Heparin inhibited the hemagglutinin activity of herpes simplex virus (
HSV) type 1. The minimal inhibitory concentration of heparin required
to inhibit 8 hemagglutination (HA) U of HSV ranged from 0.005 to 0.01
U/ml. Mouse erythrocytes failed to combine with the HA inhibitory fact
or of heparin. On the other hand, mouse erythrocytes treated with hepa
rinase had greatly reduced agglutinability by HSV. Virus-heparin compl
ex formation was observed by sedimenting heparin with the virus partic
les.