MedImmune, Inc. announced that the U.S. Food and Drug Administration (FDA) has approved the company´s supplemental biologics license application (sBLA) to use reverse genetics technology to construct new vaccine strains to produce seasonal influenza vaccines, including FluMist (Influenza Virus Vaccine Live, Intranasal) and the next-generation, refrigerator-stable formulation, CAIV-T (cold adapted intranasal vaccine -- trivalent). Creation of new vaccine strains is the first step (and often a production-limiting one) in the influenza vaccine manufacturing process. Use of reverse genetics (also known as "plasmid rescue") technology enhances the safety, specificity, reliability and efficiency with which new vaccine strains can be produced.

"Reverse genetics represents an important breakthrough in commercial influenza vaccine processes by improving the efficiency of producing new influenza vaccine strains on an annual basis," said George W. Kemble, Ph.D., vice president, research and development, vaccines. "This technology enables scientists to replace cumbersome seasonal vaccine strain development methods that were created in the 1960s with modern techniques, which should allow us to accelerate the availability of influenza vaccines to the public.

"For producing pandemic influenza vaccine seeds, reverse genetics has the added benefit of allowing scientists to remove potentially pathogenic portions of the virus, thereby creating a safer production process for the vaccines," Dr. Kemble commented further.

Toward this end, MedImmune has already begun applying its plasmid rescue technology to pandemic research efforts. Last month, the National Institutes of Health (NIH) began enrolling participants in a Phase 1 study of an intranasal H5N1 influenza vaccine candidate based on MedImmune´s live, attenuated vaccine technology, which also utilized reverse genetics technology. Investigators at MedImmune and Johns Hopkins Bloomberg School of Public Health Center for Immunization Research, where the study is being conducted, are hopeful that a live, attenuated intranasal influenza vaccine would be as effective against potential pandemic A strains as it has been shown to be against seasonal matched and mismatched A strains of influenza.

Most influenza vaccine manufacturing companies and governmental agencies are now using reverse genetics technology in their development of pandemic vaccine candidates because it allows them to avoid working directly with the infectious, circulating pandemic strains. As the owner or exclusive licensee of the key patent estates for use of the reverse genetics technology in human influenza vaccines, MedImmune remains committed to making sure that the technology is accessible to government institutions and industry manufacturers. As such, the company has offered other influenza vaccine manufacturers non-exclusive licenses to this intellectual property estate for use in manufacturing seasonal or pandemic vaccines.