MECHANISM OF INACTIVATION OF ENVELOPED VIRUSES BY THE BIOSURFACTANT SURFACTIN FROM BACILLUS-SUBTILIS

The antiviral activity of surfactin, a cyclic lipopeptide antibiotic a nd biosurfactant produced by Bacillus subtilis, was determined for a b road spectrum of different viruses, Semliki Forest virus (SFV), herpes simplex virus (HSV-I, HSV-2), suid herpes virus (SHV-1), vesicular st omatitis virus (VSV), simian immunodeficiency virus (SIV), feline cali civirus (FCV)! murine encephalomyocarditis virus (EMCV). in vitro expe riments showed biphasic virus inactivation kinetics for enveloped viru ses during treatment. inactivation oi enveloped viruses, especially he rpes-and retroviruses, was much more efficient than that of non-envelo ped viruses. For those viruses susceptible to its action, surfactin wa s active at 25 mu M in medium containing 5% fetal calf serum (FCS). Co ncentrations up to 80 mu M of surfactin led to a titre reduction of >4 .4 log(10) CCID50/ml for HSV-1 in 15 min and for SIV and VSV in 60 min . The inactivation rate increased linearly with the incubation tempera ture by a factor 2.4/10 degrees C and logarithmically with the concent ration. Serum components. probably proteins and/or lipids, influence t he effective surfactin concentration. A disruption oi the viral lipid membrane and partially of the capsid was observed by electron microsco py. These findings suggest that the antiviral action, postulated also in other investigations, seems to be due to a physicochemical interact ion of the membrane-active surfactant with the virus lipid membrane. S urfactin may be useful for application in virus safety enhancement oi biotechnological and pharmaceutical products. (C) 1997 The Internation al Association of Biological Standardization.