Thursday, March 24, 2022
Deltacron: What scientists know so far about this new hybrid coronavirus
In many countries, as restrictions lift and freedoms are restored, there's a general feeling that the pandemic is over. There is, however, still the significant concern that a dangerous new variant could emerge.
This happened when Omicron arrived, but we got lucky with that one. Omicron turned out to be more transmissible, but mercifully it hasn't caused an increase in severe disease in most countries where it is dominant.
The race is on to find a variant-proof vaccine
In a state-of-the-art science lab, nestled into the genteel slopes of the NSW Southern Highlands, a group of genetically engineered mice have become frontline soldiers in the fight against COVID-19.
But this wasn't guaranteed. Variants crop up randomly, and new ones have the potential to be more dangerous than previous ones. Another has just arrived, and is currently going by the name deltacron. It is – as you can probably guess – a hybrid of Delta and Omicron, the two variants dominant most recently.
Deltacron's story begins in mid-February, when scientists at the Institut Pasteur in Paris uploaded a genetic sequence of the coronavirus that looked very different from previous sequences. The virus sample had come from an elderly man in northern France and looked odd. Most of its genetic sequence was the same as Delta's, which was dominant worldwide up until late last year, but the part of the sequence that encodes the virus's spike protein – a key part of its external structure, which it uses to get inside cells in the body – came from Omicron.
By March, three further hybrid genetic sequences had been reported, this time in the US. There are now over 60 logged across France, the Netherlands, Denmark, the US and the UK.
There may, however, be different deltacrons. Scientists at the Institut Pasteur have said the deltacron sequences reported in the UK and US have certain differences from those found in other countries. They've said that it might be necessary to add a number to these different forms of deltacron, to indicate which is which.
It's not unusual for viruses to mix and match parts of themselves if two different viruses infect one cell. This is called "recombination", as one virus combines parts of its genetic sequence with parts from another related virus as it assembles copies of itself. It appears to happen at random during viral replication.
What will our next COVID winter look like?
With influenza infections dropping to record lows during the social distancing phase of the pandemic, we are in uncharted waters as we approach winter with a new sub-variant in play.
However, when there's a transfer of power from one viral variant to another – with one variant becoming less common and another more so, meaning both are circulating in the population and there's a chance for them to simultaneously infect people – the chance of recombination happening increases. This will have been the situation as Omicron emerged to displace Delta as the most dominant form worldwide.
Recombination usually creates a new virus that isn't viable, as the mixing of different genes can interfere with the virus's ability to make the proteins it needs to survive. But sometimes one does survive, and that appears to be what's happened with deltacron.
Indeed, as the deltacron hybrids found in the US/UK appear to be different from those found in mainland Europe, it's possible that this has happened multiple times separately.
A chip off the old block?
At the moment it's hard to say in what ways deltacron will resemble its parents. Delta and Omicron are quite different viruses. They differ in how they infect cells and how they evade immunity. We still don't know enough about deltacron to be able to tell how different it's going to be to either.
Because it's been found in multiple nearby countries, it's likely that deltacron can spread. However, Omicron itself is continuing to spread widely in Europe, so it's still the variant we need to be watching carefully right now.
Time will tell if deltacron will displace Omicron, and whether deltacron will be any better at evading immunity and if it will cause more severe disease. There are currently too few deltacron cases to draw any conclusions on these issues. What we need are experiments to determine the properties of deltacron – scientists have started that process and have been able to infect cells with it, so hopefully we'll have answers in time.
In the meantime, we need to keep an eye on it. The fact that deltacron has probably spread across borders emphasises the need for ongoing genomic surveillance to keep tabs on how the virus is changing and moving. As the coronavirus is continuing to spread widely and infect large numbers of people, it's likely that more variants will emerge – including through recombination.
We can, though, be somewhat confident that prior infection with other variants, as well as vaccination, will offer protection from severe disease should deltacron begin to dominate. We know that vaccines, which are based on the original Wuhan strain of the virus, also protect against severe disease with the more recent variants. Time will tell whether Delta and Omicron have produced a wild child for us to worry about.
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A patch instead of an injection?
Australian biotech firm Vaxxas says it will conduct the world’s first human clinical trial of a Covid-19 vaccine patch after securing exclusive rights to a US developed vaccine candidate.
Vaxxas CEO David Hoey said an agreement with the University of Texas and the National Institute of Health gave it exclusive usage of the vaccine in patches, and meant that Vaxxas could now timetable phase one trials of the Covid patch in Adelaide later this year.
Mr Hoey said 50 to 100 people would take part in the trial. They would need to have already been vaccinated three times with an approved vaccine. He said an independent investigator would conduct the trial which was primarily about the safety of the vaccine.
“We’ll then go into a phase two study based on the outcome of phase one and then to a larger phase three study as well.”
Vaxxas argues that vaccine patches are not only less painful and less invasive than regular injections, they also enable vaccines to be dispensed more efficiently over time. The vaccine candidate being used was a relatively inexpensive non mRNA vaccine that survived at room temperature.
Mr Hoey said it could be mailed as Covid patches in the post, or distributed in the developing world. “It’s appropriate for every geography on the planet,” he said.
“As the Covid pandemic transitions to becoming some kind of endemic disease … we see this as a patch that doesn’t need to be refrigerated, is easy to administer, and is something that can have global appeal.
“It’s taking Australian technology, and putting it at the centre of addressing a real global problem and this is the first step.”
Mr Hoey said Vaxxas would look at the blood response to vaccination and see how much it increased the immune response to Covid-19.
He paid tribute to biologist Jason McLellan who with fellow researchers had invented “the next generation of the core piece” of current approved vaccines and the vaccine used in the patch was from the same stable.
McLellan, professor in the Department of Molecular Biosciences at The University of Texas, is also credited with leading a team that produced the first molecular structure of the virus’s spike protein in early 2020.
Mr Hoey said Vaxxas wanted to have its Covid patches available in the market in less than 36 months.
Meanwhile, work is continuing on building Vaxxas’s hi-tech laboratory at Northshore, Hamilton in Brisbane, where the company plans to employ 120 people. Vaxxas plans to produce up to 300 million patch doses each year at full capacity.
Mr Hoey said Vaxxas also had been working on a patch for influenza. It had conducted a study with more than 200 people published two years ago where influenza vaccine was stable at 40 degrees Celsius for 12 months. That again would enable easier distribution of patches at room temperature.
The flu patch was due to go into clinical trials in Australia next year.
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Also see my other blogs. Main ones below:
http://edwatch.blogspot.com (EDUCATION WATCH)
http://antigreen.blogspot.com (GREENIE WATCH)
http://pcwatch.blogspot.com (POLITICAL CORRECTNESS WATCH)
http://australian-politics.blogspot.com/ (AUSTRALIAN POLITICS)
http://snorphty.blogspot.com/ (TONGUE-TIED)
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