Researchers at Cal’s school of public health have successfully genetically modified the Salmonella bacterium in order to use it for the treatment of viral infections, such as cytomegalovirus. This anti-viral treatment/ technique utilizes the salmonella bacterium as a “safe transport vehicle for virus-stopping enzymes.” Specifically, salmonella acts as a vector for delivering RNAse P ribozyme to infected cells. Ribonuclease P rybozyme is a unique enzyme that “targets the overlapping mRNA region of M80.5 and protease, two murine cytomegalovirus (MCMV) proteins essential for viral replication.”
The treatment operates upon the fact that Salmonella evolved as bacteria capable of surviving the human digestive system. Salmonella was a particularly appealing vehicle for the anti-viral treatment as the food-borne pathogen- turned gene therapy agent because it could be swallowed (providing a much easier means of administration than vaccine injections). Furthermore, Salmonella could be attenuated to create a strain of bacteria with low cytotoxicity and pathogenicity.
Researchers Liu and Lu tested the capacity of Salmonella to bring viral rybozymes into the human cell. They experiments were first carried out in cell cultures, then tested in vivo in murine models. The strains of bacteria were also mutated and tested to ensure that they would not cause sickness in the mice. When the CMV infected mice were administered the bacteria containing the ribozyme plasmid it became evident that the active form of the bacteria at least doubled the life of the CMV infected mice.
Bacteria seem extremely useful as anti-viral gene-therapy. They can deliver necessary genes and enzymes to host cell populations, and can be grown with relative ease low cost in cell cultures. Who knows, this technique could also be used to treat many other viral infections.