The role of lactoferrin
Lactoferrin is a highly conserved natural pleiotropic glycoprotein of 80 kDa and 703 amino acidic residues, it binds iron and is expressed and secreted by glandular cells. It can be found in most body fluids the molecule is equipped with in vitro antiviral properties against a wide range of viruses including SARS CoV, a virus belonging to the coronavirus family and naturally related to SARS CoV2, responsible for the current Covid19 pandemic. It presents immune-modulating and anti-inflammatory characteristics that can modify the host’s responses to infections, thus it can be useful in association with other drugs in the most severe cases. Isolated for the first time in cow’s milk and then in breast milk, it is used as a nutritional additive and if administered in doses between 4.5 and 100 mg per day, is free of toxicity. There are also liposomal formulations. The antiviral activity of Lf has been demonstrated for the first time in infected mice where it induced polycythemia of the Friend virus complex in 1980. It attacks naked and enveloped viruses, both DNA and RNA, such as cytomegalovirus, herpes simplex virus, human immunodeficiency virus (HIV), rotavirus, poliovirus, respiratory syncytial virus, hepatitis B and C virus (HCV) parainfluenza virus, alphavirus, hantavirus, human papillomavirus, adenovirus, enterovirus 71, echovirus 6, influenza A virus and the Japanese encephalitis virus, with EC 50 (actual concentration) in vitro of Lf generally numbered in the micro-molar when against viruses. The ability of Lf to inhibit viral entry can be explained by the binding with cell’s surface molecules (proteoglycans of heparan sulfate, HSPG) or viral particles (see HCV) or both. In addition to preventing the access of the virus, it can contribute by blocking the replication mechanisms of the virus once it enters. The theory according to which children between the ages of 0 and 10, therefore breastfeeding or using milk derivatives containing this molecule, have a reduced incidence of contracting the virus has been demonstrated, although it still needs to be validated. Furthermore, zinc saturated lactoferrin can be used in anti-inflammatory and preventive therapy against Covid19 (18).