[nudephil (OP)]

Here's a question that's come in from Alex:

Is it possible to get the COVID-19 virus to fluoresce using a reagent?

If it were possible, might it be possible to detect infected persons by having them breath out while spraying the reagent into their breath stream from a compressed can?

Any response?

[alancalverd]

Simpler, less hazardous and more accurate to collect exhalate and test it immediately, on site, in vitro.

Can't say more as I have a technical and financial interest in a company doing just that, right now, but watch this space!

[evan_au]

Is it possible to get the COVID-19 virus to fluoresce using a reagent?

Yes. This is often how virus or bacterial infections are diagnosed.
A sample is exposed to an antibody, which is specific to a particular pathogen. If the pathogen is present, the antibody will stick to the pathogen.
- In some cases, the antibody itself fluoresces
- In other cases, a second, fluorescent antibody binds to the first antibody
- These are generally laboratory-run tests.
- These antibodies are too expensive to go spraying into the air...

The antibodies need to be chosen carefully, so it doesn't react with other, regular coronaviruses.
See: https://en.wikipedia.org/wiki/Direct_fluorescent_antibody

Some labs are also running RNA sequences of positive COVID-19 cases.
- Modern high-speed genetic sequencing uses fluorescent marking of the base pairs to read the genetic code
- This is a general technique that can be used for any genome (it was developed for the Human Genome Project),
- It is much slower than the antibody tests mentioned above.
See: https://en.wikipedia.org/wiki/DNA_sequencing#Single_molecule_real_time_(SMRT)_sequencing 

[Bored chemist]

Is it possible to get the COVID-19 virus to fluoresce using a reagent?

Yes. This is often how virus or bacterial infections are diagnosed.
A sample is exposed to an antibody, which is specific to a particular pathogen. If the pathogen is present, the antibody will stick to the pathogen.
- In some cases, the antibody itself fluoresces
- In other cases, a second, fluorescent antibody binds to the first antibody
- These are generally laboratory-run tests.
- These antibodies are too expensive to go spraying into the air...

The antibodies need to be chosen carefully, so it doesn't react with other, regular coronaviruses.
See: https://en.wikipedia.org/wiki/Direct_fluorescent_antibody

Some labs are also running RNA sequences of positive COVID-19 cases.
- Modern high-speed genetic sequencing uses fluorescent marking of the base pairs to read the genetic code
- This is a general technique that can be used for any genome (it was developed for the Human Genome Project),
- It is much slower than the antibody tests mentioned above.
See: https://en.wikipedia.org/wiki/DNA_sequencing#Single_molecule_real_time_(SMRT)_sequencing 

Million dollar question: does the antibody fluoresce without the virus?