Contribution of RNA-RNA Interactions Mediated by the Genome Packaging Signals for the Selective Genome Packaging of Influenza A Virus.

The influenza A virus genome is composed of eight single-stranded negative-sense viral RNA segments (vRNAs). The eight vRNAs are selectively packaged into each progeny virion. This process likely involves specific interactions between the vRNAs via segment-specific packaging signals located in both the 3'- and 5'-terminal regions of the respective vRNAs. To assess the importance of vRNA-vRNA interactions via packaging signals for selective genome packaging, we generated mutant viruses possessing silent mutations in the packaging signal region of the hemagglutinin (HA) vRNA. A mutant virus possessing silent mutations in nucleotides (nt) 1664 to 1676 resulted in defects in HA vRNA incorporation and showed a reduction in viral growth. After serial passage, the mutant virus acquired additional mutations in the 5'-terminal packaging signal regions of both the HA and polymerase basic 2 (PB2) vRNAs. These mutations contributed to the recovery of viral growth and HA vRNA packaging efficiency. In addition, an RNA-RNA interaction between the 5' ends of HA and PB2 vRNAs was confirmed in vitro, and this interaction was disrupted following the introduction of silent mutations in the HA vRNA. Thus, our results demonstrated that RNA-RNA interactions between the packaging signal regions of HA vRNA and PB2 vRNA are important for selective genome packaging. IMPORTANCE While numerous viral genomes comprise a single genome segment, the influenza A virus possesses eight segmented genomes. Influenza A virus can benefit from having a segmented genome because the segments can reassort with other strains of the influenza virus to create new genetically distinct strains. The influenza A virus efficiently incorporates one copy of each of its eight genomic segments per viral particle. However, the mechanism by which each segment is specifically selected is poorly understood. The genome segments contain RNA signals that facilitate the incorporation of segments into virus particles. These regions may facilitate specific interactions between the genome segments, creating an eight-segment complex, which can then be packaged into individual particles. In this study, we provide evidence that RNA signals contribute to specific interactions between two of the influenza virus genome segments.

Accumulation of phosphorylated TDP-43 in the cytoplasm of Schwann cells in a case of sporadic amyotrophic lateral sclerosis.

We report for the first time the presence of phosphorylated transactivation response DNA-binding protein of 43 kDa (p-TDP-43)-immunoreactive cytoplasmic inclusions in Schwann cells in an autopsy case of sporadic amyotrophic lateral sclerosis (ALS). An 81-year-old woman with no family history of neuromuscular disorders noticed difficulty in handling chopsticks due to weakness of the hands. She then developed weakness of the lower and upper limbs and dyspnea. Neurological examination at the age of 83 years revealed disorientation, severe weakness of the facial muscles, tongue, neck and extremities, and fasciculations in the thighs. She exhibited hyperactive jaw jerk and lower limb deep tendon reflexes and normal upper limb deep tendon reflexes, and left extensor plantar response was observed. The patient was diagnosed as having sporadic ALS. An autopsy performed at the age of 84 years revealed widespread p-TDP-43-immunoreactive neuronal and glial cytoplasmic inclusions in the cerebrum, brain stem, and spinal cord, in addition to some Bunina bodies. Moreover, a small number of p-TDP-43-immunoreactive inclusions were found in the facial or accoustic nerve (indistinguishable), spinal cord anterior roots, cauda equina, and peripheral nerves in the dorsal root ganglia. Immunohistochemical staining for p-TDP-43 revealed just a few p-TDP-43-immunoreactive inclusions surrounding axons in the cervical and lumbar anterior roots. Double immunofluorescence analysis revealed that these inclusions were co-localized with S-100 protein ß, suggesting that these inclusions were localized in the cytoplasm of Schwann cells. The peripheral nervous system including Schwann cells may be involved in TDP-43 pathology in ALS.

Influenza C and D Viruses Package Eight Organized Ribonucleoprotein Complexes.

