Electroeluted outer membrane proteins as immunogens.

Electroeluted outer membrane proteins [(EOmp), (35-37 KDa, porins)] were highly immunogenic in New Zealand White rabbits. An ELISA peak titer of 51,200 to EOmp as compared to 6,400 for non-eluted outer membrane protein (Omp) was demonstrated. EOmp enhanced the antigenicity of Omp possibly due to epitopes which were masked in the non-eluted antigen. Non-eluted, partially purified, Omp elicited high anti-lipopolysaccharide (LPS) titers (25,600); however, electroelution diminished LPS contamination (non detection of LPS chemically and on immunoblots) and greatly reduced the anti-LPS titer (400). It is biologically significant that anti-EOmp antibodies cross-reacted with wild-type urinary pathogens. Specificity for Omp reactivity was demonstrated by ELISA and on immunoblots with absorbed EOmp (LPS-free) antisera. These findings strengthen the rationale for exploring the protective potential of anti-Omp antibodies.