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Emerging
Evidence of Brain Tissue Invasion by Hepatitis C Virus
It has been reported that hepatitis C virus (HCV) infection
is associated with cognitive dysfunction,
fatigue and
psychological disorders (e.g., depression), which do not correlate
with the severity of liver disease and cannot be accounted
for by hepatic encephalopathy or drug
abuse.
There
is also emerging evidence that HCV infection can have negative
neurocognitive effects in HIV cohorts. Magnetic resonance
spectroscopy has suggested the likely existence of a biological
basis for these effects.
HCV
replicative forms have recently been detected in autopsy brain
tissue and the infected cells have been identified as CD68-positive
(macrophages/microglia).
These
findings raise the possibility that HCV infection of the brain
could be directly related to the reported neuropsychological
and cognitive changes.
HCV
is not strictly hepatotropic, as it can also replicate in
leukocytes, including monocytes/macrophages.
The
latter cells could provide access of HCV into the central
nervous system ('Trojan horse' mechanism) in
a process similar to that postulated for HIV-1.
In
support of this hypothetical mechanism come reports showing
a close relationship between HCV sequences present in the
brain and cerebrospinal
fluid and sequences found in lymph nodes and
peripheral blood mononuclear cells.
However,
despite some similarities there is a fundamental difference
between HIV-1 and
HCV infection as the latter does not progress into AIDS-type
dementia.
From the Department of Medicine, Mayo Clinic Scottsdale,
Scottsdale, Arizona,Institute of Infectious Diseases, Warsaw
Medical Academy, Poland, Barrow Neurological Institute, Phoenix,
Arizona.
11/09/05
Reference
T
Laskus and others. Emerging evidence of hepatitis C virus
neuroinvasion. AIDS 19(Suppl 3): S140-144. October 2005.
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