Design of oligonucleotide arrays to detect point mutations: molecular typing of antibiotic resistant strains of Neisseria gonorrhoeae and hantavirus infected deer mice.

Microarrays are promising tools for use in molecular diagnostics due to their ability to perform a multitude of tests simultaneously. In the case of genotyping many such tests will require discrimination of sequence at the single nucleotide level. A number of challenges exist including binding of optimal quantities of probe to the chip surface, the use of uniform hybridization conditions across the chip and the generation of labeled target. We investigated two model systems to test out the efficacy and ease with which probes can be designed for this purpose. In the first of these we designed primers to identify five mutations found in two genes from N. gonohorroeae, gyrA and parC that have been implicated in ciprofloxacin resistance. In the second system we used a similar strategy to identify four mutations in AT rich mitochondrial DNA from deer mice. These mutations are associated with deer mice subspecies that originate from different geographical regions of Canada and harbor different hantavirus strains. In every case we were able to design probes that could discriminate mutations in the target sequences under uniform hybridization conditions, even when targets were fairly long in length, up to 400 bp. Our results suggest that microarray analysis of point mutations might be very useful for automated identification and characterization of pathogens and their hosts.