Prophylactic papillomavirus vaccines

Inter-epitope spacer variation within polytopic L2-based human papillomavirus antigens affects immunogenicity

The human papillomavirus minor capsid protein L2 is being extensively explored in pre-clinical studies as an attractive vaccine antigen capable of inducing broad-spectrum prophylactic antibody responses. Recently, we have developed two HPV vaccine antigens - PANHPVAX and CUT-PANHPVAX- both based on heptameric nanoparticle antigens displaying polytopes of the L2 major cross-neutralizing epitopes of eight mucosal and twelve cutaneous HPV types, respectively. Prompted by the variable neutralizing antibody responses against some of the HPV types targeted by the antigens observed in previous studies, here we investigated the influence on immunogenicity of six distinct glycine-proline spacers inserted upstream to a specific L2 epitope. We show that spacer variants differentially influence antigen immunogenicity in a mouse model, with the antigen constructs M8merV6 and C12merV6 displaying a superior ability in the induction of neutralizing antibodies as determined by pseudovirus-based neutralization assays (PBNAs). L2-peptide enzyme-linked immunosorbent assay (ELISA) assessments determined the total anti-L2 antibody level for each antigen variant, showing for the majority of sera a correlation with their repective neutralizing antibody level. Surface Plasmon Resonance revealed that L2 epitope-specific, neutralizing monoclonal antibodies (mAbs) display distinct avidities to different antigen spacer variants. Furthermore, mAb affinity toward individual spacer variants was well correlated with their neutralizing antibody induction capacity, indicating that the mAb affinity assay predicts L2-based antigen immunogenicity. These observations provide insights on the development and optimization of L2-based HPV vaccines.

The contribution of bovines to human health against viral infections

In the last 40 years, novel viruses have evolved at a much faster pace than other pathogens. Viral diseases pose a significant threat to public health around the world. Bovines have a longstanding history of significant contributions to human nutrition, agricultural, industrial purposes, medical research, drug and vaccine development, and livelihood. The life cycle, genomic structures, viral proteins, and pathophysiology of bovine viruses studied in vitro paved the way for understanding the human counterparts. Calf model has been used for testing vaccines against RSV, papillomavirus vaccines and anti-HCV agents were principally developed after using the BPV and BVDV model, respectively. Some bovine viruses-based vaccines (BPIV-3 and bovine rotaviruses) were successfully developed, clinically tried, and commercially produced. Cows, immunized with HIV envelope glycoprotein, produced effective broadly neutralizing antibodies in their serum and colostrum against HIV. Here, we have summarized a few examples of human viral infections for which the use of bovines has contributed to the acquisition of new knowledge to improve human health against viral infections covering the convergence between some human and bovine viruses and using bovines as disease models. Additionally, the production of vaccines and drugs, bovine-based products were covered, and the precautions in dealing with bovines and bovine-based materials.

Four Simple Biomimetic Mineralization Methods to Improve the Thermostability and Immunogenicity of Virus-like Particles as a Vaccine against Foot-and-Mouth Disease

The need for a cold chain system during storage and transport substantially increases the cost of vaccines. Virus-like particles (VLPs) are among the best countermeasures against foot and mouth disease virus (FMDV). However, VLPs are composed of pure proteins, and thus, are susceptible to heat. To address this problem, four simple biomimetic mineralization methods with the use of calcium phosphate were developed to improve heat tolerance via biomineralization. The results showed that biomineralization can significantly improve the heat resistance of VLPs. The biomineralized VLPs can be stored at low as 25 °C for eight days, and 37 °C for four days. Animal experiments showed that biomineralization had no effect on the immunogenicity of VLPs or the expression of specific antibodies (Abs) and neutralizing Abs. Even after heat treatment at 37 °C for four days, the biomineralized VLPs remained immunogenic and produced highly specific and neutralizing Abs with a high rate of protection. These results suggest that these biomineralization approaches can promote the thermal stability of VLPs against and significantly reduce dependence on cold storage and delivery systems.

Carcinogenesis Associated with Human Papillomavirus Infection. Mechanisms and Potential for Immunotherapy

Human papillomavirus (HPV) infection is responsible for approximately 5% of all cancers and is associated with 30% of all pathogen-related cancers. Cervical cancer is the third most common cancer in women worldwide; about 70% of cervical cancer cases are caused by the high-risk HPVs (HR HPVs) of genotypes 16 and 18. HPV infection occurs mainly through sexual contact; however, viral transmission via horizontal and vertical pathways is also possible. After HPV infection of basal keratinocytes or ecto-endocervical transition zone cells, viral DNA persists in the episomal form. In most cases, infected cells are eliminated by the immune system. Occasionally, elimination fails, and HPV infection becomes chronic. Replication of HPVs in dividing epithelial cells is accompanied by increased expression of the E6 and E7 oncoproteins. These oncoproteins are responsible for genomic instability, disruption of the cell cycle, cell proliferation, immortalization, and malignant transformation of HPV-infected cells. Besides, E6 and E7 oncoproteins induce immunosuppression, preventing the detection of HPV-infected and transformed cells by the immune system. HPV integration into the genome of the host cell leads to the upregulation of E6 and E7 expression and contributes to HPV-associated malignization. Prophylactic HPV vaccines can prevent over 80% of HPV-associated anogenital cancers. The vaccine elicits immune response that prevents initial infection with a given HPV type but does not eliminate persistent virus once infection has occurred and does not prevent development of the HPV-associated neoplasias, which necessitates the development of therapeutic vaccines to treat chronic HPV infections and HPV-associated malignancies.

