IgG antibody responses to Plasmodium falciparum merozoite antigens in Kenyan children have a short half-life

Abstract

Background. Data suggest that antibody responses to malaria parasites merozoite antigens are generally short-lived and this has implications for serological studies and malaria vaccine designs. However, precise data on the kinetics of these responses is lacking. Methods. IgG1 and IgG3 responses to five recombinant Plasmodium falciparum merozoite antigens (MSP-119, MSP-2 type A and B, AMA-1 ectodomain and EBA-175 region II) among Kenyan children were monitored using ELISA for 12 weeks after an acute episode of malaria and their half-lives estimated using an exponential decay model. Results. The responses peaked mainly at week 1 and then decayed rapidly to very low levels within 6 weeks. Estimation of the half-lives of 40 IgG1 responses yielded a mean half-life of 9.8 days (95% CI: 7.6 - 12.0) while for 16 IgG3 responses it was 6.1 days (95% CI: 3.7 - 8.4), periods that are shorter than those normally described for the catabolic half-life of these antibody subclasses. Conclusion. This study indicates antibodies against merozoite antigens have very short half-lives and this has to be taken into account when designing serological studies and vaccines based on the antigens. © 2007 Kinyanjui et al; licensee BioMed Central Ltd.