Phage Biology

Bacteriophage can simply be described as bacteria-specific viruses. Unlike viruses however, bacteriophages are safe to humans, animals, and quite frankly, anything that isn't a bacteria. Looking like lunar landers, bacteriophage have evolved to efficintly and effectively replicate in the presence of specific bacteria. In fact, this is a major reason why the earth isn't hip deep in bacteria - bacteriophage and bacteria have a population stability built into them that many reseachers have described as why bacteria can exist, but not overpopulate its environment.

The structure of a "typical" bacteriophage.

Phage Amplification

Lytic bacteriophage have a well described life cycle. It is this life cycle that MicroPhage is taking advantage of to provide a natural amplification of signal to easily detect as a surrogate for the target bacteria. Below is a brief description of the major steps in this process.

		(1)	(2)
Adsorption		Bacteriophage quickly find specific receptors on the surface of the target bacteria and attach in a two step process. First, a low-affinity binding occurs with the phage tail fibers to the outer membrane of the bacterium. Second, small tail fibers extend from the baseplate of the bacteriophage to form a high-affinity, irreversible bond to the bacterium. Enzymes located on this baseplate allow for "softening" of the bacterium's membrane.
Injection		Once the phage has bound irreversibly to the bacterium, and the membrane has been sufficiently compromised by its enzymes, the phage's nucleic acid is injected into the bacterium. (Shown on the right in red)
Replication		Replication follows nucleic acid injection, producing hundreds to thousands of progeny bacteriophage. The parent bacteriophage's nucleic acid inserts itself into the DNA replication process of the bacterium host, halting further growth of bacteria and "hijacking" it to instead produce proteins that will assemble and become bacteriophage.
Lysis		Depending on the bacteriophage, an additional enzyme is formed following or in concert with bacteriophage replication, producing holin or lysin which thins the bacterial membrane, allowing for the progeny phage to break out into the open environment.

Lysis occurs for each succesfully infected bacterium, and with high concentrations of bacteria, will occur almost in unison for all phage infected bacteria. The system in total can generate as much as a 5-log amplification of signal in a matter of minutes from the time of the first burst or lysis event. This increased concentration in bacteriophage, from what is part of the incubated sample to what is available post-incubation is the natural amplification process MicroPhage exclusively retains for diagnostic use.