Biology Reference
In-Depth Information
HPV16 L2 N-terminal region, approximately aa18-144, is dis-
played on the surface of the L1/L2-capsid and the antibody capable
of binding to the L2-surface region inhibits the infectivity of HPV
pseudovirions. Kondo
et al
.
48
recently showed that rabbit antisera
induced by the synthetic peptide with HPV16 L2 sequence aa18-38,
56-75, 61-75, 64-81, or 96-115 neutralize the HPV16 pseudoviri-
ons and cross-neutralize the pseudovirions of one or more of HPV18,
31 and 58. The data indicate that these antigen peptides contain
cross-neutralization L2-epitopes.
Protective Immunity with Anti-L2 Antibodies
in Animal Models
Chandrachud
et al
.
49
showed that immunization of cattle with bac-
terially expressed BPV4 L2 fused to glutathione S-transferase elic-
its neutralizing antibodies and protects the animals against BPV4
challenge.
Embers
et al
.
50
showed that immunizations of rabbits with the
peptides having amino acid sequences of rabbit oral (ROPV) and cuta-
neous (CRPV) papillomavirus L2 regions corresponding to HPV16
L2 aa108-120 protect the rabbits from challenge with ROPV and
CRPV, respectively, further indicating that the epitope(s) required for
protective immunity is located in the L2 region. The level of protec-
tion induced by these peptides is comparable to that seen with L1-
capsid vaccination.
Prophylactic HPV Vaccine
Phase I/II clinical studies showed that an L1-capsid vaccine was
well tolerable and highly immunogenic.
51-53
In the majority of the
recipients, the serum antibody titers were higher than those detected
in the natural infection.
51-53
A large-scale clinical trial in the United
States is underway with an HPV16 prophylactic vaccine using
HPV16 L1-capsids as an antigen.
1,53
Of women who received the
vaccine, 99.7% were seroconverted. At 17.4 months after com-
pletion of the vaccination regimen, the incidence of persistent
