Mary Hoelscher (pictured) and her team set their objective to develop an egg-independent strategy to combat avian influenza.
Immunization with human replication incompetent adenoviral based vaccine encoding the hemagglutinin protein subtype H5 provided effective protection from H5N1 disease, death and primary viral replication in mice. The vaccine induced a three- to eightfold increase in HA 518-epitope specific T cells secreting interferon gamma. The number of antigen-specific T cells was measured with a Kd/HA 518-specific custom Pro5® MHC Class I Pentamer to correlate antigen-specific responses with protection. The result shows the potential of the viral delivery system for an H5N1 vaccine, which is both egg and adjuvant independent and which increases stockpiling options for a pandemic influenza vaccine.
The figure shows flow cytometric analysis of spleen cells from immunized mice (three per group) stained with HA 518 Pentamer. Pentamer positive cells (circled) are shown as a percentage of CD8 T cells.
Mice that received the HAd-H5HA vaccine had a three-fold to eight-fold higher frequency of HA 518-specific CD8 T cells than mice immunized with HAd-DE1E3 or with rH5HA and alum, when delivered intranasally (in) or intramuscularly (im). Mice infected with H5N1 virus showed an HA 518-epitope specific response similar to that recorded with an H1N1 virus infection.