An investigation into the role of chronic Schistosoma mansoni infection on Human Papillomavirus (HPV) vaccine induced protective responses

Background

Schistosoma mansoni is one of the most common helminth infections affecting a large population of people in sub-Saharan Africa. This helminth infection is known to cause immunomodulation which has affected the efficacy of a number of vaccines. This study examined whether a chronic schistosoma infection has an effect on the immunogenicity of HPV vaccine which is currently administered to girls and women aged 9 to 24. Little is known about the immune responses of the HPV vaccine in individuals with chronic schistosomiasis.

Methods

This study was carried out at the Institute of Primate Research (IPR) and involved an Olive baboon model. The experimental animals were randomly placed into three groups (n = 3–4); Two groups were infected with S. mansoni cercaria, and allowed to reach chronic stage (week 12 onwards), at week 13 and 14 post-infection, one group was treated with 80mg/kg of praziquantel (PZQ). Sixty four weeks post schistosoma infection, all groups received 2 doses of the Cervarix HPV vaccine a month apart. Specific immune responses to the HPV and parasite specific antigens were evaluated.

Results

Animals with chronic S. mansoni infection elicited significantly reduced levels of HPV specific IgG antibodies 8 weeks after vaccination compared the PZQ treated and uninfected groups. There was no significant difference in cellular proliferation nor IL-4 and IFN-γ production in all groups.

Conclusion

Chronic S. mansoni infection results in reduction of protective HPV specific IgG antibodies in a Nonhuman Primate model, suggesting a compromised effect of the vaccine. Treatment of schistosomiasis infection with PZQ prior to HPV vaccination, however, reversed this effect supporting anti-helminthic treatment before vaccination.

In sub-Saharan Africa countries, vaccines are administered to people who may suffer from existing infections, especially helminth infections. These infections are known to modulate immune responses rendering some vaccines ineffective. The impact of helminth infections such as schistosomiasis on a recently introduced Human Papillomavirus (HPV) vaccine on infected or treated populations and the degree or duration has not been clearly elucidated. This study was set up to investigate whether a chronic schistosoma infection compromises the specific immune responses elicited by the HPV vaccine.

Distribution and role of high-risk human papillomavirus genotypes in women with cervical intraepithelial neoplasia: A retrospective analysis from Wenzhou, southeast China

To add the growing literature on baseline of high-risk human papillomavirus (HR-HPV) genotype distribution in cervical intraepithelial neoplasia (CIN) before the widespread using of HPV vaccines in Chinese mainland and to improve risk stratification of HR-HPV-positive women. Retrospectively, the data of age, cervical HPV genotypes, cytology, and pathology were collected from 1166 patients who received loop electrosurgical excision procedure (LEEP). HPV genotypes were analyzed with Flowcytometry Fluorescence Hybridization Method. And then HPV prevalence, HR-HPV genotype distribution and the correlation of HR-HPV genotypes with CIN2+ (CIN2 or severer) were analyzed. The role of multiple HR-HPV types infection with or without HPV16/18 in the pathogenesis of CIN2+ was also analyzed. The 6 most common HR-HPV genotypes were HPV16, 58, 52, 33, 18, and 31 in descending order. Compared to HR-HPV-negative women, HPV16, 33 or 58 positive women had higher risk of CIN2+ (OR = 5.10, 95% CI = 2.68-9.70; OR = 3.09, 95% CI = 1.39-6.84; OR = 3.57, 95% CI = 1.85-6.89, respectively). And women who were infected by multiple HR-HPV types infection with HPV16/18 also had higher risk of CIN2+ (OR = 2.58, 95% CI = 1.35-4.92). However, multiple HR-HPV types infection without HPV16/18 did not increase the risk significantly (P = .08). Compare to bivalent Cervarix^® and quadrivalent Gardasil^® , HPV prophylactic vaccine targeting HPV31, 33, 52, and 58 might provide women more protection from HPV-induced cervical cancer in China. The women who infected by HPV16, 33, 58, or multiple HR-HPV types with HPV16/18 have higher risk of CIN2+ and need to be paid more attention in screening processes. And the role of multiple HR-HPV types infection without HPV16/18 needs be further identified in more studies.

