Comparative analysis of IgG Responses to recombinant Qβ phage displayed MSP3 and UB05 in Dual HIV-malaria infected adults living in areas differing in Malaria transmission intensities
Immunoglobulin G specific responses against Plasmodium falciparum merozoite antigens such as the merozoite surface protein 3 (MSP3) and UB05 are known to play critical roles in parasitemia control and protection from symptomatic illness. However when there is intense perennial malaria transmission coupled with concurrent infection with the human immunodeficiency virus type 1 (HIV), knowledge of IgG antibody response profiles is limited. In this study we assessed the impact of dual HIV-Malaria infections on IgG subclass responses to MSP3 (Q{beta}MSP3) and UB05 (Q{beta}UB05) in individuals living in two areas of Cameroon differing in transmission intensity. We observed differences in antigen specific IgG and IgG subclass responses which was dependent upon the antigen type, malaria transmission intensity, HIV infection, malaria infection and dual HIV-malaria infections. Individuals living in high malaria transmission areas irrespective of HIV or malaria status had significantly higher IgG responses to both antigens (P=0.0001 for Q{beta}MSP3, P=0.0001 for Q{beta}UB05) than their counterpart from low transmission areas. When dual HIV-Malaria infection is considered significantly higher Q{beta}MSP3 specific IgG1 (P=0.0001) and IgG3 (P=0.04) responses in double negative individuals was associated with protection against malaria in low transmission areas. Superior Q{beta}UBO5 specific IgG1 responses (P=0.0001) in double negative individuals were associated with protection in high transmission areas in contrast to significantly higher IgG3 responses to Q{beta}UB05 (P=0.0001) which were more relevant to protection in low malaria transmission areas in the same population. Thus, understanding immune responses to Q{beta}UB05 and Q{beta}MSP3 could facilitate the development of immunotherapeutic strategies suitable for areas differing in malaria transmission intensity.