Medicago develops COVID-19 vaccine candidate using plant-based tech
Canadian biopharmaceutical company Medicago (Quebec City) has produced a virus-like particle (VLP) of the coronavirus (COVID-19) through its plant-based platform using Agrobacterium tumefaciens-mediated synthesis.
Canadian biopharmaceutical company Medicago (Quebec City) has produced a virus-like particle (VLP) of the coronavirus (COVID-19) through its plant-based platform using Agrobacterium tumefaciens-mediated synthesis. Production of the VLP is the first step in developing a vaccine for COVID-19, the company says. Once pre-clinical testing for safety and efficacy are completed, Medicago expects to discuss with the appropriate health agencies to initiate human trials of the vaccine by summer (July/August) 2020.
VLPs represent a new approach to vaccine development as they mimic the native structure of viruses, allowing them to be easily recognised by the immune system, Medicago says. Furthermore, they have the advantage that they lack core genetic material, which makes them non-infectious and unable to replicate. VLPs can be engineered to have antigens attached for use in vaccines or other immunotherapies.
Medicago is also using its technology platform to develop antibodies against SARS-CoV-2 (virus causing the COVID-19 disease) in collaboration with the Laval University’s Infectious Disease Research Centre, which is headed by Dr Gary Kobinger, who helped develop a vaccine and treatment for Ebola. These SARS-CoV-2 antibodies could potentially be used to treat people infected by the virus, the company says.
Plants as mini protein factories
Plants are highly efficient at producing proteins of varying complexity, Medicago points out. The company claims that its plant-based production platform demonstrates agility, accuracy, and speed by eliminating the risk of mutation and contamination during production, and significantly shortening production timelines.“The pace of our initial progress in COVID-19 is attributable to the capability of our plant-based platform which is able to produce vaccine and antibody solutions to counteract this global public health threat,” says the company’s chief executive officer, Dr Bruce Clark.
Genes are synthesised from the viral sequence with no live virus required. Transient expression occurs from recombinant DNA being transferred by a bacterial vector to the nucleus of plant cells without genomic integration. In the transient expression system, a culture of the bacterial vector (A tumefaciens) is forced into the leaf tissue under vacuum. Once inside the tissue, bacteria bearing the gene of interest are capable of infecting the surrounding cells and transferring the recombinant DNA (named T-DNA for transfer DNA) to the nucleus of the plant cell. Inside the nucleus, the T-DNA is eventually transcribed into proteins without being integrated in the genome.
Plants are incubated for up to 11 days in growth chambers for transient protein expression and VLP formation. Plants leaves are then harvested to extract VLPs, which are purified to obtain clinical grade active pharmaceutical ingredients, such as purified prophylactic or therapeutic proteins.
What is Coronavirus?Coronaviruses (CoV) are a large family of viruses that are common in people and many different species of animals, including camels, cattle, cats, and bats, Medicago explains. Rarely, animal coronaviruses can infect people and then spread between people such as with MERS-CoV, SARS-CoV, and the new virus named SARS-CoV-2, which is causing the “coronavirus disease 2019” (abbreviated “COVID-19”).