SURFIN4.1, a schizont-merozoite associated protein in the SURFIN family of Plasmodium falciparum

<p>Abstract</p> <p>Background</p> <p>In its effort to survive the human immune system, <it>Plasmodium falciparum </it>uses several parasite-derived antigens most of which are expressed at the surface of the parasitized red blood cells (pRBCs). Recently SURFINs, a new family of antigens encoded by the <it>surf </it>multi-gene family, has been reported. One member of the family, SURFIN_4.2, was found present both at the pRBC-surface and at the merozoite apex.</p> <p>Methods</p> <p>The presence of a second SURFIN member, SURFIN_4.1(PFD0100c, PFD0105c) is reported here. Bioinformatic tools were used to study the structure of the <it>surf</it>_4.1gene. To investigate the expression of <it>surf </it>genes PCR and real-time quantitative PCR (Rt-QPCR) were employed and Northern and Western blots were used to confirm the size of the <it>surf</it>_4.1gene and the SURFIN_4.1protein respectively. Localization of SURFIN_4.1was determined using immunofluorescence assays.</p> <p>Results</p> <p>The <it>surf</it>_4.1gene was found present in one copy by Rt-QPCR in some parasites (3D7AH1, 3D7S8, 7G8) whereas six copies of the gene were identified in FCR3 and FCR3S1.2. <it>surf</it>_4.1was found transcribed in the late asexual stages of the parasite beginning ≈32 hours post invasion and throughout the schizont stages with the level of transcription peaking at late schizogony. The levels of transcript correlated with the number of gene copies in FCR3 and 3D7S8. <it>surf</it>_4.1was found to encode a polypeptide of ≈Mw 258 kDa (SURFIN_4.1) present within the parasitophorous vacuole (PV), around free merozoites as merozoite-associated material, but not at the pRBC-surface. Despite multiple <it>surf</it>_4.1gene copies in some parasites this was not reflected in the levels of SURFIN_4.1polypeptide.</p> <p>Conclusion</p> <p>SURFIN_4.1is a member of the SURFINs, present in the PV and on the released merozoite. The results suggest different SURFINs to be expressed at different locations in the parasite and at distinct time-points during the intra-erythrocytic cycle.</p

Differential var gene expression in the organs of patients dying of falciparum malaria

Sequestration of parasitized erythrocytes in the microcirculation of tissues is thought to be important in the pathogenesis of severe falciparum malaria. A major variant surface antigen, var/Plasmodium falciparum erythrocyte membrane protein 1, expressed on the surface of the infected erythrocyte, mediates cytoadherence to vascular endothelium. To address the question of tissue-specific accumulation of variant types, we used the unique resource generated by the clinicopathological study of fatal paediatric malaria in Blantyre, Malawi, to analyse var gene transcription in patients dying with falciparum malaria. Despite up to 102 different var genes being expressed by P. falciparum populations in a single host, only one to two of these genes were expressed at high levels in the brains and hearts of these patients. These major var types differed between organs. However, identical var types were expressed in the brains of multiple patients from a single malaria season. These results provide the first evidence of organ-specific accumulation of P. falciparum variant types and suggest that parasitized erythrocytes can exhibit preferential binding in the body, supporting the hypothesis of cytoadherence-linked pathogenesis

Specific human antibody responses to Aedes aegypti and Aedes polynesiensis saliva: A new epidemiological tool to assess human exposure to disease vectors in the Pacific.

