The vampire bat, Desmodus rotundus, must find a blood meal every 1-2 days to survive. Scientists have known for years that when vampire bats tear through an animal's skin with their razor-sharp teeth, their noses guide them to the best spots – where a precise bite will strike a vein and spill forth nourishing blood. But nobody knew exactly how bats knew where to bite.

A new study shows for the first time that natural killer (NK) cells, which are part of the body's first-line defence against infection, can contribute to the immune response against HIV. In an article in the August 4 issue of Nature, a research team based at the Ragon Institute of MGH, MIT and Harvard reports that the HIV strains infecting individuals with particular receptor molecules on their NK cells had variant forms of key viral proteins, implying that the virus had mutated to avoid NK cell activity.

The research, led by Dr Clea Warburton and Dr Gareth Barker in the University's School of Physiology and Pharmacology and published in the Journal of Neuroscience, has investigated why we can recognise faces much better if we have extra clues as to where or indeed when we encountered them in the first place.