Plasma extracted from the bloodstream was stored in 80 C (Forma Scienti?c, Marietta, OH, USA)

Plasma extracted from the bloodstream was stored in 80 C (Forma Scienti?c, Marietta, OH, USA). Perseverance of anti-MSP-119 Antibodies Total IgG antibodies and particular IgG subclass antibodies were discovered by ELISA using recombinant MSP-119 antigen and a way which has previously been described16. MSP-119 specific IgM was dependant on ELISA also. quantity of total IgG and IgG subtype created. PD173955 Keywords: IgG subtypes, MSP-1, malaria Introduction There are 300C500 million cases of malaria each year, resulting in over 1 million deaths, mainly of children under 5 years of age in Africa1. Deployment of an effective malaria vaccine would have a significant public health impact. There are several antigens that are currently being evaluated from the various stages of the malaria parasite life cycle. One of these is merozoite surface protein-1 (MSP-1), which is found on the surface of the merozoites of the parasite (asexual stage). Immunization with purified MSP-1 has protected monkeys from malaria2. Protective immunity induced by immunization with MSP-1 derived polypeptides is thought to be primarily antibody dependent3. Monoclonal antibodies to MSP-1 have been shown to inhibit parasite growth in vitro4,5. MSP-1 is synthesized during schizogony as a 190C200-kDa glycoprotein6. It is subsequently proteolytically processed into a range of defined fragments6. MSP-1 is cleaved by two processing events. The primary processing products include a 42 kDa C-terminal fragment (MSP-142) while the secondary processing cleaves MSP-142 into two fragments, one of which is the 19 kDa C-terminal fragment MSP-119. Antibodies specific for the C-terminus of MSP-1 can inhibit erythrocyte invasion by a mechanism that involves inhibition of protease activity7. Some MSP-119 specific antibodies that inhibit merozoite invasion also inhibit the secondary processing of MSP-1; these are called processing inhibitory antibodies8. Some MSP-119 specific antibodies that do not inhibit processing are defined as blocking antibodies because they block the binding and functioning of these processing inhibitory antibodies and thereby facilitate processing9. PD173955 The last group of MSP-119 specific antibodies are termed neutral antibodies because they do not interfere with the binding of any of the inhibitory antibodies, and when they bind to the antigen they have no known biological effect. In one study processing PD173955 inhibitory antibodies were found in children but there was no correlation Sstr1 between MSP-119-specific total antibody titre and processing inhibitory activity10,11. PD173955 The ratio of inhibitory to blocking antibody (and their respective avidities) in a polyclonal response will determine whether or not the outcome is inhibition of invasion7. Therefore a vaccine based on MSP-1 variants to induce primarily inhibitory antibodies and not blocking antibodies may be an effective way to induce immunity to malaria12. In addition it has been shown that protection against the asexual stage of malaria seems to rely largely on specific IgG1 and IgG3 antibodies13, but whether or not such antibodies are directed against MSP-119 is unknown. The objective of the study was to determine whether or not processing-inhibitory activity and/or the presence of blocking antibodies are associated with levels of IgG, IgM or a specific IgG subclass. Methods Study area Igbo-Ora and Idere towns in Ibarapa local government area of Oyo state in southwestern Nigeria were the study sites. and are the mosquito species found in this area14. The climate consists of a warm dry season (NovemberCMarch) and a cooler rainy season (AprilCOctober). The main occupation of the men is farming and hunting while the women are peasant farmers and retail traders15. Study design The blood samples used in this study were obtained from a cross-sectional survey carried out during the dry season (JanuaryCMarch) of 1999. The samples had previously been reported to show the presence of processing inhibitory, blocking and neutral antibodies 10,11. The study protocol was reviewed and approved by the Joint Ethical Committee of the College of.