BACKGROUND:Aedes mosquitoes severely affect the health and wellbeing of human populations by transmitting infectious diseases. In French Polynesia, Aedes aegypti is the main vector of dengue, chikungunya and Zika, and Aedes polynesiensis the primary vector of Bancroftian filariasis and a secondary vector of arboviruses. Tools for assessing the risk of disease transmission or for measuring the efficacy of vector control programmes are scarce. A promising approach to quantify the human-vector contact relies on the detection and the quantification of antibodies directed against mosquito salivary proteins. METHODOLOGY/PRINCIPAL FINDINGS:An ELISA test was developed to detect and quantify the presence of immunoglobulin G (IgG) directed against proteins from salivary gland extracts (SGE) of Ae. aegypti and Ae. polynesiensis in human populations exposed to either species, through a cross-sectional study. In Tahiti and Moorea islands where Ae. aegypti and Ae. polynesiensis are present, the test revealed that 98% and 68% of individuals have developed IgG directed against Ae. aegypti and Ae. polynesiensis SGE, respectively. By comparison, ELISA tests conducted on a cohort of people from metropolitan France, not exposed to these Aedes mosquitoes, indicated that 97% of individuals had no IgG directed against SGE of either mosquito species. The analysis of additional cohorts representing different entomological Aedes contexts showed no ELISA IgG cross-reactivity between Ae. aegypti and Ae. polynesiensis SGE. CONCLUSIONS/SIGNIFICANCE:The IgG response to salivary gland extracts seems to be a valid and specific biomarker of human exposure to the bites of Ae. aegypti and Ae. polynesiensis. This new immuno-epidemiological tool will enhance our understanding of people exposure to mosquito bites, facilitate the identification of areas where disease transmission risk is high and permit to evaluate the efficacy of novel vector control strategies in Pacific islands and other tropical settings

SURFIN, a schizont-merozoite associated protein in the SURFIN family of -2

As carried out on 3D7S8 air dried monolayers. EBA175 is a micronemal protein hence localizes at the merozoite apex. The parasite nucleus was stained in blue using Hoescht. In the intact schizont SURFINand EBA175 partially co-localize as shown in the merge of the two photos. B). Co-localization between SURFIN(green) and SURFIN(red) is observed in the intact schizont as indicated by the yellow colour in the merged photos. In the ruptured schizont on the other hand, SURFIN(green) is spread around the merozoites (blue) while SURFIN(red) is observed as a distinct dot on the merozoite (blue). The merge of the two colocalization patterns shows that SURFIN(green) colocalizes with SURFIN(red) even though SURFIN(red) is more spread out around the merozoite compared to SURFINwhich is present at the apex of the merozoite (red). C). A graphical outline of a merozoite showing locations of known merozoite proteins, MSP1 and EBA175 in relation to SURFINand SURFINis depicted here. MSP1 is shown in green surrounding the merozoite, EBA175 is shown in the micronemes, SURFINin orange shown as patches of MAM around the merozoite and SURFINin red as MAM at the apical end of the merozoite.<p><b>Copyright information:</b></p><p>Taken from "SURFIN, a schizont-merozoite associated protein in the SURFIN family of "</p><p>http://www.malariajournal.com/content/7/1/116</p><p>Malaria Journal 2008;7():116-116.</p><p>Published online 1 Jul 2008</p><p>PMCID:PMC2515329.</p><p></p

SURFIN, a schizont-merozoite associated protein in the SURFIN family of -0

7G8 parasite strains revealed FCR3 and FCR3S1.2 to have six copies relative to the other strains. The relative copy number determination was conducted using as the endogenous control gene. B). Rt-QPCR reveals that transcription is initiated at ≈32 h post invasion and peaks during late schizogony. FCR3 shows ≈5-fold higher level of transcription compared to 3D7S8 at 44 h post invasion, corresponding well to the gene copy number abundance in respective genomes. Results are visualized as logtransformed values.<p><b>Copyright information:</b></p><p>Taken from "SURFIN, a schizont-merozoite associated protein in the SURFIN family of "</p><p>http://www.malariajournal.com/content/7/1/116</p><p>Malaria Journal 2008;7():116-116.</p><p>Published online 1 Jul 2008</p><p>PMCID:PMC2515329.</p><p></p

SURFIN, a schizont-merozoite associated protein in the SURFIN family of -1

Um iodide (red) was used to stain the parasite nucleus and SURFINand SURFINproteins were stained green using anti-rabbit Alexa 488. SURFINlocalizes within the parasitophorous vacuole (PV) and is observed from approximately 30 hrs post invasion. SURFINwas observed as a green dot above the food vacuole (), at 30–35 hrs parasite stages. The protein was spread around the parasitophorous vacuole (PV) at 35–40 hrs parasite stages and in the mature schizont (44–48 hrs) SURFINwas observed between the dividing merozoites. During the trophozoite and early schizont stages SURFINshows a similar pattern of staining as SURFIN.<p><b>Copyright information:</b></p><p>Taken from "SURFIN, a schizont-merozoite associated protein in the SURFIN family of "</p><p>http://www.malariajournal.com/content/7/1/116</p><p>Malaria Journal 2008;7():116-116.</p><p>Published online 1 Jul 2008</p><p>PMCID:PMC2515329.</p><p></p

Antibody responses to <i>Ae</i>. <i>aegypti</i> and <i>Ae</i>. <i>polynesiensis</i> SGE in French Polynesian residents.

