Distribution of cholera organisms in experimental Vibrio cholerae infections: proposed mechanisms of pathogenesis and antibacterial immunity.

This study was undertaken to determine the sequence of events in the microenvironment of the intestinal tract that culminate in the symptoms of cholera and to attempt to define more clearly the mechanisms involved in antibacterial immunity. The extent to which mucus occurs in the normal intestine of rabbits and the appearance of the intestinal villi in unfixed frozen sections was demonstrated. The villi and intervillous spaces were found to be normally covered by a layer of mucoid material that formed a mucous zone between the intestinal contents and the tips of the villi. The distribution of cholera organisms in normal and immunized animals was demonstrated by the staining of frozen-tissue sections with specific fluorescent antibody. Study of tissue sections from normal animals showed that the onset of fluid accumulation was concomitant with the establishment of large masses of organisms in the intervillous spaces and crypts of the intestine after the successful penetration of this mucous zone. Tissue sections from animals actively or passively immunized against a cell wall antigen of Vibrio cholerae showed clumping of vibrios in the lumen and restricted distribution in the lumen and luminal border of the mucous zone. Antibody was not lytic in vivo.