The R614E mutation of mouse Mx1 protein contributes to the novel antiviral activity against classical swine fever virus.

Mx proteins are interferon-induced GTPases that have broad antiviral activity against a wide range of RNA and DNA viruses. We previously demonstrated that porcine Mx1 protein (poMx1) inhibited the replication of classical swine fever virus (CSFV), an economically important Pestivirus, and that mouse Mx1 did so as well. It is unknown why the nucleus-localizing mouse Mx1 inhibits CSFV replication which occurs in the cytoplasm. To the end, we assessed the anti-CSFV actions of wild type mouse Mx1 and seven previously reported mutants (K49A, G83R, A222V, A516V, G540E, R614E and ΔL4) and identified the molecular mechanism of R614E action against CSFV replication. A series of experiments revealed that mmMx1 (R614E) mutant reposted to the cytoplasm and interacted with the CSFV nucleocapsid protein (Core), thereby inhibiting viral replication. These findings broaden our understanding of the function of Mx protein family members against CSFV and suggest that the relative conservation of Mx1 among species is the basis of broad-spectrum antiviral properties.

Antiviral activity of doxycycline against vesicular stomatitis virus in vitro.

Doxycycline (Dox) is a tetracycline derivative with broad-spectrum antimicrobial activities that is used as an effector substance in inducible gene-expression systems. We investigated the antiviral activity of Dox against vesicular stomatitis virus (VSV) infection in cultured H1299 cells. Dox at concentrations of 1.0-2.0 µg ml(-1) significantly inhibited VSV replication and the VSV-induced cytopathic effect in dose-dependent manners, suggesting that Dox may have broader activity in inhibiting viral replication, in addition to its well-defined bacteriostatic activity. Dox exerted its antiviral effect at the early-mid stage of VSV infection, suggesting that it did not interfere with VSV infectivity, adsorption, or entry into target cells. These results indicate that Dox can inhibit VSV infection and may therefore have potential applications for the treatment of viral infections.

The potential molecular effects of bursal septpeptide II on immune induction and antitumor activity.

The bursa of Fabricius (BF) is the acknowledged central humoral immune organ in birds. Bursal septpeptide II (BSP-II) is an immunomodulatory bioactive peptide isolated from BF. To understand the effects of BSP-II on immune induction, gene expression profiles of hybridoma cells treated with BSP-II were evaluated. Pathway analysis showed that regulated genes were involved in cytokine-cytokine receptor interactions, T cell receptor signaling pathway, and pathway in cancer. It was observed that BSP-II reduced tumor cells proliferation and stimulated p53 expression. These results indicate potential mechanisms underlying the effects of the humoral immune system on immune induction, including antitumor activities. Our study has provided a novel insight into immunotherapeutic strategies for treating human tumors.

Identification and characterization of novel immunomodulatory bursal-derived pentapeptide-II (BPP-II).

The bursa of Fabricius, the acknowledged central humoral immune organ, plays a vital role in B lymphocyte differentiation. However, there are few reports of the molecular basis of the mechanism on immune induction and potential antitumor activity of bursal-derived peptides. In this paper, a novel bursal-derived pentapeptide-II (BPP-II, MTLTG) was isolated and exerted immunomodulatory functions on antibody responses in vitro. Gene microarray analyses demonstrated that BPP-II regulated expression of 2478 genes in a mouse-derived hybridoma cell line. Immune-related gene ontology functional procedures were employed for further functional analysis. Furthermore, the majority of BPP-II-regulated pathways were associated with immune responses and tumor processes. Moreover, BPP-II exhibited immunomodulatory effects on antigen-specific immune responses in vivo, including enhancement of avian influenza virus (H9N2 subtype)-specific antibody and cytokine production and modification of T cell immunophenotypes and lymphocyte proliferation. Finally, BPP-II triggered p53 expression and stabilization and selectively inhibited tumor cell proliferation. These data identified the multifunctional factor, BPP-II, as a novel biomaterial representing an important linking between the humoral central immune system and immune induction, including antitumor. Information generated in this study elucidates further the mechanisms involved in humoral immune system and represents the potential basis of effective immunotherapeutic strategies for treating human tumors and immune improvement.

Glycyrrhetinic acid extracted from Glycyrrhiza uralensis Fisch. induces the expression of Toll-like receptor 4 in Ana-1 murine macrophages.

Glycyrrhetinic acid (GA) is an active component of licorice root that has long been used as a herbal medicine for the treatment of peptic ulcer, hepatitis, and pulmonary and skin diseases in Asia and Europe. In this study, we analyzed the effect of GA extracted from Glycyrrhiza uralensis Fisch. on the expression of Toll-like receptors (TLRs) that play key roles in regulating the innate immune response against invading pathogens. Stimulation of Ana-1 murine macrophages with GA induced a significant dose-dependent expression of TLR-4, and its mRNA expression that increased from 3-h post-treatment was approximately fivefold over the level in the mock-treated cells. No endotoxin contamination contributed to the GA-induced TLR-4 expression, because polymyxin B treatment did not alter the upregulated expression of TLR-4 in GA-treated cells. Several molecules, such as myeloid differentiation factor 88, interferon-ß, and interleukin-6, which are involved in the TLR-4 downstream signaling pathway, were upregulated significantly in response to GA stimulation. Our findings demonstrate that GA is able to induce the expression of TLR-4 and activate its downstream signaling pathway.

