Toxoplasma gondii RON4 binds to heparan sulfate on the host cell surface

Toxoplasma gondii rhoptry neck protein 4 (TgRON4) is a component of the moving junction, a key structure for host cell invasion. We previously showed that host cellular β-tubulin is a binding partner of TgRON4 in the invasion process. Here, to identify other binding partners of TgRON4 in the host cell, we examined the binding of TgRON4 to components of the host cell surface. TgRON4 binds to various mammalian cells, but this binding disappeared in glycosaminoglycan- and heparan sulfate-deficient CHO cells and after heparitinase treatment of mammalian cells. The C-terminal half of TgRON4 showed relatively strong binding to cells and heparin agarose. A glycoarray assay indicated that TgRON4 binds to heparin and modified heparin derivatives. Immunoprecipitation of T. gondii-infected CHO cell lysates showed that TgRON4 interacts with glypican 1 during Toxoplasma invasion. This interaction suggests a role for heparan sulfate in parasite invasion.

Pull-down method to access the cell surface receptor for Toxoplasma gondii

Protein X, which is expressed on the surface of Toxoplasma and is thought to interact with host molecules, was expressed as a GST recombinant protein, conjugated to sepharose 4B, and used to pull down biotin-labeled 293T cells. The product was analysis by 2D-PAGE and Western blotting. Mass spectrometry revealed the reacted spots from the gel to be heat shock proteins.

Characterization of a Toxoplasma gondii calcium calmodulin-dependent protein kinase homolog

Background

Toxoplasma gondii is an obligate intracellular parasite of the phylum Apicomplexa and a major pathogen of animals and immunocompromised humans, in whom it causes encephalitis. Understanding the mechanism of tachyzoite invasion is important for the discovery of new drug targets and may serve as a model for the study of other apicomplexan parasites. We previously showed that Plasmodium falciparum expresses a homolog of human calcium calmodulin-dependent protein kinase (CaMK) that is important for host cell invasion. In this study, to identify novel targets for the treatment of Toxoplasma gondii infection (another apicomplexan parasite), we sought to identify a CaMK-like protein in the T. gondii genome and to characterize its role in the life-cycle of this parasite.

Methods

An in vitro kinase assay was performed to assess the phosphorylation activities of a novel CaMK-like protein in T. gondii by using purified proteins with various concentrations of calcium, calmodulin antagonists, or T. gondii glideosome proteins. Indirect immunofluorescence microscopy was performed to detect the localization of this protein kinase by using the antibodies against this protein and organellar maker proteins of T. gondii.

Results

We identified a novel CaMK homolog in T. gondii, T. gondii CaMK-related kinase (TgCaMKrk), which exhibits calmodulin-independent autophosphorylation and substrate phosphorylation activity. However, calmodulin antagonists had no effect on its kinase activity. In T. gondii-infected cells, TgCaMKrk localized to the apical ends of extracellular and intracellular tachyzoites. TgCaMKrk phosphorylated TgGAP45 for phosphorylation in vitro.

Conclusions

Our data improve our understanding of T. gondii motility and infection, the interaction between parasite protein kinases and glideosomes, and drug targets for protozoan diseases.

Akabane virus nonstructural protein NSm regulates viral growth and pathogenicity in a mouse model

The biological function of a nonstructural protein, NSm, of Akabane virus (AKAV) is unknown. In this study, we generated a series of NSm deletion mutant viruses by reverse genetics and compared their phenotypes. The mutant in which the NSm coding region was almost completely deleted could not be rescued, suggesting that NSm plays a role in virus replication. We next generated mutant viruses possessing various partial deletions in NSm and identified several regions critical for virus infectivity. All rescued mutant viruses produced smaller plaques and grew inefficiently in cell culture, compared to the wild-type virus. Interestingly, although the pathogenicity of NSm deletion mutant viruses varied in mice depending on their deletion regions and sizes, more than half the mice died following infection with any mutant virus and the dead mice exhibited encephalitis as in wild-type virus-inoculated mice, indicating their neuroinvasiveness. Abundant viral antigens were detected in the brain tissues of dead mice, whereas appreciable antigen was not observed in those of surviving mice, suggesting a correlation between virus growth rate in the brain and neuropathogenicity in mice. We conclude that NSm affects AKAV replication in vitro as well as in vivo and that it may function as a virulence factor.

