Salmonella enterica serovar Typhi Ty21a expressing human papillomavirus type 16 L1 as a potential live vaccine against cervical cancer and typhoid fever.
Human papillomavirus (HPV) vaccines based on L1 virus-like particles (VLPs) can prevent HPV-induced genital neoplasias, the precursors of cervical cancer. However, most cervical cancers occur in developing countries, where the implementation of expensive vaccines requiring multiple injections will be difficult. A live Salmonella-based vaccine could be a lower-cost alternative. We previously demonstrated that high HPV type 16 (HPV16)-neutralizing titers are induced after a single oral immunization of mice with attenuated Salmonella enterica serovar Typhimurium strains expressing a codon-optimized version of HPV16 L1 (L1S). To allow the testing of this type of vaccine in women, we constructed a new L1-expressing plasmid, kanL1S, and tested kanL1S recombinants of three Salmonella enterica serovar Typhi vaccine strains shown to be safe in humans, i.e., Ty21a, the actual licensed typhoid vaccine, and two highly immunogenic typhoid vaccine candidates, Ty800 and CVD908-htrA. In an intranasal mouse model of Salmonella serovar Typhi infection, Ty21a kanL1S was unique in inducing HPV16-neutralizing antibodies in serum and genital secretions, while anti-Salmonella responses were similar to those against the parental Ty21a vaccine. Electron microscopy examination of Ty21a kanL1S lysates showed that L1 assembled in capsomers and capsomer aggregates but not well-ordered VLPs. Comparison to the neutralizing antibody response induced by purified HPV16 L1 VLP immunizations in mice suggests that Ty21a kanL1S may be an effective prophylactic HPV vaccine. Ty21a has been widely used against typhoid fever in humans with a remarkable safety record. These finds encourage clinical testing of Ty21a kanL1S as a combined typhoid fever/cervical cancer vaccine with the potential for worldwide application.
Institute of Microbiology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, CH-1011 Lausanne, Switzerland.
Dominique
D
Fraillery
David
D
Baud
Susana Yuk-Ying
SY
Pang
John
J
Schiller
Martine
M
Bobst
Nathalie
N
Zosso
Françoise
F
Ponci
Denise
D
Nardelli-Haefliger
D000818:Animals; D019496:Cancer Vaccines / Q000235:genetics / Q000276:immunology*; D036022:Capsid Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D002478:Cells, Cultured; D005260:Female; D005822:Genetic Vectors; D052162:Human papillomavirus 16 / Q000276:immunology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009856:Oncogene Proteins, Viral / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D053918:Papillomavirus Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D010957:Plasmids / Q000235:genetics / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D012485:Salmonella typhi / Q000235:genetics / Q000276:immunology*; D014435:Typhoid Fever / Q000276:immunology / Q000517:prevention & control*; D014436:Typhoid-Paratyphoid Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D002583:Uterine Cervical Neoplasms / Q000276:immunology / Q000517:prevention & control*; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D017778:Vaccines, Combined / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology
D019496:Cancer Vaccines; D036022:Capsid Proteins; D009856:Oncogene Proteins, Viral; D053918:Papillomavirus Vaccines; D011135:Polysaccharides, Bacterial; C072772:Ty21a typhoid vaccine; D014436:Typhoid-Paratyphoid Vaccines; D014613:Vaccines, Attenuated; D017778:Vaccines, Combined; D014614:Vaccines, Synthetic; C063317:L1 protein, Human papillomavirus type 16