NAMPT suppresses glucose deprivation-induced oxidative stress by increasing NADPH levels in breast cancer

Nicotinamide phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme involved in NAD+ biosynthesis. Although NAMPT has emerged as a critical regulator of metabolic stress, the underlying mechanisms by which it regulates metabolic stress in cancer cells have not been completely elucidated. In this study, we determined that breast cancer cells expressing a high level of NAMPT were resistant to cell death induced by glucose depletion. Furthermore, NAMPT inhibition suppressed tumor growth in vivo in a xenograft model. Under glucose deprivation conditions, NAMPT inhibition was found to increase the mitochondrial reactive oxygen species (ROS) level, leading to cell death. This cell death was rescued by treatment with antioxidants or NAD+. Finally, we showed that NAMPT increased the pool of NAD+ that could be converted to NADPH through the pentose phosphate pathway and inhibited the depletion of reduced glutathione under glucose deprivation. Collectively, our results suggest a novel mechanism by which tumor cells protect themselves against glucose deprivation-induced oxidative stress by utilizing NAMPT to maintain NADPH levels.

The effects of mesenchymal stem cells injected via different routes on modified IL-12-mediated antitumor activity

Owing to its tumor tropism and prolonged transgene expression, mesenchymal stem cell (MSC) has been considered as an ideal delivery vehicle for cancer gene therapies or therapeutic vaccines. In this study, we demonstrated that intratumoral (i.t.) injection of MSCs expressing modified interleukin-12 (MSCs/IL-12M) exhibited stronger tumor-specific T-cell responses and antitumor effects as well as more sustained expressions of IL-12 and interferon (IFN)-γ in both sera and tumor sites than did IL-12M-expressing adenovirus (rAd/IL-12M) in mice bearing both solid and metastatic tumors. Subcutaneous (s.c.) injection of MSCs/IL-12M at contralateral site of tumor exhibited similar levels of serum IL-12 and IFN-γ as i.t. injection, but much weaker antitumor effects in both B16F10 melanoma and TC-1 cervical cancer models than i.t. injection. Although intravenous (i.v.) injection elicited earlier peak serum levels of cytokines, it induced weaker tumor-specific T-cell responses and antitumor effects than i.t. injection, indicating that serum cytokine levels are not surrogate indicators of antitumor effects. Taken together, these results indicated that MSC is more efficient than adenovirus as a cytokine gene delivery vehicle and that i.t. injection of MSCs/IL-12M is the best approach to induce strong tumor-specific T-cell responses that correlate with anti-metastatic effects as well as inhibition of solid tumor growth, although MSCs themselves have an ability to migrate into the tumor site. In addition, MSCs/IL-12M embedded in Matrigel (MSCs/IL-12M/Matrigel) exhibited significant antitumor effects even in immunodeficient mice such as SCID and BNX mice lacking T, B and natural killer (NK) cells, but not in IFN-γ knockout mice. Our findings provide an optimal approach for designing an efficient clinical protocol of MSC-based cytokine gene therapy to induce strong tumor-specific T-cell responses and therapeutic anticancer efficacy.

Cross-priming as a predominant mechanism for inducing CD8(+) T cell responses in gene gun DNA immunization

DNA immunization induces CD8(+) CTL responses by bone marrow-derived APCs, which are directly transfected with a plasmid DNA and/or acquire Ags from DNA-transfected non-APCs. To investigate the relative contribution of DNA-transfected APCs vs non-APCs to the initiation of CD8(+) T cell responses, we used tissue-specific promoter-directed gene expression and adoptive transfer systems in gene gun DNA immunization. In this study, we demonstrated that non-APC-specific gene expressions induced significant CD8(+) CTL and IFN-gamma-producing cells and Ab responses, whereas APC-specific gene expressions led to moderate CTL and IFN-gamma-producers, but no Ab responses. Interestingly, mice immunized with a non-APC-specific plasmid induced more rapid, vigorous, and prolonged proliferation of adoptively transferred Ag-specific CD8(+) T cells than APC-specific plasmid-immunized mice. In addition, the in vivo proliferative responses elicited by a non-APC-specific plasmid administration were dependent on TAP, but were independent of CD4(+) T cell help. Collectively, our results suggest that cross-priming, in which Ags expressed in non-APCs are taken up, processed, and presented by APCs, plays an important role in the initiation, magnitude, and maintenance of CD8(+) T cell responses in gene gun DNA immunization.

The enhanced effect of a hexameric deoxyriboguanosine run conjugation to CpG oligodeoxynucleotides on protection against allergic asthma

BACKGROUND

Oligodeoxynucleotides containing a CpG motif (CpG ODNs), as potent inducers of T(H)1 immunity, are considered promising candidates for immune modulation in asthma. We have previously demonstrated that conjugation of a hexameric deoxyriboguanosine run to the 3' terminus (3' dG(6)-run) of phosphodiester (PE) CpG ODNs enhanced their immuno-stimulatory activities in vitro.

OBJECTIVE

This study aimed to evaluate the effect of a 3' dG(6)-run conjugation to PE or phosphorothioate (PS) CpG ODNs on protection against murine allergic asthma in vivo.

METHODS

Balb/c mice were sensitized to ovalbumin by intraperitoneal injection with or without CpG ODNs (PS CpG ODNs, PE CpG ODNs, and those with 3' dG(6)-run) and subsequently challenged with ovalbumin. We evaluated airway hyperresponsiveness, eosinophil proportion in bronchoalveolar lavage fluid, airway inflammation, and ovalbumin-specific antibody responses.

RESULTS

The conjugation of a 3' dG(6)-run to PE CpG ODNs enhanced the production of IFN-gamma from ovalbumin-specific T(H) cells and prevented the development of asthma in terms of airway hyperresponsiveness, airway eosinophilia, and ovalbumin-specific IgE responses; these effects were comparable to those of PS CpG ODNs. Enhanced effects of the 3' dG(6)-run were also observed in PS CpG ODNs, though they were lower than those in PE CpG ODNs.

CONCLUSION

This study suggests that conjugation of a 3' dG(6)-run to CpG ODNs might provide an effective method for immune modulation of allergic asthma.

A novel function of phosphorothioate oligodeoxynucleotides as chemoattractants for primary macrophages

Phosphorothioate cytosine-guanine oligodeoxynucleotides (CpG PS-ODNs) has been reported to induce Th1 immune responses against coadministered Ags more efficiently than phosphodiester CpG ODNs (CpG PO-ODNs). Here, we demonstrated that PS-ODNs, but not PO-ODNs, have a chemotactic effect on primary macrophages, which is independent of the CpG motif. In addition, the conjugation of a hexameric dG run (dG(6) run) at the 3' terminus reduced the concentration required for the optimal chemotactic activity of PS-ODNs by approximately 10-fold. Endosomal maturation blockers, such as monensin and chloroquine, inhibited the chemotactic effect of PS-ODNs. The inhibition of the activities of p38 mitogen-activated protein (MAP) kinase, and extracellular signal-related kinases (ERKs) as well as phosphoinositide 3-kinase with their specific inhibitors also resulted in suppressing the chemotaxis of primary macrophages induced by PS-ODNs. These results indicate that the PS-ODN-mediated chemotaxis requires the activation of ERKs, p38 MAP kinase, and phosphoinositide 3-kinase as well as endosomal maturation. In addition, the phosphorylations of the p38 MAP kinase, ERKs, and protein kinase B, Akt, were induced by PS-ODN, which were further enhanced by the presence of both a dG(6) run and CpG motifs. Our findings suggest that the chemotactic activity of PS-ODNs may be one of the mechanisms by which PS-ODNs exhibit stronger immunomodulatory activities than PO-ODNs in vivo.

Induction of apoptosis in p53-deficient human hepatoma cell line by wild-type p53 gene transduction: inhibition by antioxidant

We investigated the role of wild-type (wt)-p53 as an inducer of apoptotic cell death in human hepatoma cell lines. Following the retrovirus-mediated transduction of the wt-p53 gene, Hep3B cells lacking the endogenous p53 expression began to die through apoptosis in 4 h. They showed a maximal apoptotic death at 12 h, whereas HepG2 cells expressing endogenous p53 did not. However, the transduction of the wt-p53 gene elicited growth suppression of both Hep3B and HepG2 cells. P21(WAF1/CIP1), a p53-inducible cell cycle inhibitor, was induced, not only in Hep3B cells undergoing apoptosis, but also in HepG2 cells. The kinetics of the p21(WAF1/CIP1) induction, DNA fragmentation, and growth suppression of the Hep3B cells showed that DNA fragmentation and growth suppression progressed rapidly following p21(WAF1/CIP1) accumulation. N-acetyl-cysteine or glutathione, potent antioxidants, strongly inhibited the DNA fragmentation, but did not reduce the elevated level of p21(WAF1/CIP1). These findings suggested that p21(WAF1/CIP1) was not a critical mediator for the execution of p53-mediated apoptosis, although it contributed to the growth inhibition of cells undergoing apoptosis. Furthermore, p53-mediated apoptosis could be repressed by antioxidants.

