IS IT HUMAN...IS IT NOT? WHAT EXACTLY DO WE HAVE ON OUR HANDS ...AND GLASSWARE?
A review letter submitted by
Martin Schwemmie, et al presented a very
skeptical view of human BDV infection. This research team asserts
that the staggering genetic similarity between human bornavirus RW98 and
the rat-adapted laboratory strain of bornavirus is not
They suggest that the two genomes are too homologous to be unrelated and
suggest that RW98 represents not a human bornavirus strain but a
contamination of human specimens with the laboratory viral strain.
Schwemmie, M, et al. "Sequence similarities between human bornavirus isolates and laboratory strains question human origin." The Lancet, v354, Dec. 4, 1999.
However, another research team
answered Schwemmie's skepticism with
an isolation of a human-specific BDV strain that is not genetically
to the lab rat strain. Planz, et al found that granulocytes
the major if not the sole cell type harboring BVD-specific nucleic
acid in human blood. The virus isolated from these cells is
different enough to negate the assertion that human bornavirus does not
exist, as proposed by Schwemmie.
Planz, O, et al. "Pathogenesis of borna disease virus: granulocyte fractions of psychiatric patients harbor infectious virus in the absence of antiviral antibodies". Journal of Virology, 1999 Aug, 73(8):6251-6.
DOES IT DRIVE YOU CRAZY ... OR DO YOU DRIVE IT CRAZY?
Still, because bornavirus remains new on the research market, its clinical correlation to psychiatric disorders in humans is difficult to prove. It was determined a few years ago that BDV is present in the brains of a significant portion of patients exhibiting behavioral anomalies. But does the virus cause anomalies such as severe depression and schizophrenia or is its presence a mere coincidence? Scientists have made significant efforts to resolve this enigma.
In an attempt to determine the
frequency of persistent BDV in the
human central nervous system, Czygan et al analyzed a large collection
of autopsy brain samples. Reverse transcription-nested PCR
was performed to detect BVD RNA. Surprisingly, only 3 samples from
persons with psychiatric disorders and prominent hippocampal degeneration
exhibited the presence of viral RNA. Another 86 samples from
with various psychiatric disorders (including schitzophrenia, affective
disorders, etc.) were negative for BDV. The study convinced the team
thatpersistent BDV infections are quite rare in humans, although it may
be associated with hippocampal degeneration.
Czygan, M, et al. "Borna disease virus in human brains with a rare form of hippocampal degeneration but not in brains of patients with common neuropsychiatric disorders." Journal of Infectious Diseases, 1999 Nov, 180(5):1695-9.
In contrast to the above
article, series of studies by Chen
et al have confirmed that Taiwanese patients with schitzophrenia and
do, in fact, have a higher prevalence of BDV-specific antibodies and BDV
transcripts than do controls. This provides a positive
between the virus and psychiatric disorders. Interestingly,
the team also analyzed blood samples of patients' family members and
health workers and determined that they, too, exhibit a significantly
rate of BDV infection than the control population. This
the evidence of human-to-human transmission of Borna disease virus.
Chen, CH, et al. "High seroprevalence of Borna virus infection in schitzophrenic patients, family members and mental health workers in Taiwan." Molecular Psychiatry, 1999 Jan, 4(1):33-8.
The same research team later
isolated BDV RNA from the peripheral
blood cells of 10 out of 74 schizophrenic patients (or 14%), as compared
to only one infected person out of 69 controls. Furthermore,
seven out of 45 mental health workers were found to be positive for BDV,
representing a 15% infection rate, as compared to 1.4% rate among the
subjects. These quantitative data suggest that Borna disease virus
may, indeed, contribute to the pathogenesis of schitzophrenia.
Chen, CH, et al. "Detection of Borna disease virus RNA from peripheral blood cells in schitzophrenic patients and mental health workers." Molecular Psychiatry, 1999 Nov, 4(6):566-71.
NOW THAT WE KNOW WHAT IT IS, WHAT DO YOU SUGGEST WE DO ABOUT IT?
Several drugs are now being studied and tested as potential antiviral agents for Borna disease virus. Currently, most of these drugs are still being tested on laboratory animals, but who knows what another year will bring...
guanosine analog ribavirin has been shown
to inhibit viral activity in vitro. Twelve hours following a
treatment, the Jordan et al team found a significant reduction in both
the level of virus and viral transcripts. Ribavirin acts to reduce
intracellular GTP pool, thus inhibiting transcription and capping of BDV
Jordan, I, et al. "Inhibition of Borna disease virus replication by ribavirin." Journal of Virology, 1999 Sep, 73(9):7903-6.
Interferon-alpha (IFN) is also proving to
be a highly effective retroviral drug for BDV. Hallensleben, et al
found that BDV replication cycle was significantly blocked by IFN in
monkeys, although this antiviral effect was not seen in all cell
Hallensleben, W. "Inhibition of Borna disease virus multiplication by interferon:cell differences in susceptibility." Archives of Virology, 1999, 144(6):1209-16.
Amantadinesulfate is a useful antiviral
in the treatment of a wide spectrum of viral
infections. However, it has also been reported as producing some
mild antidepressive effects. Research carried out by Ferszt, et al
tested this phenomenon and the results are very promising for anti-BDV
treatment. In a clinical study, 30 depressed patients with various
states of BDV infection were given oral amantadine for 8 to 12
The treatment produced antidepressive response in 19 of the 30 patients,
suggesting, once again, that the depression was associated with a viral
infection which is susceptible to the antiviral properties of
Ferszt, R. "Amantadine revisited: an open trial of amantadinesulfate treatment in chronically depressed patients with Borna disease virus infection". Pharmacopsychiatry, 1999 Jul, 32(4):142-7.