Plasmodium falciparum: Immunogenicity of Alum-Adsorbed Clinical-Grade TBV25–28, a Yeast-Secreted Malaria Transmission-Blocking Vaccine Candidate

• Published in: Experimental parasitology 2001-02, Vol.97 (2), p.61-69
• Main Authors: Gozar, Mary Margaret G, Muratova, Olga, Keister, David B, Kensil, Charlotte R, Price, Virginia L, Kaslow, David C
• Format: Article
• Language: English
• Subjects: Adjuvants, Immunologic; Alum Compounds; Animals; Anopheles freeborni; Antibodies, Protozoan - biosynthesis; Antibodies, Protozoan - blood; Enzyme-Linked Immunosorbent Assay; Hydrogen-Ion Concentration; Immunization, Secondary; Malaria Vaccines - immunology; Malaria Vaccines - standards; Malaria, Falciparum - prevention & control; Mice; ookinetes; Pfs25; Pfs25 antigen; Pfs28; Pfs28 antigen; Plasmodium falciparum; Plasmodium falciparum - immunology; Protozoan Proteins - immunology; Rabbits; Recombinant Fusion Proteins - immunology; Saponins; transmission-blocking vaccine; Vaccines, Synthetic - immunology; Vaccines, Synthetic - standards; zygotes
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1006/expr.2000.4580

Gozar, M. M. G., Muratova, O., Keister, D. B., Kensil, C. R., Price, V. L., and Kaslow, D. C. 2001. Plasmodium falciparum: Immunogenicity of alum-adsorbed clinical-grade TBV25–28, a yeast-secreted malaria transmission-blocking vaccine candidate. Experimental Parasitology97, 61–69. The fusion of Pfs25 and Pfs28, two major surface antigens on zygotes and ookinetes of Plasmodium falciparum, as a single recombinant protein (TBV25–28) was previously shown to elicit potent transmission-blocking antibodies in mice. Clinical-grade TBV25–28 was subsequently manufactured and its potency was evaluated in rabbits. Rabbits received three doses of either clinical-grade TBV25H or clinical-grade TBV25–28 adsorbed to alum with or without QS-21. As measured in a standard membrane-feeding assay, addition of QS-21 to the formulations appeared to enhance transmission-blocking potency of rabbit sera after two vaccinations but not after three vaccinations. Surprisingly, TBV25H elicited more potent transmission-blocking antibodies than did TBV25–28, a result strikingly different from those of previous mouse experiments using research-grade TBV25–28. The apparent decrease in potency of clinical-grade TBV25-28 in rabbits appears to reflect an enhancement in potency of clinical-grade TBV25H in a new formulation rather than simply a species difference in immunogenicity of TBV25–28.