Intended use
Genotyping of 14 different Chlamydia trachomatis serovars.

The RHA CT (Chlamydia trachomatist) Genotyping RHA kit is an in vitro reverse hybridization strip assay using two primer sets for the qualitative identification of 14 different Ct serovars (i.e. A, B/Ba, C, D/Da, E, F, G/Ga, H, I/Ia, J, K, L1, L2/L2a and L3). The RHA kit Ct Genotyping test is a Research Use Only (RUO) test. By serogroup and serovar identification in Ct testing, epidemiological research could further investigate possible clinical relevance of specific Ct serovars, or outbreaks in subpopulations.

Summary and explanation
Chlamydia trachomatis (Ct) is the most prevalent sexually transmitted bacterial pathogen. Most infections remain asymptomatic, but when left untreated, these infections can lead to serious diseases, such as pelvic inflammation, ectopic pregnancy and tubal infertility. Ct can be divided into three serogroups and subsequently into 19 serovars. The different serovars of Ct display diverse biological activities. Serovars A, B/Ba and C are commonly associated with an ocular disease (trachoma). Serovars D/Da, E, F, G/Ga, H, I/Ia, J and K are common in the urogenital tract and can sometimes be detected in the respiratory tract of infants, whereas serovars B and C are rarely detected in the urogenital tract. The serovars L1, L2/L2a and L3 are mainly detected in the inguinal lymph nodes and the rectum and may cause lymphogranuloma venereum. Laboratory diagnosis of Ct infection is routinely performed by molecular methods such as PCR or liquid hybridization. Most assays aim at detection of the multi copy cryptic plasmid which ensures high sensitivity but such assays have no ability to distinguish different serogroups and serovars.
The Ct Genotyping RHA kit is a follow-up for amplification using the LBP Ct PCR Primer set. This multiplex PCR detects Ct infections by targeting a 89 bp region in the cryptic plasmid and a 162-165 bp region in the genome. Amplification of the cryptic plasmid allows detection with high sensitivity, whereas the genomic amplicon enables the identification of serovar and serogroup by specific probes [1].
By detecting both the cryptic plasmid and the genomic Ct DNA the Ct Genotyping RHA kit circumvents false-negative test results in case of emerging variants that have been described [2]. 
The Ct Genotyping RHA kit allows easy and reliable detection and identification of Ct infection using a multiplex PCR targeting the cryptic plasmid and the Ct omp1 gene.

Principles of the procedure
The Chlamydia trachomatis Genotyping test is based on the reverse hybridization principle. The PCR can be performed either by use of the primers in the kit or with the amplification part of the Chlamydia trachomatis Detection kit (a PCR/DNA-Elisa screenings test). Denatured biotinylated amplicons, resulting from the amplification of regions on the cryptic plasmid and the omp1 gene with broad-spectrum primers hybridized with specific oligonucleotide probes, which are immobilized as parallel lines on membrane strips. After hybridization and stringent washing, streptavidin-conjugated alkaline phosphatase is added and bound to any biotinylated hybrid previously formed. Incubation with BCIP/NBT chromogen yields in a purple precipitate and the results can be visually interpreted.

Ordering information
REF: S-1021 RHA kit CT Genotyping 20 tests

Related product
REF: K-45 DNA ELISA kit Ct 96 tests
REF: L-4149 LMNX Kit CT Genotyping 96 tests

1) Quint et al. (2007), A Highly Sensitive, Multiplex Broad-Spectrum PCR-DNA-Enzyme Immunoassay and Reverse Hybridization Assay for Rapid Detection and Identification of Chlamydia trachomatis Serovars. J Mol Diagn 9, 631-638.

2) Ripa et al. (2007), A Chlamydia trachomatis Strain With a 377-bp Deletion in the Cryptic Plasmid Causing False-Negative Nucleic Acid Amplification Tests. Sex Transm Dis 34, 255-256.

3) Quint et al. (2007), Evaluation of a novel PCR-based assay for detection and identification of Chlamydia trachomatis serovars in cervical specimens. J Clin Microbiol 45, 3986-91.

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