Selective internalization of sodium channels in rat dorsal root ganglion neurons infected with herpes simplex virus-1

The neurotropic virus, herpes simplex type 1 (HSV-1), inhibits the excitability of peripheral mammalian neurons, but the molecular mechanism of this effect has not been identified. Here, we use voltage-clamp measurement of ionic currents and an antibody against sodium channels to show that loss of excitability results from the selective, precipitous, and complete internalization of voltage-activated sodium channel proteins from the plasma membrane of neurons dissociated from rat dorsal root ganglion. The internalization process requires viral protein synthesis but not viral encapsulation, and does not alter the density of voltage-activated calcium or potassium channels. However, internalization is blocked completely when viruses lack the neurovirulence factor, infected cell protein 34.5, or when endocytosis is inhibited with bafilomycin A(1) or chloroquine. Although it has been recognized for many years that viruses cause cell pathology by interfering with signal transduction pathways, this is the first example of viral pathology resulting from selective internalization of an integral membrane protein. In studying the HSV-induced redistribution of sodium channels, we have uncovered a previously unknown pathway for the rapid and dynamic control of excitability in sensory neurons by internalization of sodium channels.     

Proteins associated with mRNA in cells infected with herpes simplex virus

The structure of messenger ribonucleoprotein (mRNP) complexes in herpes simplex virus type 1 (HSV-1) infected cells was analyzed by examining the proteins that could be crosslinked to polyadenylated mRNAs by irradiation of intact cells with ultraviolet light. The profiles of crosslinked proteins were qualitatively similar for mRNPs from mock infected and infected cells. However, infection with wild type HSV-1 caused a decrease in the abundance of a major 52 kda protein and an increase in a 49 kda protein. These changes were observed at early times after infection. They occurred following infection with wild type HSV-1 under conditions that blocked viral gene expression, but not following infection with the virion host shutoff mutant vhs 1.     

Role of NK cells in protection of mice against herpes simplex virus-1 infection

Natural killer (NK) cells have been implicated in the recognition and killing of a variety of virus infected target cells in vitro, yet their role in vivo remains uncertain. In these experiments, the role of NK cells in the regulation of resistance to herpes simplex virus-1 (HSV-1) was studied. Adult C57BL/6 mice are resistant to HSV-1 (HFEM strain), but are rendered highly susceptible by treatment with cyclophosphamide 24 hr prior to infection. In this model, passive transfer of 10(8) normal spleen cells or 10(7) poly I:C-treated spleen cells provided protection for 72% of the recipients. Spleen cells from NK cell-deficient beige mice similarly treated failed to engender passive protection. The phenotype of the cells responsible for transferring protection was NK1.1+, and asialo GM1+. Transfer of NK cells resulted in marked reduction of HSV titers in the livers and brains of recipients. These experiments provide direct evidence for a role for NK cells in protection against development of fatal HSV infection in mice.     

Corneal latency and transmission of herpes simplex virus-1

The transmission of herpes simplex virus (HSV)-1 by corneal transplantation has rarely been reported. It is believed that these cases have resulted either from reactivated virus traveling from the trigeminal ganglion to the cornea or from latent HSV-1 in the donor cornea itself. Studies of long-term viral presence in corneal tissue have sought to determine whether there is evidence of true non-neuronal latency, although there are problems in its definition. Recent studies provide new insights into neuronal latency, while similar HSV-1 gene regulation in the cornea may implicate corneal latency in pathophysiology and as a potential risk for transplant recipients. This issue has led to concerns over eye banking, which currently screens for other infectious agents but not HSV-1. Here we review the literature regarding corneal latency and the transmission of HSV-1.     

Divergent effects of human cytomegalovirus and herpes simplex virus-1 on cellular metabolism

Viruses rely on the metabolic network of the host cell to provide energy and macromolecular precursors to fuel viral replication. Here we used mass spectrometry to examine the impact of two related herpesviruses, human cytomegalovirus (HCMV) and herpes simplex virus type-1 (HSV-1), on the metabolism of fibroblast and epithelial host cells. Each virus triggered strong metabolic changes that were conserved across different host cell types. The metabolic effects of the two viruses were, however, largely distinct. HCMV but not HSV-1 increased glycolytic flux. HCMV profoundly increased TCA compound levels and flow of two carbon units required for TCA cycle turning and fatty acid synthesis. HSV-1 increased anapleurotic influx to the TCA cycle through pyruvate carboxylase, feeding pyrimidine biosynthesis. Thus, these two related herpesviruses drive diverse host cells to execute distinct, virus-specific metabolic programs. Current drugs target nucleotide metabolism for treatment of both viruses. Although our results confirm that this is a robust target for HSV-1, therapeutic interventions at other points in metabolism might prove more effective for treatment of HCMV.     

