CLOSTRIDIUM-PERFRINGENS TYPE-E ANIMAL ENTERITIS ISOLATES WITH HIGHLY CONSERVED, SILENT ENTEROTOXIN GENE-SEQUENCES

Several Clostridium perfringens genotype E isolates, all associated wi th hemorrhagic enteritis of neonatal calves, were identified by multip lex PCR. These genotype E isolates were demonstrated to express alpha and iota toxins, but, despite carrying sequences for the gene (cpe) en coding C. perfringens enterotoxin (CPE), were unable to express CPE. T hese silent cpe sequences were shown to be highly conserved among type E isolates. However, relative to the functional cpe gene of type A is olates, these silent type E cpe sequences were found to contain nine n onsense and two frameshift mutations and to lack the initiation codon, promoters, and ribosome binding site. The type E animal enteritis iso lates carrying these silent cpe sequences do not appear to be clonally related, and their silent type E cpe sequences are always located, ne ar the iota toxin genes, on episomal DNA. These findings suggest that the highly conserved, silent cpe sequences present in most or all type E isolates may have resulted from the recent horizontal transfer of a n episome, which also carries iota toxin genes, to several different t ype A C. perfringens isolates.