One of more genuinely stupid comments I hear about HIV-1 research goes along these lines:
Why we spenden so much moneys on HIV when we aint got no vaccine and we could be spendin it on cancer/heart disease/diabeetus/whatever disease I personally am at risk for?
No, we dont have a vaccine for HIV-1 yet. But that doesnt mean HIV-1 research for the past 25 years has been ‘worthless’. HIV-1 research has wildly expanded our understanding of the human immune system, ie helps all of us.
The field has also developed an army of assays, cell lines, reagents, a million tools for characterizing HIV that did not exist before 1984. But the development of all of these new tools created a new problem: standardization. If every lab is using a different ‘home-made’ assay to study HIV, how do you compare their results?
So in 1988 the National Institute of Health created a ‘bank’ for all the tools labs had developed to help keep things standardized, the AIDS Reagent and Reference and Reagent Program. You dont have to develop and characterize your own antibodies to gp120 anymore– you just order #288 and you know exactly how much to use for a Western Blot or ELISA or whatever, and everyone ‘believes’ your results.
One of the reagents I use every day is a cell line called TZM-bl. TZM-bls are cells that used to be cervical cancer, but HIV-1 researchers got it to express all the receptors HIV-1 needs (CD4, CXCR4, CCR5) so TZMs are suceptable to HIV infection. TZMs also have a couple of genes inserted into their genome that are under the control of HIV Tat, β-galactosidase and luciferase. So, when TZMs are infected with HIV-1, they will stain blue or glow (depending on what assay you want to use).
These assays are really useful when youre trying to figure out how many infectious viruses you have in a stock solution (with HIV, you have a lot more dead viruses than you have ‘live’– you dont want to count the dead ones). You take your stock, do a series of dilutions, and see how far out you have to dilute the stock to get one blue TZM cell. Say you have to dilute it 1,000 times– that means you have 1,000 infectious viruses per X volume. So if you need 5,000 viruses for your experiment, you know exactly how much of your stock solution you need. Yay!
Well, heres where the ‘oops’ comes in. Every HIV-1 lab in the country uses TZM-bl cells for something. All from the same stock from the NIH reagent bank. Turns out this stock has been contaminated with another retrovirus– murine leukemia virus.
This doesnt effect me at all, personally. MLV is a gamma retrovirus, so it has no effect on the blue/glow assay I do every day (MLV doesnt have the right proteins to interfere with that assay, which is HIV specific), BUT it could be screwing over other labs if they are doing something different (like measuring reverse transcriptase activity levels).
This paper brings up a very, very important lesson: ALWAYS DO ALL THE RIGHT CONTROLS IN YOUR EXPERIMENTS, INCLUDING MOCK/NEGATIVE CONTROLS!!!
This lab discovered that something was ‘wrong’ with their cells (which turned out to be ALL of our cells) by doing all of the appropriate controls… and getting unexpected results. If they had skipped their negative controls, they wouldnt have noticed that they were getting reverse transcriptase activity off of their uninfected cells.
Can never have too many controls.