In 2012, they received the Santander Totta / NOVA University Scientific Merit Award for developing a rapid and cheaper test to diagnosis tuberculosis, based on gold nanoparticles. In January, Pedro Viana Baptista, of Faculdade de Ciência e Tecnologia (FCT), and Miguel Viveiros, of the IHMT, published an article showing that, using the same method, and within the same tube, it is still possible to determine if is a multidrug-resistant tuberculosis and specify that mutations cause resistance.
The study, published in the scientific journal Tuberculosis, use portuguese tuberculosis bacillus genotypes, but the diagnostic methodology can be adapted to any group of genetic resistance. Early detection of cases of multidrug-resistant tuberculosis in Portugal – something that this test is now facilitate – is urgently needed, once the Portuguese strains have unique characteristics that make them unresponsive to standard treatments recommended by the World Health Organization (WHO).
“We know that 75-80% of multiresistant strains in Portugal are the same genetic group of the strain Lisbon, which has features not shared with the rest of the world,” explains the researcher Miguel Viveiros. The strain Lisbon was first identified in IHMT and have been characterized in 1999 as part of a partnership with the Faculdade de Farmácia of Universidade de Lisboa. The reasons that lead to have a greater predisposition for resistance and focus on Portugal remain unclear. But they are under study. “We have made every effort to characterize it from a scientific point of view. We know that has some deletions in genes that make it more virulent” which justifies the non-responsiveness to the WHO standard treatment, says the bacteriologist of IHMT.
In 2011, there were 88.7 million new cases of TB worldwide, with an estimated 60,000 multi-drug resistant (19%). In the same year, in Portugal, the incidence amounted to 22.6 cases per 100 thousand habitants, with about 3% of multidrug-resistant cases, a significant decrease compared to 2000 (25-30%). It was then that the IHMT brought to Portugal early diagnosis by molecular biology and, with the support of the Gulbenkian Foundation, applied it in the Lisbon area. “Within 24 hours, it came to be known if individuals were sick and whether they were multi-drug resistant,” says Miguel Viveiros.
Economic method
With the new diagnostic technology based on gold nanoparticles, it is possible to get the same diagnosis less expensively and with an easy technical realization. “The big advantage of this approach is to allow sensitivities higher than the standard molecular techniques (PCR) but simply and at low cost,” says Pedro Baptista.
The first historical record of the use of gold nanoparticles dates back to 400 a.C. when the Romans created the Lycurgus cup, a bronze decorative piece with a metal alloy, and whose glass was impregnated with small gold crystals. Depending on the sunlight changes color – from red to green. The same technique was later used to produce stained in churches, using microcrystals of silver or gold.
Pedro Baptista was working with a nanoprobes system using this technology for the detection of nucleic acids, and decided to apply it to a relevant target “medically and simultaneously needed for early detection, inexpensive and specifically and with high sensitivity,” as tuberculosis.
The technique continued to be enhanced by the FCT team to “increase the complexity sequences to detect”, allowing now also identify resistance to drugs used to fight tuberculosis, says Pedro Batista. Miguel Viveiros explains that “in practice, we took the nanoparticles that are functionalized with sequences that identify the tuberculosis bacillus and the resistance of the bacillus. If, in the patient sample, there is bacillus or its DNA, these targets interact with the particles. If there is no interaction, the solution changes color to blue due to aggregation of the nanoparticles. ”
Make this technology available in pulmonology diagnostic centers could represent an important contribution to the bacteriological and medical examination of a suspected tuberculosis. “Since the Prize [Santander Totta / Universidade Nova de Lisboa] to date, our perspective has always been to put our technology available to those who can use”, in particular extend it to the network of CPLP laboratories, reinforces the IHMT investigator.
For this, the researchers waiting in the expectation that some biotech company be interested in the application of this test and develop a commercial product.
The future will pass to “simplify the process of sampling and sample processing to obtain the DNA in sufficient quantity to be analyzed,” says Pedro Baptista, noting that this may entail the development of a kit that encompasses all these steps. In this sense, we have already applied this method to a paper platform, which allows us to receive the results in a paper strip, becoming “even more simple and inexpensive diagnostic test”, a task carried out in collaboration with the Centre for Research in Materials and FCT group led by Elvira Fortunato.
They are also co-authors of the study Gold nanoprobes for multi loci assessment of multi-drug resistant tuberculosis Pedro Pedrosa and Bruno Veigas, FCT, and Isabel Couto and Diana Machado, IHMT.
