Fig. 2 Titers of serum IgG antibodies from vaccinated mice. L1N, L1A, L1P, control indicated sera from the corresponding group of mice. -1, -2, -3 indicated the first, second and third immunization. M3 indicated sera antibodies from mice immunized with HPV16 L1 expressed in  Escherichia coli.  CAMVIR-1 indicated commercial HPV16 L1 monoclonal antibody.