Virus-Like Particles May Fast-Track Vaccines

Virus-like particles could dramatically accelerate the process of vaccine production.

Virus-like particles (VLPs), mere shells of actual viruses, can be used to create vaccines in weeks instead of months, according to Novavax Inc. of Rockville, Md.

The research could make vaccine production faster and more reliable than existing methods, and save hundreds of thousands of lives.

"The outside of the virus-like particles looks like a virus," said Rahul Singhvi, the president and CEO of Novavax, "but inside there is no genetic material."

Influenza virus, for example, is a pretty simple creature. A protein coat, tipped with two major proteins, encases a strand of RNA, which is used to replicate viruses, containing eight genes.

The variations of the two major proteins, called hemagglutinin and neuraminidase, are what infectious disease officials use to identify the various strains of flu: H5N1 for bird flu and H1N1 for swine flu, for example.

To create a vaccine that preps the body's immune system to find and destroy influenza, researchers have traditionally injected a seed virus, developed by the Centers for Disease Control (CDC) in Atlanta, into chicken eggs.

The chicken eggs are allowed to incubate, and the seed virus replicates many times over within each egg. When the time is right, scientists harvest and purify the viruses, inactivate or kill them with heat or chemicals, and sometimes even chop them up for good measure. These viral particles or fragments are what scientists use to create vaccines.

The entire process can take more than six months.

VLPs, on the other hand, are made by injecting insect cells with three of the eight influenza genes. One gene contains instructions on how to build the viral shell. The other two genes code for proteins that sit on the outside of the shell.

What emerges from the insect cells are hollow particles that have the two proteins for the coming year's flu strain.

Novavax can produce vaccines sooner than traditional makers, because they don't have to wait for the CDC to create the seed virus. As soon as the genetic sequence for this year's strains are published, Novavax can synthesize the genes and inject them into insect cells without waiting for the seed virus.

Seven different strains of flu VLPs have already been injected into about 700 people in several Phase II clinical trials.

The results, according to Singhvi, have been promising. However, since they are Phase II trials, only effectiveness was tested; any possible side effects of VLPs are unknown for the moment.

Novavax hopes to have wide-spread vaccinations using VLPs in the United States as early as 2012. Other countries could fast-track the use of VLPs as soon as next year, although nothing is definite yet.

In fact, other countries might be the biggest beneficiary of VLP technology, according to Kawsar Talaat, a professor and influenza expert at Johns Hopkins University.

"If we can cut down the time it takes to develop a vaccine by months, you could save thousands, even hundreds of thousands, of cases each year," said Talaat. "This could be a huge development."

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