MicrobeWorld

Defective viruses, thought for decades to be essentially garbage unrelated to the transmission of normal viruses, now appear able to play an important role in the spread of disease, new research by UCLA life scientists indicates.

Defective viruses have genetic mutations or deletions that eliminate their essential viral functions. They have been observed for many human pathogens and are generated frequently for viruses that have high mutation rates. However, for some 40 years, it was believed that they were unimportant in natural settings.