Antibody Responses To Plasmodium Falciparum Antigens In Hiv Infected Adults In Bondo Sub County Hospital, Siaya County, Kenya

ABSTRACT

Malaria and human immunodeficiency virus (HIV) are co-endemic in sub-Saharan Africa.

Infection with HIV results in B cell anomalies. Antibodies are critical in protection against

malaria and it is hypothesized that B cell anomalies resulting from HIV infection interfere

with antibody responses contributing to severe and frequent malaria episodes. Individuals

infected with HIV have elevated antibody and C-reactive protein (CRP) levels. However, it is

unclear whether malaria-specific antibodies, particularly immunoglobulin M (IgM), total

immunoglobulin G (IgG) and IgG subclasses levels would be increased or decreased, given

the evidence of impaired B cell responses to other antigens due to HIV. Furthermore, how

malaria-specific antibodies correlate with viral load (VL) and CRP levels in HIV infected

individuals is unclear given their link in HIV disease progression. Plasmodium falciparum

(Pf) vaccines studies have associated malaria protection with antibodies against apical

membrane antigen-1 (AMA-1) and glutamate-rich protein-R0 (GLURP-R0). The current

study aimed to: determine quantities and prevalence of antibody isotypes (IgG and IgM)

against Pf antigens (AMA-1 and GLURP-R0); determine quantities and prevalence of IgG

subclasses in response to Pf selected antigens and; measure the correlation of Pf specific

antibody isotypes and subclasses with VL, CD4+ counts and CRP levels. A comparative

cross-sectional study using a sample size of 181 comprising of 52 HIV negative and 129 HIV

positive adult participants seeking care at Bondo sub-County Hospital was conducted. Data

from Bondo Sub-County hospital have shown an overlap in malaria and HIV infections.

Antibody and CRP levels were tested using ELISA. The CD4+ cell and VL counts were

obtained using FACSCount and Abbott m2000 analyzer respectively. Medians and

proportions of Pf-specific antibody levels were compared using Wilcoxon Rank-Sum and

Chi-Square tests respectively. Correlations of Pf-specific antibodies with VL and CRP were

obtained using Spearman correlation. The study found that IgM, IgG1 and IgG3 levels

against both AMA-1 and GLURP-R0 were significantly high in HIV infected individuals

(P