Escherichia coli K51 and K93 capsular polysaccharides are crossreactive with the group A capsular polysaccharide of Neisseria meningitidis. Immunochemical, biological, and epidemiological studies.

Abstract

Eleven Escherichia coli strains, crossreactive with the capsular polysaccharide (CPS) of Neisseria meningitidis group A (GrA), were detected among 645 stool isolates from healthy families in Cairo, Egypt. 10 of these strains were of the O107:K93:H27 or O107:K93:SP serotypes and may be considered descendents of a single bacterium or as a clone. The remaining crossreactive strain was of the O7:K51:H18 serotype. None of the 11 strains produced enterotoxins and none were enteroinvasive. The purified CPS of these E. coli strains, as well as a polysaccharide (PS) from B. pumilis, strain Sh17, precipitated with equine GrA (H49) antiserum. A partial identity between the E. coli K93, K51 and Sh17 PS on the one hand and the GrA CPS on the other was observed by double immunodiffusion when reacted against the H49 antiserum. Four K93 strains and one K51 strain were found among 320 E. coli strains from patients at the Clinical Center, National Institutes of Health, and three K93 strains were found in 105 stool samples from children in Copenhagen. The data from these three surveys suggest that these crossreactive E. coli are common organisms and could serve as a stimulus for "natural" GrA CPS antibodies. Quantitative precipitation analysis showed that K51, K93, and Sh17 PS precipitated 25, 46.8, and 50% of H49 antibodies, respectively. Absorption of H49 antiserum with the GrA CPS removed its precipitating activity with the E. coli K93, K51, and Sh17 PS. Absorption of H49 antiserum with either K51 CPS or Sh17 PS removed the homologous crossreactivity only, whereas K93 CPS absorbed both K93 and K51 reactivities. Antibodies, raised by intravenous injection of formalinized E. coli K93 or K51 cells into rabbits, precipitated with GrA CPS and were bactericidal against GrA meningococci. The crossreaction between the E. coli K93 and the GrA CPS was unexpected since these two CPS are compositionally so dissimilar.

Seroprevalence of Antibodies against Serogroup C Meningococci in England in the Postvaccination Era

“…Thereafter, GMCs were higher for serogroup A than for serogroup C (significantly so, with the exception of 12-to 19-year-olds), despite MCC vaccination. Since serogroup A carriage and disease are also uncommon in this setting (8,16) and the age distribution is flatter than would be expected from the age-specific patterns of meningococcal carriage, the high GMCs reported here may be attributable to the presence of cross-reacting antigens (9,21,25).…”

Prospects for Vaccine Prevention of Meningococcal Infection

“…Outbreaks of serogroup A infection were also seen in Finland during the 1970s and in Moscow as late as the 1990s (2, 225,265). It is not known why there is virtually no serogroup A disease in the United States but immunity caused by crossreactive antibodies to other organisms has been proposed as a possible mechanism (105,159,293). In a recent study, only about a quarter of preimmunization sera from North Americans participating in meningococcal vaccine trials had antiserogroup A bactericidal titers of Ն1:4 and most of the bactericidal antibodies present were against noncapsular antigens (7).…”

Immunogenicity of Meningococcal ACYW135 Polysaccharide Vaccine in Saudi Children 5 to 9 Years of Age

“…Furthermore, the carriage of serogroup Y meningococci is unlikely to contribute greatly in inducing high levels of SBA, because the carriage rate of serogroup Y is low, approximately 1%, as illustrated in the United Kingdom (10). One possible explanation may be exposure to cross-reactive epitopes, as has been described for other meningococcal polysaccharides (6,13,14).…”