Demographic and epidemiological data of individuals who were enrolled in this study.

<p>Demographic and epidemiological data of individuals who were enrolled in this study.</p

Analysis of the molecular interactions of polymorphic residues of CYP2D6 and their effects on the metabolism of primaquine.

<p>(A) The residue P34 has a buried side chain that is inserted into a predominantly hydrophobic environment (the hydrophobic interactions are depicted as gray dots) and is performing a main-chain to side-chain polar interaction with a neighboring beta strand (red dashes). The mutation P34S is predicted to destabilize the protein because it disrupts the local hydrophobic interaction network and affects the backbone rigidity. (B) The interactions for docked PQ (dark gray) and residue T107 (green). Threonine 107 is located in the vicinity of the PQ binding pocket (6.1 Å from PQ) and also nearby important catalytic residues (depicted in blue). (C) The mutation T107I results in the formation of increased local interactions, reducing CYP2D6 flexibility. Residues are colored based on their predicted effect on flexibility, ranging from more flexible (red) to less flexible (blue).</p

Analysis of the parasite haplotype and time to relapse in days for carriers of CYP2C8 polymorphisms.

<p>Frequency of parasite haplotype between patients without or with CYP2C8 mutation. Parasites were classified according to the number of identical markers: <i>identical</i> in black (10 identical markers); <i>related</i> in gray (8 to 9 identical markers); and <i>heterologous</i> in light gray (less than 8 identical markers).</p

Variation in Human Cytochrome P-450 Drug-Metabolism Genes: A Gateway to the Understanding of <i>Plasmodium vivax</i> Relapses

<div><p>Although <i>Plasmodium vivax</i> relapses are classically associated with hypnozoite activation, it has been proposed that a proportion of these cases are due to primaquine (PQ) treatment failure caused by polymorphisms in cytochrome P-450 2D6 (CYP2D6). Here, we present evidence that CYP2D6 polymorphisms are implicated in PQ failure, which was reinforced by findings in genetically similar parasites, and may explain a number of <i>vivax</i> relapses. Using a computational approach, these polymorphisms were predicted to affect the activity of CYP2D6 through changes in the structural stability that could lead to disruption of the PQ-enzyme interactions. Furthermore, because PQ is co-administered with chloroquine (CQ), we investigated whether CQ-impaired metabolism by cytochrome P-450 2C8 (CYP2C8) could also contribute to <i>vivax</i> recurrences. Our results show that CYP2C8-mutated patients frequently relapsed early (<42 days) and had a higher proportion of genetically similar parasites, suggesting the possibility of recrudescence due to CQ therapeutic failure. These results highlight the importance of pharmacogenetic studies as a tool to monitor the efficacy of antimalarial therapy.</p></div

Genotypes and allele frequencies of the <i>CYP2D6</i> gene in <i>P</i>. <i>vivax</i>-infected patients who had single or multiple episodes of relapse.

<p>Genotypes and allele frequencies of the <i>CYP2D6</i> gene in <i>P</i>. <i>vivax</i>-infected patients who had single or multiple episodes of relapse.</p

<i>Plasmodium simium</i>, a <i>Plasmodium vivax</i>-Related Malaria Parasite: Genetic Variability of Duffy Binding Protein II and the Duffy Antigen/Receptor for Chemokines

