Thread by @DrEricDing

So a new study claims #SARSCoV2 can integrate into human DNA 🧬 genome. Semi-doubtful. David Baltimore, a virologist who won the Nobel Prize, describes the findings as “unexpected” & notes that it only show that fragments of #SARSCoV2 genome integrate. 🧵
sciencemag.org/news/2020/12/c…

2) “Because it is all pieces of the coronaviral genome, it can’t lead to infectious RNA or DNA and therefore it is probably biologically a dead end. It is also not clear if, in people, the cells that harbor the reverse transcripts stay around for a long time or they die.”

3) current study only showed this integration in a lab dish, although it also cites published sequence data from humans infected with SARS-CoV-2 that suggest it has happened.

4) The authors emphasize that their results don’t imply that SARS-CoV-2 establishes permanent genetic residence in human cells to keep pumping out new copies, as HIV does.

5) People who recover from COVID-19 sometimes later test positive for SARS-CoV-2, suggesting their immune systems could not ward off a second attack by the coronavirus or that they have a lingering infection.

6) A study now hints at a different explanation in which the virus hides in an unexpected place. The work, only reported in a preprint, suggests the pandemic pathogen takes a page from HIV and other retroviruses and integrates its genetic code—but, importantly, just parts of it.

7) All viruses insert their genetic material into the cells they infect, but it generally remains separate from the cell’s own DNA. Jaenisch’s team, intrigued by reports of people testing positive for SARS-CoV-2 after recovering, wondered whether this is artifact from PCR.

8) “Why do we have this positivity, which is now seen all over the place, long after the active infection has disappeared?”

9) In addition, virologist Melanie Ott she notes that SARS-CoV-2 RNA replication takes place in the cytoplasm. “Whether it happens in infected cells and … leads to significant integration in the cell nucleus is another question.” (Ie. Cytoplasm diff location from cell nucleus)