Eric Pyrrhus

1/2
Hmm...

A recent paper looked at evolution of #SARSCoV2 *within* different tissues, which might raise a few questions.

Specifically, the authors found evidence that the #virus might evolve independently in different tissues, especially in immune-privileged sites.

But that's not all...

"High-depth sequencing characterization of viral dynamics across tissues in fatal COVID-19 reveals compartmentalized infection"
https://www.nature.com/articles/s41467-022-34256-y
#virology #epidemiology #InfectiousDisease

"We use 120 autopsy tissue specimens from six subjects to comprehensively examine SARS-CoV-2 distribution and compartmentalization among tissues, and characterize tissue-specific variants... We identified several extrapulmonary tissues that had high viral loads, some of which had strong genomic evidence for compartmentalized infection." "Compartmentalized infection, particularly in an immune privileged site, may accommodate persistent infections, particularly in immunocompromised individuals, which fosters the generation of many novel mutations. Additionally, these sites could provide a viral reservoir that leads to reactivation or recrudescence."

— from (Normandin et al., 2023) https://www.nature.com/articles/s41467-022-34256-y

High-depth sequencing characterization of viral dynamics across tissues in fatal COVID-19 reveals compartmentalized infection - Nature Communications

Here, by high-resolution SARS-CoV-2 sequencing, genomic and transcriptomic analyses from tissue samples, Normandin et al.

^Nature

in reply to Eric Pyrrhus

Eric Pyrrhus

in reply to Eric Pyrrhus • 1 year ago • •

2/2
The authors also found hints of viral "latency" associated with longer infection times.

This would suggest that the rate of viral replication might slow down as the infection proceeds, possibly resulting in a quasi-latent state characterized by very low replication and protein synthesis.

How could this be? How could an #RNA virus slow its rate of viral replication and protein synthesis to help it to persist?

Well, here's just one possible way:
https://mstdn.science/@pyrrhus/109507942028202866
#ViralPersistence

"We... found indications of latency and compartmentalization that were particularly associated with longer infection times... Viral loads were generally lower in subjects with a longer disease course. We found that N gene RNA abundance, but not the proportion of N gene sgRNA reads, also decreased with a longer time interval post symptom onset. This suggests a downregulation of viral structural components specifically later in the disease course, which could play a role in immune evasion... These findings raise the possibility that SARS-CoV-2 enters a slower replication state as infection continues, and warrants further investigation."

— from (Normandin et al., 2023) https://www.nature.com/articles/s41467-022-34256-y

#RNA #viralpersistence

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Eric Pyrrhus

Eric Pyrrhus 1 year ago • •

High-depth sequencing characterization of viral dynamics across tissues in fatal COVID-19 reveals compartmentalized infection - Nature Communications

Eric Pyrrhus

Eric Pyrrhus
1 year ago • •