Hantavirus Pulmonary Syndrome: CD8+and CD4+Cytotoxic T Lymphocytes to Epitopes on Sin Nombre Virus Nucleocapsid Protein Isolated during Acute Illness

Abstract

In 1993 a number of cases of unexplained adult respiratory syndrome occurred in the southwestern United States. The illness was characterized by a prodrome of fever, myalgia, and other symptoms followed by the rapid onset of a capillary leak syndrome with hemoconcentration, thrombocytopenia, and pulmonary edema. Viral RNA sequences in the lungs identified a new member of the hantavirus genus, Sin Nombre virus (SNV), unique to North America. Pulmonary endothelial cells were heavily infected but were not necrotic. We speculated that this capillary leak syndrome was initiated by immune responses to the SNV-infected pulmonary endothelial cells. We isolated a CD8+ cytotoxic T lymphocyte (CTL) clone directly from the blood of a patient with the acute hantavirus pulmonary syndrome (HPS) which recognizes a SNV specific epitope on the virus nucleocapsid protein (aa 234-242) that is restricted by HLA C7 and produces IFN gamma but not IL-4. We identified a second CD8+ CTL epitope located within another site aa 131-139 on the nucleocapsid protein, which is HLA B35 restricted, and a CD4+ CTL epitope located on a third site on nucleocapsid protein aa 372-380 using lymphocytes obtained during HPS from another patient that were stimulated in vitro. Hantavirus specific CD8+ and CD4+ CTL may contribute to the immunopathology and capillary leak syndrome observed in the HPS.

Role of Specific CD8+ T Cells in the Severity of a Fulminant Zoonotic Viral Hemorrhagic Fever, Hantavirus Pulmonary Syndrome

“…ϩ and CD4 ϩ T cells by cloning SNV-specific CTL lines (19). We now report two additional CD8 ϩ T cell epitopes in the SNV G2 protein (aa 664 -673 and aa 746 -755) presented by HLA-B*3501.…”

“…T cell epitopes within SNV proteins were identified as has been described (19). Briefly, PBMC were cultured and stimulated nonspecifically every 2 wk with an anti-CD3 mAb (12F6; kindly supplied by Dr. J. Wong (Harvard Medical School, Boston, MA)).…”

“…Briefly, PBMC were cultured and stimulated nonspecifically every 2 wk with an anti-CD3 mAb (12F6; kindly supplied by Dr. J. Wong (Harvard Medical School, Boston, MA)). Limiting dilution cloning was performed, and lines were initially screened in CTL assays using autologous B lymphoblastoid cell lines (B-LCLs) infected with recombinant vaccinia viruses expressing the SNV N, G1, or G2 proteins (19,25). The SNV epitopes were defined in CTL assays using B-LCL target cells pulsed with synthetic peptides.…”

“…Both in vivo (14,15) and in vitro (17,18) observations suggest that SNV is not directly cytopathic to infected cells. Instead, immunopathological mechanisms involving CTLs have been suggested (19). Lung tissues obtained at necropsy from HPS patients contain abundant large immunoblasts consisting of CD4 ϩ and CD8…”

Regulatory T cell-like responses in deer mice persistently infected with Sin Nombre virus

“…Mononuclear cell infiltrates are found in autopsy lung specimens from HCPS patients, and many of these secrete proinf lammatory cytokines, including TNF, lymphotoxin (LT), IL-2, IL-4, and IFN-␥ (3). CD4 ϩ and CD8 ϩ cytotoxic T lymphocytes (CTLs) have been isolated from Sin Nombre virus (SNV) patients, and a prominent role for CD8 ϩ CTLs has been suggested for the severity of HCPS (4,5).…”