• Evaluation and comparison of the production of the quadrivalent HPV recombinant vaccine by VLP method in two models of enveloped and non-enveloped
  • Niloofar Farajvand,1 Fatemeh Sadat Dafin,2 Farhad Akbarpour Tajrishi,3,*
    1. Department of biological sciences and technologies,Faculty of basic sciences Islamic Azad University,Yadegar -e- Imam Khomeini (RAH) Branch, Tehran, Iran
    2. Bachelor of Cell and Molecular Biology - Biochemistry, Varamin Azad Univercity - Pishva, Tehran, Iran
    3. Biology & Anatomical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran


  • Introduction: By 2022, about 220 human papillomavirus (HPV) genotypes have been identified. This large group of double-stranded DNA viruses is grouped into five genera (alpha, beta, gamma, mu and nu) based on the nucleotide sequence of the major structural protein L1, and can be classified into mucosal or cutaneous types based on their preferential infection site. Generally, HPV encodes at least six early genes (E1, E2, E4, E5, E6 and E7) and two late genes (structural L1 major and L2 minor capsid proteins). E1 and E2 are important for viral genome replication and its regulation, E4 promotes virion release from keratinocytes, while oncogenes E6 and E7 interfere with the host’s cell cycle regulators to ensure viral genome replication.
  • Methods: To develop HPV-16 L1 / L2 chimeric protein VLPs, a neutralizing cross-epitope of the HPV-16 L2 gene was first inserted into the HPV-16 L1 gene. Chimeric L1 / L2 HPV-16 was then inserted into the pPICZA plasmid and expressed in Pichia pastoris (P. pastoris). Final purification of VLPs was performed using an ultra centrifuge (130,000 g) using a sucrose density gradient of 10-40% for 4 hours at 4 ° C. SDS-PAGE and Western blotting were performed separately for L1-HPV-16 and L2-HPV-16 proteins. 55 ng of purified VLPs for detection of L1 HPV-16 and L2-HPV-16 antibodies by ELISA test separately coated with ELISA wells using commercial L1-HPV-16 and L2-HPV-16 antibodies شد. Sera of 16 patients positive for HPV-16 and 85 serum negative for HPV infection were tested for HPV-16 antibody by ELISA and the results were compared with a commercial test kit.
  • Results: It can be stated with certainty that Licensed human papillomavirus (HPV) vaccines contain virus-like particles (VLPs) self-assembled from L1 major-capsid proteins that are remarkably effective prophylactic immunogens. However, the induced type-restricted immune response limits coverage to the included vaccine types, and expensive multiplex formulations, restrictive storage and distribution conditions drive the need for next generation HPV vaccines. Vaccine candidates based upon the minor structural protein L2 are particularly promising because conserved N-terminal epitopes induce broadly cross-type neutralizing and protective antibodies.
  • Conclusion: In vivo, there are specific mechanisms that show how antibodies produced from L1 protein and L2 protein can neutralize HPV infection. Protein L1-raised antibody-mediated protection differs based upon antibody levels. High doses of protein L1 antibodies prevent viral BM binding leading to the Fc-mediated opsonization of antibody-bound viral particles by phagocytes, mainly neutrophils.
  • Keywords: human papillomavirus, HPV, VLP, protein L1