Thread by @microbeminded2

This important study found a significantly elevated frequency of #SARS-CoV-2-specific TNF-α-producing CD8+ T cells in patients with pulmonary #LongCovid (PASC). PASC subjects experienced an average symptom duration of over 6 months: journals.plos.org/plospathogens/…

2/ This is how the authors interpret the finding: "This increased frequency could be detected in response to peptide pools of all the #viral structural proteins in comparison to the resolved #COVID-19 (RC) cohort.

3/ Interestingly, these T cells were also significantly higher in female PASC participants compared to males, which may contribute to the higher prevalence of PASC in #women

4/TNF-α-producing CD8+ T cells also expressed the highest levels of Ki-67, indicating recent activation and proliferation.

5/ Because the half-life of SARS-CoV-2-specific T cells is between three and five months and most of our #PASC participants donated blood over 6 months from symptom onset, it suggests these cells are maintained by viral #antigen.

6/ The presence of persistent viral #reservoirs of SARS-CoV-2 has been proposed as a possible explanation of PASC pathophysiology.

7/ Studies in macaques and humans demonstrated viral replication can persist months after initial #infection in multiple organ systems and viral presence in cerebrospinal fluid has been observed in neurological PASC

8/ Alternatively, damage resulting from severe disease during acute infection has also been proposed as a cause of PASC. However, our results don’t support this idea since 60% of our #pulmonary PASC cohort initially experienced mild disease, yet still developed PASC.

9/ Furthermore, there was no difference in the frequency of SARS-CoV-2-specific T cells when #hospitalized and non-hospitalized PASC participants were compared.

10/ Thus, our findings that pulmonary PASC participants have elevated levels of #SARS-CoV-2-specific T cells months after initial infection suggest ongoing viral replication that is maintaining the pool of inflammatory T cells."