Influenza A and B viruses have eight-segmented, single-stranded, negative-sense RNA genomes, whereas influenza C and D viruses have seven-segmented genomes. Each genomic RNA segment exists in the form of a ribonucleoprotein complex (RNP) in association with nucleoproteins and an RNA-dependent RNA polymerase in virions. Influenza D virus was recently isolated from swine and cattle, but its morphology is not fully studied. Here, we examined the morphological characteristics of D/bovine/Yamagata/10710/2016 (D/Yamagata) and C/Ann Arbor/50 (C/AA), focusing on RNPs packaged within the virions. By scanning transmission electron microscopic tomography, we found that more than 70% of D/Yamagata and C/AA virions packaged eight RNPs arranged in the "1+7" pattern as observed in influenza A and B viruses, even though type C and D virus genomes are segmented into only seven segments. These results imply that influenza viruses generally package eight RNPs arranged in the "1+7" pattern regardless of the number of RNA segments in their genome.IMPORTANCE The genomes of influenza A and B viruses are segmented into eight segments of negative-sense RNA, and those of influenza C and D viruses are segmented into seven segments. For progeny virions to be infectious, each virion needs to package all of their genomic segments. Several studies support the conclusion that influenza A and B viruses selectively package eight distinct genomic RNA segments; however, the packaging of influenza C and D viruses, which possess seven segmented genomes, is less understood. By using electron microscopy, we showed that influenza C and D viruses package eight RNA segments just as influenza A and B viruses do. These results suggest that influenza viruses prefer to package eight RNA segments within virions independent of the number of genome segments.

Generation of a purely clonal defective interfering influenza virus.

Defective interfering (DI) influenza viruses carry a large deletion in a gene segment that interferes with the replication of infectious virus; thus, such viruses have potential for antiviral therapy. However, because DI viruses cannot replicate autonomously without the aid of an infectious helper virus, clonal DI virus stocks that are not contaminated with helper virus have not yet been generated. To overcome this problem, we used reverse genetics to generate a clonal DI virus with a PB2 DI gene, amplified the clonal DI virus using a cell line stably expressing the PB2 protein, and confirmed its ability to interfere with infectious virus replication in vitro. Thus, our approach is suitable for obtaining purely clonal DI viruses, will contribute to the understanding of DI virus interference mechanisms and can be used to develop DI virus-based antivirals.

Establishment of a human hepatocellular cell line capable of maintaining long-term replication of hepatitis B virus.

Hepatitis B virus (HBV) is a virus whose replication cycle cannot be completely reproduced using cultured cell lines. Here, we report an engineered cell line capable of supporting the complete HBV life cycle. We generated HepG2 cells over-expressing the HBV entry receptor human NTCP (sodium taurocholate cotransporting polypeptide), and defective in RIG-I (retinoic acid-inducible gene-I)-like receptor signaling, by knocking down the IPS-1 (IFNß-promoter stimulator-1) adaptor molecule. The resultant NtG20.i7 cells were susceptible to HBV, and its replication was detectable at 14 days post-infection and persisted for at least 35 days with a gradual increase of HBV core expression. The cells produced infectious HBV in the culture supernatant, and the addition of preS1 peptide myr47-WT, which blocks HBV entry, impaired the persistence of the infection. These findings suggest that the persistence of the infection was maintained by continuous release of infectious HBV virions and their re-infection. This system is useful for expanding our basic understanding of the HBV replication cycle and for screening of anti-HBV chemicals.

Multiple Roles of the Cytoplasmic Domain of Herpes Simplex Virus 1 Envelope Glycoprotein D in Infected Cells.

