Relationship between iss gene and the virulence of avian Escherichia coli

The presence of iss gene was tested by amplification,and the sequences of studied strains were analyzed in comparison with AF042279 in GenBank(iss gene from avian Escherichia coli isolate).It was found that all of the 21 isolates had iss gene,which was different from the other isolates.Amplification of iss gene might be related to the copy-number of plasmid,in which iss gene was located.Each iss gene from 16 of 21 isolates shared 100% identity,and E1 shared 93.5% identity with AF042279 in GenBank,respectively.Each from E33 and O78 shared 99.4% identity,and E4 and E21 shared 99.7% identity with AF042279 in GenBank,respectively.It suggested that iss gene might be highly conserved.And iss gene might be related to the virulence of avian E.coli.Relationship between iss gene and virulence of avian E.coli might be associated with the copy-number of iss,not its sequence.