Although PCR is usually associated with thermal cycling, the original patent by Mullis et al. [2] disclosed the use of a helicase as a means for denaturation of double stranded DNA thereby including isothermal nucleic acid amplification.
Thus, a simultaneous chain reaction develops, resulting in exponential amplification of the selected target sequence (see Vincent et al.., 2004[4] for a schematic diagram).
[6] The advantages of HDA is that it provides a rapid method of nucleic acid amplification of a specific target at an isothermic temperature that does not require a thermal cycler.
Normally primer and buffer optimisation is tested and achieved through PCR, raising the question of the need to spend extra on a separate system to do the actual amplification.
Despite the selling point that HDA negates the use of a thermal cycler and therefore allows research to be conducted in the field, much of the work required to detect potentially hazardous microorganisms is carried out in a research/hospital lab setting regardless.