Serological survey of caprine arthritis-encephalitis virus infection in Japan

A serological survey of caprine arthritis-encephalitis virus (CAEV) infection was conducted from September 2006 to February 2007 in Japan. A total of 857 serum samples were collected from 113 herds in 28 prefectures and were analyzed for the presence of CAEV antibodies using agar gel immunodiffusion test. The seroprevalence of CAEV infection at the herd and animal levels was 15.0% (17/113) and 10.0% (86/857), respectively. Large farms with more than 10 goats and with animals for dairy and breeding purposes had higher seroprevalence (P<0.05). The results of this study provide useful information to consider effective control programs against CAEV infection in Japan.

Akabane virus utilizes alternative endocytic pathways to entry into mammalian cell lines

The entry mechanisms of Akabane virus (AKAV), Bunyaviridae family, have not yet been determined. In this study, chemical inhibitors were used to analyze endocytic mechanisms during AKAV infection of mammalian cell lines. The analyses using drug treatments followed by quantitative measurement of viral RNA and N protein revealed that AKAV enters non-bovine-derived cell lines (Vero, HmLu-1 and BHK cells) in a manner indicative of clathrin endocytosis. By contrast, AKAV infection in bovine-derived cell lines (LB9.K and MDBK cells) is independent of this pathway. Further analyses indicated that AKAV entry into bovine cell lines involves a non-clathrin, non-caveolae endocytic pathway that is dependent on dynamin. We conclude that although both cell types require a low pH for AKAV penetration, AKAV utilizes alternative entry pathways into mammalian cell lines.

Characterization and binding analysis of a microneme adhesive repeat domain-containing protein from Toxoplasma gondii

The intracellular parasite Toxoplasma gondii invades almost all nucleated cells, and has infected approximately 34% of the world's population to date. In order to develop effective vaccines against T. gondii infection, understanding of the role of the molecules that are involved in the invasion process is important. For this purpose, we characterized T. gondii proteins that contain microneme adhesive repeats (MARs), which are common in moving junction proteins. T. gondii MAR domain-containing protein 4a (TgMCP4a), which contains repeats of 17-22 amino acid segments at the N-terminus and three putative MAR domains at the C-terminus, is localized near the rhoptry of extracellular parasites. Following infection, TgMCP4a was detected in the parasitophorous vacuole. The recombinant Fc-TgMCP4a N-terminus protein (rTgMCP4a-1/Fc) showed binding activity to the surface proteins of Vero, 293T, and CHO cells. The recombinant GST-TgMCP4a N-terminus protein (rTgMCP4a-1/GST), which exhibited binding activity, was used to pull down the interacting factors from 293T cell lysate, and subsequent mass spectrometry analysis revealed that three types of heat shock proteins (HSPs) interacted with TgMCP4a. Transfection of a FLAG fusion protein of TgMCP4a-1 (rTgMCP4a-1/FLAG) into 293T cell and the following immunoprecipitation with anti-FLAG antibody confirmed the interactions of HSC70 with TgMCP4a. The addition of rTgMCP4a-1/GST into the culture medium significantly affected the growth of the parasite. This study hints that T. gondii may employ HSP proteins of host cell to facilitate their growth.

Characterization of the interaction between Toxoplasma gondii rhoptry neck protein 4 and host cellular β-tubulin

Toxoplasma rhoptry neck protein 4 (TgRON4) is a component of the moving junction macromolecular complex that plays a central role during invasion. TgRON4 is exposed on the cytosolic side of the host cell during invasion, but its molecular interactions remain unclear. Here, we identified host cellular β-tubulin as a binding partner of TgRON4, but not Plasmodium RON4. Coimmunoprecipitation studies in mammalian cells demonstrated that the C-terminal 15-kDa region of β-tubulin was sufficient for binding to TgRON4, and that a 17-kDa region in the proximal C-terminus of TgRON4 was required for binding to the C-terminal region of β-tubulin. Analysis of T. gondii-infected lysates from CHO cells expressing the TgRON4-binding region showed that the C-terminal region of β-tubulin interacted with TgRON4 at early invasion step. Our results provide evidence for a parasite-specific interaction between TgRON4 and the host cell cytoskeleton in parasite-infected cells.

