Characterization of anti-EBA175RIII-V in asymptomatic adults and children living in communities in the Greater Accra Region of Ghana with varying malaria transmission intensities.

BACKGROUND: Antibodies against Region III-V of the erythrocyte binding antigen (EBA) 175 (EBA175RIII-V) have been suggested to provide protection from malaria in a natural infection. However, the quality and quantity of naturally induced antibodies to EBA175RIII-V has not been fully characterized in different cohorts of Ghanaians. This study sought to determine the characteristics of antibodies against EBA175RIII-V in asymptomatic adults and children living in two communities of varying P. falciparum parasite prevalence in southern Ghana. METHODS: Microscopic evaluation of thick and thin blood smears was used to identify asymptomatic Plasmodium falciparum carriage and indirect enzyme linked immunosorbent (ELISA) used to assess antibody concentrations and avidity. RESULTS: Parasite carriage estimated by microscopy in Obom was 35.6% as opposed to 3.5% in Asutsuare. Levels of IgG, IgG1, IgG2, IgG3 and IgG4 against EBA175RIII-V in the participants from Obom were significantly higher (P < 0.05, Dunn's Multiple Comparison test) than those in Asutsuare. However the relative avidity of IgG antibodies against EBA175RIII-V was significantly higher (P < 0.0001, Mann Whitney test) in Asutsuare than in Obom. CONCLUSIONS: People living in communities with limited exposure to P. falciparum parasites have low quantities of high avidity antibodies against EBA175RIII-V whilst people living in communities with high exposure to the parasites have high quantities of age-dependent but low avidity antibodies against EBA175RIII-V.

Circulating epstein-barr virus in children living in malaria-endemic areas.

Children living in malaria-endemic regions have high incidence of Burkitt's lymphoma (BL), the aetiology of which involves Plasmodium falciparum malaria and Epstein-Barr virus (EBV) infections. Acute malarial infection impairs the EBV-specific immune responses with the consequent increase in the number of EBV-carrying B cells in the circulation. To further understand the potential influence of malarial infection on the EBV persistence in children living in malaria-endemic areas, we studied the occurrence and quantified cell-free EBV-DNA in plasma from 73 Ghanaian children with and without acute malarial infection. Viral DNA was detected in 40% of the samples (47% in the malaria-infected and 34% in the nonmalaria group) but was absent in plasma from Ghanaian adults and healthy Italian children. These findings provide evidence that viral reactivation is common among children living in malaria-endemic areas, and may contribute to the increased risk for endemic BL. The data also suggest that the epidemiology of EBV infection and persistence varies in different areas of the world.

Allelic polymorphisms in the repeat and promoter regions of the interleukin-4 gene and malaria severity in Ghanaian children.

Immunoglobulin E has been associated with severe malaria suggesting a regulatory role for interleukin (IL)-4 and/or IgE in the pathogenesis of severe malaria. We have investigated possible associations between polymorphisms in the IL-4 repeat region (intron 3) and promoter regions (IL-4 +33CT and - 590CT) in Ghanaian children with severe malaria. There was a significantly higher frequency of IL-4 intron-3 B1B1 genotype in the cerebral malaria group [P < 0.0001, odds ratio (OR) = 8.7]. The genotype and allele frequencies of the IL-4 -590 and +33 polymorphisms did not differ between the four study groups. Carriers of IL-4 +33T/-590T with cerebral malaria had elevated total IgE compared to non-carriers (P = 0.03). Our data suggest that IL-4 and/or IgE play a regulatory role in the pathogenesis of severe or complicated malaria.

Haptoglobin phenotypes in HIV-1-seropositive patients in Ghana: decreased risk for Hp0 individuals.

Plasma haptoglobin phenotypes were determined by polyacrylamide gel electrophoresis, followed by benzidine staining for 58 HIV-1 seropositive Ghanaians and 79 randomly selected age-matched controls. Hp0 was present in only 14% of HIV-1 seropositive individuals compared with more than 40% of the controls. The Hp0 individuals showed a highly significant reduced risk for HIV-1 infection (OR = 0. 21, 95% CI = 0.09-0.51, p = 0.0002). Hp0 may have a protective effect in HIV-1 infection.

Seroreactivity to Pf 155/RESA in two malaria endemic ecological zones in Southern Ghana.

Seroepidemiological data are becoming important tools in determining transmission patterns of malaria. We have undertaken a study in 2 different ecological zones in southern Ghana during both the dry and wet seasons. Virtually all the subjects studied were positive to the crude parasite antigen (92%), with majority showing high titres in both areas. Whilst there was a statistical difference in Geometrical Mean Titre (GMT) between the two areas, seasonal variation was not seen. Antibody levels to the Pfl55/RESA and its repeat pepetide (EENV)6 increased progres notsively with age in endemic areas. These findings have relevance in determining malaria transmission in endemic areas.

Seroreactivity to Pf 155/RESA in Two Malaria Endemic Ecological Zones in Southern Ghana

Seroepidemiological data are becoming important tools in determining transmission patterns of malaria. We have undertaken a study in 2 different ecological zones in southern Ghana during both the dry and wet seasons. Virtually all the subjects studied were positive to the crude parasite antigen (92); with majority showing high titres in both areas. Whilst there was a statistical difference in Geometrical Mean Titre (GMT) between the two areas; seasonal variation was not seen. Antibody levels to the Pfl55/RESA and its repeat pepetide (EENV)6 increased progres notsively with age in endemic areas. These findings have relevance in determining malaria transmission in endemic areas