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Fiocruz Pernambuco develops test for Zika diagnosis


Solange Argenta (Fiocruz Pernambuco)


A new technique to detect the Zika virus, which is more sensitive and cheaper than real-time PCR (the gold standard used today for the molecular diagnosis of the disease), proved to be efficient in tests with mosquito samples. Developed in a Master's Degree in Biosciences and Biotechnology in Health by the student Severino Jefferson, under the guidance of researcher Lindomar Pena, with researchers from Fiocruz Pernambuco Constância Ayres and Fábio Melo also taking part along with other professionals from the departments of Virology, Entomology and Parasitology of the institution. Entitled Development and Validation of Reverse Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) for Rapid Detection of ZIKV in Mosquito Samples from Brazil, the study was published on March 14 in the journal Nature - Scientific Reports.

This technology, called Reverse Transcription Loop-Mediated Isothermal Amplification (RT-Lamp), also has the advantage of being much faster than PCR, decreasing the 5 hour wait to get the results to less than 1 hour. This tool can be used anywhere, as a quick kit, since it does not rely on expensive and sophisticated equipment, restricted to specialized laboratories, such as PCR. Another advantage is the cost to perform each test, only R$1. Forty times cheaper than the PCR, which has an unit cost of R$40.

Lindomar Pena explains that the technique proved to be 10,000 times more sensitive than PCR and, in some cases, was able to detect a viral load where the PCR was negative."This is a specific examination for Zika, which did not show a cross reaction to other arboviruses”, he said.

A total of 60 samples of Aedes aegypti and Culex quinquefasciatus mosquitoes, naturally infected or in the laboratory with the Zika, Dengue, Yellow Fever and Chikungunya Virus, were used in the research. The next step will be the completion of testing with human samples.

When the project was launched, there was no similar studies. However, while it was being developed, around 15 projects in this field started. The difference this study of Fiocruz Pernambuco has to offer is the small number of steps required for the reaction, the low cost and simplicity of the test.

In its simplified form, the test consists of macerating a mosquito sample and placing it in a tube with the reagent. After waiting for around 20 to 40 minutes, you just need to note the color of the mixture. If it turns orange, it is negative, but if the liquid turns yellow, it indicates the presence of the Zika virus. "The idea is that you can collect, macerate mosquitos in the field - in the middle of the Amazon, for example - and get the result there and then”, says the researcher. With humans, you can collect saliva or urine from the patient with suspected Zika, perform the test and get a response at the same time.

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