Analyses of interactions between heparin and the apical surface proteins of Plasmodium falciparum

Heparin, a sulfated glycoconjugate, reportedly inhibits the blood-stage growth of the malaria parasite Plasmodium falciparum. Elucidation of the inhibitory mechanism is valuable for developing novel invasion-blocking treatments based on heparin. Merozoite surface protein 1 has been reported as a candidate target of heparin; however, to better understand the molecular mechanisms involved, we characterized the molecules that bind to heparin during merozoite invasion. Here, we show that heparin binds only at the apical tip of the merozoite surface and that multiple heparin-binding proteins localize preferentially in the apical organelles. To identify heparin-binding proteins, parasite proteins were fractionated by means of heparin affinity chromatography and subjected to immunoblot analysis with ligand-specific antibodies. All tested members of the Duffy and reticulocyte binding-like families bound to heparin with diverse affinities. These findings suggest that heparin masks the apical surface of merozoites and blocks interaction with the erythrocyte membrane after initial attachment.

Identification of mutations in TgMAPK1 of Toxoplasma gondii conferring resistance to 1NM-PP1

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1NM-PP1 resistant clones were established from chemically random mutated parasites.

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Resistant clones had a mutation in TgMAPK1.

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Resistant clones had less susceptibility to 1NM-PP1 at cell division.

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The mutation was not found at the gatekeeper residue.

Toxoplasma gondii is an important food and waterborne pathogen that causes severe disease in immunocompromised patients. Bumped kinase inhibitors (BKIs) have an antiparasitic effect on T. gondii tachyzoite growth by targeting T. gondii calmodulin-domain protein kinase 1 (TgCDPK1). To identify mutations that confer resistance to BKIs, chemical mutagenesis was performed, followed by selection in media containing either 250 or 1000 nM 1NM-PP1. Whole-genome sequence analysis of resistant clones revealed single nucleotide mutations in T. gondii mitogen-activated protein kinase 1 (TgMAPK1) at amino acids 162 (L162Q) and 171 (I171N). Plasmid constructs having the TgMAPK1 L162Q mutant sequence successfully replaced native TgMAPK1 genome locus in the presence of 1000 nM 1NM-PP1. The inhibitory effect of 1NM-PP1 on cell division observed in the parent clone was decreased in 1NM-PP1-resistant clones; however, effects on parasite invasion and calcium-induced egress were similar in both parent and resistant clones. A plasmid construct expressing the full length TgMAPK1 splicing isoform with L162Q mutation successfully complemented TgMAPK1 function in the pressure of 250 nM 1NM-PP1 in plaque assay. 1NM-PP1-resistant clones showed resistance to other BKIs (3MB-PP1 and 3BrB-PP1) with different levels. Here we identify TgMAPK1 as a novel target for 1NM-PP1 activity. This inhibitory effect is mediated through inhibition of tachyzoite cell division, and can be overcome through mutations at multiple residues in TgMAPK1.

Attenuation of an influenza A virus due to alteration of its hemagglutinin-neuraminidase functional balance in mice

Influenza A viruses possess two surface glycoproteins, hemagglutinin (HA), which binds to sialic-acid-containing receptors, and neuraminidase (NA), which removes sialic acid from host cells. It is well established that the HA-NA functional balance regulates the efficiency of virus replication. Here, we selected a plaque variant of the WSN (H1N1) strain that grew better than the wild-type virus in NA-expressing MDCK cell culture. A reverse genetics study revealed that the single mutation HA E190K, which occurs infrequently in naturally isolated H1N1 viruses, was responsible for the phenotype of this variant. Receptor assays indicated that this mutation did not affect the receptor specificity of HA but enhanced its receptor-binding affinity, resulting in altered HA-NA functional balance relative to that of the wild-type virus. We also found that this variant replicated in nasal turbinates at an equivalent level but in lungs at a lower level compared with wild-type virus, demonstrating its attenuation in mice. Together, our data demonstrated the importance of the HA-NA functional balance for influenza virus replication in an in vivo biological setting.

