IgG responses to the gSG6-P1 salivary peptide for evaluating human exposure to Anopheles bites in urban areas of Dakar region, Sénégal

Drame, Papa M.; Machault, Vanessa; Diallo, Abdoulaye Baniré; Cornélie, Sylvie; Poinsignon, Anne; Lalou, Richard; Sembène, Mbacké; Santos, Stéphanie Dos; Rogier, Christophe; Pagès, Frédéric; Hesran, Jean-Yves Le; Remoué, Franck

doi:10.1186/1475-2875-11-72

Cited by 48 publications

(72 citation statements)

References 39 publications

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“…The individual heterogeneity of the IgG responses against gSG6 in each site could explain this powerless discrimination. This phenomenon could be attributed to the heterogeneity of Anopheles exposures according to distinct human behaviors or attractive differences, as recently described [51,52]. To better appreciate the variations of anti-gSG6 IgG levels, according to Anopheles densities, a kinetic analysis of the IgG response may be more appropriate and necessary.…”

Section: Resultsmentioning

confidence: 96%

Assessment of Anopheles salivary antigens as individual exposure biomarkers to species-specific malaria vector bites

Ali

Bakli

Fontaine

et al. 2012

Malar J

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BackgroundMalaria transmission occurs during the blood feeding of infected anopheline mosquitoes concomitant with a saliva injection into the vertebrate host. In sub-Saharan Africa, most malaria transmission is due to Anopheles funestus s.s and to Anopheles gambiae s.l. (mainly Anopheles gambiae s.s. and Anopheles arabiensis). Several studies have demonstrated that the immune response against salivary antigens could be used to evaluate individual exposure to mosquito bites. The aim of this study was to assess the use of secreted salivary proteins as specific biomarkers of exposure to An. gambiae and/or An. funestus bites.MethodsFor this purpose, salivary gland proteins 6 (SG6) and 5′nucleotidases (5′nuc) from An. gambiae (gSG6 and g-5′nuc) and An. funestus (fSG6 and f-5′nuc) were selected and produced in recombinant form. The specificity of the IgG response against these salivary proteins was tested using an ELISA with sera from individuals living in three Senegalese villages (NDiop, n = 50; Dielmo, n = 38; and Diama, n = 46) that had been exposed to distinct densities and proportions of the Anopheles species. Individuals who had not been exposed to these tropical mosquitoes were used as controls (Marseille, n = 45).ResultsThe IgG responses against SG6 recombinant proteins from these two Anopheles species and against g-5′nucleotidase from An. gambiae, were significantly higher in Senegalese individuals compared with controls who were not exposed to specific Anopheles species. Conversely, an association was observed between the level of An. funestus exposure and the serological immune response levels against the f-5′nucleotidase protein.ConclusionThis study revealed an Anopheles salivary antigenic protein that could be considered to be a promising antigenic marker to distinguish malaria vector exposure at the species level. The epidemiological interest of such species-specific antigenic markers is discussed.

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Section: Resultsmentioning

confidence: 96%

Assessment of Anopheles salivary antigens as individual exposure biomarkers to species-specific malaria vector bites

Ali

Bakli

Fontaine

et al. 2012

Malar J

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“…The large heterogeneity of antibody levels observed in the young children in Dielmo in 2013 is surprising, as antibodies to gSG6 have been reported to be negatively associated with the use of LLIns in young children [65]. It contrasts with the more homogeneous response observed in the same age group 11 years earlier and suggests substantial heterogeneity of exposure of young children to Anopheles bites in 2013, as reported in low transmission conditions [62]. Presence of antibodies against gSG6 indicates continued exposure to mosquito bites in 2013 is consistent with the recorded vector density in the villages, and probably indicates exposure to Anopheline bites at a time when children are not using LLINs.…”

