title: Highly differentiated, resting gn-specific memory CD8+ T cells persist years after infection by andes hantavirus.
abstract: In man, infection with South American Andes virus (ANDV) causes hantavirus cardiopulmonary syndrome (HCPS). HCPS due to ANDV is endemic in Southern Chile and much of Argentina and increasing numbers of cases are reported all over South America. A case-fatality rate of about 36% together with the absence of successful antiviral therapies urge the development of a vaccine. Although T-cell responses were shown to be critically involved in immunity to hantaviruses in mouse models, no data are available on the magnitude, specificity and longevity of ANDV-specific memory T-cell responses in patients. Using sets of overlapping peptides in IFN-gamma ELISPOT assays, we herein show in 78 Chilean convalescent patients that Gn-derived epitopes were immunodominant as compared to those from the N- and Gc-proteins. Furthermore, while the relative contribution of the N-specific response significantly declined over time, Gn-specific responses remained readily detectable ex vivo up to 13 years after the acute infection. Tetramer analysis further showed that up to 16.8% of all circulating CD3(+)CD8(+) T cells were specific for the single HLA-B*3501-restricted epitope Gn(465-473) years after the acute infection. Remarkably, Gn(465-473)-specific cells readily secreted IFN-gamma, granzyme B and TNF-alpha but not IL-2 upon stimulation and showed a 'revertant' CD45RA(+)CD27(-)CD28(-)CCR7(-)CD127(-) effector memory phenotype, thereby resembling a phenotype seen in other latent virus infections. Most intriguingly, titers of neutralizing antibodies increased over time in 10/17 individuals months to years after the acute infection and independently of whether they were residents of endemic areas or not. Thus, our data suggest intrinsic, latent antigenic stimulation of Gn-specific T-cells. However, it remains a major task for future studies to proof this hypothesis by determination of viral antigen in convalescent patients. Furthermore, it remains to be seen whether Gn-specific T cells are critical for viral control and protective immunity. If so, Gn-derived immunodominant epitopes could be of high value for future ANDV vaccines.
authors.affiliation: Institute of Science, Medical School, Clínica Alemana Universidad del Desarrollo, Santiago, Chile. tmanigold@gmail.com
authors.forename: Tobias
authors.initials: T
authors.lastname: Manigold
authors.forename: Andrés
authors.initials: A
authors.lastname: Mori
authors.forename: Rebecca
authors.initials: R
authors.lastname: Graumann
authors.forename: Elena
authors.initials: E
authors.lastname: Llop
authors.forename: Valeska
authors.initials: V
authors.lastname: Simon
authors.forename: Marcela
authors.initials: M
authors.lastname: Ferrés
authors.forename: Francisca
authors.initials: F
authors.lastname: Valdivieso
authors.forename: Constanza
authors.initials: C
authors.lastname: Castillo
authors.forename: Brian
authors.initials: B
authors.lastname: Hjelle
authors.forename: Pablo
authors.initials: P
authors.lastname: Vial
mesh_terms: D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002469:Cell Separation; D002677:Chile; D004797:Enzyme-Linked Immunosorbent Assay; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005434:Flow Cytometry; D006476:Orthohantavirus / Q000276:immunology; D018778:Hantavirus Infections / Q000276:immunology*; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology; D007156:Immunologic Memory / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D018984:Epitopes, T-Lymphocyte; D016056:Immunodominant Epitopes