C-151. COBAS TaqMan CT Test 2.0: Detection of the Swedish Variant by NAAT

M. M. Krevolin, S-D. Lu, D. Kawa, R. Apple, J. Pane, N. Lee-Lundy;
Roche Molecular Systems, Pleasanton, CA.

Objective: Diagnosis of infection of Chlamydia trachomatis, including the Swedish variant, in urine and swab specimens using the COBAS TaqMan CT Test V2.0 Methods: The COBAS TaqMan CT Test (CTM CT) is an in vitro nucleic acid amplification test (NAAT) for the qualitative detection of Chlamydia trachomatis cryptic plasmid DNA. In mid 2006, a variant strain of Chlamydia was identified in Sweden witha 377bp deletion in the cryptic plasmid target region rendering it undetectable by the current CTM CT test. The expanded CTM CT test (Version 2.0) incorporates an added target region located off the cryptic plasmid that allows the test to detect plasmid free variants as well as the mutant strain identified in Sweden. The serovar inclusivity of the CTM CT v2.0 test was determined using ATCC CT cultures (1 IFU/PCR) in M4RT media. For each serovar, 11 replicates were processed and run by the CTM CT v2.0 Test procedures. In addition, this serovar study was repeated using only the MOMP signal probe to investigate the inclusivity of the MOMP amplification system. Results: The enhanced CTM CT test targets a highly conserved portion of the genome while retaining the ability to detect the presence of the wild type cryptic plasmid. With 5-10 copies of the wild type cryptic plasmid generally present in each elementary body of CT, it remains a preferred target for detection of wild type infection. However, all serovars were detected when using the MOMP probe alone, verifying that all known serovars of Chlamydia trachomatis can be amplified and detected by the CTM CT v2.0 Test with or without the presence of the cryptic plasmid. Conclusions: The COBAS TAQMAN CT TEST V2.0 is able to detect wild type Chlamydia strains, the newly identified Swedish variant, and plasmid free Chlamydia trachomatis.