What Does All This Mean??

• H5N1 viruses are extremely pathogenic in mice. Thus, mice provide a well-defined mammalian model for evaluating vaccine efficacy.
• The HK97 HA-DNA vaccine provided immunity against both the homologous human H5N1 isolate, HK97, and the chicken H5N1 isolate, CkHK97. This suggests that a HA-DNA vaccine can provide protective immunity against homologous strains and antigenic variants.
• The fact that a vaccine encoding for an antigenically different HA was able to prevent death in mice indicates that, in an avian influenza pandemic, a DNA vaccine encoding an antigenically related HA may provide sufficient protection to humans until a genetically matched HA-DNA vaccine could be produced.
• Even though only low levels of HI antibodies were observed after challenge with either HK97 or CkHK97, the DNA vaccination was still able to neutralize the influenza virus. This is most likely due to an immune response mediated by B-cell memory induced by vaccination.
• The smaller effects of inoculation with pTyIrHA indicate that avian viruses may not be as useful as human isolates as sources of vaccines against avian viruses introduced into the human population. This is most likely due to species differences.

Although infection may not be able to be prevented by available vaccines, they may be useful in preventing deaths until a specific vaccine against the pandemic strain can be made. DNA vaccines offer a new approach to treating an old problem.

back to list of experiments