Connect with us

International

Coronavirus: what happens when a person is simultaneously infected with two variants?

The real concern is if two variants infect the same cell and swap genetic material.

Published

on

Scientists in Brazil recently reported that two people were simultaneously infected with two different variants of SARS-CoV-2, the virus that causes COVID-19. This co-infection seemed to have no effect on the severity of patients’ illness, and both recovered without needing to be hospitalised.

Although this is one of the few such cases recorded with SARS-CoV-2 – and the study is yet to be published in a scientific journal – scientists have observed infections with multiple strains with other respiratory viruses, such as influenza. This has raised questions about how these viruses may interact in an infected person, and what it could mean for generating new variants.

Viruses are masters of evolution, constantly mutating and creating new variants with every cycle of replication. Selective pressures in the host, such as our immune response, also drive these adaptations. Most of these mutations won’t have a significant effect on the virus. But ones that give an advantage to the virus – for example, by increasing its ability to replicate or evade the immune system – are cause for concern and need to be closely monitored.

The occurrence of these mutations is down to the error-prone replication machinery that viruses use. RNA viruses, such as influenza and hepatitis C, generate a relatively large number of errors each time they replicate. This creates a “quasi-species” of the virus population, rather like a swarm of viruses, each with related but non-identical sequences. Interactions with the host cells and immune system determine the relative frequencies of the individual variants, and these coexisting variants may affect how the disease progresses or how well treatments work.

Compared with other RNA viruses, coronaviruses have lower mutation rates. This is because they are equipped with a proofreading mechanism that can correct some of the errors that occur during replication. Still, there is evidence of viral genetic diversity in patients infected with SARS-CoV-2.

The detection of multiple variants in a person could be the result of co-infection by the different variants, or the generation of mutations within the patient after the initial infection. One way to discriminate these two scenarios is by comparing the sequences of the variants circulating in the population with those in the patient. In the Brazilian study mentioned above, the variants identified corresponded to different lineages that had been previously detected in the population, implying co-infection by the two variants.

Mixing it all up

This co-infection has opened concerns of SARS-CoV-2 acquiring new mutations even more rapidly. This is because coronaviruses can also undergo large changes in their genetic sequence by a process called recombination. When two viruses infect the same cell, they can swap large parts of their genomes with each other and create completely new sequences.

This is a known phenomenon in RNA viruses. New variants of influenza are generated by a similar mechanism called “reassortment”. The genome of influenza virus, unlike coronavirus, comprises eight segments or strands of RNA. When two viruses infect the same cell, these segments mix and match to produce viruses with a new combination of genes. Interestingly, pigs can be infected with different strains of influenza viruses, and have been referred to as “mixing vessels” that shuffle them into new strains. The 2009 H1N1 pandemic virus emerged from a reassortment of a human, avian, and two swine influenza viruses.

Pigs on a farm.
Mixing vessels. krumanop/Shutterstock

With coronaviruses, which only contain one RNA strand in each virus particle, recombination can only occur between RNA strands derived from one or more viruses in the same cell. Evidence of recombination has been found both in the laboratory and in a patient infected with SARS-CoV-2, suggesting that this could drive the generation of new variants. In fact, the ability of SARS-CoV-2 to infect human cells is proposed to have developed via recombination of the spike protein between closely related animal coronaviruses.

It is important to note that this requires the two viruses to infect the same cell. Even if a person is infected with several variants, if they replicate in different parts of the body, they will not interact with each other. Indeed, this was seen in patients, where different quasi-species of coronaviruses were found in the upper and lower respiratory tracts, suggesting that viruses in these sites were not directly mixing with each other.

The evidence so far does not suggest that infection with more than one variant leads to more severe disease. And although possible, very few cases of co-infection have been reported. More than 90% of the infections in the UK currently are by B117 – the so-called Kent variant. With such a high prevalence of one variant in the population, co-infections are not likely to occur. Still, monitoring this landscape allows scientists to track the emergence of these new variants of concern and understand and respond to any changes in their transmission or vaccine efficacy.

