Biology Reference
In-Depth Information
HPV16 infection was 3.8 per 100 women-year at risk in the placebo
group and 0 per 100 women-year at risk in the vaccine group,
strongly suggesting that administration of the vaccine reduced the
incidence of both HPV16 infection and HPV16-related cervical
intraepitherial neoplasia. As predicted from type-specific neutraliz-
ing activity of anti-L1 antibodies, the cases of cervical intraepithe-
lial neoplasia that were not associated with HPV16 infection were
detected similarly among the placebo recipients and among the
vaccine recipients. Thus, one of the remaining problems to be
addressed is how to prevent infection with other high-risk HPVs.
We nasally administrated the synthetic peptide with the amino
acid sequence of HPV16 L2 aa108-120 to ten healthy volunteers to
evaluate the safety and immunogenicity of the peptide.
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The admin-
istration of the peptide — 0.1mg to five recipients and 0.5 mg to five
recipients — caused no serious local or systemic complications. The
anti-L2 antibody binding to both HPV16 and L1/L2-capsids and
neutralizing both HPV16 and 52 pseudovirions was induced in four
of the five recipients in the 0.5 mg group. Serological responses were
not induced by inoculation of 0.1 mg of the peptide. Although the
number of the recipients is small, the data suggest the HPV16 L2 pep-
tide is tolerable in humans and has the potential as a broad-spectrum
prophylactic vaccine.
Conclusion
Immunization with HPV16 L1-capsids induces in rabbits and mice
the antibodies recognizing conformation-dependent type-specific
neutralization epitopes, whereas the antibodies induced by denatured
L1-capsids do not neutralize HPV16 infectivity. A recent large-scale
clinical trial showed that an HPV16 L1-capsid vaccine candidate was
well tolerated by the participants and highly immunogenic in them.
The results obtained so far indicated that the vaccine protected the
recipients against HPV16 infection, which would progress to cervical
cancer, in an HPV type-specific manner.
HPV16 minor capsid protein L2 has a linear neutralization epi-
tope displayed on the surface of the L1/L2-capsids. The antibody
