An infectious cDNA clone of SARS-CoV-2

An infectious cDNA clone of SARS-CoV-2


A multidisciplinary team working to combat the COVID-19 virus has a system that will unlock researchers' ability to more quickly develop and evaluate developing vaccines, diagnose infected patients and explore whether or how the virus has evolved.

The scientists developed the system by engineering a reverse genetic system for SARS coronavirus 2, or SARS-CoV-2, that is causing the current COVID-19 pandemic. The study is currently available in Cell Host & Microbe.

A Reverse genetic system is one of the most useful tools for studying and combatting viruses. The system allows researchers to make the virus in the lab and manipulate it in a petri dish.

Seven cDNA fragments spanning the SARS-CoV-2 genome were assembled into a full-genome cDNA. RNA transcribed from the full-genome cDNA was highly infectious after electroporation into cells, producing 2.9×106 PFU/ml of virus. Compared with a clinical isolate, the infectious clone-derived SARS-CoV-2 (icSARS-CoV-2) exhibited similar plaque morphology, viral RNA profile, and replication kinetics. Additionally, icSARS-CoV-2 retained engineered molecular markers and did not acquire other mutations. 

Using this system, the team has engineered a version of the SARS-CoV-2 virus that is labeled with neon green. When the labeled virus infects a cell, the infected cell turns green.

"The labeled virus could be used to rapidly determine whether a patient has already been infected by the new coronavirus or evaluate how well developing vaccines are inducing antibodies that block infection of the virus. The level of antibodies induced by a vaccine is the most important parameter in predicting how well a vaccine works," said the senior author. "The neon green labeled virus system allows us to test patients' samples in 12 hours in a high-throughput manner that tests many samples at once. In contrast, the conventional method can only test a few specimens at a time with a long turnaround time of a week."

"This technology can significantly reduce how long it takes to evaluate developing vaccines and ultimately bring them to the market," said the lead author.

"The genetic system allows us to study the evolution of the new coronavirus. This will help us to understand how the virus jumped from its original host bat species to humans. It remains to be determined if an intermediate host is required for the host switch from the original bats to humans for the new coronavirus," said a co-senior-author of the study. "The system has provided a critical tool for the research community."


https://www.utmb.edu/newsroom/article12413.aspx

http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Fan-infectious-cdna_2&filter=22

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