Enhancement of humoral and cell mediated immune response to HPV16 L1-derived peptides subsequent to vaccination with prophylactic bivalent HPV L1 virus-like particle vaccine in healthy females

Screening and identification of B cell epitope within the major capsid protein L1 of HPV 52, using monoclonal antibodies

The L1 protein of Human papillomavirus (HPV), the main capsid protein, induces the formation of neutralizing antibodies. In this study, HPV52 L1 protein was induced to be expressed. Monoclonal antibody (mAb) 6A7 against L1 protein were screened by cell fusion techniques. Western Blot and immunofluorescence assay (IFA) demonstrated the specificity of the mAb. The L1 protein was truncated for prokaryotic expression (N1∼N7) and Dot-ELISA showed that 6A7 recognized N3 (aa 200-350). The immunodominant regions were truncated again for expression, with 6A7 recognizing N6 (aa 251-305). The N6 proteins were further truncated and then were constructed an four-segment eukaryotic expression vector. IFA showed that 6A7 could recognize amino acid 262-279. Amino acid 262-279 was selected to be truncated into short peptides P1 and P2. Finally, Peptide-ELISA and Dot-ELISA showed that the epitope regions of mAb 6A7 were amino acid 262-273. The mAbs with defined epitopes can lay the foundation for the analysis of antigenic epitope characteristics and promote the development of epitope peptide vaccines.

Integration of healthy volunteers in early phase clinical trials with immuno-oncological compounds

Aim

Traditionally, early phase clinical trials in oncology have been performed in patients based on safety risk-benefit assessment. Therapeutic transition to immuno-oncology may open new opportunities for studies in healthy volunteers, which are conducted faster and are less susceptible to confounders. Aim of this study was to investigate to what extent this approach is utilized and whether pharmacodynamic endpoints are evaluated in these early phase trials. We conducted a comprehensive review of clinical trials with healthy volunteers using immunotherapies potentially relevant for oncology.

Methods

Literature searches according to PRISMA guidelines and after registration in PROSPERO were conducted in PubMed, Embase, Web of Science and Cochrane databases with the cut-off date 20 October 2020, using search terms of relevant targets in immuno-oncology. Articles describing clinical trials with immunotherapeutics in healthy volunteers with a mechanism relevant for oncology were included. “Immunotherapeutic” was defined as compounds exhibiting effects through immunological targets. Data including study design and endpoints were extracted, with specific attention to pharmacodynamic endpoints and safety.

Results

In total, we found 38 relevant immunotherapeutic compounds tested in HVs, with 86% of studies investigating safety, 82% investigating the pharmacokinetics (PK) and 57% including at least one pharmacodynamic (PD) endpoint. Most of the observed adverse events (AEs) were Grade 1 and 2, consisting mostly of gastrointestinal, cutaneous and flu-like symptoms. Severe AEs were leukopenia, asthenia, syncope, headache, flu-like reaction and liver enzymes increase. PD endpoints investigated comprised of cytokines, immune and inflammatory biomarkers, cell counts, phenotyping circulating immune cells and ex vivo challenge assays.

Discussion

Healthy volunteer studies with immuno-oncology compounds have been performed, although not to a large extent. The integration of healthy volunteers in well-designed proof-of-mechanism oriented drug development programs has advantages and could be pursued more in the future, since integrative clinical trial protocols may facilitate early dose selection and prevent cancer patients to be exposed to non-therapeutic dosing regimens.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=210861, identifier CRD42020210861

In silico prediction of T-cell and B-cell epitopes of human papillomavirus type 16 L1 protein

Human papillomavirus type 16 (HPV-16) is one of the most important cause of developing cervical cancer. Therefore, effective epitope-based vaccine design for HPV-16 would be of major medical benefit. The aim of our study was to identify B- and T-cell epitopes of HPV-16 L1 protein. In this study, the HPV-16 L1 gene was isolated from HPV recovered from five vaginal swab samples using specific primers and finally sequenced. The ExPASy translate tool (http://web.expasy.org/translate/) was used to convert nucleotide sequence into amino acid sequence. Bioinformatic analysis was employed to predict suitable B- and T-cell epitopes and immunogenicity, allergenicity, and toxicity of predicted epitopes were then evaluated. Afterward, the selected T-cell epitopes were docked using Molegro Virtual Docker software. The two epitopes ₂₀₇ AMDFTTLQA₂₁₅ and ₂₀₀ MVDTGFGAM₂₀₈ have showed a very strong binding affinity to HLA-A0201 and HLA-B3501 molecules, respectively. Outcome of B-cell epitope prediction showed that epitope ₄₇₅ KAKPKFTLGKRK ATPTTSSTSTTAKRKK₅₀₂ contained overlapped epitope, which might be the epitope associated with the production of neutralizing antibody response. Based on this finding, the predicted B- and T-cell epitopes are promising targets for epitope-based vaccine development against HPV-16. Further in vivo and in vitro experiments are needed to confirm our findings.

