Emmanuel Justin Profile picture
Feb 16 9 tweets 7 min read
INFLUENZA A ... H3N2
I DON'T LIKE THIS ONE !

Since its emergence in 1968, H3N2 has undergone a considerable number of mutations. It is, in a way the "Omicron" of HxNx viruses with several types :
- H3N2 HUMAN, which was the main strain this winter 2022/23 with in US (CDC) :
2) H3N2 SWINE, which evolved from H2N2 by antigenic shift, and caused the Hong Kong Flu pandemic of 1968 and 1969 that killed between one and four million people globally.
3) H3N2 AVIAN, which infects birds and mammals.

frontiersin.org/articles/10.33…
4) H3N2 CANINE, which was identified in Asia during the 2000s with a mutation that adapted from its avian influenza origins and was recently detected in US.

"Canine influenza is on the rise among dogs in Philadelphia area"
inquirer.com/news/canine-in…
5) So far, these different types are distinct at the antigenic level with little transmission from one species to another.

journals.asm.org/doi/10.1128/JV…
and
ncbi.nlm.nih.gov/pmc/articles/P…
6) Nevertheless H3N2 continues to mutate very rapidly including in humans.

"Prevalence and mechanisms of evolutionary contingency in human influenza H3N2 neuraminidase"
nature.com/articles/s4146…
7) It is urgent to monitor and above all, to go faster in the preparation of vaccines against all HxNx.

"Ferret model to mimic the sequential exposure of humans to historical H3N2 influenza viruses"

sciencedirect.com/science/articl…
8) As the risk does not only concern H3N2, we can have also recombinants, for example with for example H5N1.
Thanks for reading.

"Reassortment between avian H5N1 and human H3N2 influenza viruses creates hybrid viruses with substantial virulence"
pnas.org/doi/10.1073/pn…

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More from @ejustin46

Feb 17
AN INCREASINGLY DIFFICULT GROWTH RATE OF VARIANTS, TO FORECAST!

Thanks to @JosetteSchoenma and @TRyanGregory
who post very high quality tweets, for their criticism of my last thread.
This helps move the discussion forward 😃 Image
2) BQ.1* appeared in Sept 2022 and spread mainly until end of 2022. The growth advantage in CoV-spectrum is 36% (sept-dec). If we check on gov.UK, since the week when it was higher than 1% of the sequences, we obtain a higher average growth rate over 50%. ImageImage
3) XBB.1* appeared in Nov. 2022 and is gradually replacing BQ.1* in Europe at the beginning of 2023. Its growth rate in CoV-spectrum is 30% and we obtain in the UK.gov data, a similar growth rate. ImageImage
Read 7 tweets
Feb 16
THE PANDEMIC HAS CHANGED FACE !
On this superb and latest graph of the UK government, we see very clearly since 6 months, a "swarm" of variants with an increasingly high number of sub-variants. Image
2) In such a situation, the singular variant approach has lost its relevance.
I therefore reprocessed the data in the 4 main families of variants in UK : BA.5*, BQ.1*, CH.1* and XBB.1* Image
3) XBB.1.5, which was announced as THE variant, which would very quickly become dominant, found itself faced with the BQ.1* family, which numbered no less than 11 descendants, and which already occupied the field. In a world in polycrisis, welcome to the world of polyvariants !!! Image
Read 5 tweets
Feb 15
THE "REGULATOR" FUNCTION of VIRUSES.
(1st part)
We sometimes hear that viruses are there, to regulate the human species which is too numerous, and which is destroying the planet.
Before wondering about the role of "regulator" of viruses, a few brief reminders.
2) Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity.
Current estimates indicate that the total number of virus particles exceeds by one order of magnitude the total number of cells or even stars.
3) In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity in a way analogous to sexual reproduction. We wouldn't be here without viruses !

ncbi.nlm.nih.gov/pmc/articles/P…
Read 14 tweets
Feb 15
COVID NEUROVASCULAR INJURY in few graphs
@MeetJess @fitterhappierAJ
@white_bite @DavidJoffe64
@arijitchakrav

Neurovascular injury with complement activation and inflammation in COVID-19
academic.oup.com/brain/article/…

Microvascular injury and thrombus formation.
2) Complement activation and immune complexes.
Immunostaining for (A and B) C1q, (C and D) C4d, (E and F) IgG, and (G and H) IgM shows minimal staining in the brains of non-COVID-19 controls and extensive deposition on endothelial cells in the blood vessels of COVID-19 patients.
3) Characterization of inflammatory infiltrates.
The perivascular region shows infiltration of (A) CD68+ macrophages, (B) CD3+ T cells, (C) CD4+ T cells, (D) CD8+ T cells and (E) a few CD20+ B cells.
Read 6 tweets
Feb 14
ETA in NIGERIA
Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria
nature.com/articles/s4146…

1. Genomic epidemiology of SARS-CoV-2 in Nigeria. Image
2. Bayesian phylogeographic reconstruction of the B.1.1.318 variant. Image
3. Bayesian phylogeographic reconstruction of the B.1.525 variant. Image
Read 4 tweets
Feb 12
SOME ARE LUCKY TO HAVE A CRYSTAL BALL !
I am amazed to see some "experts" announcing the end of the pandemic, or that there will be no more peaks based on data or trends which represent only 20% of the reality of the pandemic.

2) In a recent study on viral interference, 2 graphs perfectly illustrates what is happening recently. With each emergence of a new variant mounts an interferon response leading to temporary immunity (red) to a subsequent infection, immunity which wanes with time.
3) Within a population, some people (shown in black) will be susceptible to infection, while others who were recently infected or recently vaccinated, will have varying levels of immunity (shown in shades of red).
Source : knowablemagazine.org/article/health…

rupress.org/jem/article/21…
Read 7 tweets

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