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Evaluation of malaria status and immune response to Plasmodium falciparum MSP-2

Abstract number: 1732_40

Khosravi A., Hommel M.

Objectives of study: MSP-2 is a highly polymorphic 45–53 kDa merozoite surface antigen and very immunogenic malaria antigen, which is considered as a promising vaccine candidate. The 3 S and 5 S end regions of the gene are highly conserved, whereas a large central region is variable. Many studies have suggested a protective role for specific IgG antibodies against variable regions of MSP-2. This study was designed to analyse the reactivity of human sera from people living in a malaria-endemic area of The Gambia (village of Keneba) against different domains of MSP-2. The association of haemoglobin and parasitaemia as two indicators of clinical malaria with acquired immunity were analysed to elucidate the pattern of protective immunity.

Materials and Methods: The current study was designed and carried out in Liverpool School of Tropical Medicine. 179 human sera were randomly selected from McGregor's Keneba Sera Collection (1966–1980). Different domains of MSP-2 were synthesized using GST gene fusion system and crude schizont extract was prepared from in vitro culture of Plasmodium falciparum. Total IgG and IgG subclass responses were measured by ELISA after a checkerboard study was performed for each antigen to standardise the concentration of both antigens and antibody.

Results: Most sera predominantly recognized the immunodominant regions of the molecule. Increasing the age was negatively correlated with parasitaemia and positively with IgG antibody responses and haemoglobin levels indicating that total IgG responses to domains 2, 3 and crude schizont extract coincidental to a decrease in parasitaemia density and frequency. IgG3 response was the main IgG in those who had no parasitaemia at the final time point. IgG2 and IgG3 were increased amongst individuals with no parasitaemia and with higher levels of haemoglobin at higher ages that had exposure to parasite over a long period of time.

Conclusion: IgG3 was the main antibody, mainly against domain 3 of MSP-2, that was associated with increase in haemoglobin levels and decrease in parasitaemia suggesting that domain 3 is preferred over other domains and crude schizont extract in presenting a clearer picture of immunity against malaria. These results could be an evidence of protective role of these antibodies against malaria disease and, therefore, domains 3 can be considered as reliable vaccine candidate antigens.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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