On January 10, when Chinese researchers published the genome of a mysterious, fast-spreading, virus, it confirmed Dan Barouch’s greatest worry. The genome was similar to that of the coronavirus that caused the 2003 SARS outbreak, yet it also had striking differences. “I realized immediately that no one would be immune to it,” says Barouch, director of virology and vaccine research at Beth Israel Deaconess Medical Center in Boston.
Within days his laboratory and dozens of others around the world started designing vaccines that they hoped could protect billions of people against the SARS-CoV-2 virus, the biggest challenge to global health and prosperity since World War II. By early April almost 80 companies and institutes in 19 countries were working on vaccines, most gene-based instead of using traditional approaches, such as those that have been employed in influenza vaccines for more than 70 years. The labs predicted that a commercial vaccine could be available for emergency or compassionate use by early 2021—incredibly fast, given that vaccines to brand-new pathogens have taken a decade to be perfected and deployed. Even the Ebola vaccine, which was fast-tracked, took five years to reach widespread trials. If Barouch and his counterparts can offer a safe, effective concoction in a year, “it will be the fastest vaccine development in history,” he says.
A conventional vaccine injected into the body inserts select pieces of a virus in cells near the injection site. The immune system recognizes molecules on these pieces, called antigens, as threats and reacts by making antibodies, molecules that can find the virus anywhere in the body and neutralize it. Once this dress rehearsal happens, the immune system remembers how to quash the invaders, so it can stop a future infection.
The established approach is to grow weakened viruses in chicken eggs—or more recently in mammalian or insect cells—and extract the desired pieces. The process can take four to six months to get the right antigens for familiar viruses that change every year, such as influenza. It can take multiple attempts over years for a new germ. That is far too slow to combat a virus that has already spread to pandemic proportions.
Instead labs are turning to gene-based vaccines. Scientists use information from the genome of the virus to create a blueprint of select antigens. The blueprint is made of DNA or RNA—molecules that hold genetic instructions. The researchers then inject the DNA or RNA into human cells. The cell’s machinery uses the instructions to make virus antigens that the immune system reacts to. Cells respond to the instructions as a normal part of their daily existence.
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