Comparative analysis of yad A amd Ail polymerase chain reaction methods for virulent Yersinia enterocolitica.
1995
Blais B.W. | Phillippe L.M.
The performance of two PCR methods targeting plasmid-borne yad A and chromosomal ail gene sequences in the analysis of a variety of virulent and avirulent Yersinia enterocolitica strains was studied and compared to observation of colonial morphology in the congo red (CR) plating test for virulence plasmid-bearing cells. In general, virulent isolates which were positive by the yad A PCR also produced P(+) colonies in the CR test. All of the yad A PCR-positive isolates were also positive in the ail PCR, and neither of the two PCR methods produced positive results with a variety of avirulent Yersinia. However, some ail PCR-positive virulent strains were negative in the yad A PCR and the CR test, possibly due to plasmid loss during prolonged storage and handling. Indeed, a substantial proportion of the bacterial population in broth cultures of virulent isolates lost the virulence plasmid after several transfers at 37 deg C, but not at 25 deg C, indicating that the plasmid is unstably inherited under certain cultural conditions.
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