Fusion expression of major antigenic segment of JEV E protein-hsp70 and the identification of domain acting as adjuvant in hsp70.

Hsp70 potentiates specific immune responses to some antigenic peptides fused to it. A recombinant hsp70 protein expression vector in methylotrophic yeast, Pichia pastoris, was developed that fused the major antigenic segment of Japanese encephalitis virus (JEV) E protein to the amino terminus of Mycobacterium tuberculosis hsp70. The C-terminal peptide binding domain of hsp70 stimulated Th1-polarizing cytokines, CC chemokines and an adjuvant effect. However, the N-terminal ATPase domain (hsp70 1-358) failed to stimulate any of these cytokines or chemokines. Based on these data, a vector was constructed that permits the fusion of major antigenic segment of E protein to the amino terminus of peptide binding domain of hsp70. Antibody titers, lymphocytes proliferation, the level of mIL-2 or mIFN-gamma and neutralizing antibodies in immunized mice showed that antigenicity of E-binding domain fusion protein was almost as effective as E-hsp70 fusion protein and more effective than carrier protein hsp70 alone. In eliciting a humoral and cellular immune response, both fusion proteins were more powerful than the major antigenic segment of E protein alone, but less effective than the segment administered with Freund's adjuvant.

[Comparison of the relative luciferase activity in secondary CEF by different heterogenous strong promoters, MDV gB promoter and the composed promoters].

To improve the protection efficiency of the recombinant Marek' s disease viruses (MDV) in chickens with or without maternal antibodies,the work of selecting the optimal promoters for the construction of recombinant MDV was carried out. Combined with the efficient genetic manipulation, the composed promoters was constructed by use of the MDV gB core promoter with the regulatory elements from the early immediately promoter and enhancer of hCMV, the promoter and enhancer of SV40 or the partial enhancer of hCMV. And these composed promoters were ligased to the luciferase to construct the eukaryotic expressing vectors and named PhCMV-gB, Psv-gB and Pen-gB, respectively. In vitro, these vectors and internal standard plasmid (pSV-beta-LacZ) were transiently co-transfected into secondary CEF by FuGene 6 Transfection Reagent. Furthermore, cells were harvested 48 hours after transfection. Then the luciferase activity was detected by a luciferase assay kit, at the same time, the beta-galactosidase enzyme activity was detected by a beta-galactosidase enzyme assay kit, and the luciferase activity was corrected by the beta-galactosidase enzyme activity to get the relative luciferase activity. The relative luciferase activity was used as the transcriptional activity. By comparison of the relative luciferase activity of every promoter, it was found that these composed promoters could more effectively drive the reporter gene expression than the full legth of gB promoter did. Among them, PhCMV-gB robustly drove the reporter gene expression. On the other hand, PSV-gB and Pen-gB appeared to have the same strength; But compared with the commercial strong promoters, the transcriptional activity of the composed promoter were less than as or the same as that of the strong promoters. Therefore, at a sense, it can be proposed that these composed promoters have not only the characteristic of MDV gB promoter, but also that of the commercial strong promoters. These provide the choices for further developing the new-type recombinant MDV vaccine.

[Influence of JEV E-HSP70 (Mycobacterium tuberculosis) fusion protein on immune response in BALB/c mice].

JEV infection can cause severe central nerve system disease which result in high mortality or developing permanent neurological sequelae in more than half of the survivors. The envelope (E) protein of JEV is the major antigen peptide fused to it. A recombinant hsp70 protein expression vector pPICZalpha-E-HSP70 in methylotrophic yeast Pichia pastoris was developed that permits major antigenic segment of JEV E protein fused to the amino terminus of M. tuberculosis hsp70. This core vector avoided inclusion bodies formed in Escherichia coli and complex purification. Moreover,it ruled out contamination of LPS. Two other vectors pPICZalpha-E and pPICZalpha-HSP70 were also constructed. The two vectors were constructed by routine molecular technique. All vectors were transformed into yeast X-33 by electroporation. Expression of the fusion protein in yeast was induced by the addition of methanol every 24 hours and analysed by SDS-PAGE and western blot. Major antigenic segment of E protein was produced at a yield of 290 mg per litter of culture, hsp70 protein at a yield of 178 mg per litter of culture and E-HSP70 fusion protein at a yield of 33 mg per litter of culture in methylotrophic yeast Pichia pastoris. To examine cell and body immune response after BALB/c mice were immunized with E-hsp70 fusion protein expressed in Pichia pastoris, there were three groups with ten mice in each group. 5.7 microg (50pmol) of E-hsp70 fusion protein, 2.2 microg (50pmol) major antigenic segment of E protein and a mixture of hsp70 and major antigenic segment of E protein (1:1) including 3.5 microg (50pmol) Hsp70 and 2.2 microg (50pmol) major antigenic segment of JEV E protein were used per mouse i.p. on day 0 and day 21. The production of mIL-2 was quantitated by semi-quantitative RT-PCR. Besides, proliferation of lymphocytes was measured by MTT and titers of antibody was determined by ELISA. These data show that the fusion protein is a more powerful antigen than major antigenic segment of JEV E protein. So it also illustrates the effectiveness of hsp70 in eliciting a humoral and cellular response to an attached molecule in the absence of adjuvant and affirms the potential utility of hsp70 in vaccine development.