rich (TR) domain in the C-terminal region. In this study, we recombinantly expressed all 36 PvTRAgs using a cell-free expression system, and, for the first time, profiled the IgG antibody responses against all PvTRAgs in the sera from 96 vivax malaria patients and 40 healthy individuals using protein microarray technology. The mean seropositive rate for all PvTRAgs was 60.3%. Among them, nine PvTRAgs were newly identified in this study and showed a seropositive rate of >50%. Five of them, PvTRAg_13, PvTRAg_15, PvTRAg_16, PvTRAg_26, and PvTRAg_29, produced higher levels of IgG antibody, even in low-endemicity countries. In addition, the results of an immunofluorescence analysis suggest that PvTRAgs are, at least in part, associated with caveola-vesicle complexes, a unique structure of P. vivax-infected erythrocytes. The mechanism of formation and the function of these abundant membrane structures are not known. Further investigation aimed at determining the functions of these proteins would lead to a better understanding of the blood-stage biology of P. vivax.

Evolutionary history of humanPlasmodium vivaxrevealed by genome-wide analyses of related ape parasites

“…The discrepancy in overall NI values for ape versus human P. vivax strains indicates that MK tests are likely to produce different results depending on which P. vivax strains are used. For the chimpanzee P. vivax strains, only two genes yielded significant results after correction for multiple testing ( P < 0.05), both with NI <1 indicating a significant excess of fixed, potentially adaptive, nonsynonymous differences: one was found to be orthologous to PVP01_1201800, which is an immunogenic member of the tryptophan-rich antigen family of P. vivax ( 27 , 28 ), and the other (orthologous to PVP01_1406200) encodes a conserved Plasmodium protein of unknown function. For the human P. vivax strains, five genes yielded significant MK test results, but all with NI >1, indicating an excess of nonsynonymous polymorphisms ( Dataset S1 ).…”

Naturally-Acquired Immune Response against Plasmodium vivax Rhoptry-Associated Membrane Antigen

“…Similarly, antibodies to anti- P . vivax tryptophan-rich antigen persisted stably for 5 to 12 years in Chinese residents who lived in low malaria-endemic areas [ 25 ]. Recently, P .…”

Identification of Highly Expressed Plasmodium Vivax Proteins from Clinical Isolates Using Proteomics

“…The study revealed a very high seropositivity rate amongst the P. vivax patients, indicating that the antigen generates significant humoral immune response . Alternatively, a recent study revealed mean seropositive rate of 60.3% for 36 recombinantly expressed PvTRAgs when antibody responses were measured in the sera from 96 vivax malaria patients and 40 healthy individuals using protein microarray technology . These factors need to be exploited further to test its value as a serodiagnostic marker for vivax malaria.…”