Lactoferrin, a multifunctional
iron binding
glycoprotein, plays an important role in immune regulation and defence mechanisms against bacteria, fungi and viruses.
Lactoferrin's
iron withholding ability is related to inhibition of microbial growth as well as to modulation of motility, aggregation and biofilm formation of pathogenic bacteria. Independently of
iron binding capability,
lactoferrin interacts with microbial, viral and cell surfaces thus inhibiting microbial and viral adhesion and entry into host cells.
Lactoferrin can be considered not only a primary defense factor against mucosal
infections, but also a polyvalent regulator which interacts in viral infectious processes. Its
antiviral activity, demonstrated against both enveloped and naked viruses, lies in the early phase of
infection, thus preventing entry of virus in the host cell. This activity is exerted by binding to heparan sulphate
glycosaminoglycan cell receptors, or viral particles or both. Despite the
antiviral effect of
lactoferrin, widely demonstrated in vitro studies, few clinical trials have been carried out and the related mechanism of action is still under debate. The nuclear localization of
lactoferrin in different epithelial human cells suggests that
lactoferrin exerts its
antiviral effect not only in the early phase of surface interaction virus-cell, but also intracellularly. The capability of
lactoferrin to exert a potent
antiviral activity, through its binding to host cells and/or viral particles, and its nuclear localization strengthens the idea that
lactoferrin is an important brick in the mucosal wall, effective against viral attacks and it could be usefully applied as novel strategy for treatment of
viral infections.