Biologics

Preps And L-Particles
Simple description
 

A herpes virus is a fairly simple structure- it has an outer layer called the envelope (like the leather of a football), an indistinct middle layer called the tegument (like the bladder of a football) and an inner core made of genetic material the nucleocapsid (like the air in a football). When herpes viruses are grown in cells in a culture dish, the cells produce two types of virus particle simultaneously- live virus particles as above, and very similar, “empty” virus particles. These “empty” particles are identical to viruses, except that they have no genetic material ie no DNA. The discovery that these particles exist was a major breakthrough, and it was made by the world renowned Herpes Virology Group of the Medical Research Council in Glasgow. Because these particles are empty, they are lighter than viruses, hence they were named “L-particles” for “Light particles”.
	The reason this was a major discovery- Because these L-particles have effectively the same outer structure as a virus, the particle will be taken up into the inside of the cell as if it were a virus. Proteins contained in the particle will thus be delivered to the inside of the cell. This ability to enter into cells means there is a great deal of potential for L-particles as a vaccine or therapy. If the L-particle was made to express (i.e.carry) a protein that would normally be found on e.g.a cancer cell, and the cell this was delivered to was an immune cell, a strong immune response could be generated. Also, because HSV has a large DNA core, it is possible to engineer several proteins simultaneously- ie it can deliver several proteins at the same time. This is a very important feature when developing cancer therapies.
Because the L-particle has no DNA it is unable to reproduce, and is therefore much safer than existing virus based therapies that use live viruses ( also known as virus vectors) The manufacture of L-particles has been adapted to make these particles in a very pure form- there is almost no contamination of the L-particles with viruses. This has been achieved by making the L-particles in the presence of DNA inhibitors. The resulting particles are very slightly different in structure, but retain the important features of L-particles. These highly purified particles are known as PREPS particles. Henderson Morley have acquired the patents for PREPS and L-particles and are now developing products in several disease areas based on these technologies.

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