RSV can be difficult to study. For one thing, the infectious particle can take different forms, ranging from 10-micron filaments to ordinary spheres. The virus can insert more than one genome into the host cells and the RNA orientation and structure are disordered, which makes it difficult to characterize.
The research team, which included scientists from Vanderbilt University and Emory University, used a probe technology that quickly attaches to RNA within cells. The probe uses multiple fluorophores to indicate the presence of the viral RNA, allowing the researchers to see where it goes in host cells and to watch as infectious particles leave the cells to spread the infection.
"Being able to see the genome and the progeny RNA that comes from the genome with the probes we use really give us much more insight into the replication cycle," Santangelo said. "This gives us much more information about what the virus is really doing. If we can visualize the entry, assembly and replication of the virus, that would allow us to decide what to go after to fight the virus."
The research depended on a new method for labelling RNA viruses using multiply-labeled tetravalent RNA imaging probes (MTRIPS). The probes consist of a chimeric combination of DNA and RNA oligonucleotide labeled internally with fluorophores tetravelently complexed to neutravidin. The chimeric combination was used to help the probes evade cellular defenses.
"There are lots of sensors in the cell that look for foreign RNA and foreign DNA, but to the cell, this probe doesn't look like anything," Santangelo explained. "The cell doesn't see the nucleic acid as foreign."
Introduced into cells, the probes quickly diffuse through a cell infected with RSV and bind to the virus's RNA. Though binding tightly, the probe doesn't affect the normal activities of the virus and allows researchers to follow the activ
|Contact: John Toon|
Georgia Institute of Technology