Lipopolysaccharide-independent radioimmunoprecipitation and identification of structural and in vivo induced immunogenic surface proteins of Salmonella typhi in typhoid fever

Aron, Lieselotte; Faundez, Gustavo; González, Carlos; Roessler, Emilio; Cabello, Felipe C.

doi:10.1016/0264-410x(93)90334-t

Cited by 19 publications

(10 citation statements)

References 39 publications

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“…In addition, OmpS1 appears to have a role in the Salmonella life cycle, since mutations causing defects in swarming motility and biofilm formation have been found to map in S. enterica serovar Typhimurium ompS1 (32,34). Moreover, vaccination of mice with S. enterica serovar Typhi and Typhimurium porins confers protective immunity against live bacteria (18,21,24), and specific humoral and cellular immune responses are mounted against S. enterica serovar Typhi outer membrane proteins in typhoid fever patients, which has allowed the design of novel diagnostic assays (1,6,33).…”

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confidence: 99%

Salmonella enterica Serovar Typhimurium ompS1 and ompS2 Mutants Are Attenuated for Virulence in Mice

et al. 2006

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Salmonella enterica Serovar Typhimurium ompS1 and ompS2 Mutants Are Attenuated for Virulence in Mice

et al. 2006

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“…Typhoid fever is a systemic infection, characterized by the presence of bacteria in the liver, spleen, and bone marrow, as S. enterica serovar Typhi invades and survives within macrophages (6). Specific humoral and cellular immune responses are mounted against Salmonella outer membrane proteins (OMPs) (2,53,51). Salmonella enterica serovar Typhimurium and S. enterica serovar Typhi OMPs have proven to be relevant immunogens for protection of mice challenged with virulent strains (23,35).…”

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OmpR and LeuO Positively Regulate the Salmonella enterica Serovar Typhi ompS2 Porin Gene

2004

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The Salmonella enterica serovar Typhi ompS2 gene codes for a 362-amino-acid outer membrane protein that contains motifs common to the porin superfamily. It is expressed at very low levels compared to the major OmpC and OmpF porins, as observed for S. enterica serovar Typhi OmpS1, Escherichia coli OmpN, and Klebsiella pneumoniae OmpK37 quiescent porins. A region of 316 bp, between nucleotides ؊413 and ؊97 upstream of the transcriptional start point, is involved in negative regulation, as its removal resulted in a 10-fold increase in ompS2 expression in an S. enterica serovar Typhi wild-type strain. This enhancement in expression was not observed in isogenic mutant strains, which had specific deletions of the regulatory ompB (ompR envZ) operon. Furthermore, ompS2 expression was substantially reduced in the presence of the OmpR D55A mutant, altered in the major phosphorylation site. Upon random mutagenesis, a mutant where the transposon had inserted into the upstream regulatory region of the gene coding for the LeuO regulator, showed an increased level of ompS2 expression. Augmented expression of ompS2 was also obtained upon addition of cloned leuO to the wild-type strain, but not in an ompR isogenic derivative, consistent with the notion that the transposon insertion had increased the cellular levels of LeuO and with the observed dependence on OmpR. Moreover, LeuO and OmpR bound in close proximity, but independently, to the 5 upstream regulatory region. Thus, the OmpR and LeuO regulators positively regulate ompS2.

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“…These immune responses primarily occur against the lipopolysaccharide (LPS) and major outer membrane (OM) proteins, including porins and OmpA (1,7,21,28,40,42). However, the number and variety of antibodies with distinct specificities and the identity of epitopes that they recognize are not well understood.…”

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“…OmpA, like porins and LPS, is also a target of the host immune response (1,19,28,31,48), but its role in immunoprotection is not clearly understood. Some studies suggest that antibodies specific for OmpA or its homolog do not confer passive protection (13,20,49,51).…”

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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

et al. 2003

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We examined the way the major outer membrane protein OmpA of Salmonella enterica serovar Typhimurium is recognized by the mouse immune system, by raising a panel of 12 monoclonal antibodies (MAbs) against this protein. Interaction between OmpA and these MAbs is competitively inhibited with several-hundredfold dilutions of mouse polyclonal sera obtained by immunization with live or heat-killed whole cells, suggesting that OmpA is one of the immunodominant antigens of serovar Typhimurium. All of the MAbs were specific for an identical epitope(s) located on the C-terminal domain of OmpA, as indicated by the use of OmpA fragments generated by protease or cyanogen bromide treatment and by competitive inhibition enzyme-linked immunosorbent assay. This epitope was highly conserved within (but not outside) the family Enterobacteriaceae. The strong immunogenicity of this epitope was surprising because the C-terminal domain of OmpA, usually thought to be located in the periplasm, is not expected to be exposed on the bacterial cell surface. A MAb, however, reacted in a cytofluorometry assay more strongly with outer-membrane-permeabilized cells than with untreated cells, a result supporting the predominantly periplasmic localization of the epitope. Significant, though low-level, reactivity of intact cells nevertheless suggests that in some cells the C-terminal domain of OmpA is exposed on the surface, a result consistent with the proposal that OmpA can fold into one of the two alternate conformations.

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Lipopolysaccharide-independent radioimmunoprecipitation and identification of structural and in vivo induced immunogenic surface proteins of Salmonella typhi in typhoid fever

Cited by 19 publications

References 39 publications

Salmonella enterica Serovar Typhimurium ompS1 and ompS2 Mutants Are Attenuated for Virulence in Mice

Salmonella enterica Serovar Typhimurium ompS1 and ompS2 Mutants Are Attenuated for Virulence in Mice

OmpR and LeuO Positively Regulate the Salmonella enterica Serovar Typhi ompS2 Porin Gene

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

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