Share this page!

Rajeev Jayadevan Profile picture
Twitter logo
29 Nov, 5 tweets, 2 min read
P681R Mutation located next to the furin cleavage site of Spike protein of Delta variant appears to increase its ability to create syncytium.

Among all the variants to date, delta does this the most. But the mutation alone doesn’t mean anything.

1/3
nature.com/articles/s4158…
Other sub-lineages of delta with the same mutation failed to make an impact. Thus, the success of a variant depends on more than the sum of its mutations.

Clearly, almost like a lottery, some combinations work better than others, while the remainder (vast majority) perish.

2/3
The omicron variant has three mutations at the furin cleavage site, H655Y, N679K and P681H (not P681R). Thanks @firefoxx66 (for👇)

P681H sits 5 residues upstream of the FCS, was seen in variants circulating in the UK, (alpha), US as well as Nigeria.

3/3
covariants.org/variants/21K.O…
About syncytium formation. For those new to cell biology, when several cells combine (fuse) together e.g. after a viral infection, it is called a syncytium. It has many nuclei (a typical cell only has one). Our heart muscle is naturally a syncytium. See whole thread for context.
Attaching an older thread I made on how the SARS-CoV2 virus fuses with the human cell.

See thread above 👆 for context

• • •

Missing some Tweet in this thread? You can try to force a refresh
　

Keep Current with Rajeev Jayadevan

Rajeev Jayadevan Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @RajeevJayadevan

Rajeev Jayadevan Profile picture
2 Dec
Evidence that T cell immunity generated by vaccine is not fooled by mutations or variants

Study from India shows CD4 & CD8 T cell response was conserved for delta & for the older version of the virus.

This is because there are UNCHANGEABLE parts of the spike protein.

1/16
For those new to immunology, broadly speaking:

🔹Neutralising antibody levels correlate with protection from infection in the nose and throat, while T cell Immunity guards against organ damage and severe disease.

Will explain below 👇

2/
🌳 Imagine the spike protein to be a mango tree. Antibodies target the fruit, while T cells target large branches. Mutations are like mangoes that change their appearance. Hence, a few antibodies can get ‘fooled’.

But the branches are unchanged; hence T cells work as usual.

3/
Read 19 tweets
Rajeev Jayadevan Profile picture
1 Dec
Updates from this week’s Tuesday COVID-19 meeting that I have been chairing since the onset of the pandemic.

This week we audited 105 deaths, and found something significant:

🔹Unvaccinated individuals were 17.6 times more likely to die, compared to vaccinated.

More updates👇
In a Kerala village of 15,000 (adult) population, only 38 were unwilling to take vaccine.

🔹This translates to a vaccination acceptance of 99.8%

Note: we don’t have mandates here.

The few remaining unvaccinated were recently or currently infected (90 day gap advised)

2/2
Tuesday COVID-19 meeting update #3

Although “overall CFR (case fatality rate) is low”, doctors pointed out that this is a misleading statement, underestimating the destructive power of the virus. It is like saying “everyone in India is 28 years old”

CFR is high @ older age

1/3
Read 5 tweets
Rajeev Jayadevan Profile picture
30 Nov
Had tweeted on this topic since last year.

Mutations are more likely to occur when the virus gets a chance to LIVE FOR A LONG TIME (a few months, as opposed to 10-14 days in most healthy people) in an individual patient, e.g. immunosuppressed.

1/6
nejm.org/doi/full/10.10…
The reason is that 1-2 weeks might not be enough for virus to STUDY our immune system, MUTATE, and THEN select the best candidates from all the mutants produced.

Therefore, it is far more likely to occur after prolonged SARS-CoV2 virus infections.

2/
Besides, these patients could easily get infected at hospitals from other patients who could be harbouring chronic infection by the virus which has already added a few mutations.

Plasma therapy (essentially an antibody buffet) helped addition of mutations in such patients.

3/
Read 10 tweets
Rajeev Jayadevan Profile picture
25 Nov
Apples 🍎 to oranges 🍊 comparison alert

Ref. A recent small retrospective study on Covaxin showed “50% effectiveness”. See link for paper & comment

I saw @GargiRawat was unfairly criticised for reporting

See thread; it takes time to understand👇

1/16

thelancet.com/journals/lanin…
1. The original efficacy study on Covaxin was a randomised controlled trial involving over 25,798 people.

This showed 77.8% efficacy against symptomatic disease, 93.4% against severe disease, 63.6% for asymptomatic and 65.2% at delta variant. Had tweeted in detail earlier.

2/
A randomised study starts with 2 groups of people. One gets vaccine, the other gets placebo. They are observed “prospectively” that is looking forward-during a study period. Disease outcomes are measured & compared between the groups. The % difference is reported as efficacy.

3/
Read 20 tweets
Rajeev Jayadevan Profile picture
25 Nov
From our weekly COVID-19 meetings that had been going on ever since the pandemic started, we issued several advisories to policy makers, media, doctors and the general public.

From this week:

🚩Ignoring early symptoms (e.g. fever) can lead to severe outcomes.

Thread 👇

1/5
COVID-19 has established treatments available such as

1. dexamethasone (saved more lives than all other drugs in COVID-19; but ONLY when used in the right patient, at the right time, in the right dose)

and

2. monoclonal antibodies (only for select indications)

2/
If the diagnosis is delayed, these medications cannot be given, we call it “the window of therapeutic opportunity”

Which means the drugs don’t produce the desired effect once that window has passed

Which means our delay is allowing preventable complications to set in

3/
Read 5 tweets
Rajeev Jayadevan Profile picture
25 Nov
Myocarditis with mRNA vaccine.

“Patients invariably had chest pain” is a misleading statement.

It is more like “In all REPORTED cases of myocarditis, chest pain was present”

Note myocarditis need not cause chest pain, hence not all patients will seek medical attention.

1/
The diagnostic criteria of “myocarditis” are given below.

However, patients are more likely to notice chest pain than other symptoms. Hence these people get diagnosed, (and reported).

Chest pain is more likely in those who ALSO have PERICARDITIS.

2/
ahajournals.org/doi/pdf/10.116…
Myocarditis can occur with other symptoms like palpitations, shortness of breath or may not cause overt symptoms.

Myocarditis might only cause ECG or ECHO cardiogram abnormalities or isolated elevation in cardiac enzymes like Troponin.

This means we could be missing cases.

3/
Read 9 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal

Thank you for your support!

Follow Us on Twitter!

Like this author's thread?

Get emails when @RajeevJayadevan has new unrolls!

Check out other threads from @RajeevJayadevan!

Read all threads by @RajeevJayadevan

:(