Abstract
Surface exposed protein antigens of the malaria parasite Plasmodium falciparum frequently harbor multiple dimorphic amino acid positions. These are associated with parasite immune evasion and represent a major obstacle for subunit vaccine design. Here, we have analyzed the flexibility of the humoral immune response against a semiconserved sequence (YX 44LFX 47KEKMX 52L) of the key malaria blood stage vaccine candidate merozoite surface protein-1 (MSP-1). Monoclonal antibodies (mAbs) raised against one of the six described natural sequence variants of MSP-1 43–53 were analyzed for cross-reactivity with the other allelic forms, which differ in one to three positions from the immunizing sequence. Enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) spectroscopy demonstrated marked differences in mAb binding avidity to the variant sequences and isothermal titration calorimetry (ITC) provided evidence for a very low affinity of some of the interactions. In immunofluorescence analysis (IFA) and Western blotting analysis, the mAbs nevertheless stained all analyzed parasite clones expressing MSP-1 43–53 variant sequences. When used for the evaluation of humoral immune responses in clinical malaria vaccine trials, these two commonly used methods may thus not be suitable to distinguish biologically functional high affinity antibody responses from irrelevant low-affinity cross-reactivities.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
