Hi, It depends on your retroviral vector, GFP used etc, but if the virus works you should see the signal  about 48h after transduction. Did you use polybrene  before infection? Are you shure your virus has a good titer?  If you see the signal but it is weak  do not use phenol red  and protein containing media for microscopy.

What was the volume of virus that you used and how many cells did you infect? With neat supernatant, sometimes the expression intensity is quite low.

To maximise the dose, you could concentrate your supernatant with an overnight spin (20hours) at 4500rpm and resuspend in a smaller volume (say 0.1ml). That would allow you to get more viral genomes into a small pool of cells and thus see greater expression intensity.

Thank you Maria. I can detect after 4-5 days with weak signal. polybrene was used at the time of transduction but I don't know about the titer of virus. Do you mean the media without phenol red and protein when I see the signal through microscopy?

 Thank you Joy, \

Actually I have used Platinum A cell (293T cell based cells) for the virus production.

Thank you for your suggestion.

Hi John,

Thank you for your suggestion. I am trying to concentrate the virus. I hope it helps me.