Hep E Vaccine Developed Using Novel Liposome Technology

Biopharmaceutical company Lipoxen PLC (London, UK, www.lipoxen.co.uk)has developed a Hepatitis E vaccine using its novel vaccine deliverytechnology "ImuXen," which the company claims to be easy tomanufacture. According to the company, the proprietary liposomalformulation method delivers vaccine materials to the immune system in amanner designed to emulate the response of a natural encounter with theinfection agent. Results of a recently completed preclinical study haveshown that the technology gives rise to "very strong antibody againstthe vaccine immunogen" while offering "complete protection" from liverdisease. The immunological responses is reportedly similar to thatachieved by live attenuated vaccines, while "avoiding completely" therisk of infection associated with some live attenuated vaccines.

ImuXen technology uses novel liposome-based constructs to boost theeffectiveness of DNA, protein, and polysaccharide vaccines as well asvaccines containing DNA and its encoded antigen. The technology wasdesigned to resolve problems associated with current subunit antigensand plasmid DNA vaccines. According to the company, current vaccinescomprising microbial subunit antigens often are unable to induceappropriate immune responses and are associated with instability in thebody. Furthermore, plasmid DNA vaccines, which involve plasmid DNAencoding the subunit antigen and transfecting the cells to produce thesubunit vaccine, suffer from degradation problems after injection.

The liposomes used to deliver the vaccine in the Hep E vaccine are"microscopic spherules consisting of an aqueous core surrounded bylipidic bilayers composed of natural lipids normally found on cellmembranes as well as synthetic lipids," according to the company. Aproprietary procedure is used to entrap the vaccine within theliposomes, thus offering protection from degradation in the body.

The company also reports that co-entrapment of the DNA vaccine with theprotein vaccine it encodes in the same liposome leads to "strongerimmune responses than those seen with liposomes containing DNA or theprotein vaccine alone."

Lipoxen plans to conduct clinical trials for its Hep E vaccine in 2007