Purified bLF is a glycoprotein derived from cow’s milk that has antiviral properties to support the immune system and is routinely used in infant formula or sold as a dietary supplement.
Lactoferrin is found in most mammal milk but, unlike variants from other sources, bFL has high potency against a broad-spectrum of viruses. It also benefits from a robust supply chain and widespread availability.
Oral administration of bLF is known to improve the severity of some viral infections, but less is known about the effects of common excipients (such as dextrose and sorbitol) used to manufacture tablets and which may interfere with viral inhibition.
Tests revealed that bLF was effective against all common SARS-CoV-2 strains and researchers believe it would have similar antiviral activity against emergent strains.
“Lactoferrin’s broad inhibition of SARS-CoV-2 variants in conjunction with the low cost and ease of production make this an exciting clinical candidate for treatment or prevention of SARS-CoV-2 in the future,” the authors write.
Antiviral efficacy
There is an urgent need for alternative therapies to treat and prevent current and future coronavirus strains and especially low-cost solutions for widespread application, according to the researchers.
Peer reviews suggest using bLF as a prophylactic or post-exposure treatment for SARS-CoV-2 infection, given its broad antiviral efficacy, safety, and commercial availability. Its antiviral activity has also been associated with other strains of CoV.
“The potential for oral bLF as an antiviral agent for SARS-CoV-2 infection is supported by several previous research observations including in vitro work on the related betacoronavirus SARS-CoV,” they said.
The study aimed to evaluate the efficacy of bLF across different viral strains and its viability in a custom chewable formula.
Given that whey protein isolates and other purified dairy products have demonstrated activity against viruses in the past, the team also investigated whether other purified bioactive milk proteins have antiviral activity against SARS-CoV-2.
Study protocol
The antiviral activity of nine different dairy samples obtained from Glanbia Nutritionals including whey protein isolates, concentrates, Bioferrin 2000, and other lactoferrin enriched dairy products, were compared with purified bLF on SARS-CoV-2 in-vitro.
An image-based SARS-CoV-2 inhibition assay was designed using cells from the human lung. Protein samples were gradually introduced to cell cultures, which were subsequently infected with SARS-CoV-2 and incubated.
There was no observed efficacy against SARS-CoV-2 when researchers screened dairy proteins and bioactive peptides. They note that antiviral activity was entirely dependent on bLF and correlated to the bLF content in dairy ingredients.
“Our data suggest that the other dairy components in these products do not possess any anti-SARS-CoV-2 activity up to 400 µg/mL and that the efficacy is entirely dependent on bLF. This provides strong support for the high specificity of bLF anti-SARS-CoV-2 activity, which is not observed for other bioactive milk proteins.”
Neither dextrose or sorbitol were found to inhibit or prevent the antiviral activity of purified bLF.
Conclusion
Study results reflect previous research which demonstrated that bLF directly binds and inhibits other viruses including adenovirus, feline herpes virus (FHV-1), hepatitis C virus (HCV), and human immunodeficiency virus (HIV), however additional research is needed to confirm direct binding to SARS-CoV-2.
The authors add: “The availability, safety, and in vitro efficacy of bLF make it a promising candidate for future research in combating SARS-CoV-2.”
Source: Journal of Dairy Science
Published online: doi.org/10.3168/jds.2021-21247
‘Evaluating the in vitro efficacy of bovine lactoferrin products against SARS-CoV-2 variants of concern’
Jesse W. Wotring, Reid Fursmidt, Loren Ward, and Jonathan Z. Sexton