Herpes simplex virus 1 (HSV-1) envelope glycoprotein D (gD) plays an essential role in viral entry. The functional regions of gD responsible for viral entry have been mapped to its extracellular domain, whereas the gD cytoplasmic domain plays no obvious role in viral entry. Thus far, the role(s) of the gD cytoplasmic domain in HSV-1 replication has remained to be elucidated. In this study, we show that ectopic expression of gD induces microvillus-like tubular structures at the plasma membrane which resemble the reported projection structures of the plasma membrane induced in HSV-1-infected cells. Mutations in the arginine cluster (residues 365 to 367) in the gD cytoplasmic domain greatly reduced gD-induced plasma membrane remodeling. In agreement with this, the mutations in the arginine cluster in the gD cytoplasmic domain reduced the number of microvillus-like tubular structures at the plasma membrane in HSV-1-infected cells. In addition, the mutations produced an accumulation of unenveloped nucleocapsids in the cytoplasm and reduced viral replication and cell-cell spread. These results suggest that the arginine cluster in the gD cytoplasmic domain is required for the efficient induction of plasma membrane projections and viral final envelopment, and these functions of the gD domain may lead to efficient viral replication and cell-cell spread. IMPORTANCE: The cytoplasmic domain of HSV-1 gD, an envelope glycoprotein essential for viral entry, was reported to promote viral replication and cell-cell spread, but the role(s) of the domain during HSV-1 infection has remained unknown. In this study, we clarify two functions of the arginine cluster in the HSV-1 gD cytoplasmic domain, both of which require host cell membrane remodeling, i.e., the formation of microvillus-like projections at the plasma membrane and viral final envelopment in HSV-1-infected cells. We also show that the gD arginine cluster is required for efficient HSV-1 replication and cell-cell spread. This is the first report clarifying not only the functions of the gD cytoplasmic domain but also identifying the gD arginine cluster to be the HSV-1 factor responsible for the induction of plasma membrane projections in HSV-1-infected cells. Our results elucidate some of the functions of this multifunctional envelope glycoprotein during HSV-1 infection.

Characterization of a Herpes Simplex Virus 1 (HSV-1) Chimera in Which the Us3 Protein Kinase Gene Is Replaced with the HSV-2 Us3 Gene.

UNLABELLED: Us3 protein kinases encoded by herpes simplex virus 1 (HSV-1) and 2 (HSV-2) play important roles in viral replication and pathogenicity. To investigate type-specific differences between HSV-1 Us3 and HSV-2 Us3 in cells infected by viruses with all the same viral gene products except for their Us3 kinases, we constructed and characterized a recombinant HSV-1 in which its Us3 gene was replaced with the HSV-2 Us3 gene. Replacement of HSV-1 Us3 with HSV-2 Us3 had no apparent effect on viral growth in cell cultures or on the range of proteins phosphorylated by Us3. HSV-2 Us3 efficiently compensated for HSV-1 Us3 functions, including blocking apoptosis, controlling infected cell morphology, and downregulating cell surface expression of viral envelope glycoprotein B. In contrast, replacement of HSV-1 Us3 by HSV-2 Us3 changed the phosphorylation status of UL31 and UL34, which are critical viral regulators of nuclear egress. It also caused aberrant localization of these viral proteins and aberrant accumulation of primary enveloped virions in membranous vesicle structures adjacent to the nuclear membrane, and it reduced viral cell-cell spread in cell cultures and pathogenesis in mice. These results clearly demonstrated biological differences between HSV-1 Us3 and HSV-2 Us3, especially in regulation of viral nuclear egress and phosphorylation of viral regulators critical for this process. Our study also suggested that the regulatory role(s) of HSV-1 Us3, which was not carried out by HSV-2 Us3, was important for HSV-1 cell-cell spread and pathogenesis in vivo. IMPORTANCE: A previous study comparing the phenotypes of HSV-1 and HSV-2 suggested that the HSV-2 Us3 kinase lacked some of the functions of HSV-1 Us3 kinase. The difference between HSV-1 and HSV-2 Us3 kinases appeared to be due to the fact that some Us3 phosphorylation sites in HSV-1 proteins are not conserved in the corresponding HSV-2 proteins. Therefore, we generated recombinant HSV-1 strains YK781 (Us3-chimera) with HSV-2 Us3 and its repaired virus YK783 (Us3-repair) with HSV-1 Us3, to compare the activities of HSV-1 Us3 and HSV-2 Us3 in cells infected by viruses with the same HSV-1 gene products except for their Us3 kinases. We report here that some processes in viral nuclear egress and pathogenesis in vivo that have been attributed to HSV-1 Us3 could not be carried out by HSV-2 Us3. Therefore, our study clarified the biological differences between HSV-1 Us3 and HSV-2 Us3, which may be relevant to viral pathogenesis in vivo.

