Bacteria used to fight sleeping sickness

By Michelle Roberts
Health reporter, BBC News

The sleeping sickness parasite gets into the bloodstream

Scientists believe they have found a way to beat sleeping sickness using a bacterium against the tsetse fly host that spreads the disease to humans.

In the same way that we have friendly bacteria in our intestines, the tsetse fly harbours bacteria in its midgut, muscle and salivary glands.

Experts in Belgium have genetically modified these "good bugs" so they attack the culprit parasite carried by the fly.

But work is needed to hone the process.

The latest findings are published in the open access journal Microbial Cell Factories.

The disease

Sleeping sickness, or human African trypanosomiasis, is a potentially fatal disease that plagues many regions of Africa.

Although the number of people being infected with the disease has been going down thanks to better diagnosis and treatment, there were still more than 7,000 new cases recorded in 2010.

The parasite causing sleeping sickness is transmitted to humans through the bite of the infected tsetse fly.

This causes fever, headaches, aching joints and itching. Then follows the second stage of disease as the parasites cross the blood-brain barrier to infect the central nervous system.

The person then becomes confused, poorly co-ordinated and experiences the sleep disturbances which give the disease its name.

Without treatment, sleeping sickness is fatal.

But current therapies often have unpleasant side-effects.

Alternatives

The drug most commonly used to treat the condition is a derivative of arsenic developed more than 50 years ago. And the treatment can be excruciatingly painful and potentially fatal. Often described by patients as "fire in the veins," between 5% and 20% of those treated die of complications from the injected drug.

And so scientists are seeking alternatives.

The Belgium team at the Institute of Tropical Medicine in Antwerp have focused on finding a way to destroy the sleeping sickness parasite - trypanosome - that the tsetse fly carries.

They found bacteria called Sodalis glossinidius, which naturally live in the fly and can be used to mount an attack from the inside.

Altering the genes of the bacteria led it to release fragments of antibodies known as nanobodies against the parasite.

With more work, the researchers hope to be able to produce targeted nanobodies which could kill or block the development of trypanosome.

Dr David Horn of the London School of Hygiene and Tropical Medicine said: "This is a neat and promising concept. The goal now will be to develop a deliverable toxin, not necessarily a nanobody, which exhibits anti-trypanosomal activity in the fly."

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Skin transformed into brain cells

By James Gallagher
Health and science reporter, BBC News

Skin cells have been converted directly into cells which develop into the main components of the brain, by researchers studying mice in California.

The experiment, reported in Proceedings of the National Academy of Sciences, skipped the middle "stem cell" stage in the process.

The researchers said they were "thrilled" at the potential medical uses.

Far more tests are needed before the technique could be used on human skin.

Stem cells, which can become any other specialist type of cell from brain to bone, are thought to have huge promise in a range of treatments. Many trials are taking place, such as in stroke patients or specific forms of blindness.

One of the big questions for the field is where to get the cells from. There are ethical concerns around embryonic stem cells and patients would need to take immunosuppressant drugs as any stem cell tissue would not match their own.

An alternative method has been to take skin cells and reprogram them into "induced" stem cells. These could be made from a patient's own cells and then turned into the cell type required, however, the process results in cancer-causing genes being activated.

“We are thrilled about the prospects for potential medical use of these cells”

Prof Marius Wernig Stanford University School of Medicine

Direct approach

The research group, at the Stanford University School of Medicine in California, is looking at another option - converting a person's own skin cells into specialist cells, without creating "induced" stem cells. It has already transformed skin cells directly into neurons.

This study created "neural precursor" cells, which can develop into three types of brain cell: neurons, astrocytes and oligodendrocytes.

These precursor cells have the advantage that, once created, they can be grown in a laboratory into very large numbers. This could be critical if the cells were to be used in any therapy.

Brain cells and skin cells contain the same genetic information, however, the genetic code is interpreted differently in each. This is controlled by "transcription factors".

The scientists used a virus to infect skin cells with three transcription factors known to be at high levels in neural precursor cells.

After three weeks about one in 10 of the cells became neural precursor cells.

Lead researcher Prof Marius Wernig said: "We are thrilled about the prospects for potential medical use of these cells.

"We've shown the cells can integrate into a mouse brain and produce a missing protein important for the conduction of electrical signal by the neurons.

"More work needs to be done to generate similar cells from human skin cells and assess their safety and efficacy."

Dr Deepak Srivastava, who has researched converting cells into heart muscle, said the study: "Opens the door to consider new ways to regenerate damaged neurons using cells surrounding the area of injury."

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