Inhibition of HSV-1 and vaccinia virus replication by cephalosporin derivatives

Derivatives of beta-lactam antibiotics of the cephalosporin type at 0.02-1 mM concentrations interfered with in vitro replication of two DNA-containing viruses, herpes simplex I and vaccinia, but showed no effects on two RNA-viruses, lymphocytic choriomeningitis virus and vesicular stomatitis virus, or on cell viability. The exact structure of the active compounds remains unknown, but opening of the beta-lactam ring appears to be a prerequisite for their formation. Whereas cephalosporin derivatives were most active, no active products were obtained from penicillins and monobactams. The potential of these unexpected antiviral effects of widely used beta-lactam antibiotics remains subject of further study.