Antibody responses to two new Lactococcus lactis-produced recombinant Pfs48/45 and Pfs230 proteins increase with age in malaria patients living in the Central Region of Ghana

Background: Recent advances in malaria control efforts have led to an increased number of national malaria control programmes implementing pre-elimination measures and demonstrated the need to develop new tools to track and control malaria transmission. Key to understanding transmission is monitoring the prevalence and immune response against the sexual stages of the parasite, known as gametocytes, which are responsible for transmission. Sexual-stage specific antigens, Pfs230 and Pfs48/45, have been identified and shown to be targets for transmission blocking antibodies, but they have been difficult to produce recombinantly in the absence of a fusion partner. Methods: Regions of Pfs48/45 and Pfs230 known to contain transmission blocking epitopes, 6C and C0, respectively, were produced in a Lactococcus lactis expression system and used in enzyme linked immunosorbent assays to determine the seroreactivity of 95 malaria patients living in the Central Region of Ghana. Results: Pfs48/45.6C and Pfs230.C0 were successfully produced in L. lactis in the absence of a fusion partner using a simplified purification scheme. Seroprevalence for L. lactis-produced Pfs48/45.6C and Pfs230.C0 in the study population was 74.7 and 72.8%, respectively. Conclusions: A significant age-dependent increase in antibody titers was observed, which suggests a vaccine targeting these antigens could be boosted during a natural infection in the field.