Evaluation of in vivo and in vitro biological activity of a Vibrio cholerae 01 hemolysin.
OBJECTIVE
To evaluate the hemolysin effect by ileal loop model produced by Vibrio cholerae O1 strains, compared with the cellular lysis or cytotoxic activity (CA) observed in cell culture.


METHODS
We studied nine V. cholerae O1 strains, obtained during the Mexican outbreak of cholera (1990-1993), which had CA in Vero and CHO cells. Hemolysin was monitored with the hemolysis test. Titers of CA were calculated by CD50, and the association between CA and cholera toxin (CT) production was discarded by means of neutralization tests using an anti-CT polyclonal antibody. The CT production was measured with ELISA test. The LAL assay was performed in order to study relationships between the CA and bacterial lipopolysaccharide. Strains with CA were evaluated in rabbit and rat ileal loop models; hemorrhagic fluid was also measured. Tissues from ileal loop were included in paraffin to detect intestinal epithelial damage.


RESULTS
The hemolysin CA was not neutralized with the anti-CT polyclonal antibody. However, the associated factor of CA was heat labile. CA in cell cultures was not related to the bacterial lipopolysaccharide. The ileal loop test exhibited the presence of hemorrhagic tissue with inflammation.


CONCLUSIONS
The V. cholerae O1 strains isolated were able to secrete hemolysin which, in turn, caused CA in cell cultures and produced the hemorrhagic and inflammatory effects observed in the ileal loop of rabbit and rat models.
Arellano Galindo
José
J
Laboratorio de Bacteriología Médica, Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México, DF México.
Rodriquez Angeles
María Guadalupe
MG
Guadarrama
Norma Valázquez
NV
Esteban
Enrique Santos
ES
Cerezo
Silvia Giono
SG
D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism* / Q000494:pharmacology*; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D002772:Cholera Toxin / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D006460:Hemolysin Proteins / Q000378:metabolism* / Q000494:pharmacology*; D006461:Hemolysis / Q000187:drug effects; D008070:Lipopolysaccharides / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D014709:Vero Cells; D041241:Vibrio cholerae O1 / Q000378:metabolism*
D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D008070:Lipopolysaccharides; C073845:hemolysin, Vibrio; D002772:Cholera Toxin