Retrovirus freezing - (Aug/22/2008 )

Hi everybody,
I have one question for people who are working on retroviruses. In my lab, retroviral vectors are used to infect cells just when they have been produced, so that we do not freeze the viruses for other later applications. With your experience, do you think that it is possible to freeze the viruses, without deteriorating them too much ? Moreover, we do not concentrate the viruses before infection. Is it possible to freeze the unconcentrated viruses ?
Thanks for your answer.
Christophe.

I too prefer using fresh retroviruses for infection. We too do not concentrate the virus. We have tried storing viruses up to a month at 4C with very little loss of efficiency or storing for several months (or may be it could stay indefinitely) by snap freezing viral supernatant in liquid nitrogen or dry ice. Following article I assume has the information even though I do not have access to the full article! May be someone with access can post it here.
Efficient Manipulation of Hedgehog/GLI Signaling Using Retroviral Expression SystemsBy: Maria Kasper

I work with HIV (a retrovirus) and we store aliquots at -80 and thaw them for use. They lose some of their infectivity by repeated freezing and thawing (we do not have to concentrate our stocks before use, but I assume your retroviruses are in RPMI-DMEM or some other medium as are our stocks).