Nucleic Acid Analyzer (HANAA)
█ AGNIESZKA LICHANSKA
HANAA is an acronym for the hand-held advanced nucleic acid analyzer. It was developed by the Lawrence Livermore National Laboratory in 1999 based on a previous model of the nucleic acid analyzer ANAA produced in 1997. HANAA is a real time polymerase chain reaction (PCR) based system for detecting pathogens (diseasecausing organisms). It is highly sensitive as it can detect 200 organisms per milliliter. Although a number of rapid real time PCR instruments were constructed, HANAA is the first hand-held device allowing easy testing of samples directly in the field, and was employed by the United Nations inspectors in Iraq during their 2003 searches for biological weapons.
Technology behind HANAA
The instrument takes advantage of real time PCR technology that was developed in recent years. PCR amplification of DNA requires repetitive sample heating (to approximately 95°C (or 203°F) and cooling to a lower temperature specific for the sample (usually 50–72°C, or 122–161°F). Traditional instruments require two to three hours to complete a PCR run and additional time to run the products on a gel to detect positive samples. New real-time PCR instruments have heating and cooling systems allowing a reduction of the running time to less than 30 minutes. The same instruments also allow observation of product formation during the run. This is achieved by incorporation of fluorescent detection methods to visualize product formation.
The main part of the instrument is a sample module containing a miniaturized silicon thermal cycle of high heating and cooling efficiency. These small thermal units are a major breakthrough in technology as they can be efficiently supported by batteries. In comparison, most of the existing real-time systems are comparatively larger and heavier and cannot be operated in the field with ease, despite the similarly good technology for detection or time of analysis. HANAA also has an advantage over its predecessor ANAA, which was as big as a small suitcase. HANAA fits into a palm and weighs just under one kilogram (around two pounds). It can operate 1.4 to 5.5 hours depending on the battery used. A run on the instrument is approximately 7–20 minutes depending on the program used for detection.
The PCR process used by HANAA is based on using TaqMan-type probes, which rely on a short DNA oligonucleotide being labeled by two fluorescent molecules, a quencher and a reporter. When a probe anneals to DNA, there is no signal as the short distance between the quencher and the reporter results in the reporter's fluorescence being quenched. However, during amplification, the reporter molecule is released and an increase in fluorescence is observed.
HANAA has four chambers for analysis and can perform two independent identifications in each chamber, therefore it is able to test for up to eight pathogens at one time. Each of the sample units can be run independently, which makes the instrument highly flexible in use. The unit is operated by a keypad, with all the menu options and results displayed on a LCD (liquid crystal display) screen as text or bar charts. A positive sample is announced by an audible alarm.
The instrument and technology are still dependent on the quality of the sample and lack of any possible PCR inhibitors in the sample. However, sample preparation is relatively simple. A template for PCR is prepared by placing sample in a liquid buffer in a small (0.020 ml) test tube and reagents are added directly to the same tube.
Potential uses for HANAA are in the areas of pathogen detection, military or counter-terrorist applications by army and police, identification of genetically modified organisms (Department of Agriculture), and diagnostic at the first point of contact, especially in a case of bioterrorist attack. The main advantage of the instrument is the ease of operation, coupled with the short training time (just a one-day session is required).
█ FURTHER READING:
Lawrence Livermore National Laboratories. "Chemical and Biological Detection Technologies." < http://www.llnl.gov/nai/rdiv/chbio.html > (15 January 2003).
Ronald Koopman et al. HANAA: Putting DNA Identification in the Hands of First Responder. < http://coffee.phys.unm.edu/BTR/2001%20Conference/pdf/Koopman_Ronald.pdf > (15 January 2003).