Evidence that leptospiral lipopolysaccharide is not an important protective antigen.

CBA/N mice, which could not produce antibodies against lipopolysaccharide (LPS) from either Escherichia coli or Leptospira interrogans serovar pomona, produced levels of agglutinating antibodies against leptospires similar to those produced by immunologically normal CBA mice. CBA/N mice were thus resistant to acute leptospiral infection and CBA/N immune serum passively protected immunosuppressed mice from infection. The results suggest that antibodies against LPS are not important in protection against experimental leptospiral infection in mice.