The details of the mechanism by which severe acute respiratory syndrome-associated coronavirus (SARS-CoV) causes severe pneumonia are unclear. We investigated the immune responses and pathologies of SARS-CoV-infected BALB/c mice that were immunized intradermally with recombinant vaccinia virus (VV) that expressed either the SARS-CoV spike (S) protein (LC16m8rVV-S) or simultaneously all the structural proteins, including the nucleocapsid (N), membrane (M), envelope (E), and S proteins (LC16m8rVV-NMES) 7–8 wk before intranasal SARS-CoV infection. The LC16m8rVV-NMES-immunized group exhibited as severe pneumonia as the control groups, although LC16m8rVV-NMES significantly decreased the pulmonary SARS-CoV titer to the same extent as LC16m8rVV-S. To identify the cause of the exacerbated pneumonia, BALB/c mice were immunized with recombinant VV that expressed the individual structural proteins of SARS-CoV (LC16mOrVV-N, -M, -E, -S) with or without LC16mOrVV-S (i.e., LC16mOrVV-N, LC16mOrVV-M, LC16mOrVV-E, or LC16mOrVV-S alone or LC16mOrVV-N + LC16mOrVV-S, LC16mOrVV-M + LC16mOrVV-S, or LC16mOrVV-E + LC16mOrVV-S), and infected with SARS-CoV more than 4 wk later. Both LC16mOrVV-N-immunized mice and LC16mOrVV-N + LC16mOrVV-S-immunized mice exhibited severe pneumonia. Furthermore, LC16mOrVV-N-immunized mice upon infection exhibited significant up-regulation of both Th1 (IFN-γ, IL-2) and Th2 (IL-4, IL-5) cytokines and down-regulation of anti-inflammatory cytokines (IL-10, TGF-β), resulting in robust infiltration of neutrophils, eosinophils, and lymphocytes into the lung, as well as thickening of the alveolar epithelium. These results suggest that an excessive host immune response against the nucleocapsid protein of SARS-CoV is involved in severe pneumonia caused by SARS-CoV infection. These findings increase our understanding of the pathogenesis of SARS.

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Severe acute respiratory syndrome (SARS) is characterized by rapidly progressing respiratory failure resembling acute/adult respiratory distress syndrome (ARDS) associated with uncontrolled inflammatory responses. Here, we demonstrated that, among five accessory proteins of SARS coronavirus (SARS-CoV) tested, 3a/X1 and 7a/X4 were capable of activating nuclear factor kappa B (NF-jB) and c-Jun N-terminal kinase (JNK), and significantly enhanced interleukin 8 (IL-8) promoter activity. Furthermore, 3a/X1 and 7a/X4 expression in A549 cells enhanced production of inflammatory chemokines that were known to be up-regulated in SARS-CoV infection. Our results suggest potential involvement of 3a/X1 and 7a/X4 proteins in the pathological inflammatory responses in SARS.

While the 2002-2003 outbreak of severe acute respiratory syndrome (SARS) resulted in 774 deaths, patients who were affected with mild pulmonary symptoms successfully recovered. The objective of the present work was to identify, using SARS coronavirus (SARS-CoV) mouse infection models, immune factors responsible for clearing of the virus. The elimination of pulmonary SARS-CoV infection required the activation of B cells by CD4(+) T cells. Furthermore, passive immunization (post-infection) with homologous (murine) anti-SARS-CoV antiserum showed greater elimination efficacy against SARS-CoV than that with heterologous (rabbit) antiserum, despite the use of equivalent titers of neutralizing antibodies. This distinction was mediated by mouse phagocytic cells (monocyte-derived infiltrating macrophages and partially alveolar macrophages, but not neutrophils), as demonstrated both by adoptive transfer from donors and by immunological depletion of selected cell types. These results indicate that the cooperation of anti-SARS-CoV antibodies and phagocytic cells plays an important role in the elimination of SARS-CoV.

Cyclosporin A (CsA) inhibits replication of the HCV subgenomic replicon, and this effect is believed to not be mediated by its immunosuppressive action. We found that DEBIO-025, a novel non-immunosuppressive cyclophilin inhibitor derived from CsA, inhibited HCV replication in vitro more potently than CsA. We also examined the inhibitory effect of DEBIO-025 on naive HCV genotypes 1a or 1b in vivo using chimeric mice with human hepatocytes. These mice were treated for 14 days with DEBIO-025, pegylated-interferon ␣؊2a H epatitis C virus is a small enveloped RNA virus that belongs to the Flaviviridae family. 1 A hallmark of HCV infection is its high propensity to establish a persistent infection that evades the host immune response, leading to chronic liver disease, chronic hepatitis, cirrhosis, and hepatocellular carcinoma. 2,3 Although approximately 170 million individuals are infected with HCV worldwide, drugs that are specifically active against hepatitis C are not yet available.Currently, the main therapy for chronic hepatitis C is a combination of pegylated interferon alpha (Peg-IFN) and ribavirin. In the intention-to-treat analysis, this combination therapy led to a sustained virological response in approximately 55% 4,5 of patients infected with any HCV genotype and in 42% 4 to 46% 5 of patients with genotype 1. The results of clinical trials were based on selected patients. The proportion of elderly patients was low, and patients with HBV or HIV coinfection, renal disease, post-transplantation status, or hematological disorders were excluded. [4][5][6][7][8] Because approximately 50% of patients show a poor response to combined treatment with Peg-IFN and ribavirin, effective therapies are urgently needed.We previously reported that combination therapy of interferon (IFN) ␣-2b and cyclosporin A (CsA) for 24 weeks produced a sustained virological response in 42% of patients with both HCV genotype 1b and high viral levels. 9 High blood levels of CsA correlate with virological response during treatment for HCV, but occasionally can cause adverse events related to immunosuppression. 10 CsA also suppresses HCV replication in vitro, by inhibiting the interaction between HCV nonstructural protein 5B and cyclophilin. 11