Interferon and the Treatment of Hepatitis C: What Are They? How Can They Be Useful in Treating Disease?
Interferons (INF) are proteins that are produced by a virus infected cell. They are known to interfere with viral replication in previously infected tissue cells. INF-a and INF-b are the molecules thought to have the effect of blocking the spread of viruses to other, uninfected cells.
In this particular blog I would like to discuss INF-a specifically. INF-a is actually a family of closely related proteins. Because of its ability to hinder viral replication, a modified version INF-a is used as a treatment for hepatitis C (HCV).
HCV is a virus that damages. For reasons that are not understood, viruses in the liver often become invisible to the immune system. This invisibility prevents the immune system from recognizing the virus, thus allowing it to multiple out of control. By giving a hepatitis C infected patient INF-a, it allows their immune system to detect the virus, and it prevents or slows the replication of the virus in the liver.
Specifically, INF-a operates in three ways:
1. The INF-a attaches to healthy cells to prevent the HCV virus from attacking healthy cells.
2. It marks the infected cells – this alerts the immune system as to which cells have the HCV virus, and prevents the virus from replicating.
3. INF-a helps the body rid itself of infected cells, while preventing healthy cells from becoming infected.
Currently, INF-a, coupled with ribavirin, is the standard of treatment for HCV patients. Unfortunately, it only succeeds in clearing the virus in approximately 30-40% of people. This is due to a genotypic interaction which may be discussed in later blogs.
Hi ChristineT7630,
ReplyDeleteI was interested by "It marks the infected cells." Can you elaborate? Does it make infected cells more visible to killer T cells, for example, and if so, how?
Is there any data suggesting that the IFN-a producing cells are not functioning to produce interferon? And if the cells are producing it in response to viral infection, why they are not secreting it? I am just wondering if the virus is actually going undetected or if it someone preventing a part of viral recongnition from occuring, by preventing IFN-a secretion!
ReplyDeleteThank you!
Ok....So I just looked at my post and 2 things:
ReplyDelete1. The first line of paragraph 2 should read "HCV is a virus that
damages the liver." I'm not sure what happened to those last 2
words!
2. When I say that INF-a "marks" the infected cells, I mean that INF-a
binds to high affinity receptors on the surface of the target
(infected) cell.
INF-a "fights" HCV in "marked" cells in 2 ways:
1. It induces a non-specific antiviral state in the target cell, which
causes an inhibition in HCV replication.
2. It induces immunomodulatory effects that increase host immune
responses against the HCV virus.
Is this enough elaboration? Or is more appropriate?
TanyaC7630 - I do not know of any evidence suggesting that the HCV virus prevents cells from naturally secreting INF-a. To my knowledge, cells are still producing INF-a, just not enough to rid the body of infection.
Also, about 20% of individuals who come into contact with HCV are able to fight it off themselves, so the virus is not going undetected.In fact, the test for HCV is actually just a measure of HCVsAb!
Thanks for commenting!! And I'm sorry that this response was so slow!