Analysis of the humoral immune responses among cynomolgus macaque naturally infected with Reston virus during the 1996 outbreak in the Philippines

Background

Ebolaviruses induce lethal viral hemorrhagic fevers (VHFs) in humans and non-human primates, with the exceptions of Reston virus (RESTV), which is not pathogenic for humans. In human VHF cases, extensive analyses of the humoral immune responses in survivors and non-survivors have shown that the IgG responses to nucleoprotein (NP) and other viral proteins are associated with asymptomatic and survival outcomes, and that the neutralizing antibody responses targeting ebolaviruses glycoprotein (GP_1,2) are the major indicator of protective immunity. On the other hand, the immune responses in non-human primates, especially naturally infected ones, have not yet been elucidated in detail, and the significance of the antibody responses against NP and GP_1,2 in RESTV-infected cynomolgus macaques is still unclear. In this study, we analyzed the humoral immune responses of cynomolgus macaque by using serum specimens obtained from the RESTV epizootic in 1996 in the Philippines to expand our knowledge on the immune responses in naturally RESTV-infected non-human primates.

Results

The antibody responses were analyzed using IgG-ELISA, an indirect immunofluorescent antibody assay (IFA), and a pseudotyped VSV-based neutralizing (NT) assay. Antigen-capture (Ag)-ELISA was also performed to detect viral antigens in the serum specimens. We found that the anti-GP_1,2 responses, but not the anti-NP responses, closely were correlated with the neutralization responses, as well as the clearance of viremia in the sera of the RESTV-infected cynomolgus macaques. Additionally, by analyzing the cytokine/chemokine concentrations of these serum specimens, we found high concentrations of proinflammatory cytokines/chemokines, such as IFNγ, IL8, IL-12, and MIP1α, in the convalescent phase sera.

Conclusions

These results imply that both the antibody response to GP_1,2 and the proinflammatory innate responses play significant roles in the recovery from RESTV infection in cynomolgus macaques.

Can health systems be enhanced for optimal health services through disease-specific programs? Results of field studies in Viet Nam and Cambodia

Developing better health systems is the key to delivering optimal health services, although more evidence of effective strategies to do so is needed. Field surveys were conducted in Viet Nam and Cambodia to identify best practices in addressing health system bottlenecks to scale up disease control programs. The two countries were compared over time using a framework for analysis developed by the authors. In Viet Nam, a health system was in place for decades at the central to municipal levels, although it was fragile until the 1990s, when the government started taking measures. In Cambodia, the previous health system had been destroyed during previous internal conflict. In the post-conflict period, the health system was rebuilt with support for programs followed by centralization of health services. In different settings, different measures were taken to deal with similar bottlenecks. In Cambodia, vertical programs were dominant, so the government sought to centralize drug management to deal with shortages of essential drugs, while Viet Nam sought to mobilize resources to ensure drug distribution at all levels. This study shows there is no single successful approach to health systems, and a systemic approach needs to be taken because elimination of one bottleneck may reveal another. Efforts to enhance disease-specific programs may not always contribute to overall enhancement of the health system, and the best possible approach may not be the same in different countries. Further study is needed to explore common issues and principles for effective strategies to enhance health systems in different contexts.

A novel PAN/apple domain-containing protein from Toxoplasma gondii: characterization and receptor identification

Toxoplasma gondii is an intracellular parasite that invades nucleated cells, causing toxoplasmosis in humans and animals worldwide. The extremely wide range of hosts susceptible to T. gondii is thought to be the result of interactions between T. gondii ligands and receptors on its target cells. In this study, a host cell-binding protein from T. gondii was characterized, and one of its receptors was identified. P104 (GenBank Access. No. CAJ20677) is 991 amino acids in length, containing a putative 26 amino acid signal peptide and 10 PAN/apple domains, and shows low homology to other identified PAN/apple domain-containing molecules. A 104-kDa host cell-binding protein was detected in the T. gondii lysate. Immunofluorescence assays detected P104 at the apical end of extracellular T. gondii. An Fc-fusion protein of the P104 N-terminus, which contains two PAN/apple domains, showed strong affinity for the mammalian and insect cells evaluated. This binding was not related to protein-protein or protein-lipid interactions, but to a protein-glycosaminoglycan (GAG) interaction. Chondroitin sulfate (CS), a kind of GAG, was shown to be involved in adhesion of the Fc-P104 N-terminus fusion protein to host cells. These results suggest that P104, expressed at the apical end of the extracellular parasite, may function as a ligand in the attachment of T. gondii to CS or other receptors on the host cell, facilitating invasion by the parasite.

