Des O'Connor wrote:
> Ill correct my spelling this time...arggg
>> Rabies..Rhbado virus is immunologically shielded because it is covered in a
> phospholipid membrane derived from the outer cell wall of the host cell in
> which the
> viral nuclearic acid was synthesised. This outer layer not only shields
> antigenic determinants but also by degree confers selfness.
>> Rabies is also a 'slow' virus and has the characteristics of evoking only a
> week immune response.
Although the virion is enveloped, with the lipid envelope derived from the
cytoplasmic membrane (eukaryotic cells don't have cell walls) of the host cell
in which the virus replicated, there are virus-specific proteins and
glycoproteins inserted into the envelope that are quite good antigens. The
lipid envelope does not shield viral antigens nor does it convey "selfness"
since lipid components are not particularly antigenic. The problem is that the
vast majority of viral replication occurs in nerve cells and the nervous sytem
is an "immunologically privileged site," which means that there really aren't
many cells from the immune system present there. As a result, there isn't much
there to respond to antigens present on the rabies virus virions.
Larry D. Farrell, Ph.D.
Professor of Microbiology
Idaho State University