Experimental Vaccine Promising in Early Study

An influenza vaccine produced with the use of insect cells appeared safe and produced an immunogenic response in healthy adults, suggesting promise as an alternative to using embryonated eggs for the development of influenza vaccine, according to a preliminary study published in the April 11 issue of The Journal of the American Medical Association (JAMA).

"All currently licensed influenza vaccines in the United States are produced in embryonated hen's eggs. There are several well-recognized disadvantages to the use of eggs as the substrate [the base on which an organism lives or grows] for influenza vaccine," the study authors wrote.

The authors add that development of alternative substrates for influenza vaccine production has been identified as a high priority. Another potential alternative is use of the influenza virus hemagglutinin (HA) using recombinant DNA techniques.

The experimental influenza vaccine consisted of recombinant HA expressed in insect cells by a recombinant baculovirus (rHA0). The clinical trial was conducted at three U.S. academic medical centers during the 2004-2005 influenza season and included 460 healthy adults. Participants were randomly assigned to receive a single injection of: placebo; 75 micrograms of an rHA0 vaccine containing 15 micrograms of hemagglutinin from influenza A/New Caledonia/20/99 (H1N1) and influenza B/Jiangsu/10/03 virus and 45 micrograms of hemagglutinin from influenza A/Wyoming/3/03 (H3N2); or 135 micrograms of rHA0 containing 45 micrograms of hemagglutinin each from all three components. Serum samples were taken before and 30 days following immunization.

According to the findings, the rHA0 vaccine is well tolerated in healthy adults and immunogenic at both doses evaluated, and the study showed preliminary evidence of protection against influenza infection and disease. The safety data are consistent with the safety profile observed in previous studies of rHA0 vaccine, according to the study authors.