Laying the groundwork

In December 2019, Merck received FDA approval for the Ebola vaccine trademarked Ervebo. Merck had distributed this vaccine for free in the Democratic Republic of the Congo over the last year and a half. The vaccine is based on a viral vector developed in the lab of John Rose, PhD, professor emeritus of pathology and senior research scientist in the Department of Pathology during an eight-year period in the 1990s. Rose is currently the director of Yale’s Molecular Virology Program. The Ebola vaccine based on Rose’s research has proven to be close to 100% effective in preventing Ebola infection.

“It’s incredibly rewarding to know that one’s efforts have made a tangible difference in the world,” said Rose. “Merck has provided the vaccine for free to over 250,000 people.”

Rose said that the project started out as a method to develop a general vaccine platform for viruses and other pathogens. His lab’s work with this vaccine system focused initially on multiple viruses including HIV, a notoriously tricky and mutable foe. His laboratory also distributed the viral genetic system to over 100 other labs, including the one that eventually developed the Ebola vaccine.

The method relies on genetic engineering of a relatively benign animal virus called vesicular stomatitis virus (VSV) to express protein antigens from dangerous viruses or other pathogens. This system can be used to generate vaccines against multiple threats. For example, it can even protect against plague caused by the Yersinia pestis bacterium.

It can also protect against coronaviruses. Rose and colleagues published a paper in 2005 demonstrating a VSV-based vaccine that protects against SARS coronavirus in the wake of the SARS outbreak.

“A VSV vector worked for SARS, so almost certainly will for other coronaviruses like the 2019-nCoV,” wrote Rose via email. “The recombinant vaccine could be made in a week, but approval for use could take years. SARS was contained through public health measures, long before a vaccine could be tested and approved.”

While the legal mechanisms by which different vaccines are tested and approved for use are endeavors in their own right apart from research, the news is good: if the current outbreak of coronavirus were to intensify dangerously, researchers would have little difficulty in creating vaccines.

Vaccines for HIV and Zika using the VSV platform are still under development, but show great promise. And Rose is happy his team had an opportunity to work on a project of lasting importance. “The researchers who worked on this project are spread to the four winds, and many have their own labs now,” he said. “Knowing that we’ve made a significant contribution to humankind in terms of understanding how viruses work, and offering ways to combat them, is a very good feeling.”