Comparison of Immunogenicities of RecombinantPlasmodium vivaxMerozoite Surface Protein 1 19- and 42-Kilodalton Fragments Expressed inEscherichia coli

Abstract

The 42-and 19-kDa C-terminal fragments of merozoite surface protein 1 (MSP-1 42 and MSP-1 19 , respectively) are both promising blood-stage vaccine candidate antigens. At present, it is not clear which of the two antigens will be more suitable for inclusion in a cocktail malaria vaccine. In the present study, we expressed the two C-terminal fragments of Plasmodium vivax MSP-1 (PvMSP-1) in an Escherichia coli expression system and purified them by using a rapid two-step protocol. Both of the products were recognized by monoclonal antibodies against PvMSP-1 as well as by immune sera from several individuals exposed to P. vivax. We analyzed and compared the immunological responses to recombinant PvMSP-1 19 and PvMSP-1 42 in mice by using six different adjuvant formulations. Moderate to high antibody responses were observed with both of the antigens in different adjuvant formulations. Surprisingly, alum, which is generally considered to be a poor adjuvant for recombinant malaria antigens, was found to be as good an adjuvant as Montanide ISA 720, ASO2A, and other adjuvant formulations. Most adjuvant formulations induced high levels of immunoglobulin G1 (IgG1), followed by IgG3 and IgG2. Lymphocytes from animals in the PvMSP-1 42 -and PvMSP-1 19 -immunized groups showed proliferative responses upon stimulation with the respective antigens, and high levels of interleukin-4 (IL-4), IL-5, and gamma interferon were detected in the culture supernatants. Immunodepletion studies with sera from mice immunized with these two antigens showed that while immunization with PvMSP-1 42 does produce a PvMSP-1 19 -specific response, a substantial portion is also focused on structures in PvMSP-1 42 not represented by the epidermal growth factor-like domains of PvMSP-1 19 . These findings may have implications for the design of MSP-1-based vaccine constructs.

Merozoite Surface Protein 1 of Plasmodium vivax Induces a Protective Response against Plasmodium cynomolgi Challenge in Rhesus Monkeys

“…PvMSP-1 42 -Montanide ISA720 adjuvant combination has been shown to induce both B-and T-cell responses in mice (14,36). We have also reported the induction of high-titer invasion inhibitory antibodies to Montanide ISA720 formulated Apical Membrane Antigen-1 of P. falciparum (15).…”

Immune Responses of Mice with Different Genetic Backgrounds to Improved Multiepitope, Multitarget Malaria Vaccine Candidate Antigen FALVAC-1A

“…These observations are consistent with our earlier observations (33,37,45) that copolymer CRL-1005 and Montanide ISA-720 adjuvants induced higher and long-lasting antibody titers to FALVAC-1A than QS-21 and AlPO4 adjuvants did. These adjuvants, CRL-1005 and Montanide ISA-720 (both water-inoil), have been shown to induce both Th1 and Th2 responses and possibly CTL responses (2,11,19,25,27,31,32,35,39,44). Outbred ICR mice induced epitope-specific antibodies with higher antibody titers than inbred mice did, and CRL-1005 and ISA-720 adjuvants were better at inducing epitopespecific antibodies in mice than QS-21 and AlPO4 adjuvants were.…”

Aotus Lemurinus Griseimembra Monkeys: A Suitable Model for Plasmodium Vivax Sporozoite Infection

“…[19][20][21][22] However, continued progress urgently requires models with which to test their protective efficacy. Aotus lemurinus griseimembra monkeys supports growth of P. vivax asexual blood forms and therefore allow the assessment of vaccines targeting this parasite stages.…”