I am using a Baculovirus system in insect cell sf21 for the production of recombinant protein. I did the transfection approx 80 hour before now its showing the needle like structure in media, My doubt is its bacterial contamination. But on the otherhand cell appear healthy in plate and there is no cytopath character change in the transfected cell. Kindly tell me the cytopathic character for SF21 cell appeared due to transfectection.
The needle-like structures could be a result of a component of the media or precipitating. If the cells are alive you could see if a media change helps? Bacterial contamination will give a very high background in the plate under a microscope, make the media cloudy and kill the cells.
Do you have an uninfected flask/well at the same starting confluency to compare to? I am not sure what you mean by cytopathic characters, but infected cells will stop doubling, which will be noticeable if the cells are not already confluent. They will become larger compared to uninfected control cells. You may notice a granular appearance of the cytoplasm or appearance of vesicles.
Floating cells can indicate cell death, but SF21 viability in adherent culture is not contact dependent and depending on media, can be loosely adherent so it is not a reliable indicator. Dead cells will eventually disintegrate.
I hope this helps a little.
I agree totaly with Alison Catherine Lilley beside the CPE could be dependent on what type of strategy of expresion you folow direct or indirect and which promotor which gene you delet to describe correctly the CPE
as for the needle-like structure it could be cristals of precipitated media component or it could be the resulted lipoprotien
Maybe the needle like structure is just the sf21. I saw this phenomenon in Sf9 when they grew too old in the adherent culture(usually with very little medium). I think you can ask lifetechnologies for help. see the attachment P80.
lifetechnologies.com/support or email [email protected]
wish you good luck.
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