Antibody prevalence and levels to plasmodium falciparum circumsporozoite protein and schizont extract in individuals living in Kipsamoite, Nandi County, Kenya
Walukhu, Michael Kisongochi
MetadataShow full item record
Malaria continues to be a major public health concern despite the concerted efforts to eliminate it. The quest for a vaccine remains a top priority. Antibodies to Plasmodium falciparum antigens are involved in prevention of infection and disease in animal models. The role of these antibodies has also been demonstrated in human with some of the antigens being targeted as lead candidates in vaccine development. However, the association of age and gender with antibody responses to these antigens is not clearly understood. Moreover, most of the studies have been done in endemic areas with little emphasis in areas of low and unstable malaria transmission. This study sought to determine whether age and gender affect antibody responses to P. falciparum antigens by measuring antibody levels and prevalences to recombinant circumsporozoite protein (CSP) and crude schizont extract (SE) in individuals of all ages living in an area where malaria transmission is low and unstable in western highlands of Kenya. Both male and female of all ages were recruited, blood samples collected and plasma obtained. Sixty samples were randomly selected and categorized into three age groups; <8years (n=25), 8-18years (n=21) and >18years (n=14). The participants were also categorized into males (n=30) and females (n=30) to determine the effect of gender on antibody responses. Seven samples from malaria narve individuals from North America were used as negative controls while 30 pooled plasma samples from individuals in areas of stable malaria transmission were used as positive controls. Measurement of parasitaemia in all samples was done by light microscopy using both thin and thick blood smear. Haemoglobin levels were measured by photometry while IgG antibodies levels in plasma were measured by Enzyme Linked Immunosorbent Assay (ELISA). Data analysis was done by Graphpad Prism 6 using non-parametric Wilcoxon rank sum, Mann Whitney 1), Kruskall- Wallis and Spearman rank correlation tests. The prevalence of antibodies was generally low across all age groups ranging from 0% to 14.29% at arbitrary units (AU»2 for the two antigens. The antibody prevalence however increased with age. Males had significantly higher antibody prevalence than females with males having 10% while females 3.33% at AU>2 for both antigens P<0.05." The levels of IgG antibodies were generally low and there were no significant differences among the age groups and between male and females (P>0.05). There was a correlation between antibody levels to CSP and SE (r=0.5977; P<0.05). The study "provides preliminary findings associating antibody responses with the exposure to malaria infection. It therefore recommends a longitudinal study on more antigens to inform exploration of multi-antigen vaccines and also adopt several control measures including Epidemic Preparedness and Response (EPR). It further recommends profiling immune responses of individuals living in epidemic prone areas.
- MST-Zoological Sciences