Borna Virus

[Peter Charles]

Len,

I'm jumping into this without having seen the original
post to which you are replying, so I'm not sure what
the original poster was trying to say about the observation
that a few percent of the population have anti-Borna virus
antibodies.  I do recollect reading something several years 
ago about Borna and mental illness.  

My comments concern the persistance of RNA viruses.
There are several examples of RNA viruses which persist in the
host in the abscence of any (observable) illness.  Most members
of the Arenaviridae (LCMV, Junin, Machupo, and of course, Lassa)
have adopted persistance as a way of life.  These viruses infect 
their respective rodent host early in life and are excreted for the
life of the animal, with little observable deleterious effect on the 
host.  Persistance has also been observed in the case of an Alphavirus,
Sindbis.  Griffin's lab showed that viral transcripts were still detectable
many months after the mouse recovered from acute encephalitis, implying
that transcription of the viral genome was still occuring inspite of
an appropriate immune response, and in the abscence of any signs of disease.

Additionally, virtually all of the arboviruses set up a persistant 
infection in the insect vector that seems to have little effect on the 
insect (I think that there is some argument here, though-- I do recall
a paper or two that showed decreased feeding of some mosquito strains
following viral infection).

And, of course, let's not forget that retroviruses are technically RNA
viruses.  Although they do seem to cause disease eventually in the host.

Anyway, my point is that RNA viruses do not exclusively set up lytic, acute
infections, and some are capable of long term persistance in the host.

Peter Charles, PhD
Department of Pathology (Neuropathology)
Albert Einstein College of Medicine