Genetic Polymorphism and Molecular Typing

Despite the fact that pathogenic treponemes are closely related, a recent molecular system, based on two genes, arp (AF 411124) and the T. pallidum repeat gene (tpr; 8), has been used to type clinical isolates of T. pallidum.[14-16] The arp gene varies in the number of repeats of a 60-bp sequence, with clinical isolates demonstrating variations from 4 to 22 repeats. The tpr gene family consists of 12 genes (A to L). The typing system uses primers that amplify the tpr E, G, and J genes followed by Mse I endonuclease digestion and the RFLP patterns of the tpr genes. The system has been successfully used in several endemic regions and in outbreak situations in industrialized countries. However, this molecular typing method cannot distinguish between subspecies of T. pallidum. Other members of the tpr gene family (tpr D and K) have shown genetic polymorphism and multiple alleles, but may not be suitable for development into a typing system.[17,18]

Paster et al.[19] differentiated T. pallidum from oral and other spirochetes using a dendrogram generated from the 16S rRNA sequence, relying on a single base pair change. Several genes have been reported to have single base pair mutational differences when comparing T. pallidum with other nonvenereal treponemes.[20,21] However, unless the functions of the genes are known, a single base pair mutation alone may not be sufficient for typing purposes.

Was this article helpful?

0 0
Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

Get My Free Ebook

Post a comment