Viruses and Parasites

Stephen Kayes skayes at USAMAIL.USOUTHAL.EDU
Wed Apr 8 11:42:48 EST 1998


Graham:

I logged on to  your webpage and looked at the EM.  Truely
beautiful.  However, like you, I am not a virologist. Thus, I went
and found one of the virologists in our microbiology group and
asked him to look at it.  He and I both were taken with the
structure but before he ventures a guess, he would like to know
the location that is depicted.  Is this the interface between the
nucleus (electron-lucent half of the picture) and the cytoplasm
(electron-denser half which appears to have some
microfilaments running from 11:00 O'clock to 5:30) or is the
picture of the plasmamembrane juxtaposing the extracellular
space.  Another question that comes to mind looking at this
micrograph is what is the nature of the    structure (very dense) 
which resembles a toadstool or plug which inserts through the
membrane?

For the remainder of the group still interested in the occurene of
viruses in parasites, I would like to call attention to the following
reference:

Wickner, R. B.  1996.  Viruses of yeasts, fungi, and parasitic
microorganisms.  IN: Fields Virology. 3rd Edition.  Fields, B. N.,
Knipe, D. M., and Howley, P. M.  Lippincott-Raven, Philadelphia. 
pp. 557-585.  

This chapter has 282 references although many pertain to yeast
and fungi.  As has already been pointed out in previous threads,
most of the viruses in parasites are described from Leishmania,
Giardia, Trichomonas and Entamoeba.

Steve Kayes

>>> Graham Clark <graham.clark at LSHTM.AC.UK> 4/8/98  3:55
am >>>
There are lots of viruses or virus-like particles reported from =

parasitic protozoa but most do not appear to damage the cells as
=

far as we can see. (These include the Giardia, Trichomonas, =

Leishmania, Eimeria, Plasmodium, etc. viruses.) One exception
is in
Entamoeba histolytica where several transmissible, lytic viruses
were reported in a series of at least seven papers and a review in
=

the 1970's. The review is by Diamond et al 1976 Protozoal
viruses. =

Adv. Virus Res. 20: 87-112. There were three morphologically
distinct virus-like particles described and they appeared to have 
=

double stranded nucleic acid genomes. (Most protozoal viruses
appear to
have double stranded RNA genomes.) Nothing has been done
on the =

Entamoeba viruses since the late 1970's.

With regard to Rhabdoviruses, these have also been described
from =

Entamoeba. I have temporarily placed an electron micrograph of
what
appears to be one on the Entamoeba website. I would appreciate
comments
from any virologists on its identification and also any suggestions
for how I might go about purifying them for further study - they
appear =

to be 'exiting' into the culture medium but are probably low in
number.

The EM is found at:

http://www.lshtm.ac.uk/mp/bcu/enta/virus.gif

(TEM courtesy of Dr. Arturo Gonzalez-Robles, CINVESTAV-IPN,
Mexico City)

Graham
-- =

C. Graham Clark, Ph.D.
Department of Infectious and Tropical Diseases,
London School of Hygiene and Tropical Medicine,
Keppel Street, London WC1E 7HT, England, G.B.

Tel: ++44-171-927-2351
FAX: ++44-171-636-8739
e-mail: g.clark at lshtm.ac.uk
Homepage: http://www.lshtm.ac.uk/mp/bcu/enta/mpvbgcla.htm

Please visit the Entamoeba Homepage -
http://www.lshtm.ac.uk/mp/bcu/enta/home.htm



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