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Posted 30 October 2013. PMN Crop News.


Agdia Commercializes Rapid Molecular Test for Candidatus Liberibacter Asiaticus (HLB)


Source: Agdia Press Release. www.agdia.com


Elkhart, Indiana (October 18, 2013)--Agdia announces the commercialization of a rapid nucleic acid test for detection of Candidatus Liberibacter asiaticus (Las), a bacterium that causes citrus greening disease (also known as Huanglongbing or HLB) in citrus crops.

 

Citrus greening is one of the most devastating diseases to citrus crops around the world. The bacterium that causes the disease is spread by the Asian citrus psyllid (ACP). Symptoms can include misshapen and / or bitter tasting fruit, as well as fruit drop. Trees that are infected with Las can suffer from reduced fruit quality and yield. The economic impact of the disease is enormous. One study suggests that from 2006 - 2011 the State of Florida has lost $3.63 billion in revenues and 6,611 jobs as a result of citrus greening and its negative impact on orange juice production. That study can be found at edis.ifas.ufl.edu/fe903.

Until now, testing for this pathogen could only be completed using Polymerase Chain Reaction (PCR) which requires samples to be sent to a central laboratory capable of completing the analysis. PCR is a very sensitive and specific DNA testing method, but it must be completed by highly skilled technicians and requires the use of expensive thermal cycling equipment as well as DNA extraction kits.

Agdia's test, AmplifyRP Acceler8, is based on recombinase polymerase amplification (RPA) technology. It enables ultra-rapid amplification of target DNA at a single operating temperature with sensitivity comparable to that of PCR. In contrast to PCR, AmplifyRP Acceler8 does not require DNA purifications, expensive equipment, or highly trained technicians. The entire testing process can be completed in about 30 minutes using a crude extract and a portable heat block.

To use the test, a sample is placed inside an extraction bag along with an extraction buffer. The user then rubs the outside of the bag with a blunt object, such as a pen cap, to extract the sample. Following this step, a small volume of the extract is transferred to a reaction tube which contains all of the amplification reagents. Once the sample has been added, the tube is closed and heated inside a small portable heat block for 20 minutes. The entire tube is then added to an amplicon detection chamber (pictured) which contains a lateral flow strip. If the target DNA is present, two lines will appear on the strip indicating a positive result. A negative result would be indicated by only one line being present.

AmplifyRP Acceler8 kits for Las are available for purchase from Agdia immediately. A starter pack, which includes the portable heat block and some dispensing equipment, is required for first time users at a cost of only $300.