In an article over on Popsci, they mention that the CDC will attempt to grow samples from a 60-year-old vial of smallpox virus in petri dishes. I thought viruses required living cells to reproduce since they’re effectively just little RNA syringes.
Am I wrong about viruses? or is there more to the process than the article explains (a vague “… will try to grow the contents of the vials in petri dishes, to see if …”)
You use a petri dish in which a culture of appropriate cells are growing, and you infect those cells with the virus. It infects and reproduces.
Also, although there are RNA viruses, the smallpox virus uses DNA as its genetic material.
The Petridish will have human cells growing in it too. Petridish is just the plastic container. You can put agar in it and grow bacteria or molds, or put cells in it to grow viruses.
So, can you get these pre-cultured dishes (with the cells already in them) from a supply house, or do the labs have to grow their own?
And here I thought I was being clever to remember that viruses had RNA rather than DNA. shrug
Sorry, Stillettos, I meant dishes with a film of agar (or some other growth medium). I’m used to seeing them on Mythbusters where it’s always a “germs” experiment they’re being used in, so the ones they use always have a brown film of agar on the inside bottom of each container.
If you need a cell line you don’t have, you can order them from a supplier. They’ll come either in a liquid culture or frozen. You can then spread them out on an appropriate nutrient agar plate or cell culture flask or whatnot, and passage them into new growth media every few weeks or so.
See ATCC.
How to culture small pox : " To develop a modern smallpox vaccine, we have adapted vaccinia virus that was derived from the existing Dryvax vaccine for growth in a human diploid cell line."
Diploid is really referring to normal.
I thought it was interesting to find out what it really means to say “diploid cell line”.
I knew of HeLa cells but they are cancerous , being Henrietta Lacks’ cervical cancer - abnormal. But there is diploid WI-38 as a common diploid cell line
“WI-38 is a diploid human cell culture line composed of fibroblasts derived from lung tissue of a three month old white female fetus.”.
Diploid means simply that there are two copies of every chromosome in every cell. Human cells, in order to be grown in culture, need to be “immortalized”, or else they die off after 40 or so replications. Immortalization is done by fusing the cell of interest with a cancer cell line, which ignores this replication limit. However, chromosomal instability is a common phenomenon in various cancers, meaning that the chromosome number can vary (sometimes widely) from cell to cell and from generation to generation. Obviously, if your cell line that you’re experimenting on is gaining and losing chromosomes willy-nilly, that can effect your research. So a stably diploid human cell line is a nontrivial achievement.
Petri dish has become a bit of shorthand for a dish containing bacterial growth media, even among scientists.
Here is an image search for cell culture in petri dishes. The pink/red stuff is the culture medium. Usually, the cells are grown as a layer on the bottom of the plate, but some cell lines grow as a suspension. As others have said, the virus is added to these cells and it’s able to infect them and replicate. In most cases, the infected cells burst open releasing new virus particles into the culture medium.
I don’t know of any way to purchase plates with cells already growing in them. Eukaryotic cells are not as hardy in culture as bacterial cells. As a result, they need to be protected for shipping by freezing or in a special liquid medium as mentioned above.