Since then, VLP flu vaccines have moved onto the fast track, and VLP vaccines have done well in animal trials against avian, swine, and seasonal flu, and against Ebola as well. Now two of the leading developers, Novavax, of Maryland, and Medicago, of Quebec City, have taken VLP flu vaccines all the way through preclinical animal testing and into human clinical trials, two of which are beginning this month.
The companies use different manufacturing processes. Medicago grows its VLPs in transgenic tobacco plants, which are simple to manipulate, fast to grow, and easily raised in high-tech greenhouses that can be built almost anywhere. The company injects full-grown tobacco plants with genetic information from a target virus, and the plants produce VLPs in their biomass that can be extracted a few weeks later. Novavax uses an insect cell-culture approach, growing its VLPs in a line of identical “immortalized” cells taken 20 years ago from a caterpillar called a fall armyworm. The armyworm cells are injected with a recombinant baculovirus–a virus that only infects insects–that is tweaked to resemble a targeted flu virus. The cell responds by producing and secreting VLPs that have a shell identical to that of the flu virus but contain no flu RNA.
Both processes are relatively cheap and fast. To illustrate, the 400-person phase I clinical trial of Novavax’s swine flu vaccine candidate that began in Mexico this week was developed from the genetic information released on the H1N1 virus in early May and has already been through the design, small-scale production, and animal testing phases. Over this same time span, conventional makers have just barely started making the first deliveries of a vaccine that required no fresh design, no animal testing, and only minimal human testing.
The VLP effort, of course, may trip on any number of obstacles. Yet unless this trial by Novavax and a parallel avian-flu trial by Medicago reveal a fundamental flaw in the VLP approach–in contradiction of the successful animal trials of these vaccines and a successful phase I human trial of Novavax’s seasonal flu vaccine–VLP vaccines seem within reach of becoming the sort of effective, safe, and quickly produced flu vaccine the world lacks.