Imagine you could have a vaccine once a year that protects you against dozens of infections.
Not just viral offenders such as flu or Covid, but bacterial bugs that can lead to pneumonia or meningitis.
Even house dust-mite allergies – a major trigger for asthma attacks – could be kept at bay. What’s more, the vaccine would be squirted up your nose rather than injected (good news for people with a fear of needles). It might sound like a pipe dream, but such a vaccine has just been successfully tested in mice.
The research is at an early stage but could potentially revolutionise the prevention of many diseases triggered by airborne viruses, bacteria or allergens.
‘We were interested in this idea [of a universal vaccine for all infectious organisms] because it sounded a bit outrageous,’ says Professor Bali Pulendran, an immunology expert at Stanford University in the US, who led the latest research. ‘Nobody was seriously entertaining that something like this could ever be possible.’
The broad principle behind vaccines has changed little since British doctor Edward Jenner developed the very first (for smallpox) in the 1790s.
Typically, they mimic some feature of the pathogen in question – whether it’s a flu virus or the bacteria that causes tuberculosis – and, once inside the body, our immune system recognises it as foreign and despatches fighter cells, called antibodies, to attack and destroy the invading organism. The next time the body encounters the pathogen, it is ready to fight it off.
For years, scientists have been trying to develop a universal flu jab – one that protects against all current and future strains. But the latest innovation goes further
Triggering this defence mechanism involves using a weakened version of the bug itself, or (as with Covid jabs) a protein or fragment of genetic material from the virus.
In a few cases, vaccines provide protection for life (for example, hepatitis B, the highly contagious liver infection). But others, such as flu, must be given annually because the virus constantly mutates.
For years, scientists have been trying to develop a universal flu jab – one that protects against all current and future strains. But the latest innovation goes further – and works in a completely different way.
Rather than mimic foreign organisms to get the immune system’s attention, it turbocharges the innate immune response – the body’s first defence against intruders.
When the innate response is activated, white blood cells called phagocytes are sent out to devour foreign bacteria or viruses.
But these cells can’t differentiate between types of intruder. Their job is to fend off any initial attack until the second line of defence (the adaptive immune system) is able to muster antibodies or T-cells specific to the pathogen, which can take several days. The innate immune system then stands down. Scientists wanted to see if boosting the innate immune response would give long-lasting protection against a range of pathogens.
They developed a vaccine that contains a protein, called toll-like receptor 4 (TLR4), which co-ordinates the innate immune system’s response to attacks.
But it also communicates with the adaptive immune system so it can formulate an appropriate targeted response to the invader.
Professor Bali Pulendran, an immunology expert at Stanford University in the US, led the latest research into a universal vaccine
Scientists hope that introducing the protein puts the innate immune system on permanent high alert.
To test the theory, mice were given drops into the nose in doses a week apart. The mice were then exposed to Covid and cold viruses. The results, published in the journal Science, showed the mice were protected against infection by their innate immune system for at least three months, rather than a few days as normal.
Researchers then tried it on two types of bacterial infection that can cause pneumonia. When the vaccinated mice were repeatedly exposed to the bugs, again they resisted infection for at least three months.
The scientists then exposed the mice to house dust mites. The lungs of unvaccinated mice filled with mucus when exposed, while in the vaccinated mice they remained clear, as the turbocharged innate immune system dealt with the allergens before they could do damage. Human trials are now planned.
Eleanor Riley, a professor of immunology and infectious diseases at Edinburgh University, said it’s not yet clear how effective these might be. ‘Then there’s the question of potential side-effects,’ she says.
‘The innate immune response is inflammatory and is what gives us fever, muscle pain and weakness when we get an infection – it’s meant to be temporary because that type of chronic inflammation lasting for months or years can be bad for the body.’ (It’s been linked with increased risk of cancer and heart disease.)
Dr Julian Tang, a professor of respiratory sciences at Leicester University, said: ‘The immune system is very complex and may react differently in different species, so I’d be careful about trying to predict the outcomes until you have some real-world data in humans.’
