Int J Biochem Mol Biol 2011;2(3):207-218

Original Article
The intact structural form of LLO in endosomes cannot protect against listeriosis

Estela Rodriguez-Del Rio, Elisabet Frande-Cabanes, Raquel Tobes, Eduardo Pareja, M. Jesús Lecea-Cuello, Marta Ruiz-Sáez, Eugenio
Carrasco-Marín, Carmen Alvarez-Dominguez

Grupo de Genómica, Proteómica de Infecciones Bacterianas e Inflamación. Fundación Marqués de Valdecilla-IFIMAV and Hospital Santa Cruz
de Liencres (HUMV). Santander. Cantabria. Spain. Bioinformatics Unit, Era7 Information Technologies SL, BIC Granada CEEI, Parque
Tecnológico de Ciencias de la Salud-Armilla. 18100-Granada, Spain.

Received April 25, 2011; accepted July 12, 2011; Epub July 15, 2011; Published August 30, 2011

Abstract: LLO is the major immuno-dominant antigen in listeriosis and is also required for protective immunity. Two forms of LLO can be
observed in endosomal membranes, a LLO intact form and a Ctsd-processed LLO1-491 form. Endosomes obtained from resting
macrophages contained only LLO intact forms, while endosomes obtained from IFN- activated macrophages contained both forms. Both
types of endosomes elicited LLO90-91/CD8+ and LLO189-201/CD4+ specific immune responses. However, only endosomes containing the
Ctsd-processed LLO1-491 form showed significant CD4+ and CD8+ T cell responses similar to LM infected bone marrow derived
macrophages and characteristic of protective Listeria immunity. Moreover, endosomes with intact LLO could not confer protection as vaccine
carriers against murine listeriosis. While endosomes with Ctsd-processed LLO1-491 form showed a moderate ability, slightly lower than high
efficiency vaccine vectors as MØ infected with LM. These studies argue that all cell-free membrane vesicles might serve as valid vaccine
carriers against infectious agents. Exclusively those cell-free vesicles MIIC competent for LLO processing are protective vaccines vectors since
they recruit significant numbers of mature dendritic cells to the vaccination sites and contain a LLO1-491 form accessible for MHC class I
presentation. (IJBMB1104007).

Keywords: LLO structural forms, listeriosis, endosomes, vaccines

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Address all correspondence to:
Dr. Carmen Alvarez-Dominguez
Grupo de Genómica, Proteómica de Infecciones Bacterianas e Inflamación
Fundación Marqués de Valdecilla-IFIMAV and Hospital Santa Cruz de Liencres (HUMV)
Santander, Cantabria, Spain.
E-mail: calvarez@humv.es
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