<p>The figure presents the individual IgG responses (ΔOD) against <i>Ae</i>. <i>aegypti</i> (A) and <i>Ae</i>. <i>polynesiensis</i> (B) SGE in metropolitan France (n = 66) and in Tahiti and Moorea islands (French Polynesia, n = 47) residents. Each triangle or dot represents an individual sample and the horizontal bar indicates the median value. The dotted lines correspond to the positivity thresholds calculated from the cohort of metropolitan French residents, not exposed to these <i>Aedes</i> species (0.16 for <i>Ae</i>. <i>aegypti</i> and 0.13 for <i>Ae</i>. <i>polynesiensis</i>). The percentage of responders (positive samples) in the Tahiti-Moorea cohort is shown above the plot. The non-parametric Mann-Whitney test was used to compare groups.</p

Evolution of antibody responses to <i>Ae</i>. <i>aegypti</i> and <i>Ae</i>. <i>polynesiensis</i> SGE in military personnel.

<p>The figure presents individual IgG responses (ΔOD) to <i>Ae</i>. <i>aegypti</i> (A) and <i>Ae</i>. <i>polynesiensis</i> (B) SGE of French military personnel (n = 13) assigned in Tahiti island (French Polynesia). Blood from the same individual was sampled two weeks after arrival and one year later (paired data). Each triangle or dot represents an individual serum and the horizontal bar indicates the median value. The dotted lines correspond to the positivity thresholds calculated from the cohort of metropolitan French residents (0.16 and 0.13 for <i>Ae</i>. <i>aegypti</i> and <i>Ae</i>. <i>polynesiensis</i>, respectively). Percentages of responders are shown above each plot. The non-parametric Wilcoxon test was used to compare the paired groups.</p

Antibody responses to <i>Ae</i>. <i>aegypti</i> and <i>Ae</i>. <i>polynesiensis</i> SGE from cohorts from different contexts of exposure.

<p>The figure presents the individual IgG responses (ΔOD) against <i>Ae</i>. <i>aegypti</i> (A) and <i>Ae</i>. <i>polynesiensis</i> (B) SGE of residents from Martinique (n = 46), New-Caledonia (n = 19), Bolivia (n = 30) and Reunion (n = 33). The horizontal bars indicate the median value in each group and the dotted lines correspond to the positivity thresholds calculated from the cohort of metropolitan French residents. The percentage of responders in each cohort is shown above the plot. Residents from Martinique, New Caledonia and Bolivia, are typically exposed to <i>Ae</i>. <i>aegypti</i> bites. In Reunion island, <i>Ae</i>. <i>albopictus</i> is the main <i>Aedes</i> species while <i>Ae</i>. <i>aegypti</i> is cryptic. <i>Ae</i>. <i>polynesiensis</i> is not present in these islands or countries.</p

Frequency of sequence groups in transcripts from the organs of paediatric malaria patients

<p><b>Copyright information:</b></p><p>Taken from "Differential gene expression in the organs of patients dying of falciparum malaria"</p><p></p><p>Molecular Microbiology 2007;65(4):959-967.</p><p>Published online Jan 2007</p><p>PMCID:PMC2170262.</p><p>© 2007 Liverpool School of Tropical Medicine; Journal compilation © 2007 Blackwell Publishing Ltd</p> Shading represents the sequence groups as identified by , which are characterized by the number of cysteine residues and other semi-conserved motifs known as positions of limited variance. The data are expressed as the percentage of types within each organ containing the corresponding sequence motifs. Brn, brain; Lng, lung; Hrt, heart; Spl, spleen