How might viruses help cure genetic diseases?
Viruses get inside host cells and take over their cellular machinery by inserting their own DNA into it.
So virus could be used as a vehicle to deliver the right gene in cells where it is lacking.
Viruses can enter a cell and make it follow specific orders. If scientists could program a virus (edit it's DNA) to do what they want it to, the virus could enter a cell and fix it.
Nonpathogenic virus, used to carry relevant genetic information in target cell, are called vectors.
For example, cancerous cells are cells that are mutated (their DNA is wrong) and they are reproducing continuously. If a virus was programmed to enter the specific cancerous cells and change its DNA to stop reproducing, the cancerous cells would die off and stop spreading around the body.
Some of these things may not be possible yet, but this is how some diseases might be cured using viruses.
Read this to know about a successful gene therapy story.