Integrated analysis of recombinant BPV-1 L1 protein for the production of a bovine papillomavirus VLP vaccine

Bovine papillomatosis is an infectious disease that is caused by bovine papillomavirus (BPV), which results in important economic losses. However, no BPV vaccines or effective treatment methods are commercially available to date. Moreover, the absence of papillomavirus replication in vitro makes the use of recombinant protein a promising candidate for vaccine formulations. Hence, we developed an integrated study on the L1 capsid protein of BPV-1, obtained from a bacterial expression system, regarding its purification, biosafety, thermostability and immunogenicity. The results indicated an absence of genotoxicity of the purified recombinant L1 protein, β-sheet prevalence of secondary structure folding, protein stability under high temperatures as well as the presence of capsomeres and VLPs. In addition, preliminary experimental vaccination of calves showed the production of specific antibodies against BPV-1 L1.

Papillomaviruses: a systematic review

In the last decades, a group of viruses has received great attention due to its relationship with cancer development and its wide distribution throughout the vertebrates: the papillomaviruses. In this article, we aim to review some of the most relevant reports concerning the use of bovines as an experimental model for studies related to papillomaviruses. Moreover, the obtained data contributes to the development of strategies against the clinical consequences of bovine papillomaviruses (BPV) that have led to drastic hazards to the herds. To overcome the problem, the vaccines that we have been developing involve recombinant DNA technology, aiming at prophylactic and therapeutic procedures. It is important to point out that these strategies can be used as models for innovative procedures against HPV, as this virus is the main causal agent of cervical cancer, the second most fatal cancer in women.

Escherichia coli-derived virus-like particles in vaccine development

Recombinant virus-like particle-based vaccines are composed of viral structural proteins and mimic authentic native viruses but are devoid of viral genetic materials. They are the active components in highly safe and effective vaccines for the prevention of infectious diseases. Several expression systems have been used for virus-like particle production, ranging from Escherichia coli to mammalian cell lines. The prokaryotic expression system, especially Escherichia coli, is the preferred expression host for producing vaccines for global use. Hecolin, the first licensed virus-like particle vaccine derived from Escherichia coli, has been demonstrated to possess good safety and high efficacy. In this review, we focus on Escherichia coli-derived virus-like particle based vaccines and vaccine candidates that are used for prevention (immunization against microbial pathogens) or disease treatment (directed against cancer or non-infectious diseases). The native-like spatial or higher-order structure is essential for the function of virus-like particles. Thus, the tool box for analyzing the key physicochemical, biochemical and functional attributes of purified virus-like particles will also be discussed. In summary, the Escherichia coli expression system has great potentials for producing a range of proteins with self-assembling properties to be used as vaccine antigens given the proper epitopes were preserved when compared to those in the native pathogens or disease-related target molecules.

Targeting synthetic Human Papillomavirus (HPV) L2 disulfide-induced N-terminus conformational epitopes for pan-HPV vaccine development

BACKGROUND

Current vaccines against Human Papillomavirus (HPV) are highly effective and based on recombinant virus-like particles (VLPs) of the major capsid protein L1. Since these vaccines are HPV type-specific and expensive for global implementation, an alternative, broader-spectrum immunogen would be the N-terminus of the minor capsid protein L2 that induces low titered broadly cross-neutralizing antibodies. Here we analyzed the reactivity of different synthetic L2 peptides containing N-terminus amino acids 17-36 in order to test their antigenicity.

METHODS

Different synthetic peptides were designed to target the 17-36 amino acid sequences, present in highly antigenic amino-terminus of L2 protein. Six different peptides including Cys22-Cys28 disulfide bonded cyclized L2 peptide were examined for their antigenicity against mouse monoclonal antibody RG-1 and rabbit polyclonal antisera to HPV L2 by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Here we report that the cyclized form of synthetic L2 peptide, which is formed through Cys22-Cys28 disulfide bridges, has the highest reactivity to antibodies than other synthetic L2 peptides.

CONCLUSION

A cyclized L2 peptide has potential to be an excellent candidate to formulate a low-cost, broadly protective pan-oncogenic HPV vaccine.

The dichotomy of pathogens and allergens in vaccination approaches

Traditional prophylactic vaccination to prevent illness is the primary objective of many research activities worldwide. The golden age of vaccination began with an approach called variolation in ancient China and the evolution of vaccines still continues today with modern developments such as the production of Gardasil(TM) against HPV and cervical cancer. The historical aspect of how different forms of vaccination have changed the face of medicine and communities is important as it dictates our future approaches on both a local and global scale. From the eradication of smallpox to the use of an experimental vaccine to save a species, this review will explore these successes in infectious disease vaccination and also discuss a few significant failures which have hampered our efforts to eradicate certain diseases. The second part of the review will explore designing a prophylactic vaccine for the growing global health concern that is allergy. Allergies are an emerging global health burden. Of particular concern is the rise of food allergies in developed countries where 1 in 10 children is currently affected. The formation of an allergic response results from the recognition of a foreign component by our immune system that is usually encountered on a regular basis. This may be a dust-mite or a prawn but this inappropriate immune response can result in a life-time of food avoidance and lifestyle restrictions. These foreign components are very similar to antigens derived from infectious pathogens. The question arises: should the allergy community be focussing on protective measures rather than ongoing therapeutic interventions to deal with these chronic inflammatory conditions? We will explore the difficulties and benefits of prophylactic vaccination against various allergens by means of genetic technology that will dictate how vaccination against allergens could be utilized in the near future.