FIG. 3.

Immunological responses of mice vaccinated with Pvs25 or Pvs28, as determined by ELISA. Several strains of mice were vaccinated with Pvs25 (filled columns) or Pvs28 (open columns). Serum samples collected 2 weeks after the third vaccination were serially diluted, and ELISAs were performed on plates coated with the immunizing antigen. Sera from preimmune mice and mice injected with alum alone did not recognize these proteins (data not shown). Antibody titers were calculated as the serum dilution giving an optical density of 0.2. Results are expressed as the arithmetical mean value from four mice.