Short peptides with induced beta-turn inhibit the interaction between HIV-1 gp120 and CD4

To identify novel peptides that inhibit the interaction between human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 and CD4, we constructed a targeted phage-displayed peptide library in which phenylalanine and proline were fixed at the fourth and sixth positions, respectively, because Phe43 and the adjacent beta-turn of CD4 are critical for interaction with gp120. Two synthetic peptides were selected after three rounds of biopanning against gp120, and one of them, G1 peptide (ARQPSFDLQCGF), exhibited specific inhibition of the interaction between gp120 and CD4 with an IC(50) of about 50 microM. Structural analysis using NMR demonstrated that G1 peptide forms a compact cyclic structure similar to the CD4 region interacting with gp120. Two derivatives of G1 peptide, a linear hexameric peptide (G1-6) and a cyclic nonameric peptide (G1-c), were synthesized based on the structure of the G1 peptide. Interestingly, they showed higher inhibitory activities than did G1 peptide with IC(50)'s of 6 and 1 microM, respectively. Thus, this study might provide a new insight into the development of anti-HIV-1 inhibitors.

Short peptides with induced beta-turn inhibit the interaction between HIV-1 gp120 and CD4

To identify novel peptides that inhibit the interaction between human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 and CD4, we constructed a targeted phage-displayed peptide library in which phenylalanine and proline were fixed at the fourth and sixth positions, respectively, because Phe43 and the adjacent beta-turn of CD4 are critical for interaction with gp120. Two synthetic peptides were selected after three rounds of biopanning against gp120, and one of them, G1 peptide (ARQPSFDLQCGF), exhibited specific inhibition of the interaction between gp120 and CD4 with an IC(50) of about 50 microM. Structural analysis using NMR demonstrated that G1 peptide forms a compact cyclic structure similar to the CD4 region interacting with gp120. Two derivatives of G1 peptide, a linear hexameric peptide (G1-6) and a cyclic nonameric peptide (G1-c), were synthesized based on the structure of the G1 peptide. Interestingly, they showed higher inhibitory activities than did G1 peptide with IC(50)'s of 6 and 1 microM, respectively. Thus, this study might provide a new insight into the development of anti-HIV-1 inhibitors.

Hepatitis C virus core protein promotes cell proliferation through the upregulation of cyclin E expression levels

AIMS/BACKGROUND

The hepatitis C virus (HCV) core protein is known to play an important role in hepatocarcinogenesis. Recent studies have suggested that the increased proliferation rate of hepatocytes is a major risk factor for the development of hepatocellular carcinoma. In this study, we investigated whether the HCV core protein promotes the cell growth rate through the modulation of cyclin E expression levels.

METHODS/RESULTS

HCV core stable transfectant Rat-1 cell lines showed a markedly increased proliferation rate compared to mock cells. Cyclin E expression and its associated kinase activities were remarkably increased in HCV core stable transfectants. Cyclin E mRNA levels were also upregulated in these cell lines.

CONCLUSIONS

Our data suggest that the HCV core protein promotes cell proliferation through upregulation of the cyclin E expression levels, implying this property of HCV core protein plays an important role in hepatocarcinogenesis.

Enhancement of VP1-specific immune responses and protection against EMCV-K challenge by co-delivery of IL-12 DNA with VP1 DNA vaccine

It has been reported that co-delivery of IL-12 DNA with a DNA vaccine further enhances antigen (Ag)-specific protective immunity in pathogenic challenge models. However, the enhancing effects of antibody by IL-12 have been controversial. To clarify this issue, we constructed an IL-12 expression vector, co-immunized IL-12 DNA with an encephalomyocarditis virus (EMCV)-D VP1 plasmid vaccine, and then evaluated immune modulatory effects and protection against lethal EMCV-K challenge. We observed that VP1-specific IgG production, as well as seroconversion rates, were significantly enhanced by IL-12 co-injection, indicating that IL-12 can enhance antibody responses in this model system. In particular, co-injection with VP1 plus IL-12 DNA into the same leg enhanced systemic Ag-specific IgG production to a significantly greater extent than either the separate leg injection of VP1 and IL-12 DNA or VP1 DNA vaccine alone. This suggests that local co-expression of IL-12 along with antigens is more important for enhanced antibody production. Furthermore, IgG2a isotype was significantly enhanced by IL-12 DNA co-injection, indicating a Th1 bias. In addition, co-delivery of IL-12 DNA was demonstrated to enhance VP1-specific Th cell proliferative responses. When animals were challenged with a lethal dose of EMCV-K, IL-12 DNA-co-immunized animals exhibited enhanced survival, as compared to VP1 DNA vaccine alone. These studies suggest that IL-12 plays an important role in increasing Ag-specific Th1 type antibody and cellular responses, resulting in enhanced protection against lethal EMCV-K challenge.

HCV core protein modulates Rb pathway through pRb down-regulation and E2F-1 up-regulation

It has been recognized that the HCV (hepatitis C virus) core protein plays an important role in hepatocarcinogenesis. The functional inactivation of the Rb pathway appears to be a major event for multi-step cancer carcinogenesis. To elucidate the role of the HCV core protein in hepatocarcinogenesis, we investigated the effect of the HCV core protein on the Rb pathway in both Rat-1 cell lines, stably expressing the HCV core protein and the doxycycline-regulated cell lines. The HCV core stable transfectants showed a dramatic decrease in the pRb levels and E2F-1 up-regulation. In the doxycycline-regulated cell lines, the pRb levels were significantly decreased which are followed by E2F-1 up-regulation. HCV core stable transfectants showed higher cell growth rates and were sensitize to apoptosis. Thus, our results first indicate that the HCV core protein decreases the expression of pRb, thereby allowing E2F-1 to be constitutively active, which is thought to result in rapid cell proliferation or sensitizing to apoptosis.

Hepatitis C virus core protein inhibits interleukin 12 and nitric oxide production from activated macrophages

A characteristic feature of hepatitis C virus (HCV) infection is a high frequency of persistence and the progression to chronic liver diseases. Recent data suggest that prevalent T helper (Th) 2 immunity as well as weak HCV-specific T-cell response is associated with viral persistence. Here, we showed that the production of interleukin 12 (IL-12) and nitric oxide (NO) that is critical for the induction of Th1 and innate immunity, but not that of tumor necrosis factor alpha (TNF-alpha), was significantly suppressed in both HCV core-expressing macrophage cell lines and mouse peritoneal macrophages treated with recombinant core protein. In addition, IL-12 p40 promoter activity was repressed by the presence of HCV core in macrophages stimulated with lipopolysaccharride (LPS) following IFN-gamma treatment, indicating that IL-12 production may be downregulated at the transcriptional level. We also found that proliferation of T cells and IFN-gamma production in mixed lymphocyte reactions (MLR) with core-expressing cells were inhibited. Taken together, our results suggest that HCV core protein could play roles in suppressing the induction of Th1 immunity through inhibition of IL-12 and NO production.

Effects of a hexameric deoxyriboguanosine run conjugation into CpG oligodeoxynucleotides on their immunostimulatory potentials

CpG oligodeoxynucleotides (ODNs) are promising immunomodulatory agents for treating human diseases and vaccine development. Phosphodiester CpG ODNs were demonstrated to have poor immunostimulatory potentials for cytokine production. However, the conjugation of consecutive deoxyriboguanosine residues, called a dG run, at the 3' terminus of phosphodiester CpG ODNs significantly enhanced TNF-alpha and IL-12 production from mouse splenic dendritic cells (DCs). The optimal induction of cytokine production was achieved by the addition of a hexameric dG (dG6) run. In contrast, the existence of a dG6 run either at the 5' terminus of phosphodiester CpG ODNs or at the 3' terminus of phosphorothioate CpG ODNs diminished CpG-mediated cytokine induction, suggesting that the effects of a dG run depend on its location and the chemical property of the ODN backbone, respectively. In addition, we provided the evidence that the conjugation of a dG6 run caused the structural transformation of CpG ODNs, which facilitates their targeting into mouse APCs such as splenic DCs, B cells, and peritoneal macrophages with a scavenger receptor type A ligand specificity. Among primary APCs, DCs were the most potent for CpG ODN-mediated IL-12 production. Furthermore, we demonstrated that the conjugation of a dG6 run into the 3' terminus of phosphodiester CpG ODNs was crucial for their ability to generate Th1 immunity in vivo. Thus, the conjugation of a dG6 run into phosphodiester CpG ODNs would be an alternative way to optimize their immunostimulatory potentials in vitro and in vivo.

