An HPV 16 L1-based chimeric human papilloma virus-like particles containing a string of epitopes produced in plants is able to elicit humoral and cytotoxic T-cell activity in mice.
BACKGROUND
Even though two prophylactic vaccines against HPV are currently licensed, infections by the virus continue to be a major health problem mainly in developing countries. The cost of the vaccines limits wide-scale application in poor countries. A promising strategy for producing affordable and efficient vaccines involves the expression of recombinant immunogens in plants. Several HPV genes have been expressed in plants, including L1, which can self-assemble into virus-like particles. A plant-based, dual prophylactic/therapeutic vaccine remains an attractive possibility.


RESULTS
We sought to express in tomato plants chimeric HPV 16 VLPs containing L1 fused to a string of epitopes from HPV 16 E6 and E7 proteins. The L1 employed had been modified to eliminate a strong inhibitory region at the 5' end of the molecule to increase expression levels. Several tomato lines were obtained expressing either L1 alone or L1-E6/E7 from 0.05% to 0.1% of total soluble protein. Stable integration of the transgenes was verified by Southern blot. Northern and western blot revealed successful expression of the transgenes at the mRNA and protein level. The chimeric VLPs were able to assemble adequately in tomato cells. Intraperitoneal administration in mice was able to elicit both neutralizing antibodies against the viral particle and cytotoxic T-lymphocytes activity against the epitopes.


CONCLUSIONS
In this work, we report for the first time the expression in plants of a chimeric particle containing the HPV 16 L1 sequence and a string of T-cell epitopes from HPV 16 E6 and E7 fused to the C-terminus. The particles were able to induce a significant antibody and cytotoxic T-lymphocytes response. Experiments in vivo are in progress to determine whether the chimeric particles are able to induce regression of disease and resolution of viral infection in mice. Chimeric particles of the type described in this work may potentially be the basis for developing prophylactic/therapeutic vaccines. The fact that they are produced in plants, may lower production costs considerably.
Paz De la Rosa
Georgina
G
Centro de Investigación y de Estudios Avanzados (CINVESTAV), Unidad Irapuato, Km, 9,6 Libramiento Norte, 36500 Carretera Irapuato-León, Irapuato, Guanajuato, Mexico. ginapazz@yahoo.com
Monroy-García
Alberto
A
Mora-García
María de Lourdes
Mde L
Peña
Cristina Gehibie Reynaga
CG
Hernández-Montes
Jorge
J
Weiss-Steider
Benny
B
Gómez-Lim
Miguel Angel
MA
D000818:Animals; D000917:Antibody Formation; D036022:Capsid Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D015870:Gene Expression; D005818:Genetic Engineering; D052162:Human papillomavirus 16 / Q000235:genetics / Q000276:immunology*; D006801:Humans; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009856:Oncogene Proteins, Viral / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D050725:Papillomavirus E7 Proteins; D030361:Papillomavirus Infections / Q000276:immunology* / Q000821:virology; D053918:Papillomavirus Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D012097:Repressor Proteins / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014771:Virion / Q000235:genetics / Q000276:immunology
D036022:Capsid Proteins; C068651:E6 protein, Human papillomavirus type 16; D000939:Epitopes; D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D053918:Papillomavirus Vaccines; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C059731:oncogene protein E7, Human papillomavirus type 16; C063317:L1 protein, Human papillomavirus type 16