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A multiplex assay for the simultaneous detection of antibodies against 15 Plasmodium falciparum and Anopheles gambiae saliva antigens.

Ambrosino E, Dumoulin C, Orlandi-Pradines E, Remoue F, Toure-Baldé A, Tall A, Sarr JB, Poinsignon A, Sokhna C, Puget K, Trape JF, Pascual A, Druilhe P, Fusai T, Rogier C - Malar. J. (2010)

Bottom Line: The multiplex assay was optimized for most but not all of the antigens.It was rapid, reproducible and required a small volume of serum.The multiplex assay developed here provides a useful tool to evaluate immune responses to multiple Ags in large populations, even when only small amounts of serum are available, or Ab titres are low, as in case of travellers.

View Article: PubMed Central - HTML - PubMed

Affiliation: IRBA & UMR6236, Marseille, France.

ABSTRACT

Background: Assessment exposure and immunity to malaria is an important step in the fight against the disease. Increased malaria infection in non-immune travellers under anti-malarial chemoprophylaxis, as well as the implementation of malaria elimination programmes in endemic countries, raises new issues that pertain to these processes. Notably, monitoring malaria immunity has become more difficult in individuals showing low antibody (Ab) responses or taking medications against the Plasmodium falciparum blood stages. Commonly available techniques in malaria seroepidemiology have limited sensitivity, both against pre-erythrocytic, as against blood stages of the parasite. Thus, the aim of this study was to develop a sensitive tool to assess the exposure to malaria or to bites from the vector Anopheles gambiae, despite anti-malarial prophylactic treatment.

Methods: Ab responses to 13 pre-erythrocytic P. falciparum-specific peptides derived from the proteins Lsa1, Lsa3, Glurp, Salsa, Trap, Starp, CSP and Pf11.1, and to 2 peptides specific for the Anopheles gambiae saliva protein gSG6 were tested. In this study, 253 individuals from three Senegalese areas with different transmission intensities and 124 European travellers exposed to malaria during a short period of time were included.

Results: The multiplex assay was optimized for most but not all of the antigens. It was rapid, reproducible and required a small volume of serum. Proportions of Ab-positive individuals, Ab levels and the mean number of antigens (Ags) recognized by each individual increased significantly with increases in the level of malaria exposure.

Conclusion: The multiplex assay developed here provides a useful tool to evaluate immune responses to multiple Ags in large populations, even when only small amounts of serum are available, or Ab titres are low, as in case of travellers. Finally, the relationship of Ab responses with malaria endemicity levels provides a way to monitor exposure in differentially exposed autochthonous individuals from various endemicity areas, as well as in travellers who are not immune, thus indirectly assessing the parasite transmission and malaria risk in the new eradication era.

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The proportion of seropositive individuals increases with malaria exposure level. Among the adults (124 travelers, 45 from Dielmo, 40 from Ndiop and 38 from Diama), the proportion of seropositives for Lsa1-41 (p < 0.001), Lsa1J (p < 0.001), Lsa3NR2 (p < 0.001), Glurp (p < 0.001), GlurpP3 (p < 0.001), Salsa1 (p < 0.001), Salsa2 (p < 0.001), StarpR (p < 0.001), CSP (p < 0.001), SR11.1 (p < 0.001) and Saliv1 (p = 0.001) peptides differed significantly between groups (Fischer's exact test). In travellers, no Abs against Saliv1 Ag were detected; Abs were detected in exposed adults (three far left bars). 95% confidence intervals are shown in table 2.
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Figure 3: The proportion of seropositive individuals increases with malaria exposure level. Among the adults (124 travelers, 45 from Dielmo, 40 from Ndiop and 38 from Diama), the proportion of seropositives for Lsa1-41 (p < 0.001), Lsa1J (p < 0.001), Lsa3NR2 (p < 0.001), Glurp (p < 0.001), GlurpP3 (p < 0.001), Salsa1 (p < 0.001), Salsa2 (p < 0.001), StarpR (p < 0.001), CSP (p < 0.001), SR11.1 (p < 0.001) and Saliv1 (p = 0.001) peptides differed significantly between groups (Fischer's exact test). In travellers, no Abs against Saliv1 Ag were detected; Abs were detected in exposed adults (three far left bars). 95% confidence intervals are shown in table 2.

Mentions: In total, 377 individuals exposed to malaria from areas with different endemicities were tested for all of the studied Ags. Among adults, for the Ags Lsa1-41, Lsa1J, Lsa3NR2, Glurp, Salsa2, StarpR, CSP and SR11.1, the proportion of seropositive adults increased significantly with the malaria endemicity (Figure 3, bars from left to right p ≤ 0.01). For GlurpP3 and Salsa1 Ags the increase was observed with the exception of the higher exposed group from Dielmo (Figure 3, comparison among the three far left bars p ≤ 0.01). For the A. gambiae Saliv1 Ag (Figure 3, bottom left), the proportion of seropositives in transiently exposed adults was undetectable, while Abs were detected in exposed adults living in villages endemic for malaria (no significant difference among individuals from Ndiop, Diama and Dielmo). For the four remaining Ags (Lsa3RE, Trap1, Trap2, Saliv2), the proportion of seropositives in the groups was too low to yield any significant difference. All proportions of seropositive adults for the 15 tested Ags are listed in Table 2, with the respective CI 95% value.