Herpes Simplex Virus 1 Recruits CD98 Heavy Chain and ß1 Integrin to the Nuclear Membrane for Viral De-Envelopment.

UNLABELLED: Herpesviruses have evolved a unique mechanism for nucleocytoplasmic transport of nascent nucleocapsids: the nucleocapsids bud through the inner nuclear membrane (INM; primary envelopment), and the enveloped nucleocapsids then fuse with the outer nuclear membrane (de-envelopment). Little is known about the molecular mechanism of herpesviral de-envelopment. We show here that the knockdown of both CD98 heavy chain (CD98hc) and its binding partner ß1 integrin induced membranous structures containing enveloped herpes simplex virus 1 (HSV-1) virions that are invaginations of the INM into the nucleoplasm and induced aberrant accumulation of enveloped virions in the perinuclear space and in the invagination structures. These effects were similar to those of the previously reported mutation(s) in HSV-1 proteins gB, gH, UL31, and/or Us3, which were shown here to form a complex(es) with CD98hc in HSV-1-infected cells. These results suggested that cellular proteins CD98hc and ß1 integrin synergistically or independently regulated HSV-1 de-envelopment, probably by interacting directly and/or indirectly with these HSV-1 proteins. IMPORTANCE: Certain cellular and viral macromolecular complexes, such as Drosophila large ribonucleoprotein complexes and herpesvirus nucleocapsids, utilize a unique vesicle-mediated nucleocytoplasmic transport: the complexes acquire primary envelopes by budding through the inner nuclear membrane into the space between the inner and outer nuclear membranes (primary envelopment), and the enveloped complexes then fuse with the outer nuclear membrane to release de-enveloped complexes into the cytoplasm (de-envelopment). However, there is a lack of information on the molecular mechanism of de-envelopment fusion. We report here that HSV-1 recruited cellular fusion regulatory proteins CD98hc and ß1 integrin to the nuclear membrane for viral de-envelopment fusion. This is the first report of cellular proteins required for efficient de-envelopment of macromolecular complexes during their nuclear egress.

Phosphorylation of a herpes simplex virus 1 dUTPase by a viral protein kinase, Us3, dictates viral pathogenicity in the central nervous system but not at the periphery.