Maitreyi Shivkumar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Read More

Continue Reading

International

Dinosaur teeth reveal what they didn’t eat

Scratches on dinosaur teeth could reveal what they really ate. For the first time, dental microwear texture analysis (DMTA) has been used to infer the…

Published

on

Scratches on dinosaur teeth could reveal what they really ate. For the first time, dental microwear texture analysis (DMTA) has been used to infer the feeding habits of large theropods, including Allosaurus and T. rex. By taking 3D images of individual teeth and analyzing the pattern of marks scratched into them, researchers could reason which dinosaurs may have frequently crunched on hard bone and which may have regularly eaten softer foods and prey. This technique opens up a new avenue of research for paleontology, helping us to better understand not only dinosaurs themselves but also the environment and communities in which they lived.

Credit: 2022 D.E. Winkler

Scratches on dinosaur teeth could reveal what they really ate. For the first time, dental microwear texture analysis (DMTA) has been used to infer the feeding habits of large theropods, including Allosaurus and T. rex. By taking 3D images of individual teeth and analyzing the pattern of marks scratched into them, researchers could reason which dinosaurs may have frequently crunched on hard bone and which may have regularly eaten softer foods and prey. This technique opens up a new avenue of research for paleontology, helping us to better understand not only dinosaurs themselves but also the environment and communities in which they lived.

From Fantasia to Jurassic Park, the T. rex is seen as a terrifying apex predator that would chase down its prey and crunch on it whole. But how much did this iconic dinosaur actually chow down on bones? And what about other predatory dinosaurs that existed long before it?

Researchers from the University of Tokyo, in collaboration with teams from the University of Mainz and the University of Hamburg in Germany, have used dental microwear texture analysis (DMTA), a scanning technique to examine topographical dental wear and tear in microscopic detail, on individual dinosaur teeth from more than 100 million years ago to better understand what they may have eaten. “We wanted to test if we could use DMTA to find evidence of different feeding behaviors in tyrannosaurids (from the Cretaceous period, 145 million to 66 million years ago) compared to the older Allosaurus (from the Jurassic period, 201 million to 145 million years ago), which are both types of theropods,” explained postdoctoral fellow Daniela Winkler from the Graduate School of Frontier Sciences. “From other research, we already knew that tyrannosaurids can crack and feed on bones (from studies of their feces and bite marks on bone). But allosaurs are much older and there is not so much information about them.”

DMTA has mainly been used to study mammal teeth, so this is the first time it was used to study theropods. The same research team from the University of Tokyo also recently pioneered a study on DMTA in Japanese sauropod dinosaurs, famous for their long necks and tails. A high-resolution 3D image was taken of the tooth surface at a very small scale of 100 micrometers (one-tenth of a millimeter) by 100 micrometers in size. Up to 50 sets of surface texture parameters were then used to analyze the image, for example, the roughness, depth and complexity of wear marks. If the complexity was high, i.e., there were different-sized marks which overlaid each other, this was associated with hard object feeding, such as on bone. However, if the complexity was low, i.e., the marks were more arranged, of a similar size and not overlapping, this was associated with soft object feeding, like meat.

In total, the team studied 48 teeth, 34 from theropod dinosaurs and 14 from crocodilians (modern crocodiles and alligators), which were used as a comparison. The team was able to study original fossilized teeth and take high-resolution silicon molds, thanks to loans provided by natural history museums in Canada, the U.S., Argentina and Europe. “We actually started dental microwear research of dinosaurs in 2010,” said Lecturer Mugino Kubo from the Graduate School of Frontier Sciences. “My husband, Dr. Tai Kubo, and I had started collecting dental molds of dinosaurs and their contemporaries in North and South Americas, Europe, and of course Asia. Since Daniela joined my lab, we utilized these molds to make a broader comparison among carnivorous dinosaurs.”

“It was especially challenging to carry out this research during the pandemic,” said Winkler “as we rely on being able to gather samples from international institutions. The sample size might not be so large this time, but it is a starting point.”

