January in Context
A round-up of some of this month’s most exciting biology news.
As we enter a new year with great uncertainty, the constant onslaught of news surrounding coronavirus can seem daunting. On the political stage, we have heard concerns that “vaccine nationalism” will leave poorer countries without coverage and prolong the pandemic whilst in research news there have been reports of high-profile retracted COVID-19 papers still being cited in new research. Here at Biology in Context, we’ll stick to the science.
Delaying the second dose
As of 31st January, the UK government has reported that over 8 million people, or over 12% of the population, has received their first dose of either the Pfizer or AstraZeneca vaccine, with daily vaccinations reaching over 400,000. This speed is, in part, due to a strategy to delay the second dose of the vaccine from the recommended interval of 21 days that was shown to be effective in clinical trials, to 12 weeks after the first dose. This is despite a lack of data on the effectiveness of such an interval and with the World Health Organization (WHO) recommending a wait of no more than six weeks between the first and second doses of the Pfizer vaccine. Medical and scientific support has been divided by the decision.
The COVID-19 vaccine, like many others, consists of multiple doses with the first used to trigger an initial immune response to the virus and the second booster to trigger immunological memory. This is developed in the weeks following the first dose and allows the immune system to respond more rapidly and effectively to pathogens.
For vaccines that use harmless, modified viruses to deliver the SARS-CoV-2 genetic material to our cells, such as the AstraZeneca vaccine, delaying the second dose may actually be beneficial by allowing more time for this immunological memory to develop. However, in the case of RNA based vaccines, such as the Pfizer vaccine, this does not apply as our cells will only produce the coronavirus protein for a few days after vaccination. Some are concerned that by extending the time between the two doses, it could decrease the efficacy of the vaccine and encourage viral variants which are resistant to the vaccine to emerge.
A letter in the New England Journal of Medicine reported that the levels of neutralising antibodies, which bind to and block the effects of pathogens, fell significantly after 28 days in healthy participants who received the Moderna vaccine, which is an mRNA vaccine similar to Pfizer’s. The second dose saw a similar decrease in the secondary immune response, but over months rather than days. It is important to note that neutralising antibodies are only one part of immunity against viruses, but it may indicate that delaying the vaccine could increase the risk of infection and the chance of resistant viral variants.
Despite this, some researchers note that even partial resistance is unlikely to render a vaccine completely ineffective. The body produces many antibodies which target different regions of a pathogen, and as SARS-Cov-2 is a slowly evolving virus it is unlikely to change in such a way that none of the antibodies produced would be able to recognise it. It is thought that the first dose of the Pfizer vaccine may provide enough protection to prevent more severe symptoms. From a public health standpoint, the longer delay and subsequent increase in first doses received is considered a necessity to reduce the number of hospitalisations, thereby relieving pressure on the NHS.
Transmission after vaccination
Even those who have received both doses of a COVID-19 vaccine must stay vigilant as the data is not yet available to answer if vaccinated people can still spread the virus. Research has shown that COVID-19 vaccines cause the body to produce a class of antibodies known as IgG antibodies. These antibodies are confined to the inside of our body, such as circulating in the blood. But it is the IgA antibodies, which are present on the “outward-facing” mucosal surfaces of our bodies such as the nose, throat and lungs, that are important in preventing viral transmission. People who have caught and recovered from COVID-19 are known to produce these specialised IgA antibodies, and are unlikely to be able to spread the virus, but it is still unknown if this happens in vaccinated individuals.
In December we reported on how the B.1.1.7 COVID-19 variant first identified in the UK is different from the normal virus and how this might increase transmissibility. This month has seen confirmation of the increased rate of transmissibility and begun to answer questions over vaccine effectiveness against such COVID-19 variants.
Using epidemiological data, genetic data and mathematical modelling, two independent analyses have found that the B.1.1.7 variant is approximately 50% more transmissible than other variants. These analyses are preprints, so have not been formally peer reviewed, but similar figures coming from independent sources using different approaches lends more credibility to the data.
