# Calculation of the 1.5 μmol of viral membrabe phospholipid - How to calculate the influenza virus concentration? (Mar/20/2006 )

Dear All,
This is my first post!
Can anybody tell me how to calculate the 1.5 μmol of viral
membrane phospholipid?

==
Reference:
"Virosome-mediated delivery of protein antigens in vivo: efficient
induction of class I MHC-restricted cytotoxic T lymphocyte activity"
Vaccine 23 (2005) 1232–1241

Material and Methods
In short, virus (1.5 μmol of viral
membrane phospholipid
) was solubilized in 100mM
octa(ethyleneglycol)-n-dodecyl monoether (C12E8) (Calbiochem,
San Diego, CA) in buffer containing 5mM Hepes,
150mM NaCl and 0.1mM EDTA (HNE buffer).
==

Hope to hear from you soon.
nirajrm@yahoo.com

-Niraj-

QUOTE (Niraj @ Mar 20 2006, 08:31 PM)
Dear All,
This is my first post!
Can anybody tell me how to calculate the 1.5 μmol of viral
membrane phospholipid?

Hi Niraj,
Sorry, the short answer is no... I've had a look at this paper, and I'm not sure how they estimated the molar quantity of phospholipid which they used to make virosomes.
Influenza virions are very variable in their overall size (i.e. it's a really pleomorphic virus); although the RNA genome segments are (mostly) packaged in a regular way, the size of the capsid (and so the number of viral protein molecules and host-derived phospholipid molecules per capsid) is *very* variable; there is no 'standard' influenza capsid, and no 'standard' molar weight for a single capsid.
See: http://www-micro.msb.le.ac.uk/3035/Orthomyxoviruses.html

It's likely that they analysed their bulk viral lipids in previous work, probably by estimating the total amount of phosphorous and extrapolating a molar phospholipid concentration for their stock virus from this.
Total phosphorous analysis of lipids is reasonably straightforward, especially of you can find an analytical biochemist to help (!): see http://www.cyberlipid.org/phlipt/pl2b0007.htm#top.

If their methods aren't described in a previous publication, contact the corresponding author and ask for details.

hope that helps,

D.

-del-