Local structural elements in the mostly unstructured transcriptional activation domain of human p53

DNA transcription is initiated by a small regulatory region of transactivators known as the transactivation domain. In contrast to the rapid progress made on the functional aspect of this promiscuous domain, its structural feature is still poorly characterized. Here, our multidimensional NMR study reveals that an unbound full-length p53 transactivation domain, although similar to the recently discovered group of loosely folded proteins in that it does not have tertiary structure, is nevertheless populated by an amphipathic helix and two nascent turns. The helix is formed by residues Thr(18)-Leu(26) (Thr-Phe-Ser-Asp-Leu-Trp-Lys-Leu-Leu), whereas the two turns are formed by residues Met(40)-Met(44) and Asp(48)-Trp(53), respectively. It is remarkable that these local secondary structures are selectively formed by functionally critical and positionally conserved hydrophobic residues present in several acidic transactivation domains. This observation suggests that such local structures are general features of acidic transactivation domains and may represent "specificity determinants" (Ptashne, M., and Gann, A. A. F. (1997), Nature 386, 569-577) that are important for transcriptional activity.

Enhancement of immunoglobulin G2a and cytotoxic T-lymphocyte responses by a booster immunization with recombinant hepatitis C virus E2 protein in E2 DNA-primed mice

The induction of strong cytotoxic T-lymphocyte (CTL) and humoral responses appear to be essential for the elimination of persistently infecting viruses, such as hepatitis C virus (HCV). Here, we tested several vaccine regimens and demonstrate that a combined vaccine regimen, consisting of HCV E2 DNA priming and boosting with recombinant E2 protein, induces the strongest immune responses to HCV E2 protein. This combined vaccine regimen augments E2-specific immunoglobulin G2a (IgG2a) and CD8(+) CTL responses to a greater extent than immunizations with recombinant E2 protein and E2 DNA alone, respectively. In addition, the data showed that a protein boost following one DNA priming was also effective, but much less so than those following two DNA primings. These data indicate that sufficient DNA priming is essential for the enhancement of DNA encoded antigen-specific immunity by a booster immunization with recombinant E2 protein. Furthermore, the enhanced CD8(+) CTL and IgG2a responses induced by our combined vaccine regimens are closely associated with the protection of BALB/c mice from challenge with modified CT26 tumor cells expressing HCV E2 protein. Together, our results provide important implications for vaccine development for many pathogens, including HCV, which require strong antibody and CTL responses.

Internal cleavage of hepatitis C virus NS3 protein is dependent on the activity of NS34A protease

The nonstructural protein NS3 of the hepatitis C virus (HCV) is indispensable for virus replication and a multifunctional enzyme that contains three catalytic activities such as serine protease, helicase, and NTPase. Here, we demonstrated that the internal cleavage of the HCV NS3 protein occurs in various mammalian cells such as HepG2, COS-7, and NIH3T3. As is observed for the internal cleavage mechanism of the NS3 protein of dengue virus 2, the internal processing of HCV NS3 protein was catalyzed by the active NS3 serine protease and NS4A, but not NS3 alone. From the data acquired from extensive site-directed mutagenesis, we observed that the NS3 protein was internally cleaved at two different sites, FCH(1395) ||S(1396)KK and IPT(1428) ||S(1429)GD, within RNA helicase domain. The internal cleavage of NS3 protein by NS34A protease was also confirmed in a different isolate of HCV-1b strain. In addition, in vitro transforming assays demonstrated that the internal cleavage product of NS3, NS3a-1, appeared to have higher oncogenic potential than does intact NS3. Taken together, our results suggest that the internal cleavage of NS3 may be associated with the replication and oncogenesis of HCV.

Functional interactions between conserved motifs of the hepatitis C virus RNA helicase protein NS3

The hepatitis C virus NS3 gene encodes a RNA helicase with several sequence motifs conserved among the members of the DExH box protein family. The contributions of the sequence motifs to enzyme activity were assessed in this study by substitution of alanine for the Lys in the ATP binding motif GxGK (referred to as K1236A mutation), or for the Asp in the DExH motif (D1316A), or for the Arg in the middle of the QRxGRxGR motif known for RNA binding (R1490A). Histidine-tagged recombinant proteins of Mr 54,000 were expressed in Escherichia coli and purified by chromatography on nickel agarose. All three mutants were severely defective in ATPase and RNA helicase activities, but loss of the ATPase activity was not dependent on polynucleotide cofactors. With the exception of R1490A mutant, a stable complex was formed between dsRNA substrates and recombinant proteins, indicating that the arginine-rich motif is required for efficient RNA binding. Complex formation was not affected by omission of ATP or substitution by a non-hydrolyzable analog AMP-PCP, suggesting that neither binding nor hydrolysis of ATP is required for RNA binding. Moreover, the K1236A mutant which was defective in binding ATP exhibited an unusually strong affinity for RNA duplex. These results suggest that the conserved motifs cooperatively constitute a large functional domain rather than act as individual domains with strictly independent functions, and that alteration of one motif affects functions of other motifs in a mutually interactive fashion.

A novel function of IL-12p40 as a chemotactic molecule for macrophages

IL-12p70 plays a pivotal role in regulating the Th1/Th2 balance in the initial stage of immune responses. In contrast, IL-12p40, which is produced excess over IL-12p70, has been known to down-regulate IL-12p70-mediated responses by acting as an antagonist. To investigate in vivo function of IL-12p40, RH7777 rat hepatoma cells were engineered to inducibly express mouse IL-12p40 under the tight control of doxycycline (dox). In the absence of dox, s.c. injection of these cells into syngeneic rat was shown to generate tumors. However, the induction of IL-12p40 by dox was sufficient for inhibiting tumor formation, as well as for tumor regression. Immunohistochemical analysis showed that macrophages, but not CD4+ T, CD8+ T, and NK cells, were predominantly recruited into tumor sites as early as 3 days after IL-12p40 induction. These results were further supported by the observation that IL-12p40, but not C-terminal deletion mutants by more than 5 amino acids, was able to chemoattract peritoneal macrophages in vitro, suggesting that IL-12p40, when produced in a large excess over IL-12p70 in vivo, can initially amplify the immune responses against tumors by directly recruiting macrophages. Our findings indicate that IL-12p40 may function as an effector molecule as well as an antagonist of IL-12p70.

2.8 A resolution crystal structure of human TRAIL, a cytokine with selective antitumor activity

TRAIL is a newly identified cytokine belonging to the large tumor necrosis factor (TNF) family. TRAIL is a novel molecule inducing apoptosis in a wide variety of tumor cells but not in normal cells. To help in elucidating its biological roles and designing mutants with improved therapeutic potential, we have determined the crystal structure of human TRAIL. The structure reveals that a unique frame insertion of 12-16 amino acids adopts a salient loop structure penetrating into the receptor-binding site. The loop drastically alters the common receptor-binding surface of the TNF family most likely for the specific recognition of cognate partners. A structure-based mutagenesis study demonstrates a critical role of the insertion loop in the cytotoxic activity of TRAIL.

Enhanced cellular immunity to hepatitis C virus nonstructural proteins by codelivery of granulocyte macrophage-colony stimulating factor gene in intramuscular DNA immunization

Hepatitis C virus (HCV) nonstructural (NS) proteins appeared to be important targets for HCV vaccine development, since NS-specific T-helper-cell responses are associated with clearance from acute HCV infection. In this report, we have constructed a plasmid, pTV-NS345, that encodes the HCV NS3, NS4 and NS5 proteins (NS345) and a bicistronic plasmid, PTV-NS345/GMCSF, in which the HCV NS345 polyprotein and GMCSF are translated independently. Intramuscular inoculation with pTV-NS345 plasmid DNA into the Buffalo rats generated both antibody and T-cell proliferative responses to each NS protein. The expression of GMCSF, together with HCV NS345 proteins, appeared to significantly increase T-cell proliferative responses. In particular, the inoculation of a bicistronic plasmid generated higher T-cell proliferative responses to each NS protein than did the coinjection of two separate plasmids, pTV-NS345 and pTV-GMCSF. These results demonstrate that the codelivery of GMCSF augmented HCV NS345-specific cellular immunity and that the intensity of the immunity was differed depending on how GMCSF gene is codelivered.

