Cellular in humoral immune responses to SPf 66 malaria vaccine in an endemic area of western Kenya
Nyakeriga, Moraa Alice
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Pre-clinical and clinical trials with the synthetic malaria vaccine SPf66 suggest that the vaccine may be of beneficial value against malaria infection. Only limited information is available regarding immunologic recognition of this antigen in naturally exposed individuals following immunization. The present study is a phase 1, double-blinded placebocontrolled in Saradidi, Western Kenya. This study was conducted to investigate the cellular and humoral responses to immunization with the vaccine and compare immunogenicity of SPf66 administered by either subcutaneous (SC) or intramuscular route (IM). In this study 85 adult volunteers living in holoendemic area of western Kenya were immunized with either SPf66, SC; SPf66, IM or Engerix B (placebo), IM. Immunologic responses to SPf66 and its component peptides were measured by lymphoproliferative responses, ELISA and measurements of IL-4 and IFN-g secreting cells after in vitro stimulation with SPf66 antigens. Assays were performed before the first dose, once after the second dose, and on three other occasions after the third dose. Assays of lymphocyte proliferation and cytokine secretion detected recognition of the whole antigen in a substantial proportion of samples obtained from donors before vaccination. After the third dose of vaccine, PBMCs donated by SPf66, SC vaccines demonstrated significantly higher proliferative and IFN-g responses when exposed to the whole antigen (p<0.05). Weekly blood smears following immunization did not show significant differences between groups with regard to frequency and intensity of parasitaemia. The route of administration had a significant impact on measurement of immunogenicity.
- MST-Zoological Sciences