With increased transmissibility, doctors and researchers are rightly concerned to know if vaccines can also protect against COVID-19 variants. The biotech firm Novax have reported that two doses of their vaccine is 85% effective against the B.1.1.7 variant. Unfortunately, it was also reported that the Novax vaccine is less than 50% effective against the B.1.351 variant, which contains similar mutations to B.1.1.7 and has become the predominant variant in South Africa. It stands to be seen how vaccines already in use fare against the newer variants.
This section only covers a small part of the constantly evolving COVID-19 news and research landscape. For more information, check out the rolling selection of key COVID-19 research at Nature.
The start of 2021 has seen the discovery and understanding of some of the strange and unique features of the creatures on our planet. Let's take a look at some the best news.
Cells respond to the Earth’s magnetic field
Animals such as birds, bats and whales are known to navigate by sensing the Earth’s magnetic field but, until recently, how this magnetoreception worked was largely unknown. But now, a team from the University of Tokyo have observed a class of proteins called cryptochromes responding to magnetic fields whilst in living cells.
Cryptochromes are signalling proteins found in many plants and animals and can absorb light and then emit an electromagnetic signal. Levels of cryptochromes are particularly high in cells in the retina of migratory birds. With this understanding, it has been suspected for some time that cryptochromes might be involved in the mechanism of controlling the magnetic compass in animals but this study is the first direct evidence of the phenomenon at work.
The researchers used human cells (HeLa cells) containing a pigment to dye the cryptochromes. When the cells were irradiated with a blue light it caused the proteins to fluoresce. They then swept a magnetic field over the cells and measured the fluorescence with a highly sensitive custom microscope. Decreases in fluorescence corresponded to the magnetic field being passed over the cells, showing the direct protein response.
These findings begin to explain how some animals use the earth’s magnetic field to perceive direction, altitude or location and raises questions as to how magnetic fields may effect other biological processes, potentially even in humans.
Some Electric Eels Hunt Together
Volta eels (Electrophorus voltai) in the Amazon have been observed herding shoals of fish and delivering a coordinated electric attack for the first time.
Researchers from the Chico Mendes Institute for Biodiversity Conservation in Brazil were surprised to find groups of over 100 electric eels hunting together, a tactic known as social predation. The eels were recorded encircling shoals of thousands of small fish before launching a joint electric attack - about 890 volts per eel. In theory, attacks from just 10 Volta eels could power 100 light bulbs. This behaviour is considered rare for freshwater fish and the researchers are hoping to learn more.
Is the Platypus the key to mammalian evolution?
An article in Nature this month has presented the most comprehensive genomes of the only egg-laying mammals, or extant monotremes, the platypus and echidna. These genomes of these strange animals may provide insights into mammalian evolution.
Monotremes diverged from other mammals around 187 million years ago, and their unusual traits, such as the platypuses rubbery bill or the echidna’s venomous spikes, may have been present in our own ancestors. These nearly complete genomes from the joint efforts of researchers in Australia and China allows comparison to the genomes of other species and can begin to explain how mammals emerged and diverged from one another.
An example of this divergence is the presence of the vitellogenin gene which becomes a protein involved in the production of egg yolk. Birds typically have many copies of this gene and mammals typically have none. However, the new genomes reveal that both platypuses and echidnas have one copy of the vitellogenin gene, which will help researchers understand why they lay eggs. This, in turn, may be the key to understanding why other mammals give birth to live young.
The genomes of these fascinating species will continue to be studied to reveal their unique features and their place in the evolutionary tree.
Some identical twins do not have identical DNA, with a reported average of 5.2 mutations that arise during early development differing between them. This genetic variant may account for differences between twins.
A behavioural study from the Netherlands suggests that rhythmic hands movements we make whilst speaking affects how words are perceived. In the study, participants were more likely to report emphasis on syllables that coincided with up and down movements of the hands known as beat gestures.
Temperate data released by the EU’s Copernicus Climate Change Service this month shows that 2020 was the joint hottest year on record, alongside 2016. This makes 2011-2020 the warmest decade recorded.