Identification of cholix toxin gene in non-O1/non-O139 isolated from diarrhea patients in Bushehr, Iran.

BACKGROUND AND OBJECTIVES

Cholixin (cholix toxin) is a novel exotoxin in identified as an elongation factor II specific ADP-ribosyltransferase which inhibits protein synthesis in the eukaryotic cell. Previous researches have suggested that cholixin probably is an important virulence factor in non-O1/non-O139 (NAG) serotypes that could be related to extra-intestinal rather than intestinal infections. This study was aimed to investigate the frequency and genetic diversity of colixin gene in clinical NAG isolates.

MATERIALS AND METHODS

The presence of gene in 44 clinical NAG isolates were screened using PCR through specific primers designed for the receptor-binding domain (RBD) of gene. The five PCR products of gene were sequenced.

RESULTS

This study showed that gene presented in 19 NAG isolates. The sequences analysis of 5 out of 19 the partial genes amplicon showed that 4 of them belonged to I and the other one belonged to II subtypes. Two distinct clusters were revealed for these isolates by phylogenic analysis, too.

CONCLUSION

The gene contained high frequency among NAG isolates in Bushehr, Iran. The polymorphism study on RBD of cholixin gene is suggested as an appropriate method for phylogenic characterization of the various gene subtypes.