In patients with recurrent genital herpes supplementation with 3-5g/day PSK resulted in increased immunity and fewer sick days1. In vitro research showed PSK to inactivate a laboratory-cultured strain of herpes simplex virus (HSV) type 1 (HSV-1-GC+), together with clinically isolated strains of HSV-2, but found clinically isolated strains of HSV-1 to be resistant2.

An HSV-1 inhibitory protein has also been reported from Grifola frondosa3.

Trametes versicolor, or combinations of mushroom polysaccharide extracts help prevent recurrence of HSV outbreaks by maintaining immune competence.

1. Treatment of recurrent genital herpes with PSK. Kawana T. Proceedings of the International Symposium on Pharmacological and Clinical Approaches to Herpes Viruses and Virus Chemotherapy. Oiso, Japan, Sept. 10-13, 1984. Kono R, Nakajima A (Eds). Amsterdam : Excerpta Medica, 1985. pp. 271–272.
2. In vitro inactivation of herpes simplex virus by a biological response modifier, PSK. Monma Y, Kawana T, Shimizu F. Antiviral Res. 1997;35(3):131–138.
3. Isolation, identification and function of a novel anti-HSV-1 protein from Grifola frondosa. Gu CQ, Li JW, Chao F, Jin M, Wang XW, Shen ZQ. Antiviral Res. 2007;75(3):250–257.