The NVRL is currently changing its platform for the molecular investigation for Chlamydia trachomatis (CT). The Roche COBAS Amplicor CT assay will be replaced with the Gen-Probe Aptima Combo2 assay (to be performed on the Tigris platform) from August 4th of this year. The Aptima assay targets ribosomal RNA (rRNA) rather than DNA. The reasons for this change are as follows: