ABSTRACT
Peroral immunization with a live strain of Escherichia coli O6K13H1 against experimental ascending pyelonephritis caused by the same strain was studied in rats, and the effect of immunization on antibody titers against the O and K antigens and lipid A was determined. Peroral immunization with live bacteria protected significantly against pyelonephritis. Sera collected 1 week after infection from the immunized group were increased in immunoglobulin G (IgG) anti-O6 and IgM anti-K13 in comparison with the nonimmunized group. The peroral immunization did not correspondingly affect the response to lipid A. In urine, there was an IgG antibody response to the O6 antigen. In bronchopulmonary secretion, IgM, IgG, and IgA antibodies to O6 were detected. Perorally immunized animals had significantly higher levels of IgG and IgA anti-O6 compared with the nonimmunized group 1 week after infection. Passive transfer of anti-lipid A did not increase resistance against pyelonephritis.
