Differentiation of hard-to-type bacterial strains by RNA mismatch cleavage

Many bacteria are difficult to subtype due to high genetic relatedness. rn the cases of pathogens of medical or veterinary importance, subtyping is an essential fool of epidemiologists. This report describes a method for mole cular subtyping based on the defection of point mutations without DNA seque ncing or specialized equipment. The method, known. as RNA mismatch cleavage , hybridizes RNA transcripts derived from PCR-amplified DNA, with a control RNA transcript followed by RNase cleavage at point-mutation mismatches. Th e method was successful in distinguishing all six Brucella species tested a nd was able to distinguish 11 of the 18 biovars studied. Of the remaining s even biovars (all of which are Brucella abortus strains), three subgroups w ere identified. The method should be applicable to all hard-ro-subtype bact erial strains.