UNLABELLED: Herpes simplex virus 1 (HSV-1) encodes Us3 protein kinase, which is critical for viral pathogenicity in both mouse peripheral sites (e.g., eyes and vaginas) and in the central nervous systems (CNS) of mice after intracranial and peripheral inoculations, respectively. Whereas some Us3 substrates involved in Us3 pathogenicity in peripheral sites have been reported, those involved in Us3 pathogenicity in the CNS remain to be identified. We recently reported that Us3 phosphorylated HSV-1 dUTPase (vdUTPase) at serine 187 (Ser-187) in infected cells, and this phosphorylation promoted viral replication by regulating optimal enzymatic activity of vdUTPase. In the present study, we show that the replacement of vdUTPase Ser-187 by alanine (S187A) significantly reduced viral replication and virulence in the CNS of mice following intracranial inoculation and that the phosphomimetic substitution at vdUTPase Ser-187 in part restored the wild-type viral replication and virulence. Interestingly, the S187A mutation in vdUTPase had no effect on viral replication and pathogenic effects in the eyes and vaginas of mice after ocular and vaginal inoculation, respectively. Similarly, the enzyme-dead mutation in vdUTPase significantly reduced viral replication and virulence in the CNS of mice after intracranial inoculation, whereas the mutation had no effect on viral replication and pathogenic effects in the eyes and vaginas of mice after ocular and vaginal inoculation, respectively. These observations suggested that vdUTPase was one of the Us3 substrates responsible for Us3 pathogenicity in the CNS and that the CNS-specific virulence of HSV-1 involved strict regulation of vdUTPase activity by Us3 phosphorylation. IMPORTANCE: Herpes simplex virus 1 (HSV-1) encodes a viral protein kinase Us3 which is critical for pathogenicity both in peripheral sites and in the central nervous systems (CNS) of mice following peripheral and intracranial inoculations, respectively. Whereas some Us3 substrates involved in Us3 pathogenicity in peripheral sites have been reported, those involved in Us3 pathogenicity in the CNS remain to be identified. Here, we report that Us3 phosphorylation of viral dUTPase (vdUTPase) at serine 187 (Ser-187), which has been shown to promote the vdUTPase activity, appears to be critical for viral virulence in the CNS but not for pathogenic effects in peripheral sites. Since HSV proteins critical for viral virulence in the CNS are, in almost all cases, also involved in viral pathogenicity at peripheral sites, this phosphorylation event is a unique report of a specific mechanism involved in HSV-1 virulence in the CNS.

Herpes simplex virus 1 UL47 interacts with viral nuclear egress factors UL31, UL34, and Us3 and regulates viral nuclear egress.

UNLABELLED: Herpesviruses have evolved a unique mechanism for nuclear egress of nascent progeny nucleocapsids: the nucleocapsids bud through the inner nuclear membrane into the perinuclear space between the inner and outer nuclear membranes (primary envelopment), and enveloped nucleocapsids then fuse with the outer nuclear membrane to release nucleocapsids into the cytoplasm (de-envelopment). We have shown that the herpes simplex virus 1 (HSV-1) major virion structural protein UL47 (or VP13/VP14) is a novel regulator for HSV-1 nuclear egress. In particular, we demonstrated the following: (i) UL47 formed a complex(es) with HSV-1 proteins UL34, UL31, and/or Us3, which have all been reported to be critical for viral nuclear egress, and these viral proteins colocalized at the nuclear membrane in HSV-1-infected cells; (ii) the UL47-null mutation considerably reduced primary enveloped virions in the perinuclear space although capsids accumulated in the nucleus; and (iii) UL47 was detected in primary enveloped virions in the perinuclear space by immunoelectron microscopy. These results suggested that UL47 promoted HSV-1 primary envelopment, probably by interacting with the critical HSV-1 regulators for viral nuclear egress and by modulating their functions. IMPORTANCE: Like other herpesviruses, herpes simplex virus 1 (HSV-1) has evolved a vesicle-mediated nucleocytoplasmic transport mechanism for nuclear egress of nascent progeny nucleocapsids. Although previous reports identified and characterized several HSV-1 and cellular proteins involved in viral nuclear egress, complete details of HSV-1 nuclear egress remain to be elucidated. In this study, we have presented data suggesting (i) that the major HSV-1 virion structural protein UL47 (or VP13/VP14) formed a complex with known viral regulatory proteins critical for viral nuclear egress and (ii) that UL47 played a regulatory role in HSV-1 primary envelopment. Thus, we identified UL47 as a novel regulator for HSV-1 nuclear egress.

Role of herpes simplex virus 1 immediate early protein ICP22 in viral nuclear egress.

