
Detection of Airborne Viruses - adunk
https://www.kth.se/mst/research/sensors/project/detection-airborne-1.523039
======
bionhoward
Looks great until they hit the ELISA (antibody test) which requires pre-
existing antibodies for the target. That’s like when you search for your keys
under the streetlight when you dropped them in the dark. Anything novel
becomes an expensive and slow ordeal (aka, it doesn’t happen in practical use)
because you need “test kits” (sound familiar?) ... just imagine your malware
detector would only flag code which exactly matched exploits it had seen
already.

If they replace ELISA with a nanopore sequencer like Oxford’s MinION then you
could detect all the DNA RNA in your breath and feed that data into algorithms
like BLASTN. Suddenly you can see viruses no one ever saw, and thousands of
them at once. Meta genomics is more sensitive than ELISA because you can see
everything and more efficient because you can use the same reagents to test
for anything. Then we detect virus everywhere as soon as the sequence is
available on NCBI (we had a sequence for CoV-19 two months & four days ago)

[https://www.who.int/csr/don/12-january-2020-novel-
coronaviru...](https://www.who.int/csr/don/12-january-2020-novel-coronavirus-
china/en/)

~~~
netjiro
I don't know the technical details of MinION.

Coupling good capture with amplification and detection is required. When
working on dna detection you use something like pcr for signal amplification.

But surface detection can in some cases be more sensitive, since you generally
have a lot more surface fragments available than you have dna or rna.
Especially since many viral diseases form have huge ratios of surface
fragments per every well formed infectious viral particle.

Generally: a sequencer by itself doesn't have the sensitivity required. For
example, for norovirus we're talking about detecting a few virus particles per
cubic meter of air. You need insanely sensitive detection tech to be able to
do that.

~~~
virusduck
> I don't know the technical details of MinION.

Neither does OP.

------
netjiro
I worked on one of these projects. This technology has amazing potential for
(near) real time detection and monitoring of the spread of airborne disease
throughout society. Think shoe box sized air samplers in common spaces that
send real time data to monitoring health agencies, alert when a space is
contaminated, and so on. The same tech platform can also be used to
inexpensively and quickly test individuals.

Unfortunately the funding for continuation was lost in the shambles of the
partial collapse of Getinge a few years ago. I was not able to find anyone
else interested to continue funding the prototype development when the
remnants of Getinge did not prioritise the project.

Near real time in this case can mean as little as a few hours.

We had a total funding of ca EUR 5M for the first prototyping project. If
anyone has interest and money, I can pull together people and ip.

------
DoctorOetker
In "the andromeda strain" there is a scene where they try to determine the
size of the particle, by selecting different filtration sizes between an
infected an uninfected mouse / rat. Is this representative of how droplet
sizes are measured? Has this been measured for SARS-CoV-II?

~~~
thatcat
no

~~~
DoctorOetker
which no or both no?

~~~
thecupisblue
Well if the first one is a no, then the second one is obviously a no since
that method isn't used. Find more on virus measurement methods here:
[https://www.cambridge.org/core/journals/parasitology/article...](https://www.cambridge.org/core/journals/parasitology/article/sizes-
of-viruses-and-the-methods-employed-in-their-
estimation/BA71C94D73307F5CA7C63753135507F9)

~~~
DoctorOetker
"this" in the second sentence refers to droplet size regardless of measurement
method. I have asked for the SARS-CoV-II droplet size distribution many times
before, for example here:

[https://news.ycombinator.com/item?id=22519323](https://news.ycombinator.com/item?id=22519323)

~~~
thatcat
The droplet size distribution would be for saliva, covid19 would effect this
less than say cough velocity or other variables. The volume of fluid produced
does seem to change with illness and influenza may increase the total volume
produced in a cough with 63% of the particles in the size range of 0.35 to 10
μm as measured by a laser spectrometer in an influenza infected patient.

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4676262/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4676262/)

~~~
DoctorOetker
what I mean is that droplets produced in the lung are not necessary saliva,
and droplets produced in the nose, .... all have varying viscosities depending
on flu or cold, dry cough or not, ...

think about what you are saying, how could what you say be true, and some
diseases be more air borne than others? if a pathogen can trigger specific
immune responses that result in runny noses, or blocked noses it has some
control over the viscosity of different types of mucous our body produces...

so has this droplet size distribution been measured for covid-19?

~~~
thatcat
I mean it's not completely senseless to compare unknown psd to known psd of
sick people. It just seems that as a diagnostic metric it doesn't seem to give
you much new information and would be too error prone.

My thoughts were about fluid dynamics and what causes a particle with a mass
greater than air to become airborne in the first place - force of updraft jet
on surface area overcomes the force of weight, right? So that'd be determined
by the velocity of the air flow and the properties of the fluids interacting.
So you'd have to first either measure velocity of the ejection or make an
estimate and you'd pick a sensor to measure the different particle sizes.
Those sensors typically only give a range of particles as output such as
<2.5u, <10u, etc in ppm. You'd be forced to group the distribution into
discreet intervals and accept more inherent sensor error. Then you have a non-
homogeneous fluid with insoluble solids in it launched at variable velocities
each time so you probably would need multiple samples (how many to overcome
this variance? Can you do it with out over powering your analysis?). Whether
the data was useful would depend on some really good designs that minimize the
variance of the samples.

It would be an interesting experiment, but I doubt you would find
statistically significant results between the different illnesses based on
runny noses vs blocked noses viscosity change. I don't think you really need
to though because runny or blocked nose is already a diagnostic symptom that
doesn't require particle size distribution to determine.

