free html5 templates

   CHIC Technology

CHIC technology (Competitive Heterologous Internal Control) is our proprietary internal amplification control system included in RealCycler kits.

This technology of own development allows the use of any extraction system without loss of sensitivity, and at the same time it monitors a possible sample inhibition with high accuracy. For this reason, RealCycler Monotest, RealCycler Universal and RealCycler Chic-Out kits are compatible with almost all DNA/RNA extraction systems available in the market, without making any changes to the original protocols provided by the manufacturer.

Internal amplification control

The false negatives in the PCR-based techniques for the detection of pathogens occur when some factor prevents the generation of amplification product, regardless the presence of the pathogen in the sample. The usual cause is the presence of PCR inhibitors, that could be components of the clinical sample (hemoglobin or other proteins, mucopolysaccharides, urea, etc.) as well as components artificially added during itshandling (heparin, EDTA, proteinase K, powder from latex gloves, etc.).  Since it is an inherent feature of the samples or their processing, the inhibitions can not be detected unless specific prevention systems are used.    

The internal amplification control (IC) is a system for the detection of false negatives. It is based on the simultaneous detection of a fragment different from that of the pathogen, regardless the presence of the pathogen in the sample and therefore, it is always detected. It is made of a DNA or RNA mould, oligonucleotides, and the probe that allows its specific detection. The IC can also be used to detect problems in the DNA extraction or its absence in the amplification mix. Its use also allows the prevention of false positives due to the amplification of unspecific products. In the absence of the pathogen's DNA, the IC consumes the surplus reagent, minimizing the amplification of undesired sequences and hindering the generation of a false positive. 

The internal control CHIC is an internal control system based on our proprietary CHIC technology (Competitive Heterologous Internal Control). This technology is based on the use of heterologous DNA artificial constructions (made of combined sequences of human and microorganisms DNA) as mould for the detection of the internal control. The main feature of this technology is that the internal control amplification finds itself in a competitive disadvantage with the pathogen. In this way it does not affect the sensitivity of the method as a whole and it allows the development of highly sensitive systems. RealCycler products have this internal control system in all its editions: RealCycler Monotest, RealCycler Universal and RealCycler Chic-Out. Additionally, this technology allows the use of almost any extraction system without the loss of sensitivity and, at the same time, it monitors a possible sample inhibition with high accuracy.

CHIC features

  • Co-amplified in the reaction mix together with the detected pathogens.
  • Competitive disadvantage with the pathogen = it does not decrease the sensitivity of the pathogen detection.
  • Independent of the extraction system = almost complete compatibility with all extraction systems.  
  • It monitors inhibition with high accuracy (see examples below).

M

Negative sample
(without inhibition)

CHIC signal is detected in the HEX channel (green line) with a Ct = 31,75 (within the acceptance range: Ct CHIC < 35). The pathogen signal in the FAM channel (blue line) is flat and does not show a Ct (not detected).

NOTE: this kind of signal is observed when using water as negative control (complete absence of inhibition). In contrast, the DNA/RNA obtained from a clinical sample usually presents a certain quantity of natural inhibitors that cause a slight delay in the Ct value of CHIC, even though it usually stays within the acceptance range (see next graphic).

Negative sample
(with partial inhibition)

CHIC signal is detected in HEX channel (green line) with a Ct = 33,98 (within the acceptance range of this lot Ct CHIC < 35). Pathogen signal in the FAM channel (blue line) is flat (not detected).

NOTE: the higher Ct compared to the previous case indicates a partial inhibition of the amplification reaction. Nevertheless, the result can be accepted given that the Ct value is within the acceptance range provided by the kit..

Positive sample
(NO competition pathogen-CHIC)

Pathogen signal is detected in the FAM channel (blue line) with a Ct = 30,78. Therefore, the sample is positive regardless of the CHIC value.

NOTE: CHIC signal is detected in the HEX channel (green line) with a Ct = 31,4 (within the acceptance range). This indicates there has been no competition between CHIC and the pathogen, and suggests a low concentration of the pathogen.

Positive sample
(competition pathogen-CHIC)

The pathogen signal is detected in the FAM channel (blue line) with a Ct = 27,68. Therefore, the sample is positive regardless of the CHIC value.

NOTE: CHIC signal is detected in the channel HEX channel (green line) with a Ct = 36,38. Despite the Ct being outside the acceptance range, it does not mean inhibition but competition between the pathogen and CHIC. In this case, CHIC has been displaced because of the competitive disadvantage.

Positive sample
(competition pathogen-CHIC)

The pathogen signal is detected in the FAM channel (blue line) with a Ct = 24,55. Therefore, the sample is positive regardless of the CHIC value.

NOTE: CHIC signal in the HEX channel (green line) is flat. This indicates that there has been competition between the pathogen and CHIC, and that CHIC could not be detected because of the competitive disadvantage. The result suggests a high concentration of the pathogen.

Sample inhibited
(result NOT ACCEPTABLE)

CHIC signal detected in the FAM channel (green line) is flat as well as the pathogen signal (blue line). This indicates a total inhibition of the amplification reaction and therefore the result is not acceptable.