Differentiating turkey postvaccination isolants of Pasteurella multocida using arbitrarily primed polymerase chain reaction.

The chromosomal DNA of 29 field isolants of Pasteurella multocida from commercial turkey farms in Missouri and the avirulent Clemson University (CU) and M-9 vaccine strains of P. multocida were tested using the arbitrarily primed polymerase chain reaction (AP-PCR) in combination with 32P-labeled deoxycytidine triphosphate (dCTP) and high-resolution gel electrophoresis. The 29 field isolants of P. multocida were isolated from outbreaks of fowl cholera in turkey flocks in which vaccination with the CU vaccine had been performed within 2 weeks of the isolation, and it was suspected that the outbreak could have been due to the use of the live CU vaccine. The results of this study showed that: 1) the use of the live CU vaccine can lead to the isolation of the vaccine strain if the outbreak occurs within 2 weeks of vaccination; 2) a higher proportion of field isolants collected during 1983 and 1984, when the usage of the CU vaccine strain was highest on Missouri turkey farms, had PCR-amplified product profiles similar or identical to those of the CU vaccine strain compared with the period between 1987 and 1992, when its use was less; and 3) there was no relationship between the PCR-amplified product profiles and the serotype.