Thoracic endovascular aortic repair for aortic complications after esophagectomy for cancer: report of three cases

Aortic complications after esophageal cancer surgery are rare and usually fatal. Here, we report three patients who underwent thoracic endovascular aortic repair (TEVAR) for aortic complications after esophagectomy for cancer. In the first case, aortic rupture was caused by pyothorax due to residual tumor after esophagectomy. In the second case, aortic rupture was caused by pyothorax due to anastomotic leakage. In the third case, a pseudoaneurysm was caused by surgical injury during esophagectomy. TEVAR was safe and effective for severe aortic complications when graft infection was avoided. The first case died of sepsis on the 84th postoperative day, and the other two cases have survived 4 years and 2 years to date.

Reactivity and prevalence of neutralizing antibodies against Japanese strains of bovine viral diarrhea virus subgenotypes

Bovine viral diarrhea virus (BVDV) field isolates show genetic and antigenic diversity. At least 14 subgenotypes of BVDV-1 and 4 of BVDV-2 have been identified in Artiodactyla worldwide. Of these, 6 subgenotypes of BVDV-1 and 1 of BVDV-2 have been isolated in Japan. Previously, we reported that each subgenotype virus expresses different antigenic characteristics. Here we investigated the reactivity of neutralizing antibodies against representative strains of Japanese BVDV subgenotypes using sera from 266 beef cattle to estimate the prevalence of this epidemic virus among cattle in Japan. Antibody titers at concentrations at least 4-fold higher than antibodies against other subgenotype viruses were considered subgenotype specific. Subgenotype-specific antibodies were detected from 117 (80.7%) of 145 sera samples (69.7% against BVDV-1a, 1.4% against BVDV-1b, 8.3% against BVDV-1c, and 1.4% against BVDV-2a). The results suggest that neutralization tests are useful in estimating currently epidemic subgenotypes of BVDV in the field.

1NM-PP1 treatment of mice infected with Toxoplasma gondii

Bumped kinase inhibitors (BKIs) target analog-sensitive kinases, which the genomes of mammals rarely encode. Previously, we demonstrated that a BKI effectively suppressed the in vitro replication of Toxoplasma gondii, the causative pathogen of toxoplasmosis, by targeting T. gondii calcium-dependent protein kinase 1 (TgCDPK1) (Eukaryotic Cell, 9: 667-670). Here, we examined whether the BKI 1NM-PP1 reduced parasite replication in vivo. A high dose of 1NM-PP1, by intraperitoneal injection, just before the parasite inoculation effectively reduced the parasite load in the brains, livers, and lungs of T. gondii-infected mice, however, a low dose of 1NM-PP1 with oral administration didn't change the survival rates of infected mice.

Equine herpesvirus 4: recent advances using BAC technology

The equine herpesviruses are major infectious pathogens that threaten equine health. Equine herpesvirus 4 (EHV-4) is an important equine pathogen that causes respiratory tract disease, known as rhinopneumonitis, among horses worldwide. EHV-4 genome manipulation with subsequent understanding of the viral gene functions has always been difficult due to the limited number of susceptible cell lines and the absence of small-animal models of the infection. Efficient generation of mutants of EHV-4 would significantly contribute to the rapid and accurate characterization of the viral genes. This problem has been solved recently by the cloning of the genome of EHV-4 as a stable and infectious bacterial artificial chromosome (BAC) without any deletions of the viral genes. Very low copy BAC vectors are the mainstay of present genomic research because of the high stability of inserted clones and the possibility of mutating any gene target in a relatively short time. Manipulation of EHV-4 genome is now feasible using the power of BAC technology, and should aid greatly in assessing the role of viral genes in the virus-host interaction.

Bat coronaviruses and experimental infection of bats, the Philippines

Virus-infected fruit bats showed no signs of clinical infection.