Section: Discussionmentioning

confidence: 99%

Serological signatures of declining exposure following intensification of integrated malaria control in two rural Senegalese communities

et al. 2017

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Recent control scale-up has reduced malaria in many areas but new tools are needed to monitor further progress, including indicators of decreasing exposure to parasite infection. Although serology is considered a promising approach in this regard, the serological impact of control interventions has been so far studied using indirect quantification of exposure. Cohort surveys concomitantly recording entomological and malariometric indices have been conducted in two Senegalese settings where supervised control intensification implemented in 2006 shifted malaria from historically holoendemic in Dielmo and mesoendemic in Ndiop to hypoendemic in both settings by 2013. We analyse here serological signatures of declining transmission using archived blood samples. Responses against ten pre-erythrocytic and erythrocytic antigens from Plasmodium falciparum and P. malariae alongside an Anopheles gambiae salivary gland antigen were analysed. Cross-sectional surveys conducted before (2002) and after (2013) control intensification showed a major impact of control intensification in both settings. The age-associated prevalence, magnitude and breadth of the IgG responses to all antigens were village-specific in 2002. In 2013, remarkably similar patterns were observed in both villages, with marginal responses against all parasite antigens in the 0-5y children and reduced responses in all previously seropositive age groups. Waning of humoral responses of individuals who were immune at the time of control intensification was studied from 2006 to 2013 using yearly samplings. Longitudinal data were analysed using the Cochran-Armittage trend test and an age-related reversible catalytic conversion model. This showed that the antigen-specific antibody declines were more rapid in older children than adults. There was a strong association of antibody decline with the declining entomological inoculation rate. We thus identified serological markers of declining exposure to malaria parasites that should help future monitoring of progress towards malaria elimination.

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“…Malaria is transmitted in Dakar and its surrounding suburbs with a spatial heterogeneity of the human biting rate, which ranged from 0.1 to 250 bites per person per night during the rainy season from 2007 to 2010 [1, 2]. In 2008, the Plasmodium falciparum prevalence varied from 0.9 to 7.4% in asymptomatic women and children in Dakar [3].…”

Section: Introductionmentioning

confidence: 99%

Limited polymorphisms in k13 gene in Plasmodium falciparum isolates from Dakar, Senegal in 2012–2013

Torrentino-Madamet

Fall

Nicolas

et al. 2014

Malar J

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BackgroundThe emergence of Plasmodium falciparum resistance to artemisinin and its derivatives, manifested as delayed parasite clearance following the treatment, has developed in Southeast Asia. The spread of resistance to artemisinin from Asia to Africa may be catastrophic for malaria control and elimination worldwide. Recently, mutations in the propeller domain of the Kelch 13 (k13) gene (PF3D71343700) were associated with in vitro resistance to artemisinin and with delayed clearance after artemisinin treatment in southern Asia. The aim of the study was to characterize the genetic variability of k13 and to evaluate the molecular resistance to artemisinin for the first time in Senegal.MethodsPlasmodium falciparum isolates were collected from 138 malaria patients in Dakar and its districts during the rainy season of October 2012 to January 2013 at the Hôpital Principal de Dakar. The k13 gene was amplified using nested PCR and sequenced.ResultsA very limited variability within the k13 gene in Senegalese P. falciparum isolates was identified. No polymorphism was detected in the six k13-propeller blades. Only two mutations, T149S (6.3%) and K189T (42.2%), and one (N) or two (NN) asparagine insertion at the codon 142 (4.7 and 6.3%, respectively) were detected in the Plasmodium/Apicomplexa-specific domain. None of the polymorphisms associated with artemisinin resistance in Southeast Asia was detected in the 138 P. falciparum from Dakar.DiscussionThe present data do not suggest widespread artemisinin resistance in Dakar in 2012–2013. Notably, the C580Y, R539T or Y493H substitutions that were associated with in vitro resistance or delayed parasite clearance in Southeast Asia were not observed in Dakar, nor were any of the polymorphisms observed in parasites from Southeast Asia, nor the M476I mutation that was selected in vitro with artemisinin pressure in a African parasite line.

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IgG responses to the gSG6-P1 salivary peptide for evaluating human exposure to Anopheles bites in urban areas of Dakar region, Sénégal

Cited by 48 publications

References 39 publications

Assessment of Anopheles salivary antigens as individual exposure biomarkers to species-specific malaria vector bites

Assessment of Anopheles salivary antigens as individual exposure biomarkers to species-specific malaria vector bites

Serological signatures of declining exposure following intensification of integrated malaria control in two rural Senegalese communities

Limited polymorphisms in k13 gene in Plasmodium falciparum isolates from Dakar, Senegal in 2012–2013

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