title: IgG responses to Anopheles gambiae salivary antigen gSG6 detect variation in exposure to malaria vectors and disease risk.
abstract: Assessment of exposure to malaria vectors is important to our understanding of spatial and temporal variations in disease transmission and facilitates the targeting and evaluation of control efforts. Recently, an immunogenic Anopheles gambiae salivary protein (gSG6) was identified and proposed as the basis of an immuno-assay determining exposure to Afrotropical malaria vectors. In the present study, IgG responses to gSG6 and 6 malaria antigens (CSP, AMA-1, MSP-1, MSP-3, GLURP R1, and GLURP R2) were compared to Anopheles exposure and malaria incidence in a cohort of children from Korogwe district, Tanzania, an area of moderate and heterogeneous malaria transmission. Anti-gSG6 responses above the threshold for seropositivity were detected in 15% (96/636) of the children, and were positively associated with geographical variations in Anopheles exposure (OR 1.25, CI 1.01-1.54, p = 0.04). Additionally, IgG responses to gSG6 in individual children showed a strong positive association with household level mosquito exposure. IgG levels for all antigens except AMA-1 were associated with the frequency of malaria episodes following sampling. gSG6 seropositivity was strongly positively associated with subsequent malaria incidence (test for trend p = 0.004), comparable to malaria antigens MSP-1 and GLURP R2. Our results show that the gSG6 assay is sensitive to micro-epidemiological variations in exposure to Anopheles mosquitoes, and provides a correlate of malaria risk that is unrelated to immune protection. While the technique requires further evaluation in a range of malaria endemic settings, our findings suggest that the gSG6 assay may have a role in the evaluation and planning of targeted and preventative anti-malaria interventions.
authors: Department of Immunity and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors: Will
authors: W
authors: Stone
authors: Teun
authors: T
authors: Bousema
authors: Sophie
authors: S
authors: Jones
authors: Samwel
authors: S
authors: Gesase
authors: Rhamadhan
authors: R
authors: Hashim
authors: Roly
authors: R
authors: Gosling
authors: Ilona
authors: I
authors: Carneiro
authors: Daniel
authors: D
authors: Chandramohan
authors: Thor
authors: T
authors: Theander
authors: Raffaele
authors: R
authors: Ronca
authors: David
authors: D
authors: Modiano
authors: Bruno
authors: B
authors: Arcà
authors: Chris
authors: C
authors: Drakeley
mesh_terms: D000818:Animals; D000852:Anopheles / Q000276:immunology*; D004199:Disease Vectors; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D015994:Incidence; D007223:Infant; D019476:Insect Proteins / Q000276:immunology*; D008288:Malaria / Q000453:epidemiology / Q000276:immunology* / Q000469:parasitology / Q000635:transmission*; D010963:Plasmodium falciparum / Q000276:immunology; D012307:Risk Factors; D012471:Salivary Proteins and Peptides / Q000276:immunology*; D016036:Seroepidemiologic Studies; D013636:Tanzania / Q000453:epidemiology
chemical_list: D007074:Immunoglobulin G; D019476:Insect Proteins; D012471:Salivary Proteins and Peptides