Indeed, performing PCR(  ) revealed a few colonies that contain the BHR1 gene. You now transfect SF9 cells with each of several  positive mini-preps, in order to obtain the baculovirus containing BHR1. An example is described below:
  1. SF9 cells are transfected with DNA from several positive clones containing the whole viral genome.
  2. Plates are checked for cell death 72hrs post transfection (cell death is measured by the amount of floating cells vs. adherent cells).
  3. Plates with over 50% floating cells should be chosen for further propagating of the virus.
You now commence with  propagating of the virus () - you infect the insect cells and amplify your viral stock. You add the virus to SF9 cells in suspension culture and  examine the cells under the microscope 24, 48 and 72 hrs post-infection and then dye them with trypan blue  and assess viability. Here are your results:

Time
Post-Infection
%
Live Cells
%
Dead Cells
Debris
24 hrs
90
10
-
48 hrs
60
40
+
72 hrs
30
70
++

What are your conclusions? (Choose between possible and wrong)

1. I am too tired to conclude.
2. After 72 hours significant cell death has occurred. It is better to harvest the cells earlier in order to obtain the virus.
3. After 72 hours significant cell death has occurred. It is suitable to harvest the cells at this point in order to obtain high amounts of BHR1 protein.
4. Since you are interested in harvesting the protein you should harvest the cells at 24 hrs post-infection.