<div><p><i>Plasmodium simium</i> is a parasite from New World monkeys that is most closely related to the human malaria parasite <i>Plasmodium vivax</i>; it also naturally infects humans. The blood-stage infection of <i>P</i>. <i>vivax</i> depends on Duffy binding protein II (PvDBPII) and its cognate receptor on erythrocytes, the Duffy antigen receptor for chemokines (hDARC), but there is no information on the <i>P</i>. <i>simium</i> erythrocytic invasion pathway. The genes encoding <i>P</i>. <i>simium</i> DBP (PsDBP_II) and simian DARC (sDARC) were sequenced from Southern brown howler monkeys (<i>Alouatta guariba clamitans</i>) naturally infected with <i>P</i>. <i>simium</i> because <i>P</i>. <i>simium</i> may also depend on the DBPII/DARC interaction. The sequences of DBP binding domains from <i>P</i>. <i>vivax</i> and <i>P</i>. <i>simium</i> were highly similar. However, the genetic variability of PsDBPII was lower than that of PvDBPII. Phylogenetic analyses demonstrated that these genes were strictly related and clustered in the same clade of the evolutionary tree. DARC from <i>A</i>. <i>clamitans</i> was also sequenced and contained three new non-synonymous substitutions. None of these substitutions were located in the N-terminal domain of DARC, which interacts directly with DBPII. The interaction between sDARC and PvDBPII was evaluated using a cytoadherence assay of COS7 cells expressing PvDBPII on their surfaces. Inhibitory binding assays <i>in vitro</i> demonstrated that antibodies from monkey sera blocked the interaction between COS-7 cells expressing PvDBPII and hDARC-positive erythrocytes. Taken together, phylogenetic analyses reinforced the hypothesis that the host switch from humans to monkeys may have occurred very recently in evolution, which sheds light on the evolutionary history of new world plasmodia. Further invasion studies would confirm whether <i>P</i>. <i>simium</i> depends on DBP/DARC to trigger internalization into red blood cells.</p></div

Frequency of CYP2D6 polymorphisms and parasite haplotype among <i>P</i>. <i>vivax-</i>infected patients who had single (n = 28) or multiple (n = 18) episodes of relapse.

<p>(A) The number of CYP2D6 polymorphisms is represented by the different intensity of color as specified in the legend. A simple logistic regression model shows a significant relationship between the mutant status for CYP2D6 and the increased number of relapses (OR, 12.4; 95% CI, 2.80–88.57; <i>P</i> = .003). (B) Frequency of parasite haplotype in patients without or with CYP2D6 mutation. Parasites were classified according to the number of markers containing identical alleles: <i>identical</i> in black (parasites showing all 10 identical markers); <i>related</i> in gray (8 to 9 identical markers); and <i>heterologous</i> in light gray (less than 8 identical markers).</p

Single nucleotide polymorphisms (SNPs) in the ligand domain of the Duffy binding protein (DBPII)-encoding gene in seven isolates of <i>Plasmodium simium</i>.

<p>* Positions corresponding to <i>P</i>. <i>vivax</i> Sal-1 <i>dbp</i>, accession number M61095.1.</p><p>Underlined residues are polymorphic. Dots indicate the same residue in the sequences compared to the reference sequence.</p><p>Single nucleotide polymorphisms (SNPs) in the ligand domain of the Duffy binding protein (DBPII)-encoding gene in seven isolates of <i>Plasmodium simium</i>.</p

Genetic diversity of <i>P</i>. <i>simium</i> DBPII compared to other <i>Plasmodium</i> DBPII.

<p>^a<i>P</i>. <i>vivax</i> Sal-1, accession number M61095.1.</p><p>^b<i>P</i>. <i>cynomolgi</i> 1, accession number XM004221494.1.</p><p>^c<i>P</i>. <i>knowlesi</i> alpha, accession number M90466.1.</p><p>N: number of sequences; S: segregating sites; π: nucleotide diversity; H: haplotypes; Hd: haplotype diversity; SD: standard deviation</p><p>Genetic diversity of <i>P</i>. <i>simium</i> DBPII compared to other <i>Plasmodium</i> DBPII.</p

Schematic model of DARC showing polymorphic sites.

<p>The 2-D model of DARC from <i>Homo sapiens</i> was constructed using TOPO2 software. Polymorphic sites in primates are shown in orange, purple (SNPs exclusive to the Cercopithecidae family), green (SNPs exclusive to the Platyrrhini parvorder) and blue (SNPs exclusive to the Hominoidea superfamily). Residues involved in direct binding to DARC are indicated (20–22 and 24–26) according to Batchelor et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0131339#pone.0131339.ref053" target="_blank">53</a>]. The arrow indicates Asp42Gly. Polymorphisms were annotated only until codon 255 (fragment available in our sequences).</p