The first in a series of short essays act as “signposts” to highlight historical research on prior responses to rapidly spreading disease among populations. Exploring the world’s previous experience with epidemics and pandemics, these posts aim to help a general audience learn how past responses offer enduring lessons for the future.

Most coronaviruses invade cells much like other viruses, such as influenza, which merges its envelopes with the surface of unsuspecting cells to release genomes into the cell. Once inside, the viral genome is replicated and forms an army of new viruses. The newly formed influenza viruses assemble and bud from the cell surface, ready to invade other cells. However, coronaviruses take a different route of assembly and escape from their host cell. They use the pancakelike structure in cells, called the Golgi complex — a kind of post office for the cell that sorts and processes proteins and spits them out of the cell after enclosing the proteins in a compartment called a vesicle. Cell biologist Carolyn Machamer, Ph.D., has been studying how coronaviruses assemble in the Golgi body and then stow away in vesicles to be shipped outside of the cell.

This image reveals how tumor cells produce antigens that are captured by the immune system. Dendritic cells process these antigens and present them to the body's T cells, activating them. Once this process happens, the T cells multiply and locate the tumor, releasing factors to kill it.

Johns Hopkins clinical microbiologists Karen Carroll, M.D., and Heba Mostafa, Ph.D., M.B.B.Ch., have developed an in-house coronavirus screening test that may soon allow the health system to test as many as 1,000 people per day.

Alexandre White, Ph.D., examines the social effects of infectious epidemic outbreaks in both historical and contemporary settings, as well as the global mechanisms that produce responses to outbreak. A faculty member in the departments of history of medicine and sociology, White offers his perspective on the global response to the COVID-19 pandemic and the lessons we can learn from historic outbreaks.

How do you make a better stem cell? One that can repair damaged tissue? Researchers at Johns Hopkins bathed adult human cells in a cocktail of nutrients and chemicals that dial back the biological hands of time to a state when cells are the most “naive,” or capable of developing into any specialized cell. In this image, green-dyed naive stem cells are working to repair blood vessels (red) in the retina of a mouse bred to have diabetic retinopathy.

Ada Hamosh and Nara Sobreira have dedicated their careers to finding the genetic culprits of rare conditions. Over the years, finding answers for people with some of the most perplexing genetic conditions has tested these leading scientists’ resolve, but their combined ingenuity and experience has paid off with answers for hundreds of families. To help move the field forward, they developed an online tool that is used around the globe to speed the discovery process and connect the work of genetic investigators.

Neuroscience doctorate student Emily Han reflects on her experience as a female scientist and shares seven lessons learned from Johns Hopkins biophysicist Karen Fleming at the Gender Equity in Science at Hopkins workshop.

This 3D rendering of a eukaryotic cell is modeled using data from X-ray, nuclear magnetic resonance and cryo-electron microscopy. The photo is part of a series that appears in the “Images from Science 3” exhibition, which is currently showing in the Turner Concourse at the Johns Hopkins East Baltimore medical campus through March 20. The exhibit is open to the public.