IL-6 induces long-term protective immunity against a lethal challenge of influenza virus

The coadministration of cytokines can modulate immunity in DNA based viral vaccines. In order to determine the effects of various cytokines on long-term protection against the influenza virus, mice were intramuscularly coinoculated with plasmids that encoded either the granulocyte-macrophage colony-stimulating factor (GMCSF), interleukin-4 (IL-4), interleukin-12 (IL-12), or the interleukin-6 (IL-6) gene, in the presence of two plasmids that encoded the nucleoprotein (NP) and the hemagglutinin (HA) gene of the influenza A virus. The coadministration of IL-4, IL-6 and IL-12 transiently enhanced antibody responses against influenza virus in early time points (4 to 7 week post immunization) after post inoculation. The expression of GMCSF gene resulted in the sustained elevation of antibody responses for at least 20 weeks post inoculation. However, NP-specific CTL responses decreased in these animals. Mice that received either the IL-12 or the IL-6 gene had enhanced NP-specific CTL responses. Remarkably, the coadministration of the IL-6 gene completely protected mice from a lethal challenge with influenza virus. Conversely, mice that received the IL-4 gene appeared to be more susceptible to lethal challenge than mice that were inoculated with the NP and the HA genes alone. These results demonstrate that the use of cytokines as molecular adjuvants when coadministered in influenza DNA vaccination must be specific. Our data also demonstrates that the coadministration of IL-6 should be considered to enhance the efficacy of influenza DNA vaccines.

DNA inoculations with HIV-1 recombinant genomes that express cytokine genes enhance HIV-1 specific immune responses

Vaccination with HIV-1 DNA sequences induce both humoral and cellular immune responses in experimental animals. However, these responses are relatively weak and are often only transient in their nature. In order to enhance the level of HIV-1 specific immunity, we have engineered HIV-1 DNA constructs which contained various cytokine genes such as interleukin-2 (IL-2), granulocyte-macrophage colony stimulating factor (GM-CSF) and interferon-gamma (IFN-gamma) gene. These constructs have deleted the tat and nmf genes of HIV-1 to eliminate their immunosuppressive effects. Immunizations with these recombinant constructs elicited moderate proliferative T cell responses but poor antibody responses in rats. However, inoculations of HIV-1 DNA that contained the GM-CSF or the IL-2 gene significantly enhanced humoral and proliferative T cell responses, respectively. Thus, recombinant HIV-1 genomes such as those described here may increase the efficacy of DNA vaccination.

Identification of a domain containing B-cell epitopes in hepatitis C virus E2 glycoprotein by using mouse monoclonal antibodies

Evidence from clinical and experimental studies of human and chimpanzees suggests that hepatitis C virus (HCV) envelope glycoprotein E2 is a key antigen for developing a vaccine against HCV infection. To identify B-cell epitopes in HCV E2, six murine monoclonal antibodies (MAbs), CET-1 to -6, specific for HCV E2 protein were generated by using recombinant proteins containing E2t (a C-terminally truncated domain of HCV E2 [amino acids 386 to 693] fused to human growth hormone and glycoprotein D). We tested whether HCV-infected sera were able to inhibit the binding of CET MAbs to the former fusion protein. Inhibitory activity was observed in most sera tested, which indicated that CET-1 to -6 were similar to anti-E2 antibodies in human sera with respect to the epitope specificity. The spacial relationship of epitopes on E2 recognized by CET MAbs was determined by surface plasmon resonance analysis and competitive enzyme-linked immunosorbent assay. The data indicated that three overlapping epitopes were recognized by CET-1 to -6. For mapping the epitopes recognized by CET MAbs, we analyzed the reactivities of CET MAbs to six truncated forms and two chimeric forms of recombinant E2 proteins. The data suggest that the epitopes recognized by CET-1 to -6 are located in a small domain of E2 spanning amino acid residues 528 to 546.

A neuron-specific gene transfer by a recombinant defective Sindbis virus

We examined the possibility that Sindbis virus, an alpha virus with a single-stranded RNA genome, would be applied for neuronal gene transfer. The recombinant defective Sindbis viruses were constructed by replacing the structural genes of Sindbis virus with genes encoding beta-galactosidase (rdSind-lacZ) or enhanced green fluorescent protein (rdSind-EGFP). In neuron-glia cocultures prepared from the neocortex, hippocampus, and striatum, EGFP or beta-galactosidase was expressed selectively in neurons 24 h after infection with rdSind-EGFP or rdSind-lacZ. Most cortical neurons were infected with rdSind-lacZ at a multiplicity of infection (M.O.I.) of 5 while glial cells were little infected. In addition, transient neuron-specific expression of beta-galactosidase was observed near injection sites over the next 3 d following administration of rdSind-lacZ in adult rat. In the cortical neurons infected with rdSind-EGFP, treatment with NMDA induced neuritic blebs and cell body swelling in a Na+-dependent manner. Therefore, recombinant defective Sindbis viruses can be used as an efficient and selective vector for gene transfer into neurons and applied to investigate biological role of target genes delivered into neurons in vitro and in vivo.

Optimal induction of hepatitis C virus envelope-specific immunity by bicistronic plasmid DNA inoculation with the granulocyte-macrophage colony-stimulating factor gene

In this study, we have constructed various DNA vaccine vectors that carried hepatitis C virus (HCV) envelope genes without and with the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene in several different ways. In Buffalo rats that received plasmids carrying the HCV envelope genes, which encode envelope proteins E1 and E2, both antibody and lymphoproliferative responses against these proteins were induced. These responses were greatly enhanced by the codelivery of the GM-CSF gene. In particular, inoculation with a bicistronic plasmid that independently expressed the GM-CSF gene and the envelope genes in the same construct generated the highest antibody titers and significantly increased lymphoproliferative responses against these proteins. Moreover, strong antibody responses to homologous and heterologous hypervariable region 1 peptides were elicited in the immunized rats.

Rapid recruitment of macrophages in interleukin-12-mediated tumour regression

In order to study the mechanism of interleukin-12 (IL-12) antitumour activity, RH7777 rat hepatoma cells were engineered to express mouse IL-12 (mIL-12) (RH7777/mIL-12) under the tight control of doxycycline (dox). The production of the mIL-12 protein was regulated by the concentration of dox that was present in the culture medium. RH7777/mIL-12 cells appeared to have the same tumorigenic activity as did parental RH7777 cells, when subcutaneously injected into syngeneic rat (BUF/N) in the absence of dox. However, the tumorigenicity of RH7777/mIL-12, but not RH7777, cells were significantly decreased when dox was administrated to the animals. In addition, established tumours of RH7777/mIL-12 cells gradually disappeared upon the induction of mIL-12 by dox. To elucidate the kinetic profile of immune cells involved in the mIL-12-induced tumour regression, both histological and immunohistochemical analyses were performed 1, 3 and 14 days after the dox treatment on rats bearing tumours that were approximately 0. 5 cm in diameter. Tumour-infiltrating macrophages began to appear at the tumour site one day after dox treatment. As time elapsed, the number of tumour infiltrates including CD4+, CD8+, natural killer (NK) cells and macrophages gradually increased. In particular, CD8+ and NK cells constituted the major population of the tumour-infiltrated cells. Furthermore, it was found that resting peritoneal macrophages (PM) from rats were chemoattracted in response to mIL-12. The effects of mIL-12 on PM chemotaxis were reproducibly observed in concentrations as low as 0.1 ng/ml. These findings suggest that IL-12 can directly recruit macrophages into tumour sites which, in turn, leads to a broad and intense immunological response against tumour.

