When administered as standard three-dose schedules, the licensed HPV prophylactic vaccines have demonstrated extraordinary immunogenicity and efficacy. We summarize the immunogenicity of these licensed vaccines and the most commonly used serology assays, with a focus on key considerations for one-dose vaccine schedules. Although immune correlates of protection against infection are not entirely clear, both preclinical and clinical evidence point to neutralizing antibodies as the principal mechanism of protection. Thus, immunogenicity assessments in vaccine trials have focused on measurements of antibody responses to the vaccine. Non-inferiority of antibody responses after two doses of HPV vaccines separated by 6 months has been demonstrated and this evidence supported the recent WHO recommendations for two-dose vaccination schedules in both boys and girls 9-14 years of age. There is also some evidence suggesting that one dose of HPV vaccines may provide protection similar to the currently recommended two-dose regimens but robust data on efficacy and immunogenicity of one-dose vaccine schedules are lacking. In addition, immunogenicity has been assessed and reported using different methods, precluding direct comparison of results between different studies and vaccines. New head-to-head vaccine trials evaluating one-dose immunogenicity and efficacy have been initiated and an increase in the number of trials relying on immunobridging is anticipated. Therefore, standardized measurement and reporting of immunogenicity for the up to nine HPV types targeted by the current vaccines is now critical. Building on previous HPV serology assay standardization and harmonization efforts initiated by the WHO HPV LabNet in 2006, new secondary standards, critical reference reagents and testing guidelines will be generated as part of a new partnership to facilitate harmonization of the immunogenicity testing in new HPV vaccine trials.

Background. Human papillomavirus virus type 16 (HPV-16) and HPV-18 cause a large proportion of oropharyngeal cancers, which are increasing in incidence among males, and vaccine efficacy against oral HPV infections in men has not been previously evaluated. Methods. Sera and saliva collected in mouthwash and Merocel sponges at day 1 and month 7 were obtained from 150 men aged 27–45 years from Tampa, Florida, and Cuernavaca, Mexico, who received Gardasil at day 1 and months 2 and 6. Specimens were tested for anti–HPV-16 and anti–HPV-18 immunoglobulin G (IgG) levels by an L1 virus-like particle–based enzyme-linked immunosorbent assay. Results. All participants developed detectable serum anti–HPV-16 and anti–HPV-18 antibodies, and most had detectable antibodies in both oral specimen types at month 7 (HPV-16 was detected in 93.2% of mouthwash specimens and 95.7% of sponge specimens; HPV-18 was detected in 72.1% and 65.5%, respectively). Antibody concentrations in saliva were approximately 3 logs lower than in serum. HPV-16– and HPV-18–specific antibody levels, normalized to total IgG levels, in both oral specimen types at month 7 were significantly correlated with serum levels (for HPV-16, ρ was 0.90 for mouthwash specimens and 0.92 for sponge specimens; for HPV-18, ρ was 0.89 and 0.86, respectively). Conclusions. This is the first study demonstrating that vaccination of males with Gardasil induces HPV antibody levels at the oral cavity that correlate with circulating levels.

Background: Defects in lymphoproliferative responses to mitogens/antigens in women >45 years old with a persistent type-specific human papillomavirus (HPV) infection have been reported. Methods: To determine whether these defects were associated with altered cytokine profiles, plasma and peripheral blood mononuclear cell (PBMC) culture supernatants from 50 cases (oversampled for their reduced lymphoproliferative ability) and 50 uninfected controls (oversampled for their robust lymphoproliferative ability) were examined for 24 cytokines using multiplexed bead–based immunoassays and ELISA. Results: The following plasma cytokines were significantly increased in cases relative to controls (cases versus controls; median pg/mL): interleukin (IL)-6, 393.1 versus 14.5; IL-8, 1,128.5 versus 43.9; tumor necrosis factor-α (TNF-α), 164.1 versus 9.2; macrophage inflammatory protein-1α (MIP-1α), 1,368.9 versus 25.5; granulocyte macrophage colony-stimulating factor (GM-CSF), 13.8 versus 7.3; IL-1β, 8.3 versus 1.6 (all P < 0.0001); and IL-1α, 218.2 versus 169.5 (P = 0.02). We focused our analysis on the cytokines IL-6, IL-8, TNF-α, and MIP-1α due to their high fold change (>10) and highly statistically significant difference between cases and controls. Length of persistence or type of infection (high risk and low risk) did not affect these differences. IL-6, TNF-α, and MIP-1α levels were also increased in unstimulated PBMC culture supernatants from cases compared with controls (P < 0.05), however, the cytokine levels from phytohemagglutinin-stimulated PBMC culture supernatants were significantly lower in the cases (P < 0.0001). Conclusions: Persistent HPV infection in older women with evidence of immune deficit is associated with an increase in systemic inflammatory cytokines. Impact: Future studies are needed to determine whether the inflammatory profile is age dependent and to examine the role that inflammatory cytokines play in HPV-induced progression from infection to cervical cancer. Cancer Epidemiol Biomarkers Prev; 19(8); 1954–9. ©2010 AACR.

Through the interaction of T follicular helper (Tfh) cells and B cells, efficacious vaccines can generate high-affinity, pathogen-neutralizing antibodies, and memory B cells. Using CXCR5, CXCR3, CCR6, CCR7, PD1, and ICOS as markers, Tfh-like cells can be identified in the circulation and be classified into three functionally distinct subsets that are PD1⁺ICOS⁺, PD1⁺ ICOS^-, or PD1^-ICOS^-. We used these markers to identify different subsets of CXCR5⁺CD4⁺ Tfh-like cells in response to highly immunogenic and efficacious vaccines for human papillomaviruses (HPV): Cervarix and Gardasil. In this small study, we used PBMC samples from 11 Gardasil recipients, and 8 Cervarix recipients from the Vaccine Research Center 902 Study to examine the induction of circulating Tfh-like cells and IgD^-CD38^HiCD27⁺ memory B cells by flow cytometry. PD1⁺ICOS⁺ CXCR3⁺CCR6^-CXCR5⁺CD4⁺ (Tfh1-like) cells were induced and peaked on Day (D) 7 post-first vaccination, but not as much on D7 post-third vaccination. We also observed a trend toward increase in PD1⁺ICOS⁺ CXCR3^-CCR6^-CXCR5⁺CD4⁺ (Tfh2-like) cells for both vaccines, and PD1⁺ICOS⁺ CXCR3^-CCR6⁺CXCR5⁺CD4⁺ (Tfh17-like) subset was induced by Cervarix post-first vaccination. There were also minimal changes in the other cellular subsets. In addition, Cervarix recipients had more memory B cells post-first vaccination than did Gardasil recipients at D14 and D30. We found frequencies of memory B cells at D30 correlated with anti-HPV16 and 18 antibody titers from D30, and the induction levels of memory B cells at D30 and PD1⁺ICOS⁺Tfh1-like cells at D7 post-first vaccination correlated for Cervarix. Our study showed that induction of circulating CXCR5⁺CD4⁺ Tfh-like subsets can be detected following immunization with HPV vaccines, and potentially be useful as a marker of immunogenicity of vaccines. However, further investigations should be extended to different cohorts with larger sample size to better understand the functions of these T cells, as well as their relationship with B cells and antibodies.