Fifty-two bats captured during July 2008 in the Philippines were tested by reverse transcription–PCR to detect bat coronavirus (CoV) RNA. The overall prevalence of virus RNA was 55.8%. We found 2 groups of sequences that belonged to group 1 (genus Alphacoronavirus) and group 2 (genus Betacoronavirus) CoVs. Phylogenetic analysis of the RNA-dependent RNA polymerase gene showed that groups 1 and 2 CoVs were similar to Bat-CoV/China/A515/2005 (95% nt sequence identity) and Bat-CoV/HKU9–1/China/2007 (83% identity), respectively. To propagate group 2 CoVs obtained from a lesser dog-faced fruit bat (Cynopterus brachyotis), we administered intestine samples orally to Leschenault rousette bats (Rousettus leschenaulti) maintained in our laboratory. After virus replication in the bats was confirmed, an additional passage of the virus was made in Leschenault rousette bats, and bat pathogenesis was investigated. Fruit bats infected with virus did not show clinical signs of infection.

[Current situation and future preventive measures of foot-and-mouth disease in Japan]

Foot-and-mouth disease caused by Foot-and-mouth disease virus (FMDV) is a severe and acute vesicular disease of cloven-hoofed animals including cattle, pigs, sheep and goats. As FMDV is highly contagious and causes productivity losses among infected animals, outbreaks of the disease are a primary animal health concern worldwide. In April, 2010, the disease reoccurred in Miyazaki prefecture in 10 years. Compared to the outbreak in 2000 in which no infection among pigs was observed, a total of 292 infected farms have been involved in this outbreak, and infected animals (37,412 cattle, 42 water buffalos, 174,132 pigs, 14 goats, and 8 sheep) were culled and buried. Vaccination was decided to reduce the speed of virus spreading. Finally a total of 76,756 heads of vaccinated animals were also slaughtered. The outbreak has continued for 2.5 months, and the ban on animal movements have been eased 3 months after the first occurrence. As several factors for disease spreading have been rumored, I would like to note this point and discuss future preventive measures.

Non-muscle myosin IIA is a functional entry receptor for herpes simplex virus-1

Herpes simplex virus-1 (HSV-1), the prototype of the α-herpesvirus family, causes life-long infections in humans. Although generally associated with various mucocutaneous diseases, HSV-1 is also involved in lethal encephalitis. HSV-1 entry into host cells requires cellular receptors for both envelope glycoproteins B (gB) and D (gD). However, the gB receptors responsible for its broad host range in vitro and infection of critical targets in vivo remain unknown. Here we show that non-muscle myosin heavy chain IIA (NMHC-IIA), a subunit of non-muscle myosin IIA (NM-IIA), functions as an HSV-1 entry receptor by interacting with gB. A cell line that is relatively resistant to HSV-1 infection became highly susceptible to infection by this virus when NMHC-IIA was overexpressed. Antibody to NMHC-IIA blocked HSV-1 infection in naturally permissive target cells. Furthermore, knockdown of NMHC-IIA in the permissive cells inhibited HSV-1 infection as well as cell-cell fusion when gB, gD, gH and gL were coexpressed. Cell-surface expression of NMHC-IIA was markedly and rapidly induced during the initiation of HSV-1 entry. A specific inhibitor of myosin light chain kinase, which regulates NM-IIA by phosphorylation, reduced the redistribution of NMHC-IIA as well as HSV-1 infection in cell culture and in a murine model for herpes stromal keratitis. NMHC-IIA is ubiquitously expressed in various human tissues and cell types and, therefore, is implicated as a functional gB receptor that mediates broad HSV-1 infectivity both in vitro and in vivo. The identification of NMHC-IIA as an HSV-1 entry receptor and the involvement of NM-IIA regulation in HSV-1 infection provide an insight into HSV-1 entry and identify new targets for antiviral drug development.

Novel betaherpesvirus in bats

Because bats are associated with emerging zoonoses, identification and characterization of novel viruses from bats is needed. Using a modified rapid determination system for viral RNA/DNA sequences, we identified a novel bat betaherpesvirus 2 not detected by herpesvirus consensus PCR. This modified system is useful for detecting unknown viruses.

