Polymerase Chain Reaction
PCR Benefit Factors
1. PCR molecular analysis is 30% more sensitive than PAS with many fewer missed cases;
2. PCR molecular analysis additionally offers detection of a vast array of dermatophytes, yeast and mold, allowing for correct, targeted treatment from the start;
3. PCR testing only takes 48 hours to complete versus up to 6 weeks for culture results making culture, an additional cost, no longer necessary;
4. Testing is covered by insurance providers and applicable to patient’s deductible and/or co-pays.
Principle of a DNA Microarray
DNA microarrays consist of DNA sequences (probes) which are applied to a solid carrier material, such as glass, in microscopically small spots located at defined positions. The probes differ from one another by their DNA sequence – the order of their building blocks (nucleotides with the bases adenine, A; cytosine, C; guanine, G; thymine, T). When the DNA of a patient contains segments that match the microarray probes, the complementary DNA regions bind together – they hybridize. This binding is measured via a computer-generated reading and evaluated as a positive signal.
The sections of DNA to be investigated are amplified million-fold using polymerase chain reaction (PCR). Two starter DNA molecules (primers) define the region to be copied. If the patient DNA contains the corresponding section (target sequence), the primers bind and the target sequence is copied. This reaction is repeated many times, so that the DNA region between the primers is greatly (exponentially) amplified. The resulting PCR products are labelled with a fluorescent dye, which enables them to be detected subsequently by the microarray. If the target sequence is not present in the patient sample, then the primers cannot bind and the DNA is not amplified.
Amplification of patient DNA: Polymerase Chain Reaction (PCR)
Analysis of PCR Products on the Microarray: DNA Microarray Hybridization
The PCR products are incubated with the microarray. They are first mixed with a hybridization buffer, which provides optimal conditions for binding of the PCR products to the complementary probes on the microarray. This binding is measured via the fluorescence signals emitted by the spots.
HSV 1 & 2 / VZV
1. Herpes simplex virus types 1 and 2 (HSV-1 & HSV-2) and varicella-zoster virus (VZV) are human pathogenic viruses from the Herpesviridae family that occur worldwide
2. HSV-1 and HSV-2, which are closely related, can cause different diseases, with either asymptomatic, mild, or severe courses
3. HSV-2 generally leads to cold sores; genital infections can be caused by both virus types, but mainly by HSV-2
4. VZV is transmitted by blister fluid, conjunctival fluid, or saliva containing the virus
5. The EUROArray HSV1/2, VZV enables direct detection and differentiation between all three virus types based on swab samples from the skin, mouth mucosa, or genital mucosa of a patient