I am producing several lentiviruses for different purposes, but I am finding some amazing results: an old stock of certain virus can infect with no problem mouse and hume glioblastome cells (GL261 and U373), but a new one can not: only human cells can be properly transfected but mic can not. In this case I only can get very poor results, about 2-10 times less, depending on the virus used.
All of them have been produced following same protocol and HEK293T cells.
Anyone have face this kind of problem? I can not imagine why this is happen. Maybe a contamination of VSV-G plasmid has produce incorrect viruses? Micoplasm can not be the reason because same cells were used for both viruses.
Any idea will be wellcome. Thanks in advance!
Specificity of different stocks will be different because of differences in the virus titer. Your old stock may have more active virus particles than your new stock. Increasing the amount of virus during infection may help you to reach equal transfection levels.
The following publication gives an overview of different titration methods and it depends on your experiments which protocol to follow.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1534021/
Contamination of VSV-G may lead to less virus particles. But VSV-G protein that is secreted into the culture medium during virus production may have different effects on different cells.
Finally we have now a result that explain everything: mycoplasma contamination. My viruses seems to do their work properly...if they can enter into the target cells....:-(
Everything can happen in this situation...Thanks a lot for your kind answer!
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