LONDON Peptide Therapeutics Group plc has begun Phase I trials of its oral vaccine against traveler¿s diarrhea, caused by enterotoxigenic Escherichia coli (ETEC). The 30-patient, dose-ranging trial, which is being conducted at John Hopkins University, in Baltimore, will test two strains of live ETEC which have been attenuated through gene deletions. The aim is to determine which attenuation results in the most appropriate balance of safety and immunogenicity.

Following identification of a suitable strain, Peptide, based in Cambridge, plans to undertake an outpatient study in volunteers to confirm the results, before conducting a trial to assess the vaccine¿s ability to protect against challenge with a virulent ETEC strain. Once the vaccine is proven protective, the company plans to make the same gene deletions in other strains of ETEC, enabling it to formulate a vaccine which is effective against all common strains of ETEC.

The ETEC vaccine will be administered orally for delivery to mucosal surfaces, thus preventing initial infection by the pathogen. It is also expected to generate a systemic response, ensuring full protection from infection.

Last week, Peptide announced that it had been granted a series of U.S. patents covering its oral vaccine delivery technology, and also its oral typhoid vaccine. The patents cover attenuated strains of the bacteria Salmonella typhi, used to deliver antigens to the mucosa. CEO John Brown said, ¿The granting of these U.S. patents strengthens our dominant position in mucosal vaccine technology. The oral typhoid vaccine is progressing very well, and in addition to being a significant product in its own right, has given us considerable insight into how to develop many other oral vaccines.¿

Other applications of the technology include the development of an oral vaccine to protect against Helicobacter pylori. Clinical trials of the vaccine, which is being developed in collaboration with Pasteur Merieux-Oravax, are due to commence in 1999.