Analysis of the actinobacterial insertion in domain III of the 23S rRNA gene of uncultured variants of the bacterium associated with Whipple's disease using broad-range and 'Tropheryma whippelii'-specific PCR.

Heterogeneity in the 16S-23S rDNA spacer of uncultured 'Tropheryma whippelii' has previously been reported. In this study, the hypervariable insertion in the 23S rDNA domain III characteristic for actinobacteria was analysed. The finding of a unique sequence virtually identical among the subtypes supports the classification of 'T. whippelii' among the actinobacteria and the concept of three subtypes rather than three subspecies, and provides an alternative target for diagnostic assays.