Hepatitis C virus envelope DNA-based immunization elicits humoral and cellular immune responses

The vaccine development for hepatitis C virus (HCV) is highly urgent to prevent non A and non B hepatitis. It was recently shown that the HCV envelope proteins appeared to the key viral antigens to induce protective immunity. To generate immune responses to the HCV envelope proteins on the DNA-based immunization, various envelope gene-containing plasmids were constructed. For efficient expression and secretion of envelope proteins, the signal sequence of each envelope protein was replaced with either herpes simplex virus type-1 (HSV-1) gD or signal sequence of gD and truncated C-terminal hydrophobic regions of envelope proteins. The intramuscular injection of these plasmids generated a significant level of antibody titers to the E1 and E2 proteins, which maximally reached 850 and 25,000 respectively. The secreted form of each envelope protein and the fusion of the highly immunogenic gD proteins were shown to have no significant effect on generating immune responses to the envelope proteins. In addition, immunized rats appeared to generate antibodies directed to the homologous HVR-1 peptide. Splenic lymphocytes from immunized rats were shown to induce significant T-cell proliferative responses with the stimulation of recombinant E1 and E2 proteins. Our results demonstrated that the HCV envelope-DNA based immunization could elicit both humoral and cellular immune responses.

Immuno-stimulatory effects of bacterial-derived plasmids depend on the nature of the antigen in intramuscular DNA inoculations

The CpG motifs of bacterial-derived plasmids augment antigen-specific immune responses and steer those responses towards the T helper 1 (Th1) type. In this study, we have addressed the immuno-stimulatory effect of intramuscular co-administration of CpG motifs containing vector DNA on the modulation of immune responses to the haemagglutinin (HA) and the nucleoprotein (NP) proteins of influenza virus. The co-administration of vector DNA with a HA-encoding plasmid DNA showed a significant enhancement in the total IgG response, the generation of cytotoxic T lymphocyte (CTL), and the T-cell proliferative response. In the case of NP-encoding plasmid DNA inoculations, the co-administration of vector DNA slightly decreased the total IgG response, although the IgG2a/IgG1 ratio and the CTL responses to NP were significantly increased. These observations suggest that the immuno-stimulatory effects of bacterial-derived plasmids depend upon the nature of the co-administered antigen.

In vivo assay for hepatitis C viral serine protease activity using a secreted protein

Hepatitis C virus (HCV) is a major pathogen of community-acquired and post-transfusional non-A, non-B hepatitis. Since an in vitro replication system is not available, it is crucial to develop an efficient and sensitive assay system for screening inhibitors of HCV. The fact that the activity of HCV NS3 protease is responsible for the maturation of the nonstructural proteins and viral replication, suggests that NS3 protease is a suitable target for anti-HCV drug development. To devise an assay system in cell culture, we constructed NS3/4A-SEAP (secreted alkaline phosphatase) chimeric gene, in which the SEAP gene was fused in-frame to downstream of NS4A/4B cleavage site. In this system, the SEAP would be secreted into the extracellular media depending on the cleavage activity of the NS3 protease. Our results demonstrate that the NS3/4A-SEAP expression vector encoding wild type NS3 protease, but not mutant NS3 protease, could produce high SEAP activity in the media of both transfected cells and stable expression cell lines. Since the activity of SEAP in the culture media can be monitored quantitatively and continuously by the chemiluminescent method, this assay system will be useful for screening potential inhibitors of HCV protease.

Hepatitis C virus core from two different genotypes has an oncogenic potential but is not sufficient for transforming primary rat embryo fibroblasts in cooperation with the H-ras oncogene

Persistent infection with hepatitis C virus (HCV) is associated with the development of liver cirrhosis and hepatocellular carcinoma. To examine the oncogenic potential of the HCV core gene product, primary rat embryo fibroblasts (REFs) were transfected with the core gene in the presence or absence of the H-ras oncogene. In contrast to a previous report (R. B. Ray, L. M. Lagging, K. Meyer, and R. Ray, J. Virol. 70:4438-4443, 1996), HCV core proteins from two different genotypes (type 1a and type 1b) were not found to transform REFs to tumorigenic phenotype in cooperation with the H-ras oncogene, although the core protein was successfully expressed 20 days after transfection. In addition, REFs transfected with E1A- but not core-expressing plasmid showed the phenotype of immortalized cells when selected with G418. The biological activity was confirmed by observing the transcription activation from two viral promoters, Rous sarcoma virus long terminal repeat and simian virus 40 promoter, which are known to be activated by the core protein from HCV-1 isolate. In contrast to the result with primary cells, the Rat-1 cell line, stably expressing HCV core protein, exhibited focus formation, anchorage-independent growth, and tumor formation in nude mice. HCV core protein was able to induce the transformation of Rat-1 cells with various efficiencies depending on the expression level of the core protein. These results indicate that HCV core protein has an oncogenic potential to transform the Rat-1 cell line but is not sufficient to either immortalize primary REFs by itself or transform primary cells in conjunction with the H-ras oncogene.

Content of reduced glutathione and consequences in recipients of glucose-6-phosphate dehydrogenase deficient red blood cells

The red blood cell glucose-6-phosphate dehydrogenase (G6PD) activity of every donor was examined with automatic enzyme-coupled method. The technique of molecular biology was applied to determine the DNA mutations for the 97 donors with undetectable G6PD activity. The concentration of reduced glutathione (GSH) in the stored RBC of the 97 G6PD-deficient donors and 124 normal donors was determined with the technique of high performance liquid chromatography. Routine blood counts, bilirubin and haptoglobin levels were used to evaluate posttransfusional hemolysis for the 48 adult patients transfused with 1 U G6PD deficient and 1 U normal RBC. Most (88, 90.7%) of the 97 donors were confirmed to be G6PD deficient at the DNA level. At each age interval of storage, the GSH concentration of G6PD-deficient RBC was significantly different from that of normal RBC. The total average value of GSH (pmol/gHb) was 2.52 +/- 0.95 (mean +/- 1 standard deviation) vs. 3.74 +/- 1.43 (P < 0.001). Hemoglobin, hematocrit, bilirubin, and haptoglobin levels in the patients receiving G6PD-deficient RBC were not statistically different from those in the recipients of normal RBC; even though the age of stored blood was 26-35 days. Within the same group of patients, the results of bilirubin and haptoglobin were not significantly changed before and after transfusion. The results of this study show that the GSH concentration in the stored blood of G6PD deficient donors was 67% of that in the normal donors. However, hemolysis does not occur in adult patients transfused with 1 U G6PD-deficient RBC. It seems unnecessary to screen G6PD activity for donors of adult recipients in Taiwan.

HCV and HBV coexist in HBsAg-negative patients with HCV viraemia: possibility of coinfection in these patients must be considered in HBV-high endemic area

Hepatocellular carcinoma (HCC) is one of the most common cancers and is highly associated with hepatitis B virus (HBV) infection in Korea. The role of HBV and hepatitis C virus (HCV) in HCC patients who are negative for hepatitis B surface antigens (HBsAg) remains poorly defined. It has been suggested that HCV core protein may impair the polymerase activity of HBV in vitro, potentially lowering HBV titre in coinfected patients. Therefore, routine enzyme immunoassay may not detect HBV, in spite of the presence of HBV viraemia in low titres. The aim of this study was to confirm the coexistence of HBV viraemia in hepatitis C-infected patients with HCC who have apparent HBsAg seronegativity and to establish the need for clinical reinterpretation of enzyme immunoassay (EIA) serological tests of HBsAg in patients with HCV viraemia and HCC. The serological profiles of HBV and HCV in 616 patients with HCC were analysed and the coinfection rate of HCV and HBV investigated. Sera were obtained from 16 patients who were both anti-HCV and HCV-RNA positive but HBsAg negative, and tested for HBV by polymerase chain reaction (PCR). Eleven non-A and non-B chronic hepatitis patients without HCC who had the same profiles of anti-HCV, HCV-RNA, and HBsAg were tested for HBV by PCR. As a control group, sera were obtained from 15 patients with HCC and 30 non-A and non-B chronic hepatitis patients without HCC; both were anti-HCV, HCV-RNA, and HBsAg negative and tested for HBV PCR. Of the 616 patients with HCC, 450 (73.1%) had current HBV infection, 48 (7.8%) had anti-HCV antibodies, and nine (1.5%) had viral markers of both HCV and HBV by serological profiles. Of the 27 patients with HCV viraemia and HBsAg seronegativity (16 with HCC; 11 with non-A non-B chronic hepatitis), 14 (51.9%) showed HBV viraemia by PCR. In contrast, of the 75 patients in the control group (45 with HCC; 30 with non-A and non-B chronic hepatitis) who were both HCV PCR negative and HBsAg negative, five (11.1%) showed HBV viraemia by PCR. The PCR for HBV revealed coexistent HBV viraemia in HCV viraemia patients, despite HBsAg negativity by EIA. In HBV-endemic areas, the possibility of coinfection of HBV in HBsAg-negative patients with HCV viraemia should be considered and molecular analysis for HBV-DNA performed.

