Vaccination and virus changes
Vaccination is the primary form of protection against influenza virus infection. The challenge of vaccinating against influenza lies in the constantly changing nature of the virus itself. This requires frequent updates of vaccine antigens to ensure that the vaccine-induced immune responses defend against circulating strains. Due to the extended time required to develop/prepare a vaccine, the possibility exists that by the time a vaccine is manufactured to support a global campaign, it is no longer relevant to circulating viruses; the greater the change, the less effective the vaccine.
Virus-like particles
Virus-like particles (VLPs) are hollow structures composed of structural proteins that spontaneously assemble to form particles with a similar morphology and antigenicity as the native virus. VLPs do not contain genetic material, however, and are therefore unable to replicate. They are immunogenic, but not infectious. Because of these characteristics, VLPs are an attractive option for generating flu vaccines.
Replication-defective viruses
Replication-defective viruses contain some viral genetic material, but lack certain genes that are essential for viral genome replication and assembly of progeny virus particles. They can be propagated in complementing cell lines that express the missing viral gene product(s), allowing for viral replication, but in normal cells, viral gene expression results in production of some viral components, but no progeny virus. Replication-defective viruses can be used as a vaccine by itself, or, can be used to generate VLPs in vitro that can then be used as a vaccine. Both the replication-defective virus and the VLPs will contain most of the proteins from the parent virus from which it was derived, making it relevant to currently circulating viruses.
CompoVax’s approach
Recent advancements in reverse genetic techniques make it possible to generate influenza viruses entirely from synthetic DNA. However, the introduction of an effective, fast, and relatively inexpensive way for generating a flu vaccine that preserves the antigens of the originally isolated parent virus without requiring their de novo reconstruction is needed. CompoVax is developing a novel proprietary method to generate two seasonal products, a live replication-restricted influenza A vaccine and a VLP vaccine, that exactly match the structural protein composition of circulating virus strain(s) without the need for reverse genetics. Both vaccines can be produced in sufficient amount within two weeks of isolating a circulating virus.
