HC2 GC-ID DNA Test

An in vitro nucleic Acid Hybridization Microplate Assay with Amplification using Microplate chemiluminescene for the Qualitative Detection of Neisseria Gonorrhoeae (GC) DNA in cervical Specimen’s.

  SUMMARY AND EXPLANATION

Neisseria gonorrhoeae are non-motile. Gram negative diplococci with fairly complex growth requirements. They are aerobic, producing optimal growth at temperatures in the range of 35-37 °c in the presence of 37% co2 and ≥70% relative humidity. Presumptive diagnosis for Neisseria gonorrhoeae is traditionally obtained by isolating organisms from cultures of clinical specimens and using a gram stain for morphological examination. Definitive diagnoses can be obtained with a positive oxidase and/or catalase test of the culture. Additional confirmation of results includes carbohydrate degradation, agglutination, and sugar fermentation tests. More definitive, direct test for Neisseria gonorrhoeae include antigen detection and nucleic acid probe tests. An enzyme linked immunosorbent assay has been shown to be as sensitive and as specific as the gram stain for detecting gonococci in male urethral and first void urine specimens, but it has decreased sensitivity when applied to endocervical specimens. Because the antigen detection test may cross-react with commensal Neisseria and related species. This test can only be used for presumptive diagnosis.

More recently, nucleic acid hybridization tests have been used to evaluate clinical samples for the detection of Neisseria gonorrhoeae in high-risk populations using both endocervical and male urethral specimens.

  PRINCIPLE OF THE PROCEDURE

The hc2 GC-ID DNA Test using Hybrid Capture 2 technology is a nucleic acid hybridization assay with signal amplification that utilizes microplate chemiluminescent detection. Specimens containing the target DNA hybridize with a specific GC RNA probe. The resultant RNA:DNA hybrids are captured onto the surface of a microplate well coated with antibodies specific for RNA:DNA hybrids. Immobilized hybrids are then reacted with alkaline phosphatase conjugated antibodies specific for RNA:DNA hybrids, and detected with a chemiluminescent sunstrate. Several alkaline phosphatase molecules are conjugated to each antibody. Multiple conjugated antibodies bind to each captured hybrid resulting in substantial signal amplification. As the substrate is cleaved by the bound alkaline phosphatase, light is emitted, which is measured as relative light units (RLUs) on a luminometer. The intensity of the light emitted denotes the presence or absence of target DNA in the specimen.

An RLU measurement equal to or greater than a specified ratio to the positive cutoff (CO) value indicates the presence of GC DNA in the specimen. An RLU measurement less than a specified ratio to the positive cutoff value indicates the absence of GC DNA or DNA or GC DNA levels below the detection limit of the assay.

The GC probe contains a probe mixture specifically chosen to eliminate or minimize cross-reactivity with DNA sequences from human cells, other bacterial species, or Nesseria SPECIES OTHER THAN Neisseria gonorrhoeae. The GC probe supplied with the hc2 GC ID DNA Test is complementory to approximately.

High volume sample throughout testing with the hc2 GC ID DNA Test can be performed utilizing a general use automated pipetting and dilution system referred to as the rapid capture system (RCS). This instrument, using an application specific to the hc2 GC-ID DNA test, processes up to 352 specimens in eight hours. To enable high volume sample-throughput testing, all the procedural steps of the assay are performed by the RCS, with the exception of specimen denaturation, chemiluminescent signal detection, and result reporting.