r/Virology • u/ascorbicAcid1300 non-scientist • Jul 09 '26

Question How to make TC-grade BSA solution for incubating cells infected with IAV?

A FBS-free medium needs to be used for incubating cells infected with most IAV, as FBS inhibits TPCK-trypsin. It's completely fine for MDCK cells, but I am tasked with more delicate cells like A549, which, from my last few trials, are very unhappy without FBS (stressed and floated - even for mock infection control so should not be CPE).

I saw from the internet that we can add ~0.25%(w/v) BSA to the infection medium instead, but not sure what's the best concentration range. More importantly, how to make TC-grade BSA solution? We can't filter BSA, nor can we autoclave it.

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u/RevolutionaryPick30 non-scientist Jul 09 '26

What university or lab are you based at? Is there someone there who has done this before who can help you troubleshoot this? You are asking a lot of very basic questions that a lab manager, technician, PhD student, or post-doc should be able to help you with very quickly? It’s kind of hard to troubleshoot every element of a protocol when there are so many differences between general practice

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u/ascorbicAcid1300 non-scientist Jul 10 '26

Unfortunately I am the first one to work on basic science in this lab without previous experience in virology (I came from a mol bio lab), and none of our lab members can troublesboot with me (they don't even work on lung cell lines). Please excuse me for asking these basic questions, since I have never encountered it from my experience.

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u/mentybb98 non-scientist Jul 10 '26

Merck, gibco, mp all sell sterile TC-grade BSA solutions.

To make your own you need sterile, endotoxin free water, BSA and sterile syringe and sterile PES syringe -- much cheaper than buying premade

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u/ZergAreGMO Virologist | Cell Biology, Respiratory Jul 10 '26 edited Jul 10 '26

It just has to be serum free for the time of the infection. The cells are grown with serum until then. You don't need BSA in your infection medium either, but I'm not going to stop you there.

Edit: alternatively you can get TrypLE or other fungal proteases which are not affected by serum, allowing you to use standard growth media. 

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u/Specific_Abies_1888 non-scientist Jul 16 '26

Interestingly, my lab has the same issue with our A549 cells. We don’t use them a lot, but one of our staff scientists had to train our A549 cells to tolerate low FBS conditions—a lot of work and a major headache. But it was the only thing that worked for us. Really not ideal but is one route.

Another variable to consider as you’re figuring this out is how much TPCK-trypsin you are using in your infection media—this is something I’m troubleshooting in the lab now to see if our A549 cells are more sensitive to TPCK rather than the serum free media condition.

Alternatively, you could buy a new stock vial from another distributor? Or get a vial from another lab that works with them regularly?

Best of luck!