What exactly are virulence factors?
Virulence factors are the weapons that the bacteria use to overcome the host defenses and thrive. When I was a young medical student, at the very beginning of genetics, we were unable to characterize the genes that coded for these virulence factors. With the introduction of PCR we could easily do it. I’ve always been particularly interested in what’s called Panton-Valentine leukocidin (PVL). This is a toxin that was described by two researchers—Panton and Valentine—in 1935. They demonstrated that a strain of S. aureus with this particular toxin was very virulent. It would destroy leukocytes, which is where the term leukocidin comes from.
