➡️ Acrux XBB.2.3 was first spotted in India (Karnataka) & then in the USA—origin is somewhat unclear.
Here is the animated map by @Mike_Honey_ showing the spread of the XBB.2.3.* "Acrux" variant around the world. 2/
➡️ Singapore (26%) and India (22%) are still the hotspots.
Spain (11%) and Australia (8%) are also showing recent growth.
Spotted in many other countries including Japan, South Korea, China, the UK & the US. 3/
Though it is present in China & Japan, but still trying to find its way through some other dominant XBBs like XBB.1.5, XBB.1.16, XBB.1.9 etc 4/
➡️ #Acrux is evolving fast in to many offsprings, and one of its descendants, XBB.2.3.2 is considered to be the fastest.
According to @LongDesertTrain, XBB.2.3.2 also has an interesting mute ORF1a:R2159W (NSP3_R1341W) that has shown up in several fast-growing lineages 5/
➡️ In India, the share of #Acrux XBB.2.3 is increasing, but still it is not able to outcompete currently dominant #Arcturus. However, its offspring XBB.2.3.2 may have some edge over it 6/
Their study in both mice & humans suggests that repeated Omicron infections can diminish the adverse impact of immune imprinting and generate high neutralizing titers against XBB.1.5 and XBB.1.16 in both plasma and nasal mucosa. 1/
In mice, the efficacy of single Omicron-boosting is heavily limited by immune imprinting, especially when using variants antigenically distinct from WT, like XBB. However, this situation could be largely mitigated by a second Omicron booster. 2/
Similarly, in humans, Omicron infections could also alleviate WT-vaccination-induced immune imprinting and generate high neutralizing titers against XBB.1.5 and XBB.1.16 in both plasma and nasal mucosa. 3/
The SARS-CoV-2 surface Spike protein binds to human ACE2 receptors as a critical step in host cell infection. At the same time, S-protein binding to human antibodies neutralizes the virus and prevents interaction with ACE2. 1/
In a new study, the researchers combine these two binding properties in a simple fitness model, using structure-based computation of all possible mutation effects averaged over 10 ACE2 complexes and 10 antibody complexes of the S-protein. 2/
The ACE2-antibody selectivity change caused by mutation (i.e., the change binding to ACE2 minus the change in binding to immunity-inducing Abs) is proposed to be a key metric of virus fitness, which furthermore enables substantial systematic error cancelation when evaluated. 3/
How long population immunity induced by natural infection, primary-series vaccination, and booster vaccination against SARS-CoV-2 lasts?
A new study from Qatar offers some clues. 1/
Using a test-negative study design,
population immunity against infection of each of previous infection, primary-series vaccination, and booster vaccination were characterized at the national level month by month for 2 calendar years 2/
The 3 forms of population immunity showed rapid variation over time driven by waning of protection. Vaccine-derived population immunity declined by 1 absolute percentage point every 5 days! 3/
A plethora of respiratory viruses, including SARS-CoV-2, strategically manipulate the host's splicing machinery to circumvent antiviral responses. 1/
What is RNA splicing? ....a form of RNA processing in which a newly made precursor messenger RNA (pre-mRNA) transcript is transformed into a mature messenger RNA (mRNA). During splicing, introns (non-coding regions) are removed, & exons (coding regions) are joined together 2/
According to a new study, SARS-CoV-2 exploits the host splicing machinery to bolster viral replication & subvert the immune response by selectively upregulating unproductive splicing isoforms from antigen presentation & antiviral response genes. 3/
When is the Indian Covid surge driven by XBB.1.16 going to peak?
Y’day India reported >7500 cases. Early trends point the tally would def cross 8500 today. However, there is a lot of speculations on when the current peak of the surge would peak. Let’s look for the answers 1/
There are three different views:
1-According to @JPWeiland as far as weekly growth is concerned, it is already peaked. But the outbreak is still growing & the positivity rate is at the highest since Jan’21 BA.2 peak! 2/
2-As per the @MoHFW_INDIA’s ‘unusual’ claim, the COVID in India is moving towards the endemic stage. They expect the cases to rise for the next 10-12 days, and will gradually come down to become endemic 3/