Disease relevance of iss

• Conjugal transfer of the 1.6 and 2.4 kb integrons was successful, and in a serogroup O33 intestinal E. coli strain the iss gene was apparently cotransferred with a 1.6 kb integron [1].
• We also find that antigenically related proteins are expressed by lysogens of a number of other lambdoid coliphage, in cells carrying the cloned iss gene, and in several clinical isolates of E. coli [2].
• DNA probes for the colicin V, traT, iss, and iu genes were used in this study of four representative ColV plasmids together with 200 Escherichia coli strains isolated from the stools of patients with diarrhea and 146 E. coli strains isolated from the blood of patients with bacteremia [3].

High impact information on iss

• This property is a well known bacterial virulence determinant--indeed, bor and its adjacent sequences are highly homologous to the iss serum resistance locus of the plasmid ColV2-K94, which confers virulence in animals [4].
• Association of iss and iucA, but not tsh, with plasmid-mediated virulence of avian pathogenic Escherichia coli [5].
• Here we establish the size of pVM01 to be approximately 160 kb and show that the putative virulence genes iss (increased serum survival) and tsh (temperature-sensitive hemagglutinin) and the aerobactin operon are on the plasmid [5].
• Thus, both the aerobactin operon and iss are associated with virulence in APEC after exposure by the natural route of infection [5].
• We also showed that the iss gene, which was previously demonstrated to increase resistance to serum in certain E. coli strains, is located on plasmid pAPEC-1 of E. coli chi7122 but does not play a major role in resistance to serum for strain chi7122 [6].

Chemical compound and disease context of iss

• In both intestinal and blood E. coli isolates, the traT, iss, and aerobactin receptor genes were present at similar frequencies, but the frequency of the aerobactin synthesis genes was significantly different [3].

Biological context of iss

• All extra-intestinal strains had the colV, iss and tsh genes, but none of these genes were cotransferred with the 1.0 kb integron when conjugal transferability was tested [1].
• We compared this resistance with that specified by the iss gene of the ColV,I-K94 plasmid [7].
• The ColV plasmids from blood isolates that were tested for the presence of traT, iss, and iu genes were homogeneous and had DNA sequences that hybridized with each of the probes [3].
• The ORF in iss is preceded by sequences resembling prokaryotic ribosome binding sites and promoters [8].
• The abilities to resist host complement, presence of Colicin V activity, and presence of the increased serum survival gene cluster (iss), were used together in a logistic regression analysis to predict the percentage of embryo deaths resulting from each of 20 avian E. coli isolates used in the ELA [9].

Anatomical context of iss

• Currently, purified Iss is being used to prepare hybridomas for production of monoclonal antibodies with the goal of evaluating anti-Iss as a reagent for the detection of virulent avian E. coli [10].
• B cells from mice immunized with an Iss fusion to glutathione-S-transferase produced antibodies specifically against Iss, and these cells were used to generate the MAbs [11].

Associations of iss with chemical compounds

• Under conditions in which traT and iss conferred at least a 50- and 10-fold increase in survival, respectively, the consumption of C6, C7, C8, and C9 was the same for bacteria with and without the plasmid genes [7].
• Clinical isolates and 194 fecal isolates with biochemical phenotypes or minimum inhibitory concentrations for gentamicin and sulfamethoxazole similar to clinical isolates were tested for somatic antigens and the potential virulence genes hylE, iss, tsh, and K1 [12].

Other interactions of iss

• To determine whether integrons may play a role in avian pathogenic Escherichia coli, isolates of extra-intestinal (n = 27) and intestinal (n = 40) E. coli from dead chicks and turkey poults were analysed for the presence of class 1 integrons and of the virulence-associated genes iss, tsh and colV [1].
• Further characterization of complement resistance conferred on Escherichia coli by the plasmid genes traT of R100 and iss of ColV,I-K94 [7].
• These included sitABCD, genes of the aerobactin operon, hlyF, iss, genes of the salmochelin operon, and the 5' end of cvaB of the ColV operon [13].

Analytical, diagnostic and therapeutic context of iss

• Most isolates were PCR positive for the increased serum survival gene (iss; 97%) and the temperature-sensitive hemagglutinin gene (tsh; 93%) [14].
• These anti-Iss MAbs, when used in western blotting assays, can be used to distinguish iss-positive and -negative E. coli isolates, suggesting that they may be useful as reagents in the detection and study of virulent avian E. coli [11].

References