The fimbrial antigens ofShigella flexneri

Abstract

1. ‘Pure fimbrial antisera’ were prepared for Sh. flexneri strains of O-serotypes 1a, 2b, 3 and 4a and 5, by injecting rabbits with a living fimbriate-phase culture and absorbing the crude immune serum with a non-fimbriate-phase culture of the same strain to remove antibodies for the non-fimbrial (somatic) antigens. These sera gave at high titre a rapid, loosely floccular agglutination of all fimbriate-phase Flexneri cultures, caused adhesion of their fimbriae visible by electron-microscopy and inhibited their haemagglutinating activity. ‘Non-fimbrial antisera’, prepared by injection of non-fimbriate-phase cultures, were devoid of these activities; they gave somatic-type agglutination with fimbriate bacilli at lower titres than with homologous non-fimbriate bacilli, the fimbriae tending to mask the O-antigens and confer relative O-inagglutinability.2. Heating at 90°C. detached the fimbriae from the bacilli, so that these lost their haemagglutinating activity, fimbrial serum agglutinability and fimbrial agglutinin-binding power. When heated for 21/2 hr. at 100°C., the detached fimbriae retained agglutinin-binding power, but lost their immunogenicity.3. Cross-agglutination and absorption tests showed that the antigenic composition of the fimbriae was identical in all flexneri strains, irrespective of O-serotype. The flexneri pure fimbrial antisera agglutinated at low titre sixty out of sixty-six fimbriate Bact. coli strains. Absorption tests with a flexneri and three coli pure fimbrial antisera showed that the fimbriae of Sh. flexneri contained a major ‘flexneri-specific antigen’, found in only one coli strain, one or more minor ‘flexneri-coli antigens’ shared by a few coli strains. The coli fimbriae also contained a major, ‘coli type-specific antigen’ shared in groups of several related strains. The flexneri sera did not react with fimbriate strains of Bact. cloacae, Salmonella and Proteus.4. Fimbrial agglutinins for Sh. flexneri were found in eighty of eighty-one normal human sera at titres from 30 to 1920, and in some pre-immunization rabbit sera at titres of 30 to 60.

The Fimbrial and Non-Fimbrial Haemagglutinins of Escherichia Coli

“…The tests of many strains with antifimbrial sera confirmed the findings of Gillies and Duguid (1958) that type-1 fimbriae bear antigens distinct from the recognised 0, K, and H antigens of E. coli, including a common fimbrial antigen in all MS+ strains and other, group-specific fimbrial antigens in at least three groups of strains. The type-1 fimbrial antigens resemble K antigens in being thermolabile at 1 OO"C, superficially situated and liable to confer relative inagglutinability in 0 antiserum, but differ in degree of resistance to heat and ethanol from the L, and A, and B types of polysaccharide K antigens, and usually are so poorly developed as to be undetectable in the young broth and agar cultures tested in conventional serology (Gillies and Duguid, 1958).…”

“…93, 108 and 208, absorbed them free from non-fimbrial antibodies, and tested the absorbed sera for agglutination of the bacteria from broth cultures of 216 strains, of which 61 were MS+/MRE+, 123 MS+/MRE-, 12 MS-/MRE+, and 20 MS-/ MRE-. All the 184 MS+ strains, from 84 0 serogroups, were agglutinated by each of the three type-1 fimbrial antisera, showing that all possessed the " common coli-flexneri fimbrial antigen " of Gillies and Duguid (1958). Titres were mostly between 100 and 800, but three groups of strains were agglutinated by one or other serum to a higher titre, e.g., 1600-12,800, presumably because they shared a second, group-specific fimbrial antigen with the strain to which the serum was raised.…”

“…The type-1 fimbrial antigens resemble K antigens in being thermolabile at 1 OO"C, superficially situated and liable to confer relative inagglutinability in 0 antiserum, but differ in degree of resistance to heat and ethanol from the L, and A, and B types of polysaccharide K antigens, and usually are so poorly developed as to be undetectable in the young broth and agar cultures tested in conventional serology (Gillies and Duguid, 1958). 0rskov et al (1977) concluded that they could be considered as a variety of protein K antigens.…”

Antigenic relationships among type-1 fimbriae of Enterobacteriaceae revealed by immuno-electronmicroscopy

“…Type-1 fimbriae are antigenic (Gillies and Duguid, 1958) and share serological relationships with non-haemagglutinating type-2 fimbriae of salmonellae (Old and Payne, 1971) but not with the type-3 fimbriae of Klebsiella (Nowotarska and Mulczyk, 1977;Adegbola, 1983;Korhonen et al, 1983;Old et al, 1985). Agglutination tests have been used to demonstrate sharing of type-1 fimbrial antigens among: (i) Escherichia, Shigella and, to a lesser extent, Klebsiella (Gillies and Duguid, 1958); (ii) Citrobacter and Salmonella (Duguid and Campbell, 1969).…”

“…Agglutination tests have been used to demonstrate sharing of type-1 fimbrial antigens among: (i) Escherichia, Shigella and, to a lesser extent, Klebsiella (Gillies and Duguid, 1958); (ii) Citrobacter and Salmonella (Duguid and Campbell, 1969). There was, however, no sharing of type-1 fimbrial antigens between salmonellae on the one hand and Escherichia coli and Shigella JIexneri on the other (Duguid and Campbell, 1969).…”