Bioluminescent enzyme produced by firefly can be used to detect novel coronavirus

Brazilian researchers coupled the molecule with a protein that binds to SARS-CoV-2. The presence of antibodies against the virus in the sample is confirmed by light emission.

By José Tadeu Arantes  |  Agência FAPESP – By combining an enzyme found in fireflies with a protein that binds to the novel coronavirus, the pathogen that causes COVID-19, researchers at the Federal University of São Carlos (UFSCar) in Brazil have developed an innovative strategy to detect antibodies against virus in biological samples.

The enzyme used in the research belongs to the class of luciferases, which catalyze reactions that convert chemical energy into light energy, a phenomenon commonly referred to as bioluminescence. The firefly Amydetes vivianii produces one of the known luciferases with the brightest and most stable bioluminescence.

The insect is found on UFSCar’s Sorocaba campus and is named for Professor Vadim Viviani, who discovered the species and cloned in bacteria the DNA that encodes its luciferase. He also investigated the enzyme’s molecular structure and functions.

“We took our brightest luciferase and used genetic engineering to couple it with a protein that binds to antibodies. If antibodies against SARS-CoV-2 are present in a sample, the reaction will take place and can be detected via the emission of light,” Viviani told Agência FAPESP.

The same technology can detect proteins specific to SARS-CoV-2, evidencing infection, in the presence of specific antibodies.

The study was completed in less than a year, in step with the speed that has characterized research focusing on the pandemic. It was supported by funding awarded by FAPESP to the Thematic Project “Arthropod bioluminescence: biological diversity in Brazilian biomes, biochemical origin, structural/functional evolution of luciferases, molecular differentiation of lanterns, biotechnological, environmental and educational applications”.

Patent application filed

Viviani has filed an application for a patent on the novel bioluminescent system with INPI, the Brazilian patent office. The study is so recent that he and his group are still writing it up for publication in a scientific journal. “We’ve successfully tested the method for various antibodies, which can be detected using techniques such as western blotting or immunoblotting,” he said. 

“In immunoblotting, antigen samples are immobilized on a surface and treated with materials such as blood serum from a patient. If the material contains the antibody, it binds to the antigen, forming an antigen-antibody complex that’s revealed by a secondary antibody, usually marked with a protein that generates a fluorescent or chemiluminescent signal. In our study, the marked secondary antibody is a protein with a strong affinity for antibodies, coupled with the luciferase, which generates bioluminescence.”

Immunoblotting or western blotting is a laboratory method used to detect specific protein molecules from among a mixture of proteins in a sample of biological tissues or extracts. The method separates proteins by electrophoresis, a technique that promotes ion migration in an electric field so that they can be separated according to size and charge. 

The study was conducted at UFSCar’s Biochemistry and Bioluminescent Technology Laboratory, with Paulo Lee Ho, a researcher at Butantan Institute, collaborating.

The next step is to find out whether the amount of antibodies present in saliva or nasal swab samples is sufficient to trigger bioluminescence, enabling the biosensor to be used in a rapid non-invasive COVID-19 diagnostic test.

“To move on with this second stage of the research, we’re working with Heidge Fukumasu, a researcher at the University of São Paulo [USP]. Another avenue will involve the use of nanotechnology to develop immunoassays in collaboration with Professor Iseli Nantes and her group at the Federal University of the ABC [UFABC],” Viviani said.

“This study is an example of the many benefits a small firefly species can offer society. An example of how the biodiversity of our forests and science, both so severely endangered, can join forces to produce innovative solutions and add economic and social value to a developing country like Brazil.”