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A protein found in human breast milk could help kill drug-resistant bacteria

Natural protection.

FIONA MACDONALD
25 JAN 2016
 

Scientists have transformed a key protein in human breast milk into an 'artificial virus' that seeks out and kills bacteria on the spot - creating a powerful new weapon in the fight against drug-resistant bacteria.

The artificial virus is able to kill off bacteria almost instantly by punching holes in their cell membrane. This means the bacteria won't have a chance to build up defences against this attack, and could be a good weapon against drug-resistance. But what's really exciting is that the new virus also has the potential to deliver gene therapy to human cells, while keeping bacteria in check. In other words, scientists have just created a really kick-ass drug delivery parcel.

 

Breast milk is well known to have all kinds of amazing properties, and in addition to helping babies grow and develop, it also plays an important role in keeping them healthy while their immune system is still developing. It does this with the help of one key protein, known as lactoferrin, which is able to destroy a range of harmful bacteria, fungi and viruses.

Most of the antimicrobial properties of lactoferrin are thanks to one small fragment of amino acids, and a team of researchers from the UK National Physical Laboratory and University College London realised that in order to have such a powerful effect, these fragments must be capable of grouping together, targeting pathogens, and then killing them by bombarding their membrane.

As you can imagine, that's a pretty handy trait to have, and so the researchers looked into whether they could use that ability to create a new drug-delivery system. To do this, they re-engineered the protein fragment into a tiny building block, which then self-assembles into virus-like capsules that target bacteria and kill them.

"The result was striking," said one of the researchers, Hasan Alkassem. "The capsules acted as projectiles porating [or punching tiny holes in] the membranes with bullet speed and efficiency."

Best of all, the artificial viruses did all of that without harming human cells. Instead, they simply infected them like a virus would.

That may not sound great, but it's actually a really good thing. It means that in addition to killing bacteria, the artificial viruses will also have the drug-delivery properties of regular viruses - they infect cells and then release their genes, allowing them to hijack cellular machinery. 

Scientists have been replacing those viral genes with active drugs or gene therapy for years, effectively using viruses to deliver treatments to human cells for them.

But although that system works well, what regular viruses lack is the ability to tell the difference between human cells and bacteria, which this new artificial virus is able to do. And of course, it also goes one step further and kills off specific bacteria while it's at it - something that'll come in handy for treating a range of diseases.

"With therapeutic genes, this capability could be used to treat disorders resulting from a single mutated gene. Sickle-cell disease, cystic fibrosis or Duchenne muscular dystrophy are incurable at present, but can be cured by correcting corresponding mutated genes," said the National Physical Laboratory. "The capsules therefore can serve as delivery vehicles for cures."

There's a long way to go still before we see this happen. The breast milk-derived artificial viruses will need to be tested in animal models to make sure that they're safe and effective, and if all that goes to plan, they'll eventually need to be trialled in humans. 

But it's pretty exciting to think that we could the unique properties of human breast milk and viruses, and use them to create something that could treat a range of diseases, as well as kill drug-resistant bacteria. We'll definitely be following this research closely.

The findings have been published in Chemical Science.

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