UNLABELLED: In order to investigate the novel function(s) of the herpes simplex virus 1 (HSV-1) immediate early protein ICP22, we screened for ICP22-binding proteins in HSV-1-infected cells. Our results were as follows. (i) Tandem affinity purification of ICP22 from infected cells, coupled with mass spectrometry-based proteomics and subsequent analyses, demonstrates that ICP22 forms a complex(es) with the HSV-1 proteins UL31, UL34, UL47 (or VP13/14), and/or Us3. All these proteins were previously reported to be important for viral egress through the nuclear membrane. (ii) ICP22 colocalizes with UL31 and UL34 at the nuclear membrane in wild-type HSV-1-infected cells. (iii) The UL31-null mutation prevents the targeting of ICP22 to the nuclear membrane. (iv) The ICP22-null mutation resulted in UL31 and UL34 being mislocalized in the endoplasmic reticulum (in addition to the nuclear membrane) and significantly reduced numbers of primary enveloped virions in the perinuclear space, although capsids accumulated in the nuclei. Collectively, these results suggest that (i) ICP22 interacts with HSV-1 regulators of nuclear egress, including UL31, UL34, UL47, and Us3 in HSV-1-infected cells; (ii) UL31 mediates the recruitment and anchorage of ICP22 at the nuclear membrane; and (iii) ICP22 plays a regulatory role in HSV-1 primary envelopment, probably by interacting with and regulating UL31 and UL34. Here we report a previously unknown function for ICP22 in the regulation of HSV-1 nuclear egress. IMPORTANCE: The herpes simplex virus 1 (HSV-1) immediate early protein ICP22 is recognized primarily as a regulator of viral gene expression. In this study, we show that ICP22 interacts with the HSV-1 proteins UL31 and UL34, which play crucial roles at the nuclear membrane in HSV-1 primary envelopment during viral nuclear egress. We also demonstrate that UL31 is required for the targeting of ICP22 to the nuclear membrane and that ICP22 is required for the correct localization of UL31 and/or UL34. Furthermore, we confirm that ICP22 is required for efficient HSV-1 primary envelopment during viral nuclear egress. Thus, we report, for the first time, that ICP22 plays a regulatory role in HSV-1 nuclear egress.

Deterioration after Liver Transplantation and Transthyretin Stabilizer Administration in a Patient with ATTRv Amyloidosis with a Leu58Arg (p.Leu78Arg) TTR Variant.

We herein report a 44-year-old Japanese man with hereditary transthyretin amyloidosis (ATTRv amyloidosis) harboring the variant Leu58Arg (p.Leu78Arg) in TTR in whom we conducted an observational study with liver transplantation (LT) and transthyretin (TTR) stabilizers (tafamidis and diflunisal) for 9 years. This patient showed gradual deterioration of sensory, motor, and autonomic neuropathy symptoms after LT. Furthermore, cardiac amyloidosis gradually developed. Although the present case showed deterioration of the symptoms after disease-modifying treatments, LT might be suitable in patients with the same variant if they are young and in good condition due to a long survival after LT.

A novel mutation in the GBA2 gene in a Japanese patient with SPG46: A case report.

Hereditary spastic paraplegia (HSP) is a neurodegenerative disorder characterized by pyramidal weakness and spasticity of the lower limbs. SPG46, one of autosomal recessive HSP, is clinically characterized by spasticity and pyramidal weakness of the lower limbs, mental retardation, congenital bilateral cataract, thin corpus callosum, and hypogonadism in males. Mutations in the nonlysosomal glucosylceramidase ß2 (GBA2) gene have been identified in patients with SPG46. A Japanese woman was identified with bilateral cataracts when she was in an elementary school. She felt falling easily, speaking unclearness, and difficulty in walking and raising her left leg in her 30s. Her neurological examination at the age of 44 revealed dysarthria, spasticity in the upper and lower extremities, increased jaw jerk and tendon reflexes in the extremities, bilateral extensor plantar reflexes, ataxia, and pollakiuria. Magnetic resonance imaging showed thinning of the corpus callosum body as well as atrophy in the pons and cerebellum. A novel homozygous c.1838A > G (p.D613G) missense mutation was detected at exon 12 in GBA2. We diagnosed her illness as an autosomal-recessive form of hereditary SPG46. The clinical features matched previously reported phenotype of SPG46. This is the first report of a Japanese patient with SPG46 with a novel mutation in GBA2. We presume that the novel GBA2 missense mutation found in our patient would cause loss of GBA2 activity, resulting in the neurological manifestations of SPG46.