Winkler says what they found surprising was that they didn’t find evidence of much bone crushing behavior in either Allosaurus or tyrannosaurids, even though they know that tyrannosaurids ate bone. There may be several reasons for this unexpected outcome. It could be that although Tyrannosaurus was able to eat bone, it was less commonly done than previously thought. Also, the team had to use well-preserved teeth, so it might be that extremely damaged teeth that were excluded from this study were in such a condition because those animals fed more on bone.

Something the team did find with both the dinosaurs and crocodilians was a noticeable difference between juveniles and adults. “We studied two juvenile dinosaur specimens (one Allosaurus and one tyrannosaurid) and what we found was a very different feeding niche and behavior for both compared to the adults. We found that there was more wear to juvenile teeth, which might mean that they had to more frequently feed on carcasses because they were eating leftovers,” explained Winkler. “We were also able to detect different feeding behavior in juvenile crocodilians; however, this time it was the opposite. Juvenile crocodilians had less wear on their teeth from eating softer foods, perhaps like insects, while adults had more dental wear from eating harder foods, like larger vertebrates.”

Winkler says that the next step with dinosaurs will probably be to look in more detail at the long-necked sauropods, which the team has also been studying. But for now, she is experimenting with something much, much smaller: crickets. The insects’ mouths may be tiny and don’t have any teeth, but the researchers want to see if they can still find evidence of mouth wear using the same technique. “From what we learn using DMTA, we can possibly reconstruct extinct animals’ diets, and from this make inferences about extinct ecosystems, paleoecology and paleoclimate, and how it differs from today.” said Winkler. “But this research is also about curiosity. We want to form a clearer image of what dinosaurs were really like and how they lived all those millions of years ago.”

###

Paper Title: 

Daniela E. Winkler, Tai Kubo, Mugino O. Kubo, Thomas M. Kaiser, Thomas Tütken. First application of dental microwear texture analysis to infer theropod feeding ecology.  Palaeontology, 2022, e12632. doi:10.1111/pala.12632

Funding: 

This work was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (ERC CoG grant agreement no. 681450) to T.T. The Japan Society for the Promotion of Science under a Postdoctoral fellowship awarded to D.E.W. (KAKENHI Grant No. 20F20325).

Useful Links:

Graduate School of Frontier Sciences: https://www.k.u-tokyo.ac.jp/en/index.html

Mugino Kubo Lab: https://sites.google.com/edu.k.u-tokyo.ac.jp/mugino-kubo-lab/home

 

Research Contacts

JSPS Postdoctoral Fellow Daniela E Winkler, Ph.D.

Department of Natural Environmental Studies,
Graduate School of Frontier Sciences,
The University of Tokyo

5-1-5 Kashiwanoha, Kashiwa City, Chiba 277-8563

E-mail: daniela.eileen.winkler@edu.k.u-tokyo.ac.jp

Lecturer Mugino O. Kubo
Department of Natural Environmental Studies,
Graduate School of Frontier Sciences,
The University of Tokyo

5-1-5 Kashiwanoha, Kashiwa City, Chiba 277-8563

E-mail: mugino@k.u-tokyo.ac.jp

Press contact:
Mrs. Nicola Burghall
Public Relations Group, The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8654, Japan
press-releases.adm@gs.mail.u-tokyo.ac.jp

 

About the University of Tokyo
The University of Tokyo is Japan’s leading university and one of the world’s top research universities. The vast research output of some 6,000 researchers is published in the world’s top journals across the arts and sciences. Our vibrant student body of around 15,000 undergraduate and 15,000 graduate students includes over 4,000 international students. Find out more at www.u-tokyo.ac.jp/en/ or follow us on Twitter at @UTokyo_News_en.

 

 


Read More

Continue Reading

International

Could investing in bonds yield better returns than equities in 2023?

