Immunogenicity of malaria vaccine candidate: Glutamate Rich Protein (GLURP) in patient with Plasmodium falciparum malaria in Gezira State, Sudan

Abstract

This is a descriptive cross sectional hospital based study carried out at Wad Madani Teaching Hospital from September to December 2005 (the end of malaria transmission season). The study aimed to determine percentage and level of anti- GLURP IgG and IgG1 and IgG3 antibodies, and their relation to the level of parasitemia and Hb concentrations among subjects. A number of 114 malarial patients with Plasmodium falciparum were enrolled in the study. Enzyme linked immunosorbent assay (ELISA) was performed to detect anti- GLURP IgG antibodies. Twenty Nine of malaria patients have normal haemoglobin level, 16 with mild anemia. 50 have moderate anemia and 19 with severe anemia. Patients under five years of age comprised approximately half (49.1%) of study subject. under five years represented the most vulernable ones, where parasitemia and anemia are predominated among them. The overall prevalence of seropositive samples among study group was high ranging from (59.6%) of IgG against R2 GLURP and to (79.8%) IgG1 R0, and (78.9%) IgG3 R0. The GLURP R0-R2 induced the highest levels of antibody among the same subclass while GLURP R1 induced low levels. The acquisition of antibody is age dependent, there was a significant association between R0-R2 GLURP IgG level and subjects age (p-value<0.05).IgG3 level directed against GLURP R0 also increased with age (P value<0.05) Parasite density decreased with the increase of IgG against R2 level (P value<0.05) that is to say IgG have a role in reduction of parasitemia. The severity of anemia correlated to IgG3 against R0-GLURP, IgG1 R1 GLURP; as well as with parasitemia. Natural acquired humoral responses against R0-R2 GLURP are prevalent among falciparum malaria patient. Call for Encouraging approaches to vaccination against P.falciparum. Further studies should be conducted to clarify whether the presence of antibody responses against GLURP is associated with reduction of malaria incidence.