Kaposi's sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV-8) is a gamma-herpesvirus consistently identified in Kaposi's sarcoma (KS), primary effusion lymphoma, and multicentric Castleman's disease. KSHV infection appears to be necessary, but not be sufficient for development of KS without other co-factors. However, factors that facilitate KSHV to cause KS have not been well defined. Because patients with KS are often immunosuppressed and susceptible to many infectious agents including human herpesvirus 6 (HHV-6), we investigated the potential of HHV-6 to influence the replication of KSHV. By co-culturing HHV-6-infected T cells with KSHV-latent BCBL-1 cell line, infecting BCBL-1 cells with HHV-6 virions, and generating heterokaryons between HHV-6-infected T cells and BCBL-1 cells, we showed that HHV-6 played a critical role in induction of KSHV replication, as determined by production of lytic phase mRNA transcripts and viral proteins. We confirmed and extended the results by using a luciferase reporter assay in which KSHV ORF50 promoter, the first promoter activated during KSHV replication, drove the luciferase expression. Besides HHV-6, we also found that cytokines such as interferon-gamma partially contributed to induction of KSHV replication in the co-culture system. These findings suggest that HHV-6 may participate in KS pathogenesis by promoting KSHV replication and increasing KSHV viral load.

Innate immune response plays the key role in initiating and guiding the immune response. Elucidating the innate immune related molecular events involved in the interaction between the parasite and the host will aid in the development of an effective vaccine and anti-schistosome pharmaceuticals. In this study, we examined the regulatory effect of Schistosoma japonicum soluble egg antigen (SEA) on MHC class II expression in macrophage cell line RAW 264.7. We demonstrated that SEA possesses the ability to down-regulate IFN-γ-induced MHC class II expression in RAW 264.7 cells. The production of IL-10 and IL-6 in RAW 264.7 cells, induced by SEA, was responsible for mediating the down-regulation of MHC class II. Our findings suggest that in RAW 264.7 cells (1) IFN-γ provides a condition for lower concentrations of SEA to attenuate MHC class II expression; (2) SEA attenuated IFN-γ-induced MHC class II expression and the IL-10 and IL-6 production is mediated at least partly by the interaction of SEA with TLR4; and (3) SEA attenuated IFN-γ-induced MHC class II expression at the transcriptional level.

To identify the potential B-cell antigenic epitopes within the N-terminus of SARS-CoV (SARS-associated coronavirus, SARS-CoV) M protein and characterize monoclonal antibody (MAb) against the protein as well as its recognizing region, we expressed and purified a portion of SARS-CoV M protein (amino acid 1-43) in Escherichia coli (E. coli). By using Western blot and enzyme-linked immunosorbent assay (ELISA), we showed that the purified recombinant M protein could be recognized by four SARS-CoV-positive human sera even when those sera were 12,800-fold diluted. Furthermore, we characterized one representative IgG2 MAb, 3H9, which exhibited a strong immunoreaction to both recombinant M protein and native viral protein of SARS-CoV. We found a B-cell antigenic epitope located between amino acid 1-15 and defined the MAb recognizing region within amino acid 16-28 of M. These findings not only suggest that both recombinant M protein and its specific MAbs may be used as the diagnostic reagents for SARS, but also provide a potential target site for the design of an epitope-based vaccine against SARS.

ObjectiveTo observe the discrepancies of responses induced by Schistosoma japonicum (S. japonicum) normal cercaria antigen (NCA) and ultraviolet (UV) -radiation-attenuated cercaria antigen (UVACA) in an in vitro system.MethodsS. japonicum cercariae were collected and UVACA and NCA were prepared. Mouse macrophage model cells (RAW 264.7) were treated with medium, NCA (40 µg/mL) or UVACA (40 µg/mL) in the presence or absence of recombinant mouse interferon gamma (rmIFN-γ; 4 ng/mL) for 48 h. Cell surface staining and flow cytometry were used to assess the major histocompatibility complex (MHC)γ; 4 ng/mL) for 48 h. Cell surface staining and flow cytometry were used to assess the major histocompatibility complex (MHC) II expression, and data were expressed as mean fluorescence intensities (MFI). Interleukin (IL) -10, IL-6 and prostaglandin E2 (PGE2) in cell culture supernatant were evaluated by commercial enzyme-linked immunosorbent assays.ResultsNCA significantly suppressed IFN-γ-induced MHC II expression on RAW 264.7 cells. In the presence of IFN-γ, NCA significantly promoted IL-6, IL-10 and PGE2 secretion from RAW 264.7 cells. In the presence of IFN-γ, UVACA significantly promoted IL-10 but not IL-6 and PGE2 secretion from RAW 264.7 cells and showed no effect on IFN-γ-induced MHC II expression. Compared with UVACA, NCA significantly suppressed IFN-γ-induced MHC II expression and significantly promoted IL-6, PGE2 and IL-10 secretion from RAW 264.7 cells.ConclusionRAW 264.7 cells respond differently to NCA and UVACA. NCA can significantly suppress IFN-γ-induced MHC II expression and significantly promote IL-6, IL-10 and PGE2 secretion from RAW 264.7 cells compared with UVACA.