Phase I trial of two recombinant vaccines containing the 19kd carboxy terminal fragment of Plasmodium falciparum merozoite surface protein I (msp-1(19)) and T helper epitopes of tetanus toxoid

The safety and immunogenicity of 2 yeast-derived, blood-stage malaria vacci nes were evaluated in a phase 1 trial. Healthy adults were given 2 or 3 dos es of alum-adsorbed vaccine containing the 19 kDa carboxy-terminal fragment of the merozoite surface protein-1 (MSP-1(19)) derived from the 3D7 or the FVO strain of Plasmodium falciparum fused to tetanus toroid T-helper epito pes P30 and P2. The first 2 doses of MSP-1(19) were well tolerated. Hyperse nsitivity reactions occurred in 3 subjects after the third dose of MSP-1(19 ), including bilateral injection site reactions in 2 tone with generalized skin rash), and probable histamine-associated hypotension in 1. Serum antib ody responses to MSP-1(19) occurred in 5/16, 9/16 and 0/8 subjects given 20 mu g of MSP-119, 200 mu g of MSP-1(19), and control vaccines (hepatitis B or Td), respectively. Both MSP-1(19) vaccines were immunogenic in humans, b ut changes in formulation will be necessary to improve safety and immunogen icity profiles. (C) 1999 Elsevier Science Ltd. All rights reserved.