Biology Fall 2009--Rozema BACTERIA & VIRUSES Readings Antibiotic Resistance Clue Found US scientists have uncovered a defense mechanism in bacteria that allows them to fend off the threat of antibiotics. It is hoped the findings could help researchers boost the effectiveness of existing treatments. The study published in Science found that nitric oxide produced by the bacteria eliminates some key effects of a wide range of antibiotics. One UK expert said inhibiting nitric oxide synthesis could be an important advance for tackling tricky infections. MRSA highlights the problem of antibiotic resistance Antibiotic resistance, for example with MRSA, is a growing problem and experts have long warned of the need to develop new treatments. The latest research, done by a team at New York University, showed that in bacteria the production of nitric oxide - a small molecule made up of one nitrogen and one oxygen atom - increased their resistance to antibiotics. They found the enzymes responsible for producing nitric oxide were activated specifically in response to the presence of the antibiotics. They also showed that nitric oxide alleviates damage caused by the drugs as well as helping to neutralise many of the toxic compounds within the antibiotic. The researchers then showed that eliminating nitric oxide production in the bacteria allowed the antibiotics to work at lower, less toxic doses. More effective Study leader, Dr Evgeny Nudler, said developing new medicines to fight antibiotic resistance, such as that seen with MRSA is a "huge hurdle". "Here, we have a short cut, where we don't have to invent new antibiotics. "Instead we can enhance the activity of well-established ones, making them more effective at lower doses. Dr Matthew Dryden, consultant in microbiology and communicable disease at Royal Hampshire County Hospital and general secretary of the British Society for Antimicrobial Chemotherapy, said if the enzyme which creates nitric oxide could be inhibited, it could suppress the ability of the bacteria to counteract antibiotics. "This would be a useful therapeutic advance, especially as we are running out of new classes of antibiotics and there is less antibiotic development in general." Biology Fall 2009--Rozema What Scientists Know About Swine Flu Preliminary analysis of the swine flu virus suggests it is a fairly mild strain, scientists say. It is believed that a further mutation would be needed in order for the H1N1 virus to cause the mass deaths that have been estimated by some. But at this point, it is impossible to predict with any accuracy how the virus will continue to evolve. UK experts at the National Institute for Medical Research outlined on Friday the work they are due to start on samples of the virus sent from the US. The research, being done at the World Influenza Centre in Mill Hill, will be vital for working out the structure of the virus, where it came from, how Influenza viruses are able to swap quickly it is capable of spreading and its potential to cause illness. genetic material Structure Analysis done so far suggests what they are dealing with is a mild virus and nowhere near as dangerous as the H5N1 avian flu strain that has caused scientists so much concern over the past decade. Influenza A viruses are classified according to two proteins on the outer surface of the virus - hemagglutinin (H) and neuraminidase (N). FLU STRAINS COMPARED H1N1 (seasonal flu/swine flu) H5N1 (avian flu) Spreads easily through Can mutate rapidly coughing and sneezing Causes severe illness and can Less severe symptoms, but can trigger pneumonia be deadly Spreads easily between birds but human transmission rare The swine flu strain is a H1N1 virus, the same type as seasonal flu which circulates throughout the world every year, and kills roughly 0.1% of those infected or higher in an epidemic year. Professor Wendy Barclay, chair in influenza virology at Imperial College London says initial indications suggest there is nothing about the genetic make-up of the new virus which is a cause for particular concern. Biology Fall 2009--Rozema The key to its potential lies largely in the H1 protein. "There are two aspects - one is which receptors the virus tends to bind to and H1N1 what we see is that it is binding to the upper respiratory tract rather than deep Can spread between humans in the lungs." Attaches to receptors in the upper respiratory tract causing When a flu virus binds to the upper respiratory tract, it tends to cause mild mild illness illness but can be easily spread as people cough and sneeze, Professor Barclay A pandemic is thought to be explains. If a virus binds further down in the lungs, it tends to cause much imminent more severe illness, as in the case of the H5N1 avian flu virus which has caused concern in recent years. "With the H1 gene we also look at the cleavage site," she adds. "The virus has to be cut into two pieces to be active and it uses an enzyme in the host to do that. "Most influenza viruses are restricted to the respiratory tract because they use enzymes in the lungs. "But some, like H5 viruses can evolve to cut into two pieces outside the lungs, so they can replicate outside the respiratory tract." Predictions Scientists have also played down concerns that the milder H1N1 virus, could combine with the more dangerous H5N1 avian flu virus, causing a super virus that has the ability to both spread easily between humans and cause severe illness. This is unlikely - or at least just as unlikely as it ever was and the H5N1 virus has been around for a decade without combining with normal seasonal flu. Professor Jonathan Ball, an expert in molecular virology at the University of Nottingham said: "The chance of swine H1N1 combining with H5N1 is as likely as any other strain recombining. "What this outbreak does highlight is how difficult it is to predict new pandemic strains.” "Many people suspected that H5N1 was the most likely candidate for the next pandemic strain, but now it appears that this was a mistake - but that's not to say H5N1 or another reassortment containing parts of H5N1 may not happen in the future. “ "That's the trouble - you can't predict."