Acambis this morning said it is on track to move its investigational vaccine against Japanese encephalitis into Phase III clinical trials before the end of 2005, following results of a so-called bridging study.

A study was conducted following scale-up to full commercial manufacture, and results showed - on average – almost total (96%) seroconversion to JE-neutralising antibodies after a single dose of ChimeriVax-JE vaccine in all trial subjects. This, says the UK biotechnology company, is consistent with the profile seen in Phase I and II trials.

This is the beginning of what Acambis hopes will be a positive newsflow - the company is expecting Phase I data from a study of ChimeriVax-West Nile and the initiation over the next few weeks of a Phase I trial of its vaccine for Clostridium difficile.

Gordon Cameron, Chief Executive Officer of Acambis, said: “The bridging trial has validated our in-house manufacturing process and we have successfully crossed this major hurdle in the development of ChimeriVax-JE, which is one of our key development programmes."