CD154 signaling regulates the Th1 response to herpes simplex virus-1 and inflammation in infected corneas

Approximately 7 days after HSV-1 corneal infection, BALB/c mice develop tissue-destructive inflammation in the cornea termed herpes stromal keratitis (HSK), as well as periocular skin lesions that are characterized by vesicles, edema, and fur loss. CD4(+) T cells and Th1 cytokines contribute to both the immunopathology in the cornea and the eradication of viral replication in the skin. We demonstrate that disruption of CD40/CD154 signaling does not impact the initial expansion of CD4(+) T cells in the draining lymph nodes, but dramatically reduces the persistence and Th1 polarization of these cells. Despite the reduced Th1 response, CD154(-/-) mice developed HSK and periocular skin disease with similar kinetics and severity (as assessed by clinical examination) as wild-type (WT) mice. However, when the composition of the inflammatory infiltrate was examined by flow cytometric analysis, CD154(-/-) mice exhibited significantly fewer CD4(+) and CD8(+) T cells and neutrophils than WT mice at the peak of HSK. Moreover, CD4(+) T cells from infected corneas of CD154(-/-) mice produced significantly less IFN-gamma than those of WT mice when stimulated with viral Ags in vitro. The IFN-gamma production of cells from infected corneas of WT mice was not affected by addition of anti-CD154 mAb to the stimulation cultures. This suggests that CD154 signaling is required at the inductive phase, but not at the effector phase, of the Th1 response within the infected cornea. We conclude that local disruption of CD40/CD154 signaling is not likely to be a useful therapy for HSK.     

Dielectrophoretic manipulation and characterization of herpes simplex virus-1 capsids

The dielectrophoretic behaviour of the capsids of herpes simplex virus type-1 has been measured over a range of conductivities of KCl solutions, with and without the addition of mannitol. The dielectrophoretic response of the capsids was recorded by measuring the frequency corresponding to zero dielectrophoretic force. The data were analysed using a multi-shelled model, and the permittivity and conductivity of the particles estimated. The capsid was modelled as a porous protein shell through which suspending medium passes, an inner chamber containing suspending medium in equilibrium with the outside, and a central core of protein (the scaffold). Capsids suspended in KCl without mannitol exhibited a different behaviour to those suspended in KCl with mannitol.     

PILRalpha is a herpes simplex virus-1 entry coreceptor that associates with glycoprotein B

Glycoprotein B (gB) is one of the essential components for infection by herpes simplex virus-1 (HSV-1). Although several cellular receptors that associate with glycoprotein D (gD), such as herpes virus entry mediator (HVEM) and Nectin-1, have been identified, specific molecules that mediate HSV-1 infection by associating with gB have not been elucidated. Here, we found that paired immunoglobulin-like type 2 receptor (PILR) alpha associates with gB, and cells transduced with PILRalpha become susceptible to HSV-1 infection. Furthermore, HSV-1 infection of human primary cells expressing both HVEM and PILRalpha was blocked by either anti-PILRalpha or anti-HVEM antibody. Our results demonstrate that cellular receptors for both gB and gD are required for HSV-1 infection and that PILRalpha plays an important role in HSV-1 infection as a coreceptor that associates with gB. These findings uncover a crucial aspect of the mechanism underlying HSV-1 infection.     

