One of the challenges in vaccine development is the creation of products that contain defined antigens of high purity and efficiently induce a protective immune response. Many antigen preparations are therefore supplemented with adjuvants to enhance the body’s immune response to the specific antigens. The most commonly used and approved adjuvants for human use are aluminium salt derivatives, which are known to cause adverse reactions such as irritation and inflammation at the injection site.

Crucell’s patented virosome technology represents a new frontier in vaccinology, simultaneously improving the delivery of specific antigens to target immune cells, while bypassing the problems of conventional adjuvant-based vaccines.

Based on liposomes, virosomes are tiny spherical vesicles made up of a mixture of synthetic and natural phospholipids holding the influenza virus surface proteins haemagglutinin (HA) and neuraminidase (NA). The HA and NA proteins provide the virosomes with properties that enable them to fuse with cells of the immune system. By embedding proteins of other human pathogens in the vesicles, virosomes can deliver their content - the vaccine specific antigens - directly to their targets, thereby stimulating the immune system.

Crucell’s patented virosome technology is a broadly applicable delivery system with prospective applications in areas beyond antigen-based vaccines, such as for the delivery of DNA/RNA or therapeutic drugs. Crucell has developed several methods which allow the absorption, the chemical binding and the incorporation of antigens onto/into virosomes. Therefore, virosomes offer a flexible new tool for developing novel prophylactic and even therapeutic vaccines for a variety of diseases. The virosome technology has been licensed for a number of indications on an exclusive basis to Pevion Biotech, a joint venture company with Bachem, and is still available for licensing for a number of infectious disease areas.

Crucell is the leading company in the development and production of virosomal vaccines. Virosomes are a market approved carrier system for the delivery of pharmaceutically or immunologically active substances.

The technology has been used to develop Crucell’s product Inflexal^® V, a trivalent seasonal influenza vaccine, as well as Epaxal^®, a hepatis A vaccine.