Prevalence of antibodies against a cyclic peptide mimicking the FG loop of the human papillomavirus type 16 capsid among Tunisian women

Background

In the past decade, cervical cancer has gone from being the second to the fourth most common cancer in women worldwide, but remains the second most common in developing countries. This cancer is most commonly caused by high-risk types of human papillomavirus (HPV), mainly type 16 (HPV16), which are sexually transmitted. This study aimed to investigate the usefulness of a cyclic synthetic peptide designed from the major L1 capsid protein of HPV16 for detecting anti-HPV16 antibodies.

Methods

We designed and synthetized a peptide that corresponds to the full sequence of the surface-exposed FG loop. We tested the antigenicity of the linear and the cyclic peptides against HPV16 L1 monoclonal antibodies. We used ELISA to detect anti-peptide antibodies in sera and cervical secretions of 179 Tunisian women, and we applied polymerase chain reaction and direct sequencing methods to detect and genotype HPV DNA.

Results

Both the linear and the cyclic peptides were recognized by the same neutralizing monoclonal antibodies, but the cyclic peptide was more reactive with human sera. The prevalence of the anti-peptide antibodies in sera was higher in women with low-grade squamous intraepithelial lesions (LGSIL) than in women with high-grade squamous intraepithelial lesions (HGSIL) (44% and 15%, respectively). This contrasts with HPV16 DNA prevalence. Compared to women from the general population, systemic IgG prevalence was significantly higher among sex workers (25%; P = 0.002) and women with LGSIL (44%; P = 0.001). In addition, systemic IgA and cervical IgG prevalence was higher among sex workers only (P = 0.002 and P = 0.001, respectively). We did not observe anti-peptide IgG antibodies in women with a current HPV16 infection.

Conclusion

Anti-peptide IgG in sera or in cervical secretions could be markers of an effective natural immunization against HPV16. This may open novel perspectives for monitoring vaccinated women and for the design of synthetic peptide-based vaccines.

Proposal for cervical cancer screening in the era of HPV vaccination

Eradication of cervical cancer involves the expansion of human papillomavirus (HPV) vaccine coverage and the development of efficient screening guidelines that take vaccination into account. In Korea, the HPV National Immunization Program was launched in 2016 and is expected to shift the prevalence of HPV genotypes in the country, among other effects. The experiences of another countries that implement national immunization programs should be applied to Korea. If HPV vaccines spread nationwide with broader coverage, after a few decades, cervical intraepithelial lesions or invasive cancer should become a rare disease, leading to a predictable decrease in the positive predictive value of cervical screening cytology. HPV testing is the primary screening tool for cervical cancer and has replaced traditional cytology-based guidelines. The current screening strategy in Korea does not differentiate women who have received complete vaccination from those who are unvaccinated. However, in the post-vaccination era, newly revised policies will be needed. We also discuss on how to increase the vaccination rate in adolescence.

The Rationale for a Preventative HCV Virus-Like Particle (VLP) Vaccine

HCV represents a global health problem with ~200 million individuals currently infected, worldwide. With the high cost of antiviral therapies, the global burden of chronic hepatitis C infection (CHCV) infection will be substantially reduced by the development of an effective vaccine for HCV. The field of HCV vaccines is generally divided into proponents of strategies to induce neutralizing antibodies (NAb) and those who propose to elicit cell mediated immunity (CMI). However, for a hepatitis C virus (HCV) vaccine to be effective in preventing infection, it must be capable of generating cross-reactive CD4+, CD8+ T cell, and NAb responses that will cover the major viral genotypes. Simulation models of hepatitis C have predicted that a vaccine of even modest efficacy and coverage will significantly reduce the incidence of hepatitis C. A HCV virus like particle (VLP) based vaccine would fulfill the requirement of delivering critical conformational neutralizing epitopes in addition to providing HCV specific CD4⁺ and CD8⁺ epitopes. Several approaches have been reported including insect cell-derived genotype 1b HCV VLPs; a human liver-derived quadrivalent genotype 1a, 1b, 2, and 3a vaccine; a genotype 1a HCV E1 and E2 glycoprotein/MLV Gag pseudotype VLP vaccine; and chimeric HBs-HCV VLP vaccines. All to result in the production of cross-NAb and/or T cell responses against HCV. This paper summarizes the evidence supporting the development of a HCV VLP based vaccine.