Questions about viruses for my favorite science dogmatists:

[Orrex]

1. Would it be proper to say "the scientist grew a culture of the virus" when describing a procedure by which a stock of virus is produced? If not, what is the correct formulation?

2. If a disease were running through a population and it wasn't bacterial, how would we determine whether or not it's viral?

I'm not asking because of any ongoing debate here or elsewhere; these are purely hypothetical questions in support of a piece of fiction I'm working on.


Thanks for any info you can provide.

[lizerdbits]

1. We say growing a virus stock

which is done in cell culture.

There are multiple ways used in combination to attempt to determine if you've got virus.

1. Adding serum or plasma (I'm not sure which is more commonly used) to cell culture to see if virus grows, then DNA/RNA sequencing. You could probably also use homogenized tissue after the solids are removed if it seems to be affecting a particular organ, though this isn't something I've personally done so maybe someone else can chime in on that. You should see some CPE (cytopathic effect) if you have virus growth. The trick with that is using the right cells since not all viruses grow in all cell lines, an educated guess of the disease based on symptoms would give an idea of what it might be and steer you in that direction. And hope that person doesn't have another viral infection that infects the same cells which will give you a flask of something you don't want.

2. PCR on blood (or appropriate tissue) if you have an educated guess of what the virus might be so you've got the right primers.

3. Testing serum for antibodies by ELISA. IgG for those who recovered (plus a week or two extra if possible), IgM for those who are a couple weeks into infection or died of the disease.

4. Antigen capture (sandwich ELISA) to determine presence of a specific antigen. Also required educated guess as to what it is.

Now if this is a previously unknown virus that isn't antigenically similar to anything known #3 and #4 are out. #2 might be unless it's genetically similar to known viruses and your primers will pick up those sequences. #1 should work as long as you can isolate virus, assuming you can pick the right cell line.

[Orrex]

2. Excellent--thank you!

This will only make up a part of what I'm working on, but I'd look like a buffoon if I really got it wrong.

Now I can just blame you if I screw it up!

Hardy har har! Seriously--thanks!

:hi:

[lizerdbits]

3. Nerd to the rescue!

I hope the writing goes well! :hi:

[Orrex]

4. My writing is poignant and sublime, obviously...

:evilgrin: But sometimes I need a little help with the details!

[Warpy]

5. You grow viruses in culture media

since they're not really alive, per se, and need living cells in order to reproduce copies of themselves. Bacteria are grown in nutritive media.

A complete blood count with differential is needed to determine whether or not a disease is bacterial. Because of the old way the results were printed, we call an increase of neutrophils, especially bands and segs--immature cells--a shift to the left. When the neutrophils are in the low normal range with no immature cells, we call it a shift to the right, indicating the infection is viral.

Differential counts can show all sorts of things, but that's the basics for determining viral vs. bacterial.

[lizerdbits]

6. Cool, I didn't know that

Since I'm not really in the clinical field. The animals in our studies are deliberately infected with something known so on most studies they don't want CBCs.

[Warpy]

8. Right, in clinical practice when you've got a person in front of you

with a temperature of 104, you really can't afford to sit around with tissue cultures and wait for something to grow, then take apart its genome. You need to know very quickly whether to hit that person with antibiotics or antivirals.

If it's bacterial, cultures are taken and grown out and tested against common antibiotics to make sure you're on the right track with the antibiotic the patient is on, but generally you already know that as a patient will respond within 24-36 hours and the culture takes 72.

Viruses aren't grown out and taken apart unless there's a cluster of similar cases. An example of this would be the hantaavirus cases here in the southwest in the 1990s.

[Orrex]

7. Excellent info--thanks!

I think that I have all that I need, now--I need to be able to refer to the method without getting into the particular details, and I didn't want to reveal my ignorance via a major gaffe.

[TZ]

9. Oh come on!

Surely you want to be like the rest of literary world and just make shit up as you go when it comes to science.....


Oops wait, I was thinking of the Health scare forum....;-)