Efficacy of recombinant herpes simplex virus 1 glycoprotein D candidate vaccines in mice

To compare the immunogenity of the herpes simplex virus 1 (HSV-1/HHV-1) recombinant glycoprotein D (gD1), as a potential protective vaccine, Balb/c mice were immunized with either gD1/313 (the ectodomain of the gD1 fusion protein consisting of 313 amino acid residues), or the plasmid pcDNA3.1-gD (coding for a full length gD1 protein, FLgD1). A live attenuated HSV-1 (deleted in the gE gene), and a HSV-1 (strain HSZP)-infected cell extract served as positive controls, and three non-structural recombinant HSV-1 fusion proteins (ICP27, UL9/OBP and thymidine kinase--TK) were used as presumed non-protective (negative) controls. Protection tests showed that the LD50 value of the challenging infectious virus increased 90-fold in mice immunized with ICP27, but remained unchanged in other control mice immunized with TK and OBP polypeptides. A significant protection (the LD50 value of challenging virus increased 800-fold) was noted following immunization with gD1/313, while immunization with the gE-del virus and/or the gD1 DNA vaccine resulted in a more than 4,000-fold increase of the challenging virus dose killing 50% of the animals. Using ELISA, elevated antibody titers were detected following immunizations with gD1/313, gE-del virus, and/or HSV-1-infected-cell extract. In addition, all of the three non-structural proteins elicited a good humoral response (with titres ranging from 1:16,000 to 1:128,000). The lowest IgG response (1:8,000) was noted after immunization with the gD1 DNA vaccine. Peripheral blood leukocytes (PBLs) as well as splenocytes from mice immunized with gD1/313, gE-del virus, and gD1-plasmid responded in lymphocyte transformation test (LTT) to the presence of purified gD1/313 antigen. For PBLs, the most significant stimulation of thymidine incorporation was registered at a gD1/313 concentration of 5 microg/100 microl, while the splenocytes from DNA vaccine-immunized mice responded already at a concentration of 1 microg/100 microl.     

The three-component helicase/primase complex of herpes simplex virus-1

Herpes simplex virus type 1 (HSV-1) is one of the nine herpesviruses that infect humans. HSV-1 encodes seven proteins to replicate its genome in the hijacked human cell. Among these are the herpes virus DNA helicase and primase that are essential components of its replication machinery. In the HSV-1 replisome, the helicase–primase complex is composed of three components including UL5 (helicase), UL52 (primase) and UL8 (non-catalytic subunit). UL5 and UL52 subunits are functionally interdependent, and the UL8 component is required for the coordination of UL5 and UL52 activities proceeding in opposite directions with respect to the viral replication fork. Anti-viral compounds currently under development target the functions of UL5 and UL52. Here, we review the structural and functional properties of the UL5/UL8/UL52 complex and highlight the gaps in knowledge to be filled to facilitate molecular characterization of the structure and function of the helicase–primase complex for development of alternative anti-viral treatments.     

Gene therapy for mice sarcoma with oncolytic herpes simplex virus-1 lacking the apoptosis-inhibiting gene,icp34.5

A mutant herpes simplex virus 1, mtHSV, was constructed by inserting the E. coli beta-galactosidase gene into the loci of icp34.5, the apoptosis-inhibiting gene of HSV. The mtHSV replicated in and lysed U251 (human glioma cells), EJ (human bladder cells), and S-180 (mice sarcoma cells), but not Wish (human amnion cells) cells. With its intact tk (thymidine kinase) gene, mtHSV exhibited susceptibility to acyclovir (ACV), which provided an approach to control viral replication. An in vivo test with mtHSV was conducted in immune-competent mice bearing sarcoma S-180 tumors, which were treated with a single intratumoral injection of mtHSV or PBS. Tumor dimensions then were measured at serial time points, and the tumor volumes were calculated. Sarcoma growth was significantly inhibited with prolonged time and reduced tumor volume. There was microscopic evidence of necrosis of tumors in treated mice, whereas no damage was found in other organs. Immunohistochemical staining revealed that virus replication was exclusively confined to the treated tumor cells. HSV-1 DNA was detected in tumors, but not in the other organs by a polymerase chain reaction analysis. From these experiments, we concluded that mtHSV should be a safe and promising oncolytic agent for cancer treatment.     

Cutting edge: recombinant Listeria monocytogenes expressing a single immune-dominant peptide confers protective immunity to herpes simplex virus-1 infection

The vast majority of the world's population is infected with HSV. Although antiviral therapy can reduce the incidence of reactivation and asymptomatic viral shedding, and limit morbidity and mortality from active disease, it cannot cure infection. Therefore, the development of an effective vaccine is an important global health priority. In this study, we demonstrate that recombinant Listeria monocytogenes (Lm) expressing the H-2K(b) glycoprotein B (gB)(498-505) peptide from HSV-1 triggers a robust CD8 T cell response to this Ag resulting in protective immunity to HSV infection. Following challenge with HSV-1, immune-competent mice primed with recombinant Lm-expressing gB(498-505) Ag were protected from HSV-induced paralysis. Protection was associated with dramatic reductions in recoverable virus, and early expansion of HSV-1-specific CD8 T cells in the regional lymph nodes. Thus, recombinant Lm-expressing Ag from HSV represents a promising new class of vaccines against HSV infection.     

