Bug factories for drugs: quality control holds key to quantity

Tiny types of soil bugs already make many of the products we use in washing detergents, foods, and waste treatment, but scientists now hope that similar bacteria will also make the vaccines and drugs of the future, according to new research presented today (Tuesday, 07 September 2004) at the Society for General Microbiology’s 155th Meeting at Trinity College Dublin.

Researchers from the Institute of Cell and Molecular Studies at Newcastle University have successfully produced small quantities of a promising new vaccine for anthrax using Bacillus bacteria which have been modified to produce human medicines. “Many people already use enzymes produced by these bacteria to wash their clothes,” says Professor Colin Harwood of Newcastle University. “But the bacteria which make these enzymes, so useful for digesting dirt, have very efficient quality control systems which spot rogue proteins and enzymes and destroy them. This control mechanism stops us using these bacteria to make large quantities of the pure proteins we need for use in vaccines and other medicines.”

The scientists have spent the last ten years, working with a Europe-wide group of 11 research laboratories, discovering how bacteria move enzymes and proteins from inside their cells, where they are made, to the outside world, where they are needed.

An important component of the system for moving proteins across the cell membrane turns out to be a quality control mechanism which recognises and breaks down foreign proteins. The bacteria need this checking mechanism to survive in competitive natural environments such as the soil. But this same checking system means that any drug production is disappointingly low if we try to use the bacteria to make useful medicines.

“Bacilli could make authentic versions of some of the important proteins we have identified from the results of the Human Genome Project, at concentrations of 20 grammes per litre – which is commercially acceptable,” says Prof Harwood. “These bacteria are wonderfully efficient factories, and using them would reduce purification costs and provide structurally authentic proteins.”

“A better understanding of bacteria will allow us to produce human and animal medicines,” says Prof Harwood. “However, since the protein secretion apparatus and quality control systems are also essential for the bacteria’s survival, they also give us new targets for antibiotic drugs.”