From: Kofi on
Makes me wonder if beta amyloid fibers are part of a viral biofilm.

<http://www.sciencedaily.com/releases/2010/02/100205115946.htm>

Biofilms: Discovery of a New Mechanism of Virus Propagation

ScienceDaily (Feb. 5, 2010) � Researchers at the Institut Pasteur and
CNRS have shown for the first time that certain viruses are capable of
forming complex biofilm-like assemblies, similar to bacterial biofilms.
These extracellular infectious structures may protect viruses from the
immune system and enable them to spread efficiently from cell to cell.
"Viral biofilms" would appear to be a major mechanism of propagation for
certain viruses. They are therefore emerging as new and particularly
attractive therapeutic targets.

Researchers from the Institut Pasteur and CNRS, headed by Maria-Isabel
Thoulouze and Andr�s Alcover within the Lymphocyte Cell Biology Unit, in
collaboration with Antoine Gessain from the Oncogenic Virus Epidemiology
and Physiopathology Unit and with the Imagopole, recently identified,
for the first time in viral research, "biofilm" like structures, formed
by the HTLV-1 retrovirus on the surface of infected cells. These are
aggregates of viruses embedded in a carbohydrate-rich structure
containing cell-secreted extracellular matrix, whose synthesis is
controlled by the virus.

The HTLV-1 virus (human T-cell leukemia virus type 1) was the first
human retrovirus to be isolated, in 1980, three years prior to the
discovery of HIV, the retrovirus that causes AIDS. It infects 15 to 20
million people worldwide and causes various diseases, ranging from adult
T-cell leukemia/lymphoma to forms of neuromyelopathy (tropical spastic
paraparesis) or other chronic inflammatory syndromes, such as infectious
dermatitis, uveitis and myositis. The dissemination of HTLV-1 was known
to require infected cells and cell-cell contacts, but the transmission
mechanism itself was still a mystery.

In the biofilm -- an effective protective and adhesive barrier -- HTLV-1
is far more easily transmitted than in its free, isolated state. By
removing the viral biofilm from the surface of the infected cells,
researchers achieved an 80% reduction in infection rates, thus
underlining the importance of this transmission mode for HTLV-1.

In bacteria, the existence of biofilms has been known for many years.
They form the dental plaque on the enamel surface of teeth and are also
found in industrial systems and in our own intestinal flora. When they
colonize medical implants, such as prosthesis or catheters, they can
cause repeated infection. For these reasons, bacterial biofilms have
been the focus of intensive research in the aim to limit their
development and render them responsive to anti-bacterial treatment.

Scientists are currently seeking to characterize the mechanisms of viral
biofilm generation, and to determine whether viruses other than HTLV-1
form this kind of structure. For viruses forming biofilms, it would be
useful to define new anti-viral therapeutic strategies, which would
target, not only the virus itself, but the formation of these viral
biofilms.
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Story Source:

Adapted from materials provided by CNRS (D�l�gation Paris Michel-Ange).

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Journal Reference:

1. Ana-Monica Pais-Correia, Martin Sachse, St�phanie Guadagnini,
Valentina Robbiati, R�mi Lasserre, Antoine Gessain, Olivier Gout, Andr�s
Alcover & Maria-Isabel Thoulouze. Biofilm-like extracellular viral
assemblies mediate HTLV-1 cell-to-cell transmission at virological
synapses. Nature Medicine, 2010; 16 (1): 83 DOI: 10.1038/nm.2065