By replacing some of the genes in mammalian pathogens with those found in arctic bacteria, Francis Nano of the University of Victoria in Canada may have found the key to make a new class of vaccines.
These new strains are able to provoke an immune response in mice, but they do not cause harm as they do not travel to the warmer parts of the body, ScienceMag.org reports. With this knowledge, scientists hope to create vaccines for major bacterial infections, including tuberculosis.
Some temperature-sensitive vaccines have already been released. FluMist is composed of a weakened influenza virus that cannot live at temperatures of 37 degrees Celsius, the temperature inside the lungs. It triggers a protective immune response from inside the nose and throat instead. FluMist was developed by repeatedly growing the virus at increasingly lower temperatures and letting it adapt.
Nano and his team took a bacterial relative of Francisella tularensis - F. novicida - and replaced nine of its genes with their counterparts from Colwellia psychrrythraea, a bacterium found in arctic water and ice.
Nano then injected the altered strains into the tails of rats and found that the strain did not spread to warmer areas like the spleen and lungs. Once this was accomplished, mice, to which F. novicida is normally lethal, were then injected with the new bacteria. They survived, and, when given the unaltered virus three weeks later, were immune, ScienceMag.org reports.
Tuberculosis is Nano’s main target of in this research. His team of scientists was able to demonstrate that they could make a research stand-in for tuberculosis - Mycobacterium smegmatis - temperature sensitive, but have not yet tested it as an eventual vaccine.