PLASMODIUM-CHABAUDI - IMMUNOGENICITY OF A HIGHLY ANTIGENIC GLUTAMATE-RICH PROTEIN

The immunogenicity of a 93-kDa Plasmodium chabaudi protein that contai ns glutamate-rich tandem repeats was investigated in this study. Immun oblotting with various monoclonal antibodies indicates that this 93-kD a protein is equivalent to a potential P. chabaudi RESA analogue. Howe ver, the sequence of the P. chabaudi protein does not exhibit any sign ificant homolog; to Pf155/RESA. Antibodies against the 93-kDa protein appear early during P. chabaudi infection and reach high titers. The h ighest antibody titers are found when the parasitemia is descending, s uggesting that this protein may play some role in immunity. Immunizati on of mice with the recombinant protein also results in high antibody titers, indicating that the protein is quite immunogenic. However, mic e immunized with recombinant protein and challenged with P. chabaudi d o not exhibit a delayed appearance of parasitemia, a reduced parasitem ia, or a shortened duration of parasitemia. Glutamate-rich P. falcipar um proteins such as Pf155/RESA, are being considered as vaccine candid ates. The studies with P. chabaudi suggest that interpretation of sero logical data using glutamate-rich proteins should proceed with caution . The glutamate-rich repeats, although highly immunogenic, may not be important in host immunity against malaria. However, antibodies that a ppear late in the P. chabaudi infection do appear to play a role in an ti-malarial immunity. (C) 1997 Academic Press.