Purified Protein Vaccines, Recombinant DNA Technology, and H5N1

New vaccine would be the first cell-derived, recombinant protein-based influenza vaccine licensed in the US.

On Monday at the 12th Annual World Vaccine Congress, Daniel Adams, Executive Chairman and Global Head of Business Development and Strategy, Protein Sciences Corporation (PSC), discussed the H5N1 virus and the FluBlok trivalent seasonal influenza vaccine. Adams said that PCS, a biopharmaceutical company that develops novel vaccines using genetic engineering technology, was the first to produce a vaccine against a potential pandemic influence, achieving this in 1998 against the H5N1 Hong Kong “Bird Flu.”

Adams claimed that PSC was able to produce a vaccine in only eight weeks, even at that early stage of its technology. Subsequent clinical trials showed that people who received the vaccine were "primed" and achieved very high titers against a broad range of potentially pandemic strains when vaccinated with a vaccine from a different clade of virus more than 10 years later.

“Obviously, our technology and capabilities have come a long way since then. We began manufacturing an H1N1 swine flu vaccine (called “PanBlok”) on June 15, 2009, and were the first company to have the vaccine available for human use, in August 2009,” Adams said.

PSC’s lead product, FluBlok, is a patented influenza vaccine that has shown the potential to provide protection against influenza that is superior to vaccines on the market and in development, especially in people over 65 years, and the gap widens significantly in people over 75. According to Adams, PSC is on track to receive FDA approval around the end of 2010.

FluBlok is a trivalent, seasonal influenza vaccine consisting of three full-length recombinant hemagglutinin (rHA) influenza proteins. The vaccine is produced in a non-transformed, non-tumorigenic continuous cell line (expresSF ) derived from Sf9 cells of the fall armyworm, Spodoptera frugiperda, grown in serum-free medium. Each of the three rHAs is expressed using a viral vector (baculovirus Autographa californica Nuclear Polyhedrosis Virus) that is non-pathogenic for humans. The three individual rHAs are extracted from the insect cells with buffer and detergent, and further purified by column chromatography. The purified monovalent bulks are then blended and filled into single-dose vials that contain a total of 135µg of rHA per single (0.5 mL) dose (45µg rHA of each of the three recommended influenza strains).

If approved, FluBlok will be the first cell-derived, recombinant protein-based influenza vaccine licensed in the US, and would provide the first alternative for vaccination of persons with egg allergy.

PSC began manufacturing H1N1 “swine flu” vaccine (called “PanBlok”) on June 15, 2009, and were the first company to have the vaccine available for human use in August 2009. In 1997-98, at a much earlier phase of development of its technology, PSC received NIAID funding to develop the first pandemic flu vaccine during the Hong Kong “Bird Flu” crisis. PanBlok’s performance was similar or superior to H5 vaccines manufactured and tested in the mid-2000s by major vaccine companies. “We now have refined our technology to the point that we could begin manufacturing within a few days after the decision to manufacture a pandemic vaccine and have the first doses ready to be released within 30 days thereafter” said Adams.

Most developed countries manufacture little or nothing of the basic needs of their cultures. Therefore, in the event of a pandemic, if the developed world protects itself with vaccines that are produced in the developed world, they will nevertheless fall victim to the pandemic when the people in the developing world die off.

The BEVS technology can be successfully used to manufacture vaccines in any monoclonal antibody facility. Worldwide there exists over 2.5 million liters of such cell culture capacity, all of which could be used to produce PanBlok in an emergency, according to Adams. Technology transfer from PSC could occur within three weeks; with facilities able to produce about six billion doses of pandemic vaccine within a few months.