Sf9 Vs. Sf21 Cells for baculovirus

[Dima Klenchin]

:We've decided to get some new Sf9 cells for various reasons and when I went
:to order them, I noticed invitrogen has some new strain called Sf21.  Their
:catalogue says that some proteins express better in sf21 cells.  I was
:wondering if anyone has any experience with these cells and if they really
:work better for expression than Sf9.  I've never been impressed with the
:ammounts of protein we get with Sf9 so I'm interested in improving our
:yeilds by switching strains.
:
:Also, how are these cells (sf21) for amplifing stocks of virus?

sf9 is a clone of original sf21. There are no gross differences between 
the two. sf9 became (pretty randomly more popular - but some people 
stubbornly say the parent cell line is better. With three different 
proteins I compared 9 and 21 and I think the difference, even if it 
exists (there was some for one, but not for the other two) is smaller 
than the variability between different preps. sf9 are smaller and slightly
less fragile to shear stress - that's why I prefer them. They amplify 
virus to about the same extent. 

BTW, I also compared High5 and sf9. There is a _huge_ difference between
the two under suboptimal, very low MOI infection - High5 made > 10x
more protein under these conditions. Under optimized conditions, however, 
there again was only minor and variable difference. High5 don't grow in 
suspension and thus are more expensive to deal with on large scale. 

YMMV but I suggest sticking to what you already know works. 

        - Dima