Zombie Bacteria?

From New Scientist News:

Zombie bacteria have been created that could be used to make more stable vaccines.

Traditionally, vaccines use either "attenuated" live bacteria, grown in conditions that disable their virulent properties, or killed bacteria. Attenuated live vaccines promote a strong immune response, but can be difficult to store and transport safely, while killed bacteria don't work as well in triggering immunity.

Now there could be a third option. Sandip Datta and colleagues at the University of California, San Diego, irradiated live Listeria monocytogenes with gamma rays, breaking up their DNA so that they couldn't reproduce, but leaving enough residual metabolic activity to activate an immune response. When injected into mice, the "zombie" bugs prevented reinfection in 80 per cent of cases (Immunity, DOI: 10.1016/j.immuni.2006.05.013).

Unlike most vaccines, the irradiated Listeria don't need to be kept chilled. If the approach works with other strains of bacteria, it could lead to vaccines that are cheaper and easier to store for use in developing nations.

Ahhh, science!