[Differences in neuronal toxicity and its molecular mechanisms between methamphetamine and methylphenidate].

Methylphenidate (MPH) is commonly used in the treatment of narcolepsy and attention deficit/hyperactivity disorder (AD/HD) in Japan. MPH has been also known to have psychostimulus effects similar to methamphetamine (METH). In the present study, we compared several effects of MPH to METH. It is well-known that the repeated administration of psychostimulant drugs induces behavioral sensitization. However, MPH failed to induce sensitization to hyperlocomotion, while METH clearly induced behavioral sensitization. Moreover, the METH-induced rewarding effect was maintained even 2 weeks after withdrawal of METH. In contrast, the MPH-induced rewarding effect almost disappeared within 2 weeks after withdrawal of MPH. We next investigated the effect of METH and MPH on astrocytes, which have been known to play an important role in neuronal network systems. Both METH and MPH induced astrocytic activation in limbic neuron/glia cocultures. It is of interest to note that the METH-induced astrocytic activation was still present after an additional 2 days of culture with normal medium. Unlike METH, the MPH-induced astrocytic activation was reversed within 2 days after washout of MPH. Furthermore, high concentration of METH, but not MPH, reduced MAP2a/b positive cells and activated the immunoreactivity of the cleaved caspase-3 in primary cultured limbic neurons, whereas MPH had no such effect. Taken together, the present findings suggest that the psychostimulus effects of METH and MPH occur through different mechanisms.

Changes in the rewarding effects induced by tramadol and its active metabolite M1 after sciatic nerve injury in mice.

INTRODUCTION: The present study was designed to investigate the rewarding effects induced by tramadol and its active metabolite O-desmethyltramadol (M1) under a neuropathic pain-like state. RESULTS: In opioid receptor binding and G protein activation, we confirmed that M1, but not tramadol, showed mu-opioid receptor (MOR) agonistic activity. Furthermore, we found that the subcutaneous (s.c.) injection of tramadol and M1 each produced a significant place preference in mice, and these effects were significantly suppressed by pretreatment with the MOR antagonist beta-funaltrexamine. The dopamine level in the mouse nucleus accumbens was significantly increased by s.c. injection of either tramadol or M1. Mice with sciatic nerve ligation exhibited a marked decrease in the latency of paw withdrawal in response to a thermal stimulus only on the ipsilateral side. Under these neuropathic pain-like conditions, the rewarding effect induced by s.c. injection of either tramadol or M1 was dramatically inhibited after sciatic nerve ligation. Furthermore, the M1-induced G protein activation in the lower midbrain area was suppressed after sciatic nerve ligation. DISCUSSION: Our present data support the notion that the rewarding effect induced by tramadol is mediated mainly through metabolism to its active metabolite M1 via MOR. Furthermore, the suppression of the M1-induced G protein activation in the lower midbrain area caused by sciatic nerve ligation may be responsible for inhibiting the rewarding effects induced by s.c. injection of tramadol and M1 under a neuropathic pain-like state.

Importance of the 1+7 configuration of ribonucleoprotein complexes for influenza A virus genome packaging.

The influenza A virus genome is composed of eight single-stranded negative-sense RNAs. Eight distinct viral RNA segments (vRNAs) are selectively packaged into progeny virions, with eight vRNAs in ribonucleoprotein complexes (RNPs) arranged in a specific "1+7" pattern, that is, one central RNP surrounded by seven RNPs. Here we report the genome packaging of an artificially generated seven-segment virus that lacks the hemagglutinin (HA) vRNA. Electron microscopy shows that, even in the presence of only seven vRNAs, the virions efficiently package eight RNPs arranged in the same "1+7" pattern as wild-type virions. Next-generation sequencing reveals that the virions specifically incorporate host-derived 18S and 28S ribosomal RNAs (rRNAs) seemingly as the eighth RNP in place of the HA vRNA. These findings highlight the importance of the assembly of eight RNPs into a specific "1+7" configuration for genome packaging in progeny virions and suggest a potential role for cellular RNAs in viral genome packaging.

