P.C. Shannon

I started reading this article yesterday about using bacteriophages to treat infections, especially strains that are resistent to most antibiotics. The great thing about phages is that they can be built entirely from their DNA. Cellular processes depend on having a progenitor — one cell becomes two becomes four. It’s been a very long time since nothing became one cell. But a bacteriophage is described entirely by its DNA; no other part of the virus enters the host. (Many viruses of higher organisms, HIV for instance, contain enzymes within in the virus particle that are required to complete their life cycle. Thus the entire virus must enter the host cell.)

The other exciting thing about phages is that they are lytic — they destroy their host. So I started thinking about ways to hijack their lifecycles. It’s routine to clone a gene who’s protein you’re interested in, overexpress it in E. coli and then purify the protein. But it can be tricky to get the protein out of the bacteria. Wouldn’t it be simpler if the bacteria broke open once they filled up with the protein? It seems like you could clone the protein into a phage genome and let it go to town.

That’s pretty academic, though. Consider a patient who’s got a nasty bacterial infection, one that’s resistent to antibiotics. You could attack with phage and it would be all good, but what if we could get those bacteria to produce something else while they’re being destroyed by the phages. You’d have 1% of your phages actually be pseudo-phages, virus particles that contain non-viral DNA that encodes some other product. This other product could be a painkiller or perhaps a cytokine or other compund to boost the immune system.