Protective capacity of antibodies to outer-membrane components of Escherichia coli in a systemic mouse peritonitis model

The C-Terminal Domain of Salmonella enterica Serovar Typhimurium OmpA Is an Immunodominant Antigen in Mice but Appears To Be Only Partially Exposed on the Bacterial Cell Surface

“…However, anti-OmpA MAbs, like antiporin antibodies, could not protect mice against Salmonella infection, possibly because the access of the antibody to these proteins on the surface of OM was limited by the O chains of the LPS. Vuopio-Varkila et al (51) also reported that anti-OmpA polyclonal sera failed to protect against challenge with the encapsulated E. coli O18:K1. FIG.…”

“…Some studies suggest that antibodies specific for OmpA or its homolog do not confer passive protection (13,20,49,51). On the other hand, several investigators have shown that the C-terminal domain of OprF, the OmpA homolog in Pseudomonas aeruginosa, contains an important protective epitope (14,15,50).…”

Review: Evidence against the hypothesis that antibodies to the inner core of lipopolysaccharides in antisera raised by immunization with enterobacterial deep-rough mutants confer broad-spectrum protection during Gram-negative bacterial sepsis

“…With one exception, those studies that also evaluated the efficacy of serotype-specific antibodies demonstrated significant protection. 16,36,[39][40][41][42][43][48][49][50][51][52] The exception involved an encapsulated organism, E. coli 07:K1:NM, whose lethality in mice was reduced only by capsular antibody .44 Since no significant broad-spectrum protection against enterobacterial or Pseudomonas sepsis could be demonstrated either by active immunization with the J5 or R595 rough mutants or by passive transfer of antisera to these mutants by our laboratory or those indicated above,16,35-52 and since anti-LPS activity has been postulated as the basis of the broad-spectrum protection observed with such antisera by other investigators, 25,26 we re-evaluated the putative anti-LPS effect of these rough-mutant antisera. In these studies, all roughmutant antisera were screened to preclude polyclonal increments in O-specific antibodies to the challenge LPS, and pre-immune sera from the respective donors were employed as controls.…”

“…However, it would be feasible to provide assurances that the distribution and titers of serotype-specific antibodies to the infecting bacterial strains in the pre-and postimmune J5 sera were comparable before attributing protection to antibodies to core LPS epitopes. Assurances of comparable distribution and titers of other antibodies with proven protective activity against the infecting bacterial strains, such as antibodies to Pseudomonas exotoxin A 187,188 and to capsular antigenS, 39,42,44,115,[190][191][192] would also be important, particularly in view of the frequency of infections with Pseudomonas and encapsulated enterobacterial strains. Indeed, on the basis of clinical studies that correlated survival with titers of serotype-specific IgG antibodies184,193 or of antibodies to Pseudomonas exotoxin A 184,189 at the onset of Gram-negative bacterial sepsis, such assurances would appear to be as important as those regarding the comparable distribution of the nature and severity of underlying clinical illness.…”

Killing of Escherichia coli in the peritoneal cavity of convalescent mice; role of specific and non-specific immune mechanisms

“…For the standard mouse challenge we used E. coli strain IH 3080 (serotype 018 :K1: H7) (Vuopio-Varkila et al, 1987a), isolated from a case of human neonatal meningitis. In some experiments, other challenge strains were used (table I).…”