I am using baculovirus system for producing protein in SF21 cell. During this I found the exact band during western with anti HIS antibody in control cell line.
My first thought is cross contamination somewhere.
Are your control cells infected or non-infected? If non-infected then it should be possible to see if you have a contamination with your virus. If they are infected with a control virus it will be nearly impossible to see if you have any cross contamination. If it's happening here then have a good look at your routines to see if there's any place where a cross contamination is possible. (Giving a good cleaning to all the sterile benched would never go amiss even if that's not the problem).
It's also possible for some cross contamination to have occurred after harvest. You will have to look at your process from harvest to western to see if there's any places that this has occurred such as being careful loading the gel so not to get any spill over from adjacent wells.
Thanks Richard, I am sure about contamination is not there, My control is without infected and apart from that I am not sure can virus infect via aerosol because both the flask are growing in same chamber
I don't think you are getting transfer through aerosols, if you are culturing your cells properly with some form of physical barrier over the flask top (e.g. lid with gas permeable membrane)
It is possible depending upon your antibody and your western conditions you are detecting a native Sf9 protein with a high number of His.