Lack of development of behavioral sensitization to methylphenidate in mice: correlation with reversible astrocytic activation.

Methamphetamine is a powerfully addictive psychostimulant that dramatically affects the mammalian central nervous system. Methylphenidate has been shown to have psychostimulus effects similar to methamphetamine. In the present study, we compared several effects of methylphenidate to those of methamphetamine. The subcutaneous administration of either methamphetamine or methylphenidate increased extracellular dopamine levels in the nucleus accumbens of mice. Interestingly, methamphetamine, but not methylphenidate, also increased the extracellular serotonin levels in this area. Further, repeated treatment with methamphetamine induced the development of sensitization to hyperlocomotion, whereas methylphenidate failed to induce behavioral sensitization. Moreover, in vitro treatment with methamphetamine, but not methylphenidate, caused long-lasting astrocytic activation in limbic neuron/glia co-cultures. These findings suggest that, unlike methamphetamine, methylphenidate shows a lack of development of behavioral sensitization to its hyperlocomotion and induces reversible astrocytic activation.

Broad-spectrum antiviral agents: secreted phospholipase A2 targets viral envelope lipid bilayers derived from the endoplasmic reticulum membrane.

Hepatitis C virus (HCV), dengue virus (DENV) and Japanese encephalitis virus (JEV) belong to the family Flaviviridae. Their viral particles have the envelope composed of viral proteins and a lipid bilayer acquired from budding through the endoplasmic reticulum (ER). The phospholipid content of the ER membrane differs from that of the plasma membrane (PM). The phospholipase A2 (PLA2) superfamily consists of a large number of members that specifically catalyse the hydrolysis of phospholipids at a particular position. Here we show that the CM-II isoform of secreted PLA2 obtained from Naja mossambica mossambica snake venom (CM-II-sPLA2) possesses potent virucidal (neutralising) activity against HCV, DENV and JEV, with 50% inhibitory concentrations (IC50) of 0.036, 0.31 and 1.34 ng/ml, respectively. In contrast, the IC50 values of CM-II-sPLA2 against viruses that bud through the PM (Sindbis virus, influenza virus and Sendai virus) or trans-Golgi network (TGN) (herpes simplex virus) were >10,000 ng/ml. Moreover, the 50% cytotoxic (CC50) and haemolytic (HC50) concentrations of CM-II-sPLA2 were >10,000 ng/ml, implying that CM-II-sPLA2 did not significantly damage the PM. These results suggest that CM-II-sPLA2 and its derivatives are good candidates for the development of broad-spectrum antiviral drugs that target viral envelope lipid bilayers derived from the ER membrane.

Herpes simplex virus-1 evasion of CD8+ T cell accumulation contributes to viral encephalitis.

Herpes simplex virus-1 (HSV-1) is the most common cause of sporadic viral encephalitis, which can be lethal or result in severe neurological defects even with antiviral therapy. While HSV-1 causes encephalitis in spite of HSV-1-specific humoral and cellular immunity, the mechanism by which HSV-1 evades the immune system in the central nervous system (CNS) remains unknown. Here we describe a strategy by which HSV-1 avoids immune targeting in the CNS. The HSV-1 UL13 kinase promotes evasion of HSV-1-specific CD8+ T cell accumulation in infection sites by downregulating expression of the CD8+ T cell attractant chemokine CXCL9 in the CNS of infected mice, leading to increased HSV-1 mortality due to encephalitis. Direct injection of CXCL9 into the CNS infection site enhanced HSV-1-specific CD8+ T cell accumulation, leading to marked improvements in the survival of infected mice. This previously uncharacterized strategy for HSV-1 evasion of CD8+ T cell accumulation in the CNS has important implications for understanding the pathogenesis and clinical treatment of HSV-1 encephalitis.