Test can detect swine flu in minutes, claims scientist
[RIO DE JANEIRO] A test that uses nanotechnology to detect and diagnose infectious diseases rapidly is likely to be cheaper and quicker than established tests for diagnosing swine flu (influenza A(H1N1), says its inventor.
The ELINOR (Enhanced Luminescence of Inorganic-Organic Origin) test, developed by Brazilian researchers from the Physics Department of the Federal University of Pernambuco, uses fluorescence to detect specific viruses in patient samples.
The test relies on a fluorescent material, made up of metal nanoparticles and a polymer, attached to a 'primer' — a segment of DNA or RNA that matches a specific part of the pathogen's genetic material. A fluorescence microscope can then detect even a tiny amount of the virus.
In unpublished work, the researchers have successfully detected both dengue and human papillomavirus.
The diagnostic technique is more sensitive and a lot faster than polymerase chain reaction (PCR) — the method currently used to amplify a stretch of the virus' genetic material so there is enough present for it to be detected, according to Celso Pinto de Melo, coordinator of the research. PCR can take 72 hours but the ELINOR takes less than five minutes, he says.
"Our test does not require the amplification step of the genetic material — which is expensive — since the nanocomposite that we add to an infected sample is enough to generate an intense luminescence that can easily be seen through a fluorescence microscope," says Melo.
The ELINOR test has not, however, been used to diagnose A(H1N1), as Melo's team says it has been unable to access virus samples. He blames Brazilian bureaucracy for this set-back.
Melo says the Ministry of Health has told him that he needs to ask his Pernambuco state for samples. But the state says he must ask the Ministry of Health in Brasilia, he says.
When contacted by SciDev.Net, however, Reinaldo Guimarães, secretary of Science, Technology and Strategic Inputs at the Ministry of Health, said he would intervene.
"If he [Melo] is not able to obtain the samples in Pernambuco, we will try to get them in Rio de Janeiro and I am personally helping him," Guimarães said.
If Melo can prove the ELINOR test can detect A(H1N1) and distinguish it from seasonal flu, clinical trials will be required before the National Agency of Health Vigilance can authorise the test for general use.
Michael Jones, a senior lecturer in the division of investigative science at Imperial College London, United Kingdom, says that using a fluorescence microscope to directly detect the presence of a pathogen is potentially exciting.
But he questions whether the test will really take five minutes once sample preparation is factored in and points out that PCR can process many samples simultaneously.
The success of the test will depend on its sensitivity, he says. PCR can amplify DNA from a single cell and while this is not necessary for diagnosis, a certain threshold of sensitivity will be required. "If it could detect 100 molecules in five minutes that would be great."
Cost is another issue, Jones adds. Producing the nanocomposite will have some cost attached and fluorescence microscopes — which cost around the same as a PCR machine — are only available in pathology laboratories.
"If it really is from a sample coming in to a lab and getting a result within an hour then that really is very, very good — but what's the cost going to be?"