Researchers in Massachusetts have developed a rapid technique to detect disease-causing DNA in the field, without the need for sophisticated and expensive PCR equipment. They say the inexpensive method could help detect neglected tropical diseases, such as river blindness.
The technique, developed at New England BioLabs (NEB), Inc. (Ipswich, MA), works by removing the buffer normally used in PCR testing and adding a robust enzyme to a sample, be it blood, serum, or human skin. The reaction produces multiple protons, changing pH levels dramatically to indicate large quantities of amplified DNA made visible by traditional dyes, according to the researchers. An article on their research appeared in the journal BioTechniques in February.
Researchers at NEB’s DNA enzymes division, led by scientific director Tom Evans, PhD, prefer the loop-mediated isothermal amplification (LAMP) method for this testing. LAMP requires no thermocycler (PCR machine or DNA amplifier), provides rapid DNA amplification, and tolerates inhibitors found in dirty samples more likely to be collected in the field, according to Clotilde Carlow, PhD, scientific director of the division of genome biology at NEB. Tanner described the thermophilic bacteria that NEB cloned about 30 years ago as “a biotechnology workhorse enzyme” that works well at tropical temperatures and in LAMP testing.
The technique may be used on samples from humans, animals, and insects, according to Carlow. A graduate of the London School of Hygiene and Tropical Medicine, Carlow and others on Evans’s team are working with scientists from Cameroon and Ghana to detect several forms of filariasis, including onchocerciasis, or river blindness, which is caused by insects transmitting parasitic worms to humans.
Such field tests would allow healthcare workers to collect information to determine where such diseases are being transmitted, Carlow says. Although developed to work in tropical conditions, the test could also detect Lyme disease in ticks in more temperate climates, she added.
NEB probably will not develop a kit to test for a particular disease, according to Nathan Tanner, staff scientist in NEB’s DNA enzymes division. (Tanner appears in a video describing the testing method.)
Evans’s team plans to continue developing the technology, publish its results, and collaborate with institutes and scientists in countries where these diseases are prevalent. Its goal is to train individuals to perform the tests and work with local governments to transfer the technology, Tanner explains. The team has been working on this method for about two years.
“The idea is to be able to have a test that you can accurately perform in the field, not in a laboratory … and get a result very quickly,” Carlow says, “a result that’s easy to read and simple to interpret, and be able to make a decision right then and there as to what you want to do next.”
Does NEB hope to displace PCR testing? Evans’s team is not saying, but the study authors filed a U.S. patent application describing their method two years ago and followed with a full patent application a year ago, according to Tanner.
“We didn’t discover the fact that DNA polymerases can change pH,” Tanner says. “We’re just using it in a new way.”
“Our goal is not to make money,” Carlow adds. “It’s to get the science out there, to make it easy, affordable, and to help control these nasty diseases.”
Other scientists are also eagerly studying isothermal amplification, Carlow says.
“This type of a test has a very specific niche. It’s very adaptable, so it can detect more than one type of disease,” she says. “We’re hoping to transfer this technology to monitor and diagnose all different kinds of infections.”
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Nancy Crotti is a freelance contributor to MD+DI.
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