It’s not news that 2022 has been a tough one for stock markets. There have been sectors, like energy and utilities, that…
The post Could investing…

Published

on

It’s not news that 2022 has been a tough one for stock markets. There have been sectors, like energy and utilities, that have bucked the negative trend but the big picture has been bleak. The UK’s large cap FTSE 100 index has faired better than most and is more or less flat for the year thanks to its heavy weighting towards energy, industrial commodities, and finance.

Source: CSIMarket

But it’s been a volatile ride and the end of the year could still drag London’s benchmark index into the red.

ftse100index

Over in the USA, the major indices have suffered significant losses. The growth companies, especially in the tech sector, that saw Wall Street enjoy over a decade of strong growth with only the occasional short-lived correction have been among those hit hardest by inflation hitting decades-long highs and interest rates rising.

That’s seen the tech-heavy Nasdaq Composite register an over 30% loss for the year-to-date and the broader based S&P 500 is down a little under 18% over 2022.

nasdaq composite

However, while the hangover from the Covid-19 pandemic and Russia’s invasion of Ukraine were unpredictable events that have undoubtedly deepened stock market losses, a turn of the market cycle is not a surprise. The bull market that preceded the 2022 bear market was the longest in history, supported by unprecedented levels of quantitative easing and record-low interest rates in major developed economies.

If anything, the surprise was that the bull market for equities persisted for as long as it did and pushed valuations so high. More bearish analysts had been warning of a reversal for years before it actually transpired.

What has been far more surprising, almost unprecedented, is that bond markets have failed to live up to their traditional portfolio role of providing insurance against an equities bear market. When equities, especially growth stocks, enter bear territory, bonds usually go in the opposite direction, rising with interest rates and an influx of capital seeking a safe haven.

Traditionally, a portfolio with a 60% allocation to equities and 40% allocation to bonds should come into its own during periods like this year. The bond allocation would be expected to cushion the blow of an equities bear market, paying its way for lower returns than equities during the good times.

But in the third quarter of this year, a traditionally conservative portfolio with a 40% allocation to equities would have actually underperformed one 100% allocated to equities. Inflation remaining stubbornly high this year despite the Fed and other central banks including the Bank of England has upended the conventional investing wisdom that equities and bonds do not both move in the same direction – the foundational principle of traditional diversification strategies.

But will that change in 2023? Could bonds outperform equities next year in a way that means investors should consider increasing their portfolio weighting towards fixed-income investments?

Why have bonds not lived up to their billing in 2022?

Nothing has worked well for diversified investors this year, not equities, not bonds and not the traditional 60/40 portfolio split between the two asset classes. But will this year prove a blip or has the relationship bet equities and bonds changed fundamentally?

Analysts including Morningstar’s Lauren Solberg believe the performance of the bond market next year will be most influenced by inflation. If inflation remains high, bonds could continue to struggle alongside equities. However, if major central banks including the Fed manage to wrestle inflation back down towards target levels, especially if that is accompanied by a recession, bonds would be expected to revert to their traditional anti-correlation with equities.

This year, one they would have been expected to benefit from a flight from equities and rising interest rates, has been the worst for bonds in modern history. It’s also been the only time in history that stocks and bonds have both recorded losses for three consecutive quarters.

chart2

Source: Morningstar

Sky-high inflation, which is bad for both equities and bonds, has negated the usually positive impact on bonds of a bear market for equities and rising interest rates.

Will bonds return to form in 2023?

There is differing opinion among analysts and market observers about what 2023 might hold in store for bond markets. The more common expectation is that bonds will do a much better job at insulating portfolios than this year with yields now much higher than they were in late 2021.

However, others believe that a secular change in the correlation relationship between equities and bonds is now underway. That is based on the expectation that inflation, even if it falls meaningfully in 2023, could remain at higher levels and be more prone to volatility than it has been over the past couple of decades.

Recent research published by Truist Wealth shows that U.S. government-backed debt has delivered average annual returns of 6.6% over the past four recessions, beating both high-yield ‘junk’ and investment-grade corporate bonds. That would indicate 2023 could be a very good year for bond investors with the right exposure – a focus on government rather than private sector debt. However, we’ve already seen a significant divergence from historical patterns this year.

