All sera were tested individually by plaque reduction neutralization method by doubling dilution of each sample (1:5 to 1:80) as Figure 5B ) showed distinct association between VLP dosage and the ability to mount a neutralizing antibody response. Mice inoculated with the two highest VLP doses (treatment groups C and D) were each able to induce neutralizing antibodies by day 35. When samples from mice receiving the two lower concentrations of VLPs (3.5 ug/dose and 1.75 ug/dose, corresponding to treatment groups B and A respectively) were similarly tested, 3 of 5 and 1 of 5 mice respectively induced neutralizing antibody response; the titers ranged from 1:5 to .1:80. As expected, the control mice did not induce neutralizing response.