Scientists have cracked the code that a major group of viruses uses to efficiently piece themselves together during infection. After discovering and deciphering the code, which consists of a series of signals hidden within the virus’ genome, the researchers demonstrated that disrupting them prevents the virus from being able to assemble new and infectious copies properly. According to the researchers, this suggests that in the future it may be possible to develop drugs that target this region, which could help combat infections like the common cold, polio and Ebola.
“If you think of this as molecular warfare, these are the encrypted signals that allow a virus to deploy itself effectively,” lead researcher Peter Stockley said in a news release. “Now, for this whole class of viruses, we have found the ‘Enigma machine’—the coding system that was hiding these signals from us. We have shown that not only can we read these messages but we can jam them and stop the virus’ deployment.”
Unlike living organisms, whose genome comes in the form of DNA, viruses can have either DNA or RNA—a close chemical cousin of DNA—as their genetic material. This material can also come in two forms: a pair of strands, or a single strand. These features are how scientists classify viruses, and for the present study, researchers were looking at single-stranded RNA viruses. These simple viruses are among some of the most potent infectious pathogens known, such as hepatitis C virus, HIV, Ebola virus and norovirus.
Just like how the sequence of letters in our DNA genome determines what proteins are made, the RNA of these viruses contains the messages that create the proteins they are made of. Now, it turns out that hidden among these letters is a second code that drives an essential part of the viral life cycle: assembly. As described in the journal PNAS, this code consists of a series of protein recognition sequences hidden within multiple so-called packaging signals that are dispersed throughout the genome.
To make this discovery, scientists from the University of Leeds and the University of York first managed to successfully observe at the single-molecule level the process of viral assembly, which involves piecing together protective protein containers around the genome. Next, they generated algorithms to crack the code driving this process and then created models of this system. They then used a technique called single-molecule fluorescence microscopy, which involves using fluorescence to study individual molecules in their environment, to visualize the codes being used by a plant virus.
Importantly, the researchers also demonstrated that it should be possible to design molecules that can disrupt the code, which would have a detrimental effect on viral assembly and therefore the ability of these viruses to infect cells. This raises the possibility that in the future such molecules could be used as antiviral drugs to stop the virus from replicating in infected individuals. But first, the researchers need to extend their study by examining animal viruses as well as plant viruses.
[Via University of Leeds and PNAS]