Immunization of mice with Escherichia coli containing an antigen of the malaria parasite Plasmodium chabaudi chabaudi expressed in lambda gt11 induces high antibody titres.

Escherichia coli containing a recombinant malarial protein expressed in lambda gt11 have been evaluated as an antigen delivery system in vivo. They were generated by infecting non-suppressing E. coli cells with a clone from a cDNA library of Plasmodium chabaudi chabaudi in lambda gt11. This clone (termed clone 6) expresses part of a 93 kDa blood-stage antigen of P. c. chabaudi as beta-galactosidase fusion protein. Immunization of C57B1/6 mice with these infected E. coli cells resulted in an antibody response to the malarial part of the fusion protein comparable to that obtained with purified fusion protein preparations. This method, therefore represents a rapid secondary screening of clones from lambda gt11 expression libraries for immunogenic and potentially protective components. In addition, the administration of whole infected E. coli obviates the need for an adjuvant.