Marta Norton, chief investment officer for the Americas at Morningstar Investment Management, believes 2023 could be hold opportunities for fixed income, across government-backed and corporate bonds:

“When you look over the past 10 years, it’s really only been an equity story: It’s been such a good market to take on equity risk, a tremendously good time to be an equity investor. But today, it’s harder to know where to invest the marginal dollar. Fixed income is looking more appealing than it has in some time. You don’t have to take enormous risk to earn some return, and that’s a mindset shift to the environment we had before.”

While she acknowledges that U.S. equities now look a lot more attractively priced than they did a year ago, she cautions against investors rushing back to the market and thinks the bear cycle could last longer than many expect. She says the “buy the dip”mentality that has worked so well over the past decade could mean investors risk suffering meaningful losses by moving into a losing market.

She doesn’t advise not investing in equities but that investors should instead drip feed any investment instead of trying to time a bottom.

She is more confident in the opportunities around fixed income investments, especially higher-quality, shorter-dated fixed income, which she says comes with the added benefit of lower risk, especially if a deeper recession materialises.

Christian Mueller-Glissmann, head of asset allocation research within portfolio strategy at Goldman Sachs agrees. He notes the gap in yields between stock and bonds has narrowed substantially since the COVID-19 crisis and is now relatively low. The same is true for riskier credit, which yields relatively little compared with practically risk-free Treasuries and means investors are getting little premium for the risk of owning equities or high-yield credit in comparison to lower-risk bonds. As a result, equities and high-yield debt are particularly exposed to an economic slowdown or recession:

“That just makes equities and riskier debt very vulnerable for disappointments on growth next year”.

Lisa Shalett, chief investment officer of Wealth Management at Morgan Stanley is also championing bonds for 2023. She concludes:

“We continue to believe it is premature to call an end to the bear market for U.S. stocks. Investors may have moved on from inflation concerns, but they cannot ignore the economic picture. For now, investors should consider reducing U.S. large-cap index exposure. Instead, look to Treasuries, munis and investment-grade corporate credit. Stay patient and collect coupon income.”

What about UK Gilts vs London-listed equities?

Should investors mainly exposed to London-listed rather than Wall Street-based equities be thinking along similar lines? The FTSE 100 has remained largely flat in 2022, finally benefitting from its lack of growth stocks and heavy weighting to more traditional sectors like energy, commodities and finance.

London-listed equities were considered cheap before 2022, which is another reason valuations have not fallen in the same way as they have in the USA. On the other hand, they are also less likely to see as much upside if a recession is avoided next year and economic sentiment improves.

The FTSE 100 has also been boosted considerably by the soaring valuation of big energy companies like BP and Shell and utilities such as Centrica, which has compensated for companies in other sectors, such as consumer cyclicles, losing value. Energy prices easing off next year, which is by no means guaranteed depending on how geopolitical factors play out, would be negative for the benchmark index.

The UK’s outlook for both equities and government debt is not particularly positive. RBC Wealth Management summarises:

“A crippling cost of living, austerity measures, and the Bank of England tightening monetary policy will all conspire to create a prolonged recession in the UK, in our view. We advocate an underweight position in UK equities, although we are mindful that depressed valuations may produce interesting dividend income opportunities. We have a negative outlook on UK sovereign debt, as increased government debt issuance and the Bank of England proceeding to sell its Gilts portfolio will likely create a Gilt supply glut.”

While it may not appeal to patriotic sentiment, investors looking for the best risk-to-reward ratio in 2023 might be better served to invest in U.S. Treasuries than UK Gilts if a fixed income approach is favoured.

The post Could investing in bonds yield better returns than equities in 2023? first appeared on Trading and Investment News.

