scholarly journals The UL7 Gene of Pseudorabies Virus Encodes a Nonessential Structural Protein Which Is Involved in Virion Formation and Egress

2005 ◽  
Vol 79 (17) ◽  
pp. 11291-11299 ◽  
Author(s):  
Walter Fuchs ◽  
Harald Granzow ◽  
Robert Klopfleisch ◽  
Barbara G. Klupp ◽  
Daniela Rosenkranz ◽  
...  
Keyword(s):  
Pseudorabies Virus ◽  
Rabbit Antiserum ◽  
Wild Type Virus ◽  
Rabbit Kidney ◽  
Structural Protein ◽  
Wild Type ◽  
Survival Times ◽  
Virion Protein ◽  
Infected Cells

ABSTRACT Homologues of the UL7 gene of herpes simplex virus type 1 are conserved in alpha-, beta-, and gammaherpesviruses. However, little is known about their functions. Using a monospecific rabbit antiserum raised against a bacterial fusion protein, we identified the UL7 gene product of the neurotropic alphaherpesvirus pseudorabies virus (PrV). In Western blot analyses of infected cells and purified PrV particles the serum specifically detected a 29-kDa protein, which matches the calculated mass of the 266-amino-acid translation product of PrV UL7. For functional analysis, UL7 was deleted by mutagenesis of an infectious full-length clone of the PrV genome in Escherichia coli. The obtained recombinant PrV-ΔUL7F was replication competent in rabbit kidney cells, but maximum virus titers were decreased nearly 10-fold and plaque diameters were reduced by ca. 60% compared to wild-type PrV. Electron microscopy of infected cells revealed that in the absence of UL7, formation and nuclear egress of nucleocapsids were not affected, whereas secondary envelopment of cytoplasmic nucleocapsids appeared to be delayed and release of mature virions was less efficient. The observed replication defects were corrected by repair of the viral UL7 gene or by propagation of PrV-ΔUL7F in UL7-expressing cells. PrV-ΔUL7F was moderately attenuated in mice. Compared to wild-type virus, mean survival times were prolonged from 2 to 3 days after intranasal infection. However, neuroinvasion and transneuronal spread of PrV were not abolished in the absence of UL7. Thus, UL7 encodes a virion protein of PrV, which plays a role during virion maturation and egress both in vitro and in vivo.

scholarly journals Pseudorabies Virus Glycoprotein gK Is a Virion Structural Component Involved in Virus Release but Is Not Required for Entry

1998 ◽  
Vol 72 (3) ◽  
pp. 1949-1958 ◽  
Author(s):  
Barbara G. Klupp ◽  
Judith Baumeister ◽  
Petra Dietz ◽  
Harald Granzow ◽  
Thomas C. Mettenleiter
Keyword(s):  
Structural Component ◽  
Pseudorabies Virus ◽  
Virus Assembly ◽  
Protein A ◽  
Rabbit Antiserum ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Infected Cells ◽  
Hsv 1