Protective immunity against heterologous challenge with encephalomyocarditis virus by VP1 DNA vaccination: effect of coinjection with a granulocyte-macrophage colony stimulating factor gene

For DNA vaccination studies, recombinant VP1 protein of encephalomyocarditis virus (EMCV) was produced from Escherichia coli, and eukaryotic VP1 expression vector, pCT-Gs-VP1, was generated and used as a DNA vaccine. Mice were immunized intramuscularly (i.m.) with pCT-Gs-VP1 in the presence or absence of plasmid DNA expressing granulocyte-macrophage colony stimulating factor (GM-CSF), and were subsequently analyzed for their anti-VP1 immune responses with recombinant VP1 in ELISA. Immunization of mice with pCT-Gs-VP1 resulted in VP1-specific immune response and 43% protection from subsequent lethal heterologous challenge of EMCV. Coinjection of mice with pCT-Gs-VP1 and plasmid DNA encoding GM-CSF was shown to increase the seroconversion rate of the immunized mice with a single DNA injection, and enhanced to a higher degree VP1-specific immunity, which appeared to result in better protection (about 80%) from lethal virus challenge. Thus, our results provide evidence for the potential use of GM-CSF to induce better immune response and resistance against viral infection in DNA vaccination.

Hepatitis C virus E2 protein purified from mammalian cells is frequently recognized by E2-specific antibodies in patient sera

The envelope protein of hepatitis C virus (HCV) is composed of two membrane-associated glycoproteins, E1 and E2. To obtain HCV E2 protein as a secretory form at a high level, we constructed a recombinant chinese hamster ovary (CHO) cell line expressing a C-terminal truncated E2 (E2t) fused to human growth hormone (hGH), CHO/hGHE2t. The hGHE2t fusion protein was purified from the culture supernatant using anti-hGH mAb affinity chromatography at approximately 80% purity. The purified hGHE2t protein appeared to be assembled into oligomers linked by intermolecular disulfide bond(s) when density gradient centrifugation and SDS-polyacrylamide gel electrophoresis were employed. When the purified fusion protein was used for testing its ability to bind to antibodies specific for HCV by enzyme-linked immunosorbent assay, the protein was recognized by antibodies in sera from 90% of HCV-positive patients. Treatment of hGHE2t protein by beta-mercaptoethanol, but not by heat and SDS, significantly reduced its reactivity to the antibodies of patient sera, suggesting that intermolecular and/or intramolecular disulfide bonds are important for its ability to recognize its specific antibody and that the E2 protein contains discontinuous antigenic epitope(s).

Comparison of various expression plasmids for the induction of immune response by DNA immunization

Intramuscular injection of plasmid DNA is an efficient method to introduce a foreign gene into a live animal. We investigated several factors affecting the gene transfer efficiency and the following immune response by intramuscular injection of plasmid DNA. When the strength of several highly efficient viral promoters was compared in muscle by using the chloramphenicol acetyltransferase (CAT) gene as an indicator, cytomegalovirus (CMV) immediate early promoter was found to be stronger than any other viral promoters including Rous sarcoma virus (RSV), murine leukemia virus (SL3-3) and simian virus 40 (SV40) early promoters. Inclusion of adenovirus tripartite leader (TPL) sequences and a synthetic intron in the 5' untranslated region of mRNA moderately stimulated the CAT expression. On the other hand, the expression of encephalomyocarditis virus (EMCV) VP1 gene was greatly enhanced by the TPL sequences and an intron. The level of humoral immune response by intramuscular injection of various VP1 expression plasmids was compared. The seroconversion rate was highly dependent on the strength of the expression vector. However, the ratio of IgG1 and IgG2a immune response was not significantly variable depending on the strength of the expression vector. Also, the efficiency of the sindbis virus-based DNA vector was examined for the gene expression and immune response. Although a high level of CAT expression was obtained in muscle by using this system, VP1 was not produced as much as the conventional expression vectors. Furthermore, little humoral immune response was elicited by intramuscular injection of VP1-expressing sindbis vector, suggesting that this system was not superior to the conventional vector for DNA immunization.

Construction of hepatitis C-SIN virus recombinants with replicative dependency on hepatitis C virus serine protease activity

An in vivo assay system was developed for the serine protease of hepatitis C virus (HCV) using the sindbis (SIN) viral replication system in which HCV serine protease activity is essential for the replication of the HCV-SIN chimeric virus. Two chimeric viral cDNA clones were constructed by inserting the NS3/4A region and NS3/4A region with the putative helicase deleted, into the N-terminal region of SIN core protein. The constructs were named Tpro CT and Tpro T, respectively. BHK-21 cells transfected with the in vitro transcribed RNAs from Tpro CT and Tpro T showed specific cytopathic morphology and produced chimeric viruses, Vpro CT and Vpro T. In contrast, in vitro transcribed RNAs from Tpro CTI and Tpro TI, in which serine of catalytic triad of HCV protease was changed to alanine, were not infectious. When the chimeric viruses were passaged in BHK-21 cells at about 0.1 multiplicity of infection (MOI), Vpro T, but not Vpro CT, stably expressed HCV protease for up to five passages. Surprisingly, the cell culture media of BHK-21 cells infected with Vpro T, compared to wild-type sindbis virus, showed rapid pH changes by more than 0.8 pH degree at 72 h post-infection. HCV-SIN hybrid viruses could be used in screening the HCV protease-inhibitor in cell culture systems.

Generation of the replication-competent human immunodeficiency virus type 1 which expresses a jellyfish green fluorescent protein

The gene encoding a red-shifted green fluorescent protein variant (EGFP) was introduced into a human immunodeficiency virus type 1 (HIV-1) molecular clone by replacing the nef gene. The EGFP-expressing HIV-1 replicated efficiently in established human T cells. The expression of EGFP in the virus-infected cells was confirmed by fluorescence microscopy and also by Western blot analysis using the GFP antibodies. The EGFP gene was stably maintained in the viral genome during prolonged passages. EGFP-expressing HIV-1 could be used for anti-HIV-1 drug screening, sorting of virus-infected cells by fluorescence activated cell sorting (FACS) analysis, and for the rapid and simple detection of virus-infected cells by fluorescence microscopy.

Hepatitis C virus NS5B protein is a membrane-associated phosphoprotein with a predominantly perinuclear localization

Hepatitis C virus NS5B protein is an RNA-dependent RNA polymerase. To investigate the properties and function of this protein, we have expressed the NS5B protein in insect and mammalian cells. NS5B was found to be present as fine speckles in the cytoplasm, particularly concentrated in the perinuclear region, suggesting its association with the nuclear membrane, the endoplasmic reticulum, or the Golgi complex. This conclusion was supported by the biochemical demonstration that NS5B was associated with the membranes in the cells. Furthermore, it was shown that NS5B protein is a phosphoprotein. These properties may be related to its function as an RNA polymerase.

Significance of anti-E2 in the diagnosis of HCV infection in patients on maintenance hemodialysis: anti-E2 is frequently detected among anti-HCV antibody-negative patients

A routine screening test used in the diagnosis of hepatitis C virus (HCV) infection is the anti-HCV antibody (anti-HCV) test containing core, NS3, NS4, and NS5 antigens of HCV. When HCV infection occurs in immunocompromised hosts, antibody formation against core, NS3, or NS4 antigens may be weak in the presence of HCV viremia and cannot be detected by routine anti-HCV tests. This study proposed that in immunocompromised hosts such as patients with chronic renal failure (whose capacity to form antibodies is diminished), antibody formation against the E2 region would be preserved, because the E2/NS1 region of HCV is strongly immunogenic. The aim of this study is to evaluate the significance of anti-E2 in the diagnosis of HCV infection among patients on maintenance hemodialysis who are anti-HCV-negative, using a conventional third-generation enzyme immunoassay (EIA) kit. The E2/NS1 gene of HCV encoding the amino acid sequence 388-664 was molecularly cloned into a vector containing an SV 40 promotor and was expressed in Chinese Hamster ovary cells. Using this E2 protein, the anti-E2 test was performed by EIA on 100 patients on maintenance hemodialysis, and on 50 patients with chronic hepatitis C who were anti-HCV-positive, to evaluate the antigenecity of the E2 protein. Of the 100 hemodialysis patients, 15 (15.0%) tested anti-HCV-positive using a third generation anti-HCV ELISA kit. Of the 85 patients who tested negative for anti-HCV, nine (10.6%) were anti-E2-positive and six (66.7%) of these anti-E2 positive patients showed HCV RNA viremia by HCV reverse transcription-polymerase chain reaction. Fourty-two (84.0%) of 50 patients with chronic hepatitis C were anti-E2-positive. As a control group, we tested for anti-E2 among 30 blood donors who were anti-HCV-negative, and also among 85 patients with hepatocellular carcinoma who were anti-HCV-negative, but in both groups, none (0%) was anti-E2-positive. In conclusion, these data suggest that the E2 protein of HCV should be included in a diagnostic anti-HCV kit for the detection of HCV infection in immunocompromised patients.

