HPV16 L2 improves HPV16 L1 gene delivery as an important approach for vaccine design against cervical cancer

Correlation between cervical HPV DNA detection and HPV16 seroreactivity measured with L1-only and L1+L2 viral capsid antigens

Introduction. Persistent human papillomavirus (HPV) type 16 infection is the main causal agent of cervical cancer. Most HPV infections clear spontaneously within 1-2 years. Although not all infected women develop detectable HPV antibodies, about 60-70 % seroconvert and retain their antibodies at low levels.Aim. We investigated if cervical HPV16 DNA positivity was associated with HPV16 seroreactivity measured with two different antigen formulations. We assessed if associations were influenced by co-infection with other HPV types and HPV16 viral load.Methodology. We used baseline data for women participating in the Ludwig-McGill cohort, a longitudinal investigation of the natural history of HPV infection and cervical neoplasia. The study enrolled 2462 Brazilian women from 1993 to 1997 (pre-vaccination). ELISA assays were based on L1-only or L1+L2 virus-like particles (VLPs). Seroreactivity was expressed as normalized absorbance ratios. HPV genotyping and viral load were evaluated by PCR protocols. Pearson's r was used to measure correlations between interval-scaled variables. Serological accuracy in HPV16 DNA detection was assessed using receiver operating characteristic (ROC) curves. We analysed the association between HPV DNA positivity and HPV16 seroreactivity by linear regression.Results. Correlations between L1+L2 and L1-only VLPs for detection of HPV16 were poor (r=0.43 and 0.44 for dilutions 1 : 10 and 1 : 50, respectively). The protocol with the best accuracy was L1+L2 VLPs at serum dilution 1 : 10 (ROC area=0.73, 95 % CI: 0.65-0.85). HPV16 DNA positivity was correlated with HPV16 seroreactivity and was not influenced by co-infection or viral load. To a lesser degree, HPV16 seroreactivity was correlated with infection by other Alpha-9 papillomavirus species.Conclusion. HPV16 DNA positivity and HPV16 seroreactivity are strongly correlated. L1+L2 VLPs perform better than L1-only VLPs for detecting IgG antibodies to HPV16 in women infected with HPV16 or other Alpha-9 HPV species. This study advances our understanding of humoral immune responses against HPV16 by providing insights about the influence of VLP antigen composition to measure humoral immune response against naturally acquired HPV infection.

In silico/In vivo analysis of high-risk papillomavirus L1 and L2 conserved sequences for development of cross-subtype prophylactic vaccine

Human papillomavirus (HPV) is the most common sexually transmitted infection in the world and the main cause of cervical cancer. Nowadays, the virus-like particles (VLPs) based on L1 proteins have been considered as the best candidate for vaccine development against HPV infections. Two commercial HPV (Gardasil and Cervarix) are available. These HPV VLP vaccines induce genotype-limited protection. The major impediments such as economic barriers especially gaps in financing obstructed the optimal delivery of vaccines in developing countries. Thus, many efforts are underway to develop the next generation of vaccines against other types of high-risk HPV. In this study, we developed DNA constructs (based on L1 and L2 genes) that were potentially immunogenic and highly conserved among the high-risk HPV types. The framework of analysis include (1) B-cell epitope mapping, (2) T-cell epitope mapping (i.e., CD4⁺ and CD8⁺ T cells), (3) allergenicity assessment, (4) tap transport and proteasomal cleavage, (5) population coverage, (6) global and template-based docking, and (7) data collection, analysis, and design of the L1 and L2 DNA constructs. Our data indicated the 8-epitope candidates for helper T-cell and CTL in L1 and L2 sequences. For the L1 and L2 constructs, combination of these peptides in a single universal vaccine could involve all world population by the rate of 95.55% and 96.33%, respectively. In vitro studies showed high expression rates of multiepitope L1 (~57.86%) and L2 (~68.42%) DNA constructs in HEK-293T cells. Moreover, in vivo studies indicated that the combination of L1 and L2 DNA constructs without any adjuvant or delivery system induced effective immune responses, and protected mice against C3 tumor cells (the percentage of tumor-free mice: ~66.67%). Thus, the designed L1 and L2 DNA constructs would represent promising applications for HPV vaccine development.

DNA plasmid vaccine carrying Chlamydia trachomatis (Ct) major outer membrane and human papillomavirus 16L2 proteins for anti-Ct infection

Chlamydia trachomatis (Ct) is one of the most frequently encountered sexual infection all over the world, yielding tremendous reproductive problems (e.g. infertility and ectopic pregnancy) in the women. This work described the design of a plasmid vaccine that protect mice from Ct infection, and reduce productive tract damage by generating effective antibody and cytotoxic T cell immunity. The vaccine, s was composed of MOMP multi-epitope and HPV16L2 genes carried in pcDNA plasmid (i.e. pcDNA3.1/MOMP/HPV16L). In transfection, the vaccine expressed the chimeric genes (i.e. MOMP and HPV16L2), as demonstrated via western blot, RT-PCR and fluorescence imaging. In vitro, the vaccine transfected COS-7 cells and expressed the proteins corresponding to the genes carried in the vaccine. Through intramuscular immunization in BALB/c mice, the vaccine induced higher levels of anti-Ct IgG titer, anti-HPV16L2 IgG titer in serum and IgA titer in local mucosal secretions, compared to plasmid vaccines that carry only Ct MOMP multi-epitope or HPV16L2 chimeric component only. In mice intravaginally challenged with Ct, the vaccines pcDNA3.1/MOMP/HPV16L2 generated a higher level of genital protection compared to other vaccine formulations. Additionally, histochemical staining indicated that pcDNA3.1/MOMP/HPV16L2 eliminated mouse genital tract tissue pathologies induced by Ct infection. This work demonstrated that pcDNA/MOMP/HPV16L2 vaccine can protect against Ct infection by regulating antibody production, cytotoxic T cell killing functions and reducing pathological damage in mice genital tract. This work can potentially offer us a new vaccine platform against Ct infection.