How could enzymes be antiviral ?
I think the theory is that the proteolytic enzymes (proteases) in Virastop disable viruses, but I cannot find any scientific evidence demonstrating that this approach actually works.
It says
here that:
Enzymes, particularly the proteases, turn out to be an excellent therapy to use against a virus by working on several levels. Many viruses are surrounded by a protective protein film, something a protease enzyme can digest away. Eliminating this coating leaves the viruses unprotected and vulnerable to antivirals and destruction. There is also research showing how enzymes support the immune system helping it to more effectively work on problems in the body, including viruses.
Is there any evidence that any enzymes may be effective in the treatment of viruses? One example comes from a study by Dr. Billigmann. In 1995, he published the results of a study with enzyme therapy as an alternative in the treatment of the virus Herpes zoster. In a controlled study with 192 patients, one of the objectives was to confirm that enzyme therapy had been effective on this virus in a previous study.
The other objective was to compare the effectiveness of enzymes with that of a standard drug called acyclovir. The high costs of treatment with this drug and others often meant patients with Herpes zoster would not receive medicinal therapy. They concluded that overall the enzyme preparation showed identical efficacy with the drug acyclovir, and thus also confirmed the results of the prior study.
The above description is vague, but I think the "protective protein film" they refer to may be the viral capsid, which is the protein shell of a virus, which contains the viral genome. On top of the capsid shell,
enveloped viruses (such as herpes viruses) also have an additional lipid layer covering the capsid, whereas
naked viruses (such as enteroviruses) do not have this fatty layer, and just have the naked protein capsid shell.
The Billigmann 1995 study using enzymes to treat varicella zoster virus is
this one. In the abstract, they do not really say much about the enzymes used, nor the mechanism of action.
I found some discussion
here which is interesting:
QUESTION: Can typical protease (protein degrading enzymes such as Proteinase K) degrade the intact (infectious) virion capsid proteins?
ANSWER: Yes, but you have make sure your capsid can be digested with a certain protease. For our purpose (release of the viral genome) we digest AAV capsids at 56°C for 2 h (Proteinase K)
AAV = Adeno-associated virus.
Note that proteolytic enzymes are also called: protease, peptidase and proteinase.