This is a fascinating question. Clearly, it is difficult to say that infectious diseases are caused by defects in the immune system alone. Babies born with a dysfunctional immune system can survive forever in a germ free environment. So, exposure to pathogens is absolutely necessary for them to establish a perpetual residence in our body. At the same time, it is difficult to say that an exposure to germs alone is sufficient to cause infection because if the exposure dose is below a level that can be handled by immunity, infection cannot take place.
The truth is far more interesting than the simple view given above. HCV like other pathogens manipulates the immune response against them to its advantage. It uses its protease to inactivate a molecule called IPS1 which is crucial in immune signaling. This role of the protease exactly mimic the function of immunity's self control. Immune system's killer cells can kill infected liver cells to destroy HCV RNA. To restrain such a suicidal action, our immune system has the ability to neutralize excessive IPS1. HCV protease does mimic this very process.
PIs such as TVR inactivate HCV protease and they are powerful in blocking HCV's attempt to sabotage immune signaling. With the help of PI the revived immune system can send the specially tuned killer cells to destroy the viral RNA more effectively, and at the same time induces inflammation and side reactions seen in trial patients.
So, you may say that HCV infection has a lot to do with our immune system. But you cannot say that defects in it causes the infection.
The answer is yes. PROVE 1 data released last month indicate that TVR (VRTX's drug) is effective in bringing down the viral counts to a undetectable (UND) level very quickly (within a few weeks of treatment) for most treatment-naive patients.
Projecting from the time development of the percentage of UND patients in the course of PROVE 1 trial, I am optimistic about the chance of cure for this group of HCV patients if they are treated with TVR + IFN + RBV for 10 wks and continued with IFN + RBV for another 40 wks or so. I would put the chance of cure for such a regimen to be somewhere around 80%. However, if the regimen is changed to a shorter duration such as 12 wk +12 wk, the chance of cure would drop below 70% for the first-timer genotype 1 patients. These are very qualitative predictions of my own.
The fact that close to 50% of patients of this group can be cured with IFN + RBV alone and a probably better outcome with addition of TVR indicates to me that HCV virus does not infect and disable the immune system which destroys the virus. This is a different topic we were discussing earlier.
If you read any scientific articles specifically about the HepC virus itself, structure, mechanisms, etc, they always start out categorizing the virus as a hepatropic and lymphotropic virus. This means that HCV can infect either/or/both the liver and the lymph system. It�s a very commonly used categorization (as far back as 1985 I can recall it commonly used) but usually only professionals read such articles or it is used in consensus statements by professionals, or in university educational materials, etc. It is deliberately and very thoroughly OMITTED from all PUBLIC information.
What effect do you think leaving out that important fact has on the way this virus is perceived and responded too? Would the public panic if they were told that HCV was an immune system virus like the ones that cause AIDS? We always read � �Hepatitis C is a virus that attacks the liver.�
Fact remains that those infected with HCV have a lymphotropic virus affecting the immune system.
Really have no citations or links, just many hours spent at many HCV, blood borne pathogen , conferences consensus or otherwise. I can remember way back when the docs were fighting over which specialty would be responsible for the HCV or no A non B envelope as the virus was known way back then.
Lymphotropic is medical slang used to describe viruses that infect the immune system. T-cell lymphotropic virus is one, HIV type 1 and 2 are another. These can cause Acquired immunodeficiency syndrome (AIDS)