A single line often inverts meaning once you see what it
answers, so neighbouring messages are always shown.
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Yes - hard to culture from natural samples. First issue is you are getting animals that are likely at different stages ininfections - early, late, persistent, recovering - who knows? We don't know how long viremia lasts in Mastomys with Lassa virus. Seems much lower than in humans. Rabies - long term infections, bats carry for a loooong time eventually some [all?] get sick. For SC2 from humans unless the Ct values are really low say low 20s it's very difficult. Not to say that there is not infectious virus there and that under the right circumstance (inhaling it directly into the nasal passages or lungs even a fairly low may be all it takes. I'm just guessing but unlikely bats would produce their Covs at high levels even if you caught then just right . The intermediate hosts/reservoirs, might grow virus to higher levels (like say civets for SC1), but probably varies a lot from animal to animal like humans . Sicksnotty nose pangolins might have higher loads for their viruses, too. Same apparently true of camels for MERS-CoV. All these considerations are why no-one's cultured ebola virus from a bat yet.
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And if you just out sampling to look for diversity you are probably going to store the samples to preserve RNA rather than hope to culture anything.
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Yes - you might try to get lucky and if your cold chain was good freeze some sample away, but RNA Is the way to goin most field situations.
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But - most likely - screening by culturing is not going to be a sensitive as screening the RNA, if you know what you are doing with the RNA .
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2021-03-08 14:58
Edward C. Holmes
We and colleagues do this all the time. The plan is always to get into a cold chain as quick as possible for sequencing. We do have a portable -80C we use in some cases, but it's usually a case of storage in RNAlater.
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In general the RNA (even fragmented non-infectious) hangs a lot longer than any infectious virus.
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Yeah, culturing viruses from bats or any other animal = bloody hard. I wouldn't be surprised that if you had 50 bats all infected with SC2, you'd only be able to grow it out of one of those.
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Explains some of the problems in the diagnostic space - Start mixing in detection with antigen assays [which correlates not so well with infectious virus or RNA] and it gets complicated fast.
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But that means these ideas about WIV sampling viruses from the wild and one of the accidentally escapes might bewrong?