Read More

Continue Reading

International

Call For Investigation Into Mortality Rates As Australia Sees Death-Rate Spike

Call For Investigation Into Mortality Rates As Australia Sees Death-Rate Spike

Authored by Victoria Kelly-Clark via The Epoch Times,

Australia has…

Published

on

Call For Investigation Into Mortality Rates As Australia Sees Death-Rate Spike

Authored by Victoria Kelly-Clark via The Epoch Times,

Australia has seen a spike in its mortality rates in 2022, with the Australian Bureau of Statistics (ABS) stating that by the end of August 2022, 128,797 deaths had been registered, which is 18,671 deaths, or 17 percent, more than the historical average.

In the data release on Nov. 25, the ABS noted that of registered deaths; there had been a rise in the number of Australians dying from dementia (18.9 percent above the baseline average), diabetes (20.8 percent higher than the baseline average), cancer, and COVID-19.

Karen Cutter, a spokesperson for the Actuaries Institute of Australia (AIA) said in a media release (pdf) that even after the Institute’s COVID-19 Mortality Working Group removed all “from” and “with” COVID-19 deaths, it was not clear why Australians were dying in larger numbers from other diseases such as ischaemic heart disease, cancer, and cerebrovascular disease in 2021 and 2022.

In an analysis (pdf) from Nov. 3, the AIA noted that 1,200 more Australians had died from ischaemic heart disease than expected, while cerebrovascular disease had 450 more deaths than normal. Meanwhile, mortality rates from diabetes increased by 400 deaths, and dementia saw an extra 800 deaths.

According to the ABS, between January and August this year, 7,727 Australians died from COVID-19.

“It is not clear what might be driving this, although we expect that at least part of the excess will be in respect of people who otherwise may have succumbed to respiratory disease in 2020 and 2021,” said Cutter.

They also said that diabetes deaths have generally been higher than expected throughout the pandemic.

Cutter noted that the AIA had also noticed that of the excess deaths in the 0-44 and 45-64 age bands were small, and the number of women dying was higher than expected.

She has called on the federal government to launch an inquiry into the cause of the spike.

“The differences are worth investigation, although the small numbers mean that there is considerable natural variation,” she said.

Spiking Mortality Rates a Global Phenomenon

The spike in mortality rates is being experienced globally, with the UK’s Chief Medical Officer, Sir Chris Whitty, as well as Sir Patrick Vallance, the country’s Chief Scientific Adviser, declaring the country is facing a “prolonged period” of excess deaths after people differed treatment during the initial stages of the pandemic.

Meanwhile, the UK’s health secretary Steve Barclay said that the government needed to come clean about the excess deaths.

In a speech to the Spectator Health Summit in London on Nov. 28, Barclay said that the government must share the scale of the COVID backlog, which he estimated was now “around now 7.1 million patients.”

We know from the data that there are more 50-to 64-year olds with cardiovascular issues. It’s the result of delays in that age group seeing a GP because of the pandemic and, in some cases, not getting statins for hypertension in time,” he said.

“When coupled with delays in ambulance times, we see this reflected in the excess death numbers. In time, we may well see a similar challenge in cancer data,” Barclay said.

COVID-19 Lingering Effects

The AIA agrees that delayed medical treatment may be a cause behind Australia’s rising death rate.

In an analysis of the pandemic in 2022, they said that it was highly likely that delays in medical care was a contributing factor to the excess death rates from other diseases.

“Pressure on the health, hospital and aged care systems, including ambulance ramping and bed block, could lead to people not getting the care they require, either as they avoid seeking help, or their care is not as timely as it might have been in pre-pandemic times,” they said.

“There is some evidence that this may be affecting cancer deaths. It may also be a factor in higher deaths from other causes, such as ischaemic heart disease, diabetes, and the large ‘other’ category.”

They also noted that COVID-19 lingering health effects could also be contributing to the increased rates.

Studies show that coronavirus is associated with increased mortality risks from heart disease and other causes. However, because doctors certifying the death would not necessarily know of the infection if it had occurred months prior, this could demonstrate a causative link several months after recovery from COVID-19.

Tyler Durden Thu, 12/08/2022 - 21:00

Read More

Continue Reading

Trending