Synthetic oligodeoxyribonucleotide probes to detect verocytotoxin-producing Escherichia coli in diseased pigs

Abstract

Oligonucleotide probes constructed from the sequences published for Shiga‐like toxin I (SLT‐I) and Shiga‐like toxin II (SLT‐II) genes and antibody against the purified toxins were used to study the SLT (SLT‐IIp) produced by porcine E. coli O138 and O139 strains. By DNA hybridization assays no homology was observed between SLT‐I and SLT‐IIp. By contrast the oligonucleotide probe derived from the slt‐II A gene detected porcine strains of E. coli producing SLT‐IIp and E. coli strains associated with human disease producing SLT‐II. Homology of nucleotide sequences between SLT‐IIp and SLT‐II is reflected by serological cross‐reactivity as demonstrated by a dot blot ELISA and neutralization of SLT‐IIp with anti‐SLT‐II. The toxins were distinguishable in their ability to kill HeLa S‐3 cells. The oligonucleotide probe and anti‐SLT‐II can facilitate identification of SLT‐IIp producing E. coli to further clarify their role in diseased pigs.

Vero Toxins (Shiga‐Like Toxins) Produced by Enterohemorrhagic Escherichia coli (Verocytotoxin‐Producing E. coli)

“…Although DNA colony hybridization tests using polynucleotide and oligonucleotide probes have also been reported (16,56,61,82), polymerase chain reaction (PCR) is probably more rapid, sensitive, and specific to detect VT genes. Several primers for detecting VT1 (or SLT-I) (23,76,88), VT2 (or SLT-II) (23,41,77,88) VT2vha (or VT2v-a) (93), VT2vhb (or VT2v-b) (93), VT2vp1 (or SLT-IIv, VTe) (93), and VT2vp2 (or VTev) (42) were described.…”

Genes coding for Shiga-like toxin and heat-stabile enterotoxin in porcine strains of Escherichia coli

“…2A, lane 2). As SLT-IIv the SLT-IIp expressed by E. coil O138 strain E57 is only cytotoxic for Vero cells but not for HeLa cells [5]. Common features include elaboration of various types of cytotonic enterotoxins in ETEC and cytotoxic enterotoxins in EHEC.…”

“…This probe was recently shown to detect SLT-IIp producing E. coli [5]. The location of the oligo probe for SLT-I corresponds to the position 774-793 of the slt-I A gene published by De Grandis et al [15].…”

“…STII) expressed by enterotoxigenic Escherichia coli (ETEC) some E. coli serovars elaborate another group of toxins with enterotoxic activity. In contrast to SLT-II the SLT expressed by E. coli strains from diseased swines is cytotoxic for Vero but not for HeLa cells and is therefore termed SLT-II variant (SLT-IIv) [4] or SLT-II-pig (SLT-IIp) [5]. The prototype cytotoxins of the SLT family are Shiga-like toxin-I (SLT-I) and Shiga-like toxin-II (SLT-II).…”

Detection of Various Variant Verotoxin Genes in Escherichia coli by Polymerase Chain Reaction

“…Because of the clinical and epidemiological significance of VTEC infection in humans, it is necessary to develop a rapid, specific, and sensitive method for detecting VT, and identifying VTEC strains. Several enzyme-linked immunosorbent assays (1,21,22), DNA hybridization tests (4,16,18), and the polymerase chain reaction (PCR) (11,12,23,29) have been used so far. Of these assays, the PCR is a rapid, specific, and sensitive method for detection of VT's and specific primers for amplifying the genes of VT1, VT2, VT2vha, VT2vhb and VT2vp1 (SLT-IIv) have been reported (11,12,29).…”