Plasmodium vivax trophozoite-stage proteomes

Abstract

Plasmodium vivax is the causative infectious agent of 80–300 million annual cases of malaria. Many aspects of this parasite’s biology remain unknown. To further elucidate the interaction of P. vivax with its Saimiri boliviensis host, we obtained detailed proteomes of infected red blood cells, representing the trophozoite-enriched stage of development. Data from two of three biological replicate proteomes, emphasized here, were analyzed using five search engines, which enhanced identifications and resulted in the most comprehensive P. vivax proteomes to date, with 1375 P. vivax and 3209 S. boliviensis identified proteins. Ribosome subunit proteins were noted for both P. vivax and S. boliviensis, consistent with P. vivax’s known reticulocyte host–cell specificity. A majority of the host and pathogen proteins identified belong to specific functional categories, and several parasite gene families, while 33% of the P. vivax proteins have no reported function. Hemoglobin was significantly oxidized in both proteomes, and additional protein oxidation and nitration was detected in one of the two proteomes. Detailed analyses of these post-translational modifications are presented. The proteins identified here significantly expand the known P. vivax proteome and complexity of available host protein functionality underlying the host–parasite interactive biology, and reveal unsuspected oxidative modifications that may impact protein function. Biological significance Plasmodium vivax malaria is a serious neglected disease, causing an estimated 80 to 300 million cases annually in 95 countries. Infection can result in significant morbidity and possible death. P. vivax, unlike the much better-studied Plasmodium falciparum species, cannot be grown in long-term culture, has a dormant form in the liver called the hypnozoite stage, has a reticulocyte host–cell preference in the blood, and creates caveolae vesicle complexes at the surface of the infected reticulocyte membranes. Studies of stage-specific P. vivax expressed proteomes have been limited in scope and focused mainly on pathogen proteins, thus limiting understanding of the biology of this pathogen and its host interactions. Here three P. vivax proteomes are reported from biological replicates based on purified trophozoite-infected reticulocytes from different Saimiri boliviensis infections (the main non-human primate experimental model for P. vivax biology and pathogenesis). An in-depth analysis of two of the proteomes using 2D LC/MS/MS and multiple search engines identified 1375 pathogen proteins and 3209 host proteins. Numerous functional categories of both host and pathogen proteins were identified, including several known P. vivax protein family members (e.g., PHIST, eTRAMP and VIR), and 33% of protein identifications were classified as hypothetical. Ribosome subunit proteins were noted for both P. vivax and S. boliviensis, consistent with this parasite species’ known reticulocyte host–cell specificity. In two biological replicates analyzed for post-translational modif...

Severe malaria: what’s new on the pathogenesis front?

“…The Malaria Host-Pathogen Interaction Centre (MaHPIC) is a large international systems biology consortium developed in 2012 and based in the USA (http://www.systemsbiology.emory.edu/index.html), which allowed the development of a variety of distinctive hypothesis-generating and hypothesis-driven collaborations with scientific teams in malaria-endemic regions. These collaborations involve investigators from several countries in South America, southeastern Asia and sub-Saharan Africa, with a focus on infections caused by the predominant, less predominant, or mixed species of Plasmodium (Anderson et al, 2015; Lapp et al, 2015), to study disease states, pathogenesis and physiological or immunobiological questions through the use of untargeted high-resolution metabolomics, as well as clinical and demographic metadata (Salinas et al, 2014). In addition, the MaHPIC team is intensively studying malaria using non-human primate model systems (macaque and New World monkey species, (Joyner et al, 2015)).…”

Plasmodium Helical Interspersed Subtelomeric (PHIST) Proteins, at the Center of Host Cell Remodeling

“…Caveola-vesicle complexes (CVCs) are parasite-induced indentations in P. vivax-infected erythrocyte cell membranes. The exact structure, protein composition, and function are not yet fully understood, but CVC-81 95 is exported, is a predominant protein in these CVCs, and is found on tubular extensions going inwards from the CVC (75,76). Its orthologue in P. cynomolgi shows a similar localization (75).…”

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

“…Eliminating duplicate hits across the samples, 296/605 parasite proteins were detected once across all the replicates (Table 2, Supporting Information). These proteins represented 21% of the total parasite proteome identified (1375 proteins,) so far based on primate models. A majority of these proteins were found to be involved in translation, cytoskeleton proteins, surface proteins, histones and heat shock proteins (Figure 2A and Table 2, Supporting Information).…”

“…Due to technical challenges with P. vivax propagation in culture, previous proteomic studies focused on pooled samples and non‐human primate models (NHP). The former provided initial insights into parasite biology while studies involving NHPs greatly increased the proteome coverage of P. vivax and allowed the enrichment of specific parasite stages . A recent study involving Saimiri boliviensis as a model system further explored the interactions involving host reticulocyte proteins that may be crucial to malaria pathogenesis.…”

“…Around the same time, Anderson et al. published the most comprehensive P. vivax proteome and reported 1375 pathogen proteins using Saimiri boliviensis as the primate model . These studies focused on providing an improved understanding of P. vivax biology.…”