Cell-mediated immunity after oral immunization with ribonucleic acid-protein fractions of Vibrio cholerae L-form lysates.

Oral administration of a single dose of ribonucleic acid-protein fraction of lysates of Vibrio cholerae subtype Ogawa L-forms induced an increase in cell-mediated immunity in rabbits. This was demonstrated by an increase in leukocyte migration inhibition in peripheral blood leukocytes, in macrophages migration inhibition, and in microbicidal activity against Listeria monocytogenes in peritoneal macrophages obtained from orally immunized rabbits. Increased cell-mediated immunity was induced mainly with V. cholerae Ogawa and ribonucleic acid-protein fractions. It appeared in 20 days and persisted for at least 90 days.