Bovine viral diarrhea virus non-structural protein 5A interacts with NIK- and IKKbeta-binding protein

Bovine viral diarrhea virus (BVDV) is a positive-sense, single-stranded RNA virus that causes an economically important livestock disease worldwide. Previous studies have suggested that non-structural protein 5A (NS5A) from hepatitis C virus (HCV) and BVDV plays a similar role during virus infection. Extensive reports are available on HCV NS5A and its interactions with the host cellular proteins; however, the role of NS5A during BVDV infection remains largely unclear. To identify the cellular proteins that interact with the N terminus of NS5A and could be involved in its function, we conducted a yeast two-hybrid screening. As a result, we identified a cellular protein termed bovine NIK- and IKKbeta-binding protein (NIBP), which is involved in protein trafficking and nuclear factor kappa B (NF-kappaB) signalling in cells. The interaction of NS5A with NIBP was confirmed both in vitro and in vivo. Complementing our glutathione S-transferase pull-down and immunoprecipitation data are the confocal immunofluorescence results, which indicate that NS5A colocalized with NIBP on the endoplasmic reticulum in the cytoplasm of BVDV-infected cells. Moreover, the minimal residues of NIBP that interact with NS5A were mapped as aa 597-623. In addition, overexpression of NS5A inhibited NF-kappaB activation in HEK293 and LB9.K cells as determined by luciferase reporter-gene assay. We further showed that inhibition of endogenous NIBP by small interfering RNA molecules enhanced virus replication, indicating the importance of NIBP implications in BVDV pathogenesis. Being the first reported interaction between NIBP and a viral protein, this finding suggests a novel mechanism whereby viruses may subvert host-cell machinery for mediating trafficking as well as NF-kappaB signalling.

Functional analysis of Rousettus aegyptiacus "signal transducer and activator of transcription 1" (STAT1)

Bats are now known as the source of several diseases in humans, but few studies regarding immune responses and factors associated with bats have so far been reported. In this study, we focused on STAT1, one of the critical components in interferon (IFN)-signaling and antiviral activity, which is often targeted by viral proteins to reduce antiviral activity and increase viral replication. We found that Rousettus aegyptiacus STAT1 (bat STAT1) is phosphorylatable and translocates to the nucleus when stimulated with human IFN-alpha (hIFN-alpha). Furthermore, phosphorylation of bat STAT1 and inhibition of nuclear translocation was observed in IFN-stimulated cells infected with the HEP-Flury strain of rabies virus, in the same manner as in other mammals. Additionally, quantitative real-time RT-PCR revealed that bat STAT1 mRNA was highly expressed in the liver, while low in muscle and spleen.

Interaction of Rhei Rhizoma extract with cytochrome P450 3A and efflux transporters in rats

Traditional Chinese herbal medicines are frequently prescribed in pharmacotherapy in Japan. In the present study, we evaluated the possible interaction of several herbal extracts including Rhei Rhizoma extract with cytochrome P450 (CYP) 3A and efflux transporters such as P-glycoprotein and multidrug resistance-associated protein (MRP) 2. Rhei Rhizoma extract (100 microg/ml) significantly suppressed the CYP3A-mediated 6beta-hydroxylation of testosterone in hepatic microsomes, and increased the extent of bioavailability of midazolam, a typical CYP3A substrate, in rats. Also, Rhei Rhizoma extract (300 microg/ml) significantly suppressed P-glycoprotein-mediated efflux transport of rhodamine 123 (Rho123) in rat everted intestine. In an in-vivo study, Rhei Rhizoma extract added to intestinal perfusate at a concentration of 300 microg/ml significantly suppressed the intestinal exsorption of Rho123, though it exerted no effect on the biliary excretion of Rho123. Furthermore, the in-vitro and in-vivo MRP2-mediated intestinal efflux of 2,4-dinitrophenyl-S-glutathione was significantly suppressed by Rhei Rhizoma extract (1000 microg/ml). In conclusion, Rhei Rhizoma extract, which is taken orally at doses of 0.5-1 g each or 1-3 g daily in clinical practice, may cause pharmacokinetic herb-drug interactions in the process of the intestinal and/or hepatic CYP3A-mediated drug metabolism and P-glycoprotein- and/or MRP2-mediated efflux transport in the intestine.

