Dr Sarah Pitt, Principal Lecturer at the School of Pharmacy and Biomolecular Sciences, University of Brighton, made the news this week after announcing a breakthrough in her work with snail slime. The antibacterial properties that she has discovered could help develop medicines such as an antibiotic cream to treat burn wounds and an aerosol to treat lung infections in patients with cystic fibrosis.
The research was made possible through her successful application for an IBMS research grant. For those interested in the biomedical science, IBMS members can access the original article Antimicrobial properties of mucus from the brown garden snail Helix aspersa via the British Journal of Biomedical Science. For an overview of the science, on applying for her grant, Sarah said:
"Working with my husband, Dr Alan Gunn of Liverpool John Moores University and other colleagues, we have found that the defensive mucus produced by the brown garden snail, Cornu aspersum (also called Helix aspersa) has antimicrobial properties. I have tested samples of the mucus against a range of microorganisms, but have only observed a consistent, reproducible effect against Pseudomonas aeruginosa. In disc diffusion plate antimicrobial assays, the mucus inhibited the growth of several type culture collection strains and clinical isolates of the bacterium. This is interesting because Ps.aeruginosa is a ubiquitous, opportunistic pathogen. It infects a range of sites including deep wounds and it is also an important cause of respiratory disease in patients with cystic fibrosis. Drug resistant strains are increasingly being reported, so a novel antimicrobial treatment would be valuable.
Using HPLC and Mass spectroscopy we were able to find partial sequences for three proteins with antibacterial activity. Recently we have obtained the RNA transcriptome for the whole snail and used this to identify the full sequences for these three proteins. The one I am most interested in is a 37kDa protein, which we have named Aspernin. I will use the IBMS Research Grant for the investigation of the structure, function and mechanism of antibacterial action of Aspernin. Mucus is very difficult to work with, but now that we have the sequence, we will be able to make the protein in a suitable vector. Having the protein on its own will also allow us to do quantitative assays, in particular the minimum inhibitory concentration of Aspernin with respect to Ps. aeruginosa. We will also grow the bacterium in the presence of Aspernin and then examine what effect it has on the cell wall integrity, size and shape of the cells, using electron microscopy. We will use fluorescent-labelled amino acids to see whether it affects protein synthesis. A key experiment will be to test the effect of Aspernin on mammalian cells using an in vitro cytotoxicity assay, to ensure that the protein could be suitable for use in human medicine. With results indicating the site and possible mechanism of action, it is hoped that Aspernin could be used to develop a novel, clinically useful antibacterial treatment. At the moment, we are envisaging it being used in combination therapies with existing antibiotics, in the form of a cream as a topical application for deep wound infections and/or an aerosol to treat respiratory infections."