News in brief

A better TB vaccine, perhaps
Tuberculosis (TB) currently has only one vaccine, which has success rates of between 20% and 50%. The Australian Immunization Handbook 10th ed states that “… there is strong evidence that BCG vaccination in infancy provides greater than 70% protection against severe disseminated forms of TB disease in young children, including miliary TB and TB meningitis … The efficacy of BCG vaccine against pulmonary disease in adults is less consistent and has ranged from no protection to 80% in controlled trials”. An international team, led by scientists from the Institut Pasteur in France, has found something with potentially much better odds, according to their study published in PLOS Pathogens. They created an experimental vaccine, which when tested on mice, caused T cells to recognise a missing protein that would have otherwise left space for the TB to take hold. Their vaccine was able to produce a sufficient immune response to be highly effective in protecting against TB, suggesting that these T cells play a big part in immune protection. The authors wrote that “our results pave the way for further development of candidates in preclinical models of anti-tuberculosis vaccination”.

Zika’s weaknesses shown in mice
Antibodies that specifically protect against Zika virus infection have been identified in mice, according to a report from Washington University (WU) School of Medicine researchers published in Cell. Zika antibodies can cross-react with other flaviviruses, such as Dengue virus and West Nile virus (hinting that the antibodies target genetically distinct but structurally similar regions across this family of viruses). Laboratories must use more expensive nucleic acid-based tests, which look for the presence of viral particles, in order to confirm Zika virus infection. The WU laboratory identified antibodies by infecting mice engineered to be susceptible to Zika with the virus and collecting their antibody-producing B cells. The researchers then screened the antibodies against Zika virus surface proteins. Six candidate antibodies were found, and from these, four were able to effectively prevent or treat Zika virus infection in cells and in mice. The researchers next want to identify at which stages of pregnancy the Zika antibodies have the most protective effects against the virus. Although the antibodies were identified in mice, they can be humanised without much difficulty, they said.

Ketone drink a boost for cyclists
A drink developed for soldiers to generate energy from ketones rather than carbohydrates or fat allowed highly trained cyclists to add up to 400 metres of distance to their workouts, according to a United Kingdom-led study published in Cell Metabolism. The supplement, which will be commercially available within the year, works by temporarily switching the primary source of cellular energy from glucose or fat to ketones – molecules derived from fat that increase for people who eat a low carbohydrates diet. Ketosis is a way for humans to deal with starvation. Ketones are made in the liver from mobilized body fat, so when the body doesn’t get enough fuel from food, internal fat stores are broken down to make ketones that feed the brain. Normal metabolism is driven by the burning of carbohydrates and fat obtained in a balanced diet. The idea to develop a ketone food group came from the Defense Advanced Research Projects Agency, the research branch of the United States army, who put out a $10 million call for the development of the most efficient food for soldiers to take to a battlefield. One of the people to answer this call was University of Oxford biochemist Professor Kieran Clarke. With Dr Richard Veech at the National Institutes of Health, she assembled a team who invented the ketone ester drink. In a study of 39 cyclists, including some former Olympians, they found that the muscles use ketones when provided in the diet, and that this uptake increases in proportion to the intensity of exercise. In one experiment, the researchers gave the cyclists “energy drinks,” each infused with a different source of fuel – carbohydrates, fats, or ketones – and found that cyclists who had the ketone drink had the lowest levels of lactate, a byproduct of the body’s breakdown of glucose, which is often associated with muscular stress, or the achy, tired feeling felt after a strenuous workout. The observation could help explain why the high-performing cyclists on the ketone drink traveled an average of 400 metres farther over a half hour than those consuming the carbohydrate or fat drink.

Sniffing out new antibiotics
Bacteria found in the nose can help kill the bacterium Staphylococcus aureus (including methicillin-resistant S. aureus [MRSA]), a German study published in Nature has found. Most antibiotics have been isolated from soil-living bacteria, but identifying novel compound structures from these soil microbes has become increasingly difficult. The human body is home to an immense variety of microorganisms known collectively as the microbiota, and the inside of the nose is no exception. S. aureus is found in the noses of about 30% of humans; it has remained uncertain how the remaining 70% of the population resist colonisation by the bacterium. Andreas Peschel and colleagues reported the discovery of an antibiotic that they named lugdunin, which represents the first known example of a new class of peptide antibiotics. Lugdunin is produced by the nostril-dwelling bacterium Staphylococcus lugdunensis and, the authors demonstrated, can be used to treat S. aureus skin infections in mice. They have shown that lugdunin has potent antimicrobial activity against a wide range of Gram-positive bacteria, including MRSA, and is not prone to causing development of resistance in S. aureus. The authors also examined nasal swabs from 187 hospitalised patients and found that S. aureus colonisation was 5.9% in individuals who carry S. lugdunensis compared with 34.7% in individuals without S. lugdunensis. These data provide evidence that, in the human nose, S. lugdunensis seems to help keep S. aureus at bay.

Daily exercise offsets sitting hazards
One hour of physical activity per day, such as brisk walking, may eliminate the increased risk of death associated with sitting for 8 hours a day, according to a series of four articles on global physical activity that includes New Zealand and Australia, published in The Lancet. The articles look at over 1 million adults in relation to their sitting time, television viewing time, physical activity and mortality, the first estimate of the economic burden of physical inactivity at global and national levels. Researchers analysed data from over 1 million people from 16 studies. The research team wanted to see how many hours of daily physical activity would be required to eliminate the association between prolonged sitting time and increased risk of death. Examples of physical activity were brisk walking at 5.6 km/h or cycling for pleasure at 16 km/h. The researchers classified individuals into four equally sized groups according to how active they were – less than 5 minutes a day for the least active, up to 60–75 minutes a day for the most active. People who sat for 8 hours a day but were physically active had a much lower risk of death compared to people who sat for fewer hours a day, but were not physically active. This suggests that physical activity is particularly important, no matter how many hours a day are spent sitting. In fact, the increased risk of death associated with sitting for 8 hours a day was eliminated for people who did a minimum of 1 hour’s physical activity per day. The greatest risk of death was for people who sat for long periods of time and were inactive.