How a retrovirus, like HIV, reproduces and assembles new viruses is different than previously thought, according to researchers.
The team studied a chicken virus called Rous sarcoma virus that causes cancer in chickens and is similar to HIV.
“The question is, how do retroviruses build new virus particles?” asks Leslie Parent, professor of infectious diseases, department of medicine at Penn State. “There are no inhibitors of HIV assembly in clinical use. If we can determine how retroviruses are built, we can help stop the spread of infection through the creation of new drugs.”
The start of the replication process is the production by the retrovirus of a protein called Gag. Prior to this study, it was thought the building process happened outside the nucleus in the cyctoplasm—the material that fills the cell—and then Gag protein was sent to the plasma membrane—the outer boundary of the cell.
The researchers discovered, however, that Rous sarcoma virus takes a detour through the cell nucleus before going to the cell membrane.
The Gag protein has a signal, which tells a receptor to take it into the nucleus. Once in the nucleus, Gag binds to the viral RNA. The viral RNA alters the structure of the protein, changing the way it folds. This new configuration triggers a different signal that allows the Gag to move out of the nucleus.