The CDIATM Anatoxin-a Colloidal Gold Test Strip (Drinking and Recreational Waters) is an immunochromatographic test for the detection of Anatoxin-a in drinking and recreational waters.
The test is based on the recognition of Anatoxin-a by specific antibodies. The toxin conjugate competes for antibody binding sites with Anatoxin-a that may be present in the water sample. The test device consists of a vial containing specific antibodies for Anatoxin-a labeled with a gold colloid and a membrane strip to which a conjugate of the toxin is attached. A control line, produced by a different antibody/antigen reaction, is also present on the membrane strip. The control line is not influenced by the presence or absence of Anatoxin-a in the water sample and, therefore, should be present in all reactions. In the absence of toxin in the water sample, the colloidal gold labeled antibody complex moves with the water sample by capillary action to contact the immobilized Anatoxin-a conjugate. An antibody-antigen reaction occurs forming a visible line in the test area. The formation of two visible lines of similar intensity indicates a negative test result, meaning the test did not detect the toxin at or above the cut-off point established for the toxin. If Anatoxin-a is present in the water sample, it competes with the immobilized toxin conjugate in the test area for the antibody binding sites on the colloidal gold labeled complex. If a sufficient amount of toxin is present, it will fill all of the available binding sites, thus preventing attachment of the labeled antibody to the toxin conjugate, therefore preventing the development of a colored line. If a colored line is not visible in the test line region, or if the test line is lighter than the control line, Anatoxin-a is present at a level of concern. Semiquantitative results can be obtained by comparing the sample test strip appearance to the appearance of test strips from solutions of known Anatoxin-a concentrations (control solutions). Concentrated Anatoxin-a standards can be used to prepare Anatoxin-a controls.
Anatoxin-a is an alkaloid neurotoxin produced by some species of cyanobacteria (blue-green algae). It is one of the most toxic of the cyanobacterial toxins. In humans and other animals, the skeletal neuromuscular junction constitutes a primary target for Anatoxin-a (Anatoxin-a can also cross the blood-brain barrier). The neuromuscular junction is specialized for the rapid transmission of neuronal information from the pre-synaptic nerve terminal to the post-synaptic muscle fiber. This transmission is mediated by the synchronous release of the neurotransmitter acetylcholine (ACh), which activates nicotinic acetylcholine receptors (nAChRs) in the muscle endplate, triggering a series of events that lead to muscle contraction. Most ACh molecules are hydrolyzed by acetylcholinesterases, which are highly concentrated at the neuromuscular junction. Anatoxin-a functions as an agonist of nAChRs, like ACh, but is about 20 times more potent. Unlike ACh, it is not degraded by acetylcholinesterases and produces sustained depolarization of the muscle endplate, causing overstimulation of the muscles, leading to muscle fatigue and ultimately paralysis. Symptoms begin within 5 minutes of ingestion of Anatoxin-a and progress rapidly, resulting in cyanosis, convulsions, cardiac arrhythmia, and respiratory paralysis, which ultimately results in death due to suffocation.
Humans and other animals may be exposed to Anatoxin-a through ingestion of contaminated water, through drinking or during recreational activities in which water is swallowed. Due to the potential for serious harm and even death, many countries are expanding monitoring programs to include Anatoxin-a and are establishing regulations regarding the amount of Anatoxin-a in drinking and recreational waters. New Zealand is among those taking regulatory action, establishing a 6.0 μg/L provisional maximum acceptable value (MAV) for Anatoxin-a, and the U.S. Environmental Protection Agency (EPA) will be announcing drinking and recreational water health advisories.
The CDIATM Anatoxin-aColloidal Gold Test Strip (Drinking and Recreational Waters) is a rapid immunochromatographic test, designed solely for use in the qualitative screening of Anatoxin-a in fresh water. The CDIATM Anatoxin-a Colloidal Gold Test Strip (Drinking and Recreational Waters) provides only preliminary qualitative test results. If necessary, positive samples can be confirmed by ELISA, HPLC or other conventional methods.