PubMed Health⌕ Search

Biomedical subjects

E Neter

Publications and source records attributed to E Neter.

At least 37 records · Page 2Linked to original sources
PubMed1976

Role of a lipopolysaccharide gene for immunogenicity of the enterobacterial common antigen.

It is known that only certain strains of the family of Enterobacteriaceae, notably rough (R) mutants with the type R1 or R4 core, evoked antibodies in high titers against the common enterobacterial antigen (CA) after immunization of rabbits with heated cell suspensions. The present investigation deals with genetic and immunochemical aspects of certain R1 and R4 mutants isolated from Escherichia coli 08 and various Shigella serotypes which, unexpectedly, do not induce CA antibody formation. Immunochemical and genetical (transduction and conjugation) experiments revealed that the rough phenotype of these special mutants was evoked by a mutation of pyrE-linked rfa gene, called rfaL, which is involved in translocation of O-specific polysaccharides onto the lipopolysaccharide core. The transduction of the defective rfaL, allele into appropriate rough recipients results in transductants which have simultaneously lost the ability to evoke CA antibodies. This finding suggests that a close connection exists between the function of the rfaL gene and the expression of CA immunogenicity in R1 and R4 mutants. One of the strains synthesized neither O-hapten nor CA, suggesting a mutation in a region equivalent to the rfe genes of Salmonella.

Animals↗
PubMed1976

Enterobacterial common antigen in rfb deletion mutants of Salmonella typhimurium.

The his-rfb deletion series of Salmonella typhimurium mutants characterized previously by Nikaido et al. was examined for the presence of the enterobacterial common antigen (ECA). All deletions not extending further to the left than the genes for cytidine phosphoabequose synthesis were ECA positive, whereas longer deletions (extending to the genes for thymidine diphosphorhamnose synthesis or further) were ECA negative. When these long-his-rfb deletion strains were studied further, it became clear that they (four out of four studied) had accumulated a second mutation, called rff, close to ilv, which prevented the synthesis of ECA. When rff- was replaced by rff+, the recombinants, now having the his-rfb deletion only, produced traces of ECA, showed reduced viability, increased sensitivity to sodium dodecyl sulfate (SDS) and to a lesser extent, to other anionic detergents, and accumulated secondary "suppressor" mutations upon storage. Such suppressor-containing mutants could be isolated by selecting for resistance to 1% SDS. Thirty of 46 SDS-resistant mutants studied had a second mutation, which alone prevented the synthesis of ECA, close to ilv. This ilv-linked mutation was similar to the rff mutation of the strains studied originally. The new rff mutation was similar to previously described rfe mutations in its close linkage to ilv and association with an ECA-negative phenotype. It differed from rfe, however, by not affecting the synthesis of the O antigens (O-6,7) of group C1. In Salmonella group C1, all ECA genes identified thus far are linked to ilv (rfe and/or rff) and none is linked to rfb.

Antigens, Bacterial↗
PubMed1975

Colonization by Enterobacteriaceae of the respiratory tract of children with cystic fibrosis of the pancreas and their antibody response.

Of 72 patients with fibrosis, 49 harbored Enterobacteriaceae in the respiratory tract, including Escherichia coli, Klebsiella, and Enterobacter. Colonization by two to four genera was documented in 29 subjects. Staphylococcus aureus was recovered from 44 of these 49 patients. The distribution of serogroups of E. coli was similar to that seen in patients with urinary tract infection. Antibody response against the O antigens of the patients' own Enterobacteriaceae was documented in 29 of these 49 children and encountered more often in patients with severe disease. Colonization by Enterobacteriaceae in the absence of Pseudomonas aeruginosa was seen more frequently in children with the mild form of the illness.

Adolescent↗
PubMed1975

Antibody response of patients with malignancies to bacteremia with gram-negative bacteria.

Antibody response, determined by means of the indirect bacterial hemagglutination tests, was studied in 58 consecutive patients with various malignancies whose blood culture yielded growth of Enterobacteriaceae or Pseudomonas and from whom serum specimens were obtained. Of these patients 59% had a significant antibody response. The invading microorganisms were Escherichia coli in 33 and Klebsiella in 19 subjects, an antibody response being documented with essentially equal frequency (60 and 57% of the subjects, respectively). Two patients had positive blood cultures for both E. coli and Klebsiella, one of whom had a significant response to one isolate only. A specific antibody resonse was documented in 67% of the subjects from whom blood for antibody titration was obtained at least 5 days after the blood culture, but from only 21% of patients whose serum was procured during the first 5 days after the blood culture. Similarly, such an antibody response was identified in 73% of subjects with two consecutive serum specimens, but in only 28% of the patients with a single serum specimen for antibody titration. Documentation of the immune response may be of diagnostic aid in differentiating between infection and contamination even in patients with underlying malignancy and under potentially immunosuppressive therapy.

Adolescent↗
PubMed1974

Participation of lipopolysaccharide genes in the determination of the enterobacterial common antigen: analysis of R mutants of Salmonella minnesota.

A series of R (rough) Salmonella minnesota mutants with rfb, rfe, and rfa mutations leading to various defects in the biosynthesis of cell wall lipopolysaccharide was analyzed as to their enterobacterial common antigen (CA) content. All mutants that had functional rfe genes were CA(+) as is the wild-type parent. This includes mutants with the most defective lipopolysaccharide core types, demonstrating that core structures are not a necessary part of CA. All rfe(-) mutants (complete lipopolysaccharide core, defective synthesis of O side chains) were defective in the synthesis of CA. A smooth strain was accidentally found to be CA(-); the mutation responsible for this defect was also located, like rfe, very close to ilv.

Antigens, Bacterial↗
PubMed1972

Hemagglutinin response of human subjects to common enterobacterial antigen.

Ten human volunteers were immunized intravenously with ethanol-soluble common enterobacterial antigen (CA) obtained from Escherichia coli O111. The immunogen contained 6 mg/ml, excluding salts. The antigen was given in amounts of 2 ml each in dilutions of 1:250 (48 mug) and 1:125 (96 mug), respectively, 1 week apart. Serum specimens were obtained prior to immunization and 1 week after the last injection. The CA hemagglutinins were titrated by means of the passive hemagglutination test, with CA from E. coli O14 as indicator antigen. The injections were well tolerated without side-effects by all subjects. A significant (> fourfold) increase in the titers of CA hemagglutinins was observed following immunization in 9 out of 10 volunteers. These results indicate the feasibility of immunization with CA of human subjects and suggest exploration of immunization against infection caused by Enterobacteriaceae producing this common enterobacterial antigen.

Antibodies, Bacterial↗