A multiplex assay for the simultaneous detection of antibodies against 15 Plasmodium falciparum and Anopheles gambiae saliva antigens.

Ambrosino E, Dumoulin C, Orlandi-Pradines E, Remoue F, Toure-Baldé A, Tall A, Sarr JB, Poinsignon A, Sokhna C, Puget K, Trape JF, Pascual A, Druilhe P, Fusai T, Rogier C - Malar. J. (2010)

The proportion of seropositive individuals increases with malaria exposure level. Among the adults (124 travelers, 45 from Dielmo, 40 from Ndiop and 38 from Diama), the proportion of seropositives for Lsa1-41 (p < 0.001), Lsa1J (p < 0.001), Lsa3NR2 (p < 0.001), Glurp (p < 0.001), GlurpP3 (p < 0.001), Salsa1 (p < 0.001), Salsa2 (p < 0.001), StarpR (p < 0.001), CSP (p < 0.001), SR11.1 (p < 0.001) and Saliv1 (p = 0.001) peptides differed significantly between groups (Fischer's exact test). In travellers, no Abs against Saliv1 Ag were detected; Abs were detected in exposed adults (three far left bars). 95% confidence intervals are shown in table 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2992071&req=5

Figure 3: The proportion of seropositive individuals increases with malaria exposure level. Among the adults (124 travelers, 45 from Dielmo, 40 from Ndiop and 38 from Diama), the proportion of seropositives for Lsa1-41 (p < 0.001), Lsa1J (p < 0.001), Lsa3NR2 (p < 0.001), Glurp (p < 0.001), GlurpP3 (p < 0.001), Salsa1 (p < 0.001), Salsa2 (p < 0.001), StarpR (p < 0.001), CSP (p < 0.001), SR11.1 (p < 0.001) and Saliv1 (p = 0.001) peptides differed significantly between groups (Fischer's exact test). In travellers, no Abs against Saliv1 Ag were detected; Abs were detected in exposed adults (three far left bars). 95% confidence intervals are shown in table 2.
Mentions: In total, 377 individuals exposed to malaria from areas with different endemicities were tested for all of the studied Ags. Among adults, for the Ags Lsa1-41, Lsa1J, Lsa3NR2, Glurp, Salsa2, StarpR, CSP and SR11.1, the proportion of seropositive adults increased significantly with the malaria endemicity (Figure 3, bars from left to right p ≤ 0.01). For GlurpP3 and Salsa1 Ags the increase was observed with the exception of the higher exposed group from Dielmo (Figure 3, comparison among the three far left bars p ≤ 0.01). For the A. gambiae Saliv1 Ag (Figure 3, bottom left), the proportion of seropositives in transiently exposed adults was undetectable, while Abs were detected in exposed adults living in villages endemic for malaria (no significant difference among individuals from Ndiop, Diama and Dielmo). For the four remaining Ags (Lsa3RE, Trap1, Trap2, Saliv2), the proportion of seropositives in the groups was too low to yield any significant difference. All proportions of seropositive adults for the 15 tested Ags are listed in Table 2, with the respective CI 95% value.

Bottom Line: The multiplex assay was optimized for most but not all of the antigens.It was rapid, reproducible and required a small volume of serum.The multiplex assay developed here provides a useful tool to evaluate immune responses to multiple Ags in large populations, even when only small amounts of serum are available, or Ab titres are low, as in case of travellers.

View Article: PubMed Central - HTML - PubMed

Affiliation: IRBA & UMR6236, Marseille, France.

ABSTRACT

Background: Assessment exposure and immunity to malaria is an important step in the fight against the disease. Increased malaria infection in non-immune travellers under anti-malarial chemoprophylaxis, as well as the implementation of malaria elimination programmes in endemic countries, raises new issues that pertain to these processes. Notably, monitoring malaria immunity has become more difficult in individuals showing low antibody (Ab) responses or taking medications against the Plasmodium falciparum blood stages. Commonly available techniques in malaria seroepidemiology have limited sensitivity, both against pre-erythrocytic, as against blood stages of the parasite. Thus, the aim of this study was to develop a sensitive tool to assess the exposure to malaria or to bites from the vector Anopheles gambiae, despite anti-malarial prophylactic treatment.

Methods: Ab responses to 13 pre-erythrocytic P. falciparum-specific peptides derived from the proteins Lsa1, Lsa3, Glurp, Salsa, Trap, Starp, CSP and Pf11.1, and to 2 peptides specific for the Anopheles gambiae saliva protein gSG6 were tested. In this study, 253 individuals from three Senegalese areas with different transmission intensities and 124 European travellers exposed to malaria during a short period of time were included.

Results: The multiplex assay was optimized for most but not all of the antigens. It was rapid, reproducible and required a small volume of serum. Proportions of Ab-positive individuals, Ab levels and the mean number of antigens (Ags) recognized by each individual increased significantly with increases in the level of malaria exposure.

Conclusion: The multiplex assay developed here provides a useful tool to evaluate immune responses to multiple Ags in large populations, even when only small amounts of serum are available, or Ab titres are low, as in case of travellers. Finally, the relationship of Ab responses with malaria endemicity levels provides a way to monitor exposure in differentially exposed autochthonous individuals from various endemicity areas, as well as in travellers who are not immune, thus indirectly assessing the parasite transmission and malaria risk in the new eradication era.

Show MeSH
Related in: MedlinePlus