When the investigators looked for evidence of a specific immune response to H5N1, they found similar results. Although they were able to isolate high levels of infectious H5N1 from multiple organs in the mice vaccinated with the empty vector, and to various degrees in animals vaccinated with the vectors containing the HA subunits, they isolated only very small amounts of H5N1 from the mice immunized with the full-length HA vaccine three days after infection. Six days after infection, they could not detect any infectious H5N1 in the organs of mice immunized with the full-length HA vaccine.
Moreover, when they looked at the cellular immune response to vaccination, they found that all of the animals immunized with full-length HA or the subunit vaccines developed strong cellular immune responses. However, only the full-length HA-immunized mice developed strong T-cell responses to both of the HA subunits. According to Simon Barratt-Boyes, B.V.Sc., Ph.D., associate professor, department of infectious diseases and microbiology, University of Pittsburgh Graduate School of Public Health, and one of the co-authors of the study, the ability of this particular recombinant vaccine--a vaccine carrying only the important immune-stimulating proteins--to induce both antibody- and T cell-directed immunity is extremely encouraging.
"This means that this recombinant vaccine can stimulate several lines of defense against the H5N1 virus, giving it greater therapeutic value. More importantly, it suggests that even if H5N1 mutates, the vaccine is still likely to be effective against it. How effective, we are not su
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26-Jan-2006