**3.1.2 Antiviral activity**

Antiviral effects have also been reported for surfactin and its analogues (Naruse et al., 1990). More effective inactivation of enveloped viruses, such as retroviruses and herpes viruses, were noted compared to non-enveloped viruses, suggesting that inhibitory action links may be due to physico-chemical interactions with the virus envelope (Vollenbroich et al., 1997a). Antiviral activity of some lipopeptides therefore may take place as a result of the viral lipid envelope and capsid disintegration due to ion channels formation, with consequent loss of the viral proteins involved in virus adsorption and/or penetration (Jung et al., 2000; Seydlová & Svobodová, 2008).

*In vitro* experiments showed that both surfactin and fengycin produced by *B. subtilis* fmbj were able to inactivate cell-free virus stocks of porcine parvovirus, pseudorabies virus, newcastle disease virus and bursal disease virus and could effectively inhibit infections and replication of these viruses (Huang et al., 2006).

Sophorolipids are also claimed to have activity against human immunodeficiency virus (Shah et al., 2005) and trehalose lipids (namely trehalose dimycolate, TDM) conferred higher resistance to intranasal infection by influenza virus in mice though inducing proliferation of T-lymphocytes bearing gamma/delta T-cell receptors, associated with the maintenance of acquired resistance to the infection (Hoq et al., 1997, as cited in Franzetti et al., 2010b).

Rhamnolipid alginate complex also showed significant antiviral activity against herpes simplex virus types 1 and 2. In particular, they significantly inhibited the herpesvirus cytopathic effect in the Madin-Darby bovine kidney cell line (Remichkova et al., 2008). The suppressive effect of the compounds on herpes simplex virus replication was dosedependent and occurred at concentrations lower than the critical micelle concentration.
