The DuPont™ BAX® System uses PCR technology to amplify
(replicate) specific fragments of bacterial DNA, which are stable
and unaffected by growth environment. These fragments are genetic
sequences that are unique to the targeted organism.
In a typical application, sample DNA is combined with DNA
polymerase, nucleotides and primers. Primers are specific for a given
nucleotide sequence and determine the specificity of
the reaction.
This mixture then undergoes a series of timed heating and cooling
cycles. Heating denatures the DNA, separating it into single strands.
As the mixture cools, the primers recognize and anneal (bind) to the
targeted DNA sequence. The polymerase then uses the nucleotides
to extend the primers, thus creating two copies of the fragment
(amplification). Repeating the cycle of denaturing, annealing and
extending produces an exponential increase in the number of target
DNA fragments, creating millions of copies in a very short time.
If the target sequence is not present, no detectable amplification
takes place.
If the target sequence is present, the BAX® System detects amplified
fragments by measuring fluorescent signal, either through probes in
real-time or through intercalating dye in a subsequent phase. See next
section for details on detection.