Distribution of HCV genotypes among blood donors, patients with chronic liver disease, hepatocellular carcinoma, and patients on maintenance hemodialysis in Korea

Hepatitis C virus (HCV) is a single-stranded RNA virus related to the Flaviviridae family, and striking nucleotide sequence diversity has been reported among HCV isolates from different geographic areas. To study the distribution HCV genotypes among disease group in Korea, we subtyped HCV using the method of Okamoto et al. [(1992a): Journal of General Virology 73:673-679] and the reverse hybridization method (INNO-LiPA) on 138 patients who were HCV polymerase chain reaction (PCR)-positive: 30 blood donors, 30 with hepatocellular carcinoma (HCC), 33 with chronic hepatitis, 15 with liver cirrhosis, and 30 patients on maintenance hemodialysis in Korea. In 30 blood donors, HCV genotype 1b was most dominant (80%), followed by genotype 2a (13.3%), and 2b (6.7%). In 30 HCC cases, HCV genotype 1b was less frequent (60%), compared to blood donors, followed by genotype 2a (33.3%), and unclassified (6.7%). In 33 chronic hepatitis cases, HCV genotype 1b was also dominant (63.6%), followed by genotype 2a (30.3%), and 1a (6.1%). In 15 patients with liver cirrhosis, HCV genotype 1b was also dominant (60%), followed by genotype 2a (33.3%), and 1a (6.7%). In 30 patients on maintenance hemodialysis, HCV genotype 1b was dominant (86.7%), followed by genotype 2a (13.3%). In conclusion, among 138 HCV PCR-positive patients, type 1b was the prevailing type (71%), followed by type 2a (23.9%), type 1a (2.1%), type 2b (1.5%), and unclassified (1.5%) in Korea. The prevalence of type 1b in blood donors (80%) was higher than in patients with liver disease (61.5%) and the prevalence of type 1b was the lowest in patients with HCC (60%).

Distribution of HCV genotypes among blood donors, patients with chronic liver disease, hepatocellular carcinoma, and patients on maintenance hemodialysis in Korea

Hepatitis C virus (HCV) is a single-stranded RNA virus related to the Flaviviridae family, and striking nucleotide sequence diversity has been reported among HCV isolates from different geographic areas. To study the distribution HCV genotypes among disease group in Korea, we subtyped HCV using the method of Okamoto et al. [(1992a): Journal of General Virology 73:673-679] and the reverse hybridization method (INNO-LiPA) on 138 patients who were HCV polymerase chain reaction (PCR)-positive: 30 blood donors, 30 with hepatocellular carcinoma (HCC), 33 with chronic hepatitis, 15 with liver cirrhosis, and 30 patients on maintenance hemodialysis in Korea. In 30 blood donors, HCV genotype 1b was most dominant (80%), followed by genotype 2a (13.3%), and 2b (6.7%). In 30 HCC cases, HCV genotype 1b was less frequent (60%), compared to blood donors, followed by genotype 2a (33.3%), and unclassified (6.7%). In 33 chronic hepatitis cases, HCV genotype 1b was also dominant (63.6%), followed by genotype 2a (30.3%), and 1a (6.1%). In 15 patients with liver cirrhosis, HCV genotype 1b was also dominant (60%), followed by genotype 2a (33.3%), and 1a (6.7%). In 30 patients on maintenance hemodialysis, HCV genotype 1b was dominant (86.7%), followed by genotype 2a (13.3%). In conclusion, among 138 HCV PCR-positive patients, type 1b was the prevailing type (71%), followed by type 2a (23.9%), type 1a (2.1%), type 2b (1.5%), and unclassified (1.5%) in Korea. The prevalence of type 1b in blood donors (80%) was higher than in patients with liver disease (61.5%) and the prevalence of type 1b was the lowest in patients with HCC (60%).

A novel Bcl-2 related gene, Bfl-1, is overexpressed in stomach cancer and preferentially expressed in bone marrow

Programmed cell death (apoptosis) is an active process which is genetically encoded and plays an important role in several cellular activities such as embryonic development, deletion of autoreactive T-cells and homeostasis. Several genes regulating apoptosis have been reported, including p53, one of the tumor suppressor genes, c-myc, one of the proto-oncogenes, and various kinds of Bcl-2 related genes. A new cDNA clone which is homologous to Bcl-2, named as Bfl-1 were isolated from a human fetal liver at 22 week of gestation. This clone was identified by computer analysis of random cDNA sequences that were obtained in an effort to expand the expressed sequence tag (EST) databases to be used for human genome analysis. The homology was recognized by 72% amino acid identity to the murine A1 gene, a member of the Bcl-2-related genes. The homology to the BH1 and BH2 domains of Bcl-2 was especially significant, suggesting that Bfl-1 is a new member of the Bcl-2-related genes. Bfl-1 is abundantly expressed in the bone marrow and at a low level in some other tissues. Interestingly, a correlation was noted between the expression level of Bfl-1 gene and the development of stomach cancer in eight sets of clinical samples. It is conceivable that Bfl-1 is involved in the promotion of the cell survival in the stomach cancer development or progression.

Transactivation ability of p53 transcriptional activation domain is directly related to the binding affinity to TATA-binding protein

Tumor suppressor protein p53 is a potent transcriptional activator and regulates cell growth negatively. To characterize the transcriptional activation domain (TAD) of p53, various point mutants were constructed in the context of Gal4 DNA binding domain and tested for their transactivation ability. Our results demonstrated that the positionally conserved hydrophobic residues shared with herpes simplex virus VP16 and other transactivators are essential for transactivation. Also, the negatively charged residues and proline residues are necessary for full activity, but not essential for the activity of p53 TAD. Deletion analyses showed that p53 TAD can be divided into two subdomains, amino acids 1-40 and 43-73. An in vitro glutathione S-transferase pull-down assay establishes a linear correlation between p53 TAD-mediated transactivation in vivo and the binding activity of p53 TAD to TATA-binding protein (TBP) in vitro. Mutations that diminish the transactivation ability of Gal4-p53 TAD also impair the binding activity to TBP severely. Our results suggest that at least TBP is a direct target for p53 TAD and that the binding strength of TAD to TBP (TFIID) is an important parameter controlling activity of p53 TAD. In addition, circular dichroism spectroscopy has shown that p53 TAD peptide lacks any regular secondary structure in solution and that there is no significant difference between the spectra of the wild type TAD and that of the transactivation deficient mutant type.

Construction of a gene expression profile of a human fetal liver by single-pass cDNA sequencing

We have obtained an overall gene expression profile of a human fetal liver by sequencing the 5' ends of random cDNA clones from an unbiased cDNA library. As a result, many novel genes that might be related to liver growth and hemopoiesis have been identified. Poly (A)+ RNA was purified from the liver of a human fetus obtained at the 22nd week of gestation, and a directional library was constructed with oligo d(T)-primed cDNAs synthesized without any normalizing procedures. The 5' end of each randomly chosen clone was sequenced by the dideoxy-chain termination methods, and each sequence was used for homology search in the public databases such as GenBank, SWISS-PROT, and PIR. Of 1231 random cDNA clones analyzed, 697 clones representing 204 different transcripts (57%), were identical to previously known human genes. The spectrum of the genes in this category reflected well the physiological characteristics of the fetal liver, a combination of hepatic and hemopoietic functions. About 4% of the clones represented novel gene transcripts with significant homologies to known genes of human or other organisms. These included several genes that are known to be involved in cellular differentiation and/or proliferation. About 25% of the clones had no statistically significant match to any known genes. In summary, we have identified 546 different gene transcripts consisting of 204 known human genes, 42 homologous genes, and 300 unknown genes. Thus, this approach appears to be a highly efficient way to identify novel genes of biological interest.

