title: Low-level malaria infections detected by a sensitive polymerase chain reaction assay and use of this technique in the evaluation of malaria vaccines in an endemic area.
abstract: The feasibility of using a sensitive polymerase chain reaction (PCR) to evaluate malaria vaccines in small group sizes was tested in 102 adult Gambian volunteers who received either the malaria vaccine regimen FP9 ME-TRAP/MVA ME-TRAP or rabies vaccine. All volunteers received the antimalarial drugs primaquine and Lapdap plus artesunate to eliminate malaria parasites. Volunteers in a further group received an additional single treatment with sulfadoxine-pyrimethamine (SP) to prevent new infections. There was substantially lower T-cell immunogenicity than in previous trials with this vaccine regimen and no protection against infection in the malaria vaccine group. Using the primary endpoint of 20 parasites per mL, no difference was found in the prevalence of low-level infections in volunteers who received SP compared with those who did not, indicating that SP did not reduce the incidence of very low-density infection. However, SP markedly reduced the incidence of higher density infections. These findings support the feasibility and potential of this approach to screen pre-erythrocytic vaccines for efficacy against infection in small numbers of vaccinees in endemic areas.
authors.affiliation: Medical Research Council Laboratories, Fajara, The Gambia. ebimoukhuede@hotmail.co.uk
authors.forename: Egeruan B
authors.initials: EB
authors.lastname: Imoukhuede
authors.forename: Laura
authors.initials: L
authors.lastname: Andrews
authors.forename: Paul
authors.initials: P
authors.lastname: Milligan
authors.forename: Tamara
authors.initials: T
authors.lastname: Berthoud
authors.forename: Kalifa
authors.initials: K
authors.lastname: Bojang
authors.forename: Davis
authors.initials: D
authors.lastname: Nwakanma
authors.forename: Jamila
authors.initials: J
authors.lastname: Ismaili
authors.forename: Caroline
authors.initials: C
authors.lastname: Buckee
authors.forename: Fanta
authors.initials: F
authors.lastname: Njie
authors.forename: Saikou
authors.initials: S
authors.lastname: Keita
authors.forename: Maimuna
authors.initials: M
authors.lastname: Sowe
authors.forename: Trudie
authors.initials: T
authors.lastname: Lang
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Gilbert
authors.forename: Brian M
authors.initials: BM
authors.lastname: Greenwood
authors.forename: Adrian V S
authors.initials: AV
authors.lastname: Hill
mesh_terms: D000293:Adolescent; D000328:Adult; D006801:Humans; D008288:Malaria / Q000175:diagnosis* / Q000188:drug therapy; D017780:Malaria Vaccines / Q000009:adverse effects / Q000276:immunology*; D008875:Middle Aged; D018512:Parasitemia / Q000175:diagnosis; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D014611:Vaccination
chemical_list: D017780:Malaria Vaccines