ABSTRACT
Cervarix™ is a prophylactic human papillomavirus (HPV)-16/18 vaccine for the prevention of cervical cancer. It contains GSK Biologicals' proprietary Adjuvant System AS04. The objective of this study was to investigate the effects of Cervarix™ and of AS04 on female fertility and pre- and post-natal development in Sprague Dawley rats. Female rats were injected with vaccine, AS04, or saline 30 days before mating and on Gestation Days 6, 8, 11 and 15. Each dose of vaccine was one-fifth the human dose volume. Treatment of rats with vaccine or AS04 was not associated with any systemic toxicity and had no impact on female fertility. There were no adverse effects on pre- or post-natal development of litters from treated rats, as judged by fetal evaluation at Gestation Day 20, and growth and survival of pups to postnatal Day 25. These results support the use of the vaccine in the targeted human population.
Subject(s)
Alphapapillomavirus/immunology , Aluminum Hydroxide/toxicity , Embryonic Development/drug effects , Fertility/drug effects , Fetal Development/drug effects , Lipid A/analogs & derivatives , Papillomavirus Vaccines/toxicity , Animals , Animals, Newborn , Body Weight/drug effects , Embryo, Mammalian/drug effects , Female , Injections, Intramuscular , Lactation/drug effects , Lipid A/toxicity , Longevity/drug effects , Maternal Exposure , Pregnancy , Prenatal Exposure Delayed Effects , Rats , Rats, Sprague-Dawley , Toxicity TestsABSTRACT
Cervarix™ is a prophylactic human papillomavirus (HPV)-16/18 vaccine developed for the prevention of cervical cancer. The vaccine antigens are HPV-16 and HPV-18 L1 virus-like particles (VLPs) made from baculovirus expression vector system (BEVS)-produced HPV-16 and HPV-18 L1 proteins, respectively. In this study, we demonstrate that truncation of the nuclear targeting and DNA binding signals at the C-terminus of the HPV-16 and HPV-18 L1 proteins prevented intranuclear formation of the VLPs in the host cells and led to cytoplasmic localization of the L1 proteins as shown by in situ immunogold detection and electron microscopy. Following purification, these L1 proteins were able to form VLPs. The characteristics of these HPV-16 and HPV-18 L1 VLPs were studied using various physicochemical and immunological techniques. Amino acid analysis, SDS-PAGE and western blotting demonstrated the high purity of the L1 proteins and batch-to-batch consistency. The structure of the VLPs was shown to be similar to that reported for the native virions, as evaluated by microscopic observations, protein tomography and disc centrifugation experiments. The presence of important conformation-dependent neutralizing epitopes, such as U4, V5 and J4, was confirmed by ELISA and surface plasmon resonance. Structural robustness and consistency among batches was also observed by differential scanning calorimetry and electron microscopy. Moreover, adsorption to aluminum was shown not to impair VLP structure. In conclusion, the BEVS-produced HPV-16 and HPV-18 L1 VLPs display key structural and immunological features, which contribute to the efficacy of Cervarix™ vaccination.
Subject(s)
Papillomavirus Vaccines/chemistry , Virosomes/chemistry , Virosomes/ultrastructure , Amino Acids/analysis , Blotting, Western , Capsid Proteins/chemistry , Capsid Proteins/ultrastructure , Circular Dichroism , Cytoplasm/chemistry , Cytoplasm/ultrastructure , Electrophoresis, Polyacrylamide Gel , Enzyme-Linked Immunosorbent Assay , Epitopes/immunology , Humans , Macromolecular Substances/chemistry , Macromolecular Substances/ultrastructure , Microscopy, Immunoelectron , Oncogene Proteins, Viral/chemistry , Oncogene Proteins, Viral/ultrastructure , Protein Conformation , Vaccines, Virosome/chemistryABSTRACT
Cervarix is a recombinant human papillomavirus (HPV)-16 and -18 L1 virus-like-particle (VLP) AS04-adjuvanted vaccine designed to protect against cervical intraepithelial neoplasia and cervical cancer caused by the HPV types 16 and 18. Assessment of the stability of the vaccine during long-term storage and after transient exposure to temperatures out of normal storage range is an integrated part of vaccine quality evaluation. This assessment was done with vaccine samples stored at 2-8 degrees C for up to 36 months, with or without simulated cold chain break (either one week at 37 degrees C, or two or four weeks at 25 degrees C). Among the stability-indicating parameters, antigenicity and immunogenicity were evaluated along with L1 antigen integrity and adsorption to aluminum. Differential scanning calorimetry (DSC) was used to investigate the structural stability of the VLPs before and after vaccine formulation and over time. Cervarix was stable at 2-8 degrees C for at least three years, and the occurrence of cold chain break had no impact, as shown by unchanged product characteristics during the full storage period. DSC analysis demonstrated that the structure of the HPV-16 and -18 L1 proteins and their corresponding VLPs was not affected throughout the manufacturing process. Moreover, the structure of aluminum-adsorbed HPV-16 and -18 L1 VLPs was robust over a 14-month test period. In conclusion, Cervarix was very stable upon long-term storage at 2-8 degrees C with or without transient exposure to higher temperatures (up to 37 degrees C). The observed robust structure of the L1 VLPs contributes to the excellent stability of Cervarix.
