Removing protists from NPV solution

Dan Guyot daniel at
Tue Nov 23 17:41:13 EST 1993

Dear netters:
	One urgent question.
How can I eliminate microsporidia in my virus solution?  
I need an answer to this question by Wednesday morning (24 November 1993) 
in order to save the following experiment.
Experiment: Viability of Nuclear Polyhedrosis Virus excreted by two 
reptiles and an amphibian.
1) Determine the viability of excreted Nuclear Polyhedrosis Virus 
2) Estimate the quantity of virus ingested and excreted by the reptiles 
and amphibian.
	I fed caterpillars (Spodoptera. exigua) infected with NPV to a 
skink and a lizard and a toad.  However, I did not know that the 
caterpillars were also infected with a nasty microsporidian.  The feces 
from all three animals were collected and centrifuged to produce three 1 
ml solutions of NPV (one solution from each animal).  I want to bio-assay 
these three solutions to test the viability of the PV in them.  However, 
all threey solutions are contaminated with microsporidia (a protozoan).  
(This is an interesting finding in itself, it implies that both NPV and 
microsporidia can withstand the vagaries of a trip through the vertebrate 
digestive system.)  
	Nevertheless, I need to selectively get rid of the microsporidia 
in order test the viability of NPV with a bio-assay.  If I can separate 
NPV and microsporidia without damaging either then I can separately test 
the viability of each.
Possible solutions?	
1) use a selective anti-biotic against the microsporidia
2) pasteurize the solution and hope that one will be destroyed and the 
other won't
3) use some form of a gradient
	a) centrifuge?
	b) sucrose gradient?
	c) other?
Thanks in advance.  Please answer directly to my e-mail address below. 
This is message is being posted for me as I don't have access to this
Daniel Guyot
35/1-2 Soi Aladin
Phahonyothin Rd. 
Bangkhen, Bangkok
e-mail: daniel at

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