Human foamy virus Bel1 transactivator contains a bipartite nuclear localization determinant which is sensitive to protein context and triple multimerization domains

The Bel1 protein of human foamy virus is a 300-amino-acid nuclear regulatory protein which transactivates the gene expression directed by the homologous long terminal repeat and the human immunodeficiency virus type 1 long terminal repeat. While previous reports suggested that the single basic domain of Bel1 from residues 211 to 222 and/or 209 to 226 is necessary and sufficient for efficient nuclear localization (L. K. Venkatesh, C. Yang, P. A. Theodorakis, and G. Chinnandurai, J. Virol. 67:161-169, 1993; F. He, J. D. Sun, E. D. Garrett, and B. R. Cullen, J. Virol. 67:1896-1904, 1993), our recent data showed that another basic domain, from amino acid residues 199 to 200, is also required for nuclear localization of Bel1 (C. W. Lee, C. Jun, K. J. Lee, and Y. C. Sung, J. Virol. 68:2708-2719, 1994). To clarify this discrepancy, we constructed various bel1-lacZ chimeric constructs and several linker insertion mutants and determined their subcellular localization. When the region of Bel1 containing basic domains was placed at an internal site of the lacZ gene, the nuclear localization signal (NLS) of Bel1 consisted of two discontinuous basic regions separated by an intervening sequence. Moreover, insertion of specific amino acids between two basic regions disrupted the activity of the Bel1 NLS. On the other hand, Bel1 residues 199 and 200 were not required to direct the Bel1-beta-galactosidase chimeric protein to the nucleus when the Bel1 NLS was appended to the amino terminus of beta-galactosidase. These results indicate that the function of the Bel1 NLS is sensitive to the protein context within which the sequence is present. In addition, we demonstrated that the Bel1 protein forms a multimeric complex in the nuclei of mammalian cells by using a sensitive in vivo protein-protein interaction assay. Mutational analyses revealed that the regions which mediate multimer formation map to three domains of Bel1, i.e., residues 1 to 31, 42 to 82, and 82 to 111. Furthermore, our results show that the region of Bel1 from residues 202 to 226 prevents Bel1 from forming a multimeric complex.

The gene expression of human foamy virus does not require a post-transcriptional transactivator

Human foamy virus (HFV) comprises a complex genomic organization of gag, pol, env, and several nonstructural genes such as bel1, bel2, bel3, bet, beo, and bes located between env and 3' LTR. Among these viral nonstructural genes, bel1 appears to encode an essential transactivator of LTR-directed gene expression. To investigate the roles of the other nonstructural proteins for the viral replication, a series of proviral mutants were generated and tested for their in vitro replication. The mutations in the other than bel1 open reading frame did not show any significant effect on viral replication. The bel1 protein is the only essential transactivator for the LTR-directed transcription. To determine whether HFV has an essential post-transcriptional transactivator like the rev protein of human immunodeficiency virus type 1, or the rex protein of human T cell leukemia virus type 1, we investigated the bel1-independent expression of the HFV gag structural gene under the control of the heterologous simian virus 40 promoter. We demonstrated that the expression of the HFV gag structural gene does not require an essential post-transcriptional transactivator. Thus, it appears that the regulation of HFV gene expression is distinct from that of other human retroviruses.

Formation of intersubunit disulfide bonds and properties of the single histidine and cysteine residues in each subunit relative to the decameric structure of cyanase

Reaction of the single cysteine residue in each subunit of cyanase with certain SH reagents gives an active decameric derivative that dissociates reversibly to an inactive dimer derivative (Anderson, P. M., Johnson, W. V., Korte, J. J., Xiong, X., Sung, Y.-c., and Fuchs, J. A. (1988) J. Biol. Chem. 263, 5674-5680). Reaction of mixed disulfide dimer derivatives of cyanase with dithiothreitol at 0 degree C results in formation of a disulfide bond between the subunits in the dimer. The disulfide dimer was inactive and did not associate to a decamer; the intersubunit disulfide bond could not be formed when the dimers were associated as a decamer. The two SH groups apparently are in close proximity to each other in the dissociated dimer but not when the dimer is associated to a decamer. Substitution of glycine for the cysteine residue or of tyrosine, asparagine, glycine, valine, or leucine for the single histidine residue in each subunit gave mutant enzymes that were active. However, H113N, H113Y, and C83G were unstable at low temperature and/or ionic strength, dissociating reversibly to an inactive dimer. Efficient reassociation required the presence of bicarbonate or cyanate analog. The results are consistent with a proposed single site per subunit model explaining apparent half-site binding of substrates and the requirement of decameric structure for activity.

The Bel1 protein of human foamy virus contains one positive and two negative control regions which regulate a distinct activation domain of 30 amino acids

The Bel1 transactivator is essential for the replication of human foamy virus (HFV). To define the functional domains of HFV Bel1, we generated random missense mutations throughout the entire coding sequence of Bel1. Functional analyses of 24 missense mutations have revealed the presence of at least two functional domains in Bel1. One domain corresponds to a basic amino acid-rich motif which acts as a bipartite nuclear targeting sequence. A second, central domain corresponds to a presumed effector region which, when mutated, leads to dominant-negative mutants and/or lacks transactivating ability. In addition, deletion analyses and domain-swapping experiments further showed that Bel1 protein contains a strong carboxy-terminal activation domain. The activating region is also capable of functioning as a transcription-activating domain in yeast cells, although it does not bear any significant sequence homology to the well-characterized acidic activation domain which is known to function only in yeast and mammalian cells. We also demonstrated that the regions of Bel1 from residues 1 to 76 and from residues 153 to 225 repressed transcriptional activation exerted by the Bel1 activation domain. In contrast, the region from residues 82 to 150 appears to overcome an inhibitory effect. These results indicate that Bel1 contains one positive and two negative regulatory domains that modulate a distinct activation domain of Bel1. These regulatory domains of Bel1 cannot affect the function of the VP16 activation domain, suggesting that these domains specifically regulate the activation domain of Bel1. Furthermore, in vivo competition experiments showed that the positive regulatory domain acts in trans. Thus, our results demonstrate that Bel1-mediated transactivation appears to undergo a complex regulatory pathway which provides a novel mode of regulation for a transcriptional activation domain.

Multiple positive and negative cis-acting elements that mediate transactivation by bel1 in the long terminal repeat of human foamy virus

The bel1 protein of human foamy virus (HFV), a retrovirus, regulates expression of the gene linked to the HFV long terminal repeat (LTR) and is essential for viral gene expression. The mechanism of action of the bel1 protein is unknown, but its action is mediated through the U3 region of the LTR. To determine which U3 sequences are critical for transactivation by bel1, a series of hybrid vectors consisting of a mutant HFV LTR and the chloramphenicol acetyltransferase gene were constructed and tested for their responsiveness to the bel1 protein by using transient assays after transfection. The target sequences for transactivation by bel1 were mapped to five regions in the U3 domain of the LTR: nucleotides -559 to -506, -454 to -418, -360 to -342, -327 to -284, and -116 to -89 (+1 represents the transcription initiation site). No significant sequence similarity was identified among the five target sites. The observation that the multiple distinct elements in the HFV LTR are the targets for bel1 transactivation is different from observations with other human retroviral systems. The regulation mechanism of HFV bel1 protein-mediated transactivation appears to be analogous to that of some DNA virus transactivators that increase transcription from numerous different viral promoters with little sequence similarity shared among them. We demonstrated that multiple bel1-responsive elements (BRE) can act as bel1-dependent enhancer elements, while a single copy of one BRE, BREe, can serve as an upstream activating element in both orientations. In addition, the region between -466 and -498 was identified as responsible for the downregulation of gene expression directed by BREa, which requires its upstream sequence element to act as a bel1-dependent enhancer element in a heterologous promoter.

The Escherichia coli K-12 cyn operon is positively regulated by a member of the lysR family

A regulatory gene, cynR, was found to be located next to the cyn operon but transcribed in the opposite direction. cynR encodes a positive regulatory protein that controls the cyn operon as well as its own synthesis. Positive regulation of the cyn operon requires cyanate and the cynR protein, but the negative autoregulation of the cynR gene appears to be independent of cyanate. The predicted amino acid sequence of the cynR protein derived from the DNA sequence was found to have significant homology to the predicted amino acid sequence of the lysR family of regulatory proteins.