Hepatitis A found to cloak in membranes stolen from infected cells
"The whole universe of virology is divided into two types of viruses -- viruses that are enveloped and viruses that are not enveloped," Stanley M. Lemon, professor of medicine at UNC Lineberger and member of the Center for Translational Immunology, said. "If you look at any basic virology textbook, it will say that these are categories that distinguish all viruses."
Hepatitis A was found to not have an envelope in the environment, but takes one from the cells it grows in within an organism's liver. It will then circulate in the blood and be cloaked in these membranes.
"What we have discovered is that a virus that has been classically considered to be 'non-enveloped', that is hepatitis A virus, actually hijacks membranes from the cells it grows in to wrap itself in an envelope," Lemon said. "And that's really novel. No one has shown that previously for a virus. It really blurs that classic distinction between these two types of viruses."
Being enveloped helps Hepatitis A avoid immune systems and spread in the liver. Because Hepatitis A takes on both qualities of viruses, it takes advantage of being able to avoid immune systems and live longer outside a host.
This has made researchers ponder why the vaccine for Hepatitis A works as well as it does. With their new findings, they now know the vaccine does not work the way they previously thought it did.
"It makes us rethink completely the mechanism underlying the well-documented efficacy of hepatitis A vaccine," Lemon said. "I think this is one of the most important things to come out of the study."