Molecular cloning and sequencing of the cDNAs encoding the bat interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12p40, and tumor necrosis factor-alpha

This is the first report on the cDNA sequences of bat interleukin (IL)-2, IL-4, IL-6, IL-10, IL-12 p40, and tumor necrosis factor (TNF)-alpha. The cDNAs of bat IL-2, IL-4, IL-6, IL-10, IL-12 p40, and TNF-alpha comprise 459, 405, 624, 537, 990, and 699 base pairs respectively. Moreover, each of the cDNAs of bat IL-2, IL-4, IL-6, IL-10, IL-12 p40, and TNF-alpha contain a single open reading frames encoding 152, 134, 207, 178, 329, and 232 amino acids, respectively. The comparison of bat cytokines with Perrissodactyla (horse), Carnivora (dog and cat), and Cetartiodactyla (cattle and pig) orthologs revealed a high degree of homology. Although the N-terminal amino acids and cysteine residues are highly conserved in each mature cytokine, the deduced N-linked glycosylation sites vary across species.

Molecular cloning and expression analysis of bat toll-like receptors 3, 7 and 9

In this study, cDNA of Toll-like receptors (TLR) 3, 7 and 9 were synthesized and completely sequenced. The coding regions of cDNA for bat TLR3, TLR7 and TLR9 were 2,718, 3,150 and 3,090 bp in length, respectively. The open reading frames encoded 905, 1,049 and 1,029 amino acids for TLR3, TLR7 and TLR9, respectively. The nucleotide sequences, predicted amino acid sequences and predicted domain structures of the three bat TLRs had high homology with those of other mammals. In addition, the expression profiles of each TLR in main organs were analyzed. Expression of TLR3 was highest in the liver, whereas the expressions of TLR7 and TLR9 were highest in the spleen.

Plasmodium falciparum BAEBL binds to heparan sulfate proteoglycans on the human erythrocyte surface

Erythrocyte invasion is critical to the pathogenesis and survival of the malarial parasite, Plasmodium falciparum. This process is partly mediated by proteins that belong to the Duffy binding-like family, which are expressed on the merozoite surface. One of these proteins, BAEBL (also known as EBA-140), is thought to bind to glycophorin C in a sialic acid-dependent manner. In this report, by the binding assay between recombinant BAEBL protein and enzyme-treated erythrocytes, we show that the binding of BAEBL to erythrocytes is mediated primarily by sialic acid and partially through heparan sulfate (HS). Because BAEBL binds to several kinds of HS proteoglycans or purified HS, the BAEBL-HS binding was found to be independent of the HS proteoglycan peptide backbone and the presence of sialic acid moieties. Furthermore, both the sialic acid- and HS-dependent binding were disrupted by the addition of soluble heparin. This inhibition may be the result of binding between BAEBL and heparin. Invasion assays demonstrated that HS-dependent binding was related to the efficiency of merozoite invasion. These results suggest that HS functions as a factor that promotes the binding of BAEBL and merozoite invasion. Moreover, these findings may explain the invasion inhibition mechanisms observed following the addition of heparin and other sulfated glycoconjugates.

[Long-term results of aortic root replacement with a composite graft]

We analyzed the long-term results of aortic root replacement with a composite graft. Since 1992, 127 patients had undergone aortic root replacement with a composite graft. There were 92 men and 35 women with a mean age of 56.5 years. There were 69 patients with annuloaortic ectasia, 17 aortic dissections, and 41 ascending aortic dilatation due to aortic valve disease. Marfan syndrome was diagnosed in 19 patients. As surgical procedure, button technique was used in 90 patients, Cabrol technique in 11, and Piehler technique in 26. Open distal anastomosis was performed in 82 patients to avoid clamp injury of rest aorta. Early mortality was 3.1% and no major morbid events had occurred. Follow-up was completed in 95.9% of the patients and the mean follow-up period was 6.1 years. Actuarial survival at 5, 10, and 15 years was 86.2%, 83.4%, and 83.4%, respectively. Actuarial freedom from aortic valve reoperation at 10 and 15 years was 99.2% and 95.7%, respectively. The results of aortic root replacement with a composite graft were excellent. This procedure should be the 1st choice for surgical treatment of the aortic root disease.