Enkephalin-encoding herpes simplex virus-1 decreases inflammation and hotplate sensitivity in a chronic pancreatitis model

Background

A chronic pancreatitis model was developed in young male Lewis rats fed a high-fat and alcohol liquid diet beginning at three weeks. The model was used to assess time course and efficacy of a replication defective herpes simplex virus type 1 vector construct delivering human cDNA encoding preproenkephalin (HSV-ENK).

Results

Most surprising was the relative lack of inflammation and tissue disruption after HSV-ENK treatment compared to the histopathology consistent with pancreatitis (inflammatory cell infiltration, edema, acinar cell hypertrophy, fibrosis) present as a result of the high-fat and alcohol diet in controls. The HSV-ENK vector delivered to the pancreatic surface at week 3 reversed pancreatitis-associated hotplate hypersensitive responses for 4–6 weeks, while control virus encoding β-galactosidase cDNA (HSV-β-gal) had no effect. Increased Fos expression seen bilaterally in pain processing regions in control animals with pancreatitis was absent in HSV-ENK-treated animals. Increased met-enkephalin staining was evident in pancreas and lower thoracic spinal cord laminae I–II in the HSV-ENK-treated rats.

Conclusion

Thus, clear evidence is provided that site specific HSV-mediated transgene delivery of human cDNA encoding preproenkephalin ameliorates pancreatic inflammation and significantly reduces hypersensitive hotplate responses for an extended time consistent with HSV mediated overexpression, without tolerance or evidence of other opiate related side effects.     

Binding of herpes simplex virus-1 US11 to specific RNA sequences

Herpes simplex virus-1 US11 is a RNA-binding protein with a novel RNA-binding domain. US11 has been reported to exhibit sequence- and conformation-specific RNA-binding, but the sequences and conformations important for binding are not known. US11 has also been described as a double-stranded RNA (dsRNA)-binding protein. To investigate the US11–RNA interaction, we performed in vitro selection of RNA aptamers that bind US11 from a RNA library consisting of >10¹⁴ 80 base sequences which differ in a 30 base randomized region. US11 bound specifically to selected aptamers with an affinity of 70 nM. Analysis of 23 selected sequences revealed a strong consensus sequence. The US11 RNA-binding domain and ≤46 bases of selected RNA containing the consensus sequence were each sufficient for binding. US11 binding protected the consensus motif from hydroxyl radical cleavage. RNase digestions of a selected aptamer revealed regions of both single-stranded RNA and dsRNA. We observed that US11 bound two different dsRNAs in a sequence non-specific manner, but with lower affinity than it bound selected aptamers. The results define a relatively short specific sequence that binds US11 with high affinity and indicate that dsRNA alone does not confer high-affinity binding.     

Characterization of a major late herpes simplex virus type 1 mRNA

A major, late 6-kilobase (6-kb) mRNa mapping in the large unique region of herpes simplex virus type 1 (HSV-1) was characterized by using two recombinant DNA clones, one containing EcoRI fragment G (0.190 to 0.30 map units) in lambda. WES.B (L. Enquist, M. Madden, P. Schiop-Stansly, and G. Vandl Woude, Science 203:541-544, 1979) and one containing HindIII fragment J (0.181 to 0.259 map units) in pBR322. This 6-kb mRNA had its 3' end to the left of 0.231 on the prototypical arrangement of the HSV-1 genome and was transcribed from right to left. It was bounded on both sides by regions containing a large number of distinct mRNA species, and its 3' end was partially colinear with a 1.5-kb mRNA which encoded a 35,000-dalton polypeptide. The 6-kb mRNA encoded a 155,000-dalton polypeptide which was shown to be the only one of this size detectable by hybrid-arrested translation encoded by late polyadenylated polyribosomal RNA. The S1 nuclease mapping experiments indicated that there were no introns in the coding sequence for this mRNA and that its 3' end mapped approximately 800 nucleotides to the left of the BglII site at 0.231, whereas its 5' end extended very close to the BamHI site at 0.266.