A group of researchers has successfully cloned the novel coronavirus genome using brewer's yeast. The paper on their study was published on Nature on May 4. One edge their approach has to duplicate the virus' genome is that it's a way faster method than other traditional means.
According to Susan Weiss of the University of Pennsylvania Perelman School of Medicine, the other methods are dreary and arduous, whereas, with the use of yeast, things could be sped up faster and more stable.
Darwyn Kobasa from the University of Manitoba praised the study and their use of yeast, saying that the method was impressive and was promising. He added that during outbreaks of a novel virus, speed is indeed crucial.
Usually, when trying to come up with vaccines and treatments for disease-causing viruses, the first approach scientists would take is to reconstruct and modify the genomes of the said pathogen. Manipulations to the genetic make-up of the microbe are vital for learning more about the disease. A lot can be learned about the virus's mode of infection, replication, potential vaccines, as well as treatment.
A co-author of the study, Volker Thiel from the University of Bern, says that the idea is to find out more about the virus. He and his team, just like all the other scientists racing to contribute to the pandemic's cure, work in a high-containment facility with strict safety protocols designed to protect researchers as well as prevent accidental contamination of the virus.
Advantage of Using Yeast
The traditional way of cloning viral genomes involves stitching chunks of DNA together and introducing them to the bacteria, E. coli, for replication. This approach, however, doesn't work on all viruses.
In the case of the coronavirus, which has huge genomes, it could make is especially hard for the bacteria to handle. Additionally, parts of the SARS-CoV-2's genome is unstable and could be toxic to the E. coli.
This is where the yeast comes in handy. Since yeast cells are more prominent than bacterial cells, they can contend larger pieces of DNA. Another significant advantage of using yeast, according to Joerg Jores, another co-author of the study, is that yeast cells can assemble fragments of DNA into a single, big molecule.
So, instead of having to reconstruct the virus' DNA first before instituting it into cells, it would be possible to put all the fragments in the yeast, and it would just marvelously put them all together by itself, according to Weiss.
This natural fragment assembly is at the heart of the cloning method earlier used by the team called transformation associated recombination. (TAR)
In the study, the researchers were able to form a yeast artificial chromosome by performing a gluing process called homologous recombination. The method involved cutting away nucleotides at the end of a strand of DNA and strengthening the remaining sequences to another fragment.
The team introduced the fragments into Saccharomyces cerevisiae, which is commonly known as brewer's yeast. They chose and tested colonies for the presence of the entire genome two days later.
In vitro transcription of the DNA collected from the clones later produced RNA, which the utilized to infect cultured mammalian cells. The team also cloned a version of SARS-CoV-2 encrypting a fluorescent reporter for high-throughput drug screens.
The researchers used the TAR technique to reproduce a variety of other viruses such as MERS and Zika. However, they said that their focus at the moment is not surprisingly, the novel coronavirus.
