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).