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# Maximum possible virus titers.

Greg Tobin tobin at fcs260c.ncifcrf.gov
Wed Aug 16 15:03:27 EST 1995

```In article <01HTOAZO52N69TCQM5 at IRI.TUDELFT.NL> M.Schouwenburg at IRI.TUDelft.NL (Marcel Schouwenburg) writes:
>
>On 4-AUG-1995, poets at ccmail.orst.edu  "Steven Poet" wrote:
>
>> That seems like a pretty high dilution to me.  Are you sure your decimal
>> points are all in the right place?  I remember somewhere in the depths
>> of my memory that 10^17 poliovirus particles will fill a ping pong ball.
>> So I don't think 10^23 virus particles can be suspended in 1 ml of
>> cell culture medium.  I understand the difference between TCID50 and
>> absolute particle numbers, I'm just thinking intuitively.
>>
>> krjk1 at stirling.ac.uk (Mr K R John Kollanoor) wrote:
>>
>>> Is there a theoratical maximum for the number of virus progeny a cell
>>> culture supernatant can have?
>>> Is there any possibility of a titer of 10^-23(TCID50/ml) in any of the virus
>>> infected cell culture supernatant ?
>>> I would appreciate if someone could answer these questions.
>
>
>You're right with this, but when you only look to the number: 10^23 you must
>realise that this is so high it must be wrong. If you had that much polio
>virus particles, you would be able to lift 1 ml of the supernatant of the
>culture. I will give the calculation:
>
>- Let us only consider the RNA of the virus and take 7500 nt for the length.
>- I assume an average weight of 310 Da for a nt.
>- 1 Da = 1.65 * 10^-24 g.
>
>If you calculate the weight for 10^23 virus particles, you'll get:
>
>  10^23 vp * 7500 nt/vp * 310 Da/nt * 1.65 * 10^-24 g/Da = 383625 g
>							   ========
>(vp = virusparticles)
>
>I think this makes clear that 10^23 is a very unlikely titer, or am I doiing
>something wrong or making the wrong assumptions?
>Does anybody have any comments on this?
>
>Kind regards,
>
>Marcel
>
>

Lentiviruses are diploid so there will be 700,000 g of vRNA in a mole.  There
The mass of the virus is more heavily weighted by the proteins, water, and
lipid than the nucleic acid.

"mens sana in corpore sano"
> -----------------------------------------------------------------------------
>| Marcel Schouwenburg             | Besides working as a Radiation Safety     |
>| Health Physics Department       | Officer, I'm a student in both            |
>| Interfaculty Reactor Institute  | Nutritional Toxicology and Virology.      |
>| Delft University of Technology  | Faculty of Natural Sciences               |
>| Delft, The Netherlands          | Open university, The Netherlands          |
>| Experimental WWW-homepage at:    -------------------------------------------|
>| URL: http://www.iri.tudelft.nl/                                             |
>|                                                                             |
>|    "All reflections/opinions made are on personal name and are not          |
>|     connected to above mentioned universities unless otherwise stated."     |
>|                                                                             |
> -------------------< e-mail: schouwen at iri.tudelft.nl >-----------------------
>- end -

--
Greg Tobin, Ph.D.                        tobin at lcms-1.ncifcrf.gov

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