ABSTRACT The pseudorabies virus (PrV) gene homologous to herpes simplex virus type 1 (HSV-1) UL53, which encodes HSV-1 glycoprotein K (gK), has recently been sequenced (J. Baumeister, B. G. Klupp, and T. C. Mettenleiter, J. Virol. 69:5560–5567, 1995). To identify the corresponding protein, a rabbit antiserum was raised against a 40-kDa glutathione S-transferase–gK fusion protein expressed inEscherichia coli. In Western blot analysis, this serum detected a 32-kDa polypeptide in PrV-infected cell lysates as well as a 36-kDa protein in purified virion preparations, demonstrating that PrV gK is a structural component of virions. After treatment of purified virions with endoglycosidase H, a 34-kDa protein was detected, while after incubation with N-glycosidase F, a 32-kDa protein was specifically recognized. This finding indicates that virion gK is modified by N-linked glycans of complex as well as high-mannose type. For functional analysis, the UL53 open reading frame was interrupted after codon 164 by insertion of a gG-lacZ expression cassette into the wild-type PrV genome (PrV-gKβ) or by insertion of the bovine herpesvirus 1 gB gene into a PrV gB− genome (PrV-gKgB). Infectious mutant virus progeny was obtained only on complementing gK-expressing cells, suggesting that gK has an important function in the replication cycle. After infection of Vero cells with either gK mutant, only single infected cells or small foci of infected cells were visible. In addition, virus yield was reduced approximately 30-fold, and penetration kinetics showed a delay in entry which could be compensated for by phenotypic gK complementation. Interestingly, the plating efficiency of PrV-gKβ was similar to that of wild-type PrV on complementing and noncomplementing cells, pointing to an essential function of gK in virus egress but not entry. Ultrastructurally, virus assembly and morphogenesis of PrV gK mutants in noncomplementing cells were similar to wild-type virus. However, late in infection, numerous nucleocapsids were found directly underneath the plasma membrane in stages typical for the entry process, a phenomenon not observed after wild-type virus infection and also not visible after infection of gK-complementing cells. Thus, we postulate that presence of gK is important to inhibit immediate reinfection.

scholarly journals The UL4 gene of pseudorabies virus encodes a minor infected-cell protein that is dispensable for virus replication

2006 ◽  
Vol 87 (9) ◽  
pp. 2517-2525 ◽  
Author(s):  
Walter Fuchs ◽  
Harald Granzow ◽  
Robert Klopfleisch ◽  
Barbara G. Klupp ◽  
Thomas C. Mettenleiter
Keyword(s):  
Pseudorabies Virus ◽  
Rabbit Antiserum ◽  
Human Herpesvirus ◽  
Rabbit Kidney ◽  
Cell Protein ◽  
Growth Defect ◽  
Kidney Cells ◽  
Structural Protein ◽  
Herpesvirus 1

Although homologues of the open reading frame (ORF) UL4 of herpes simplex virus 1 (Human herpesvirus 1) have been found in the genomes of all hitherto-analysed alphaherpesviruses, little is known about their function. In a project to analyse systematically, in an isogenic and standardized assay system, the gene products of the alphaherpesvirus pseudorabies virus (PrV; Suid herpesvirus 1), the PrV UL4 gene product was identified using a monospecific rabbit antiserum prepared against a bacterial fusion protein. Western blot and immunofluorescence analyses revealed that the 146 codon UL4 ORF of PrV was translated into a nuclear 15 kDa protein which was detectable from 6 h after infection of rabbit kidney cells, but was not found in purified virus particles. For functional analysis, a UL4-negative virus recombinant (PrV-ΔUL4F) was generated by mutagenesis of an infectious full-length clone of the PrV genome in E. coli. PrV-ΔUL4F was replication-competent in rabbit kidney cells, and plaque formation was not affected by the mutation. However, maximum virus titres of PrV-ΔUL4F were decreased about fivefold compared with wild-type PrV, and electron microscopy of infected cells demonstrated an impairment of release of mature virions. This growth defect of PrV-ΔUL4F could be corrected completely by propagation in UL4-expressing cells. Correlating with the inconspicuous in vitro phenotype, neurovirulence of PrV-ΔUL4F was also not affected significantly. Thus, UL4 encodes a non-structural protein of PrV that enhances virion formation but is not essential for PrV replication in vitro or in vivo.

scholarly journals Human Cytomegalovirus pUS24 Is a Virion Protein That Functions Very Early in the Replication Cycle

2006 ◽  
Vol 80 (17) ◽  
pp. 8371-8378 ◽  
Author(s):  
Xuyan Feng ◽  
Jörg Schröer ◽  
Dong Yu ◽  
Thomas Shenk
Keyword(s):  
Human Cytomegalovirus ◽  
Mutant Virus ◽  
Replication Cycle ◽  
Immediate Early ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Virion Protein ◽  
Viral Dna ◽  
Infected Cells

ABSTRACT We have characterized the function of the human cytomegalovirus US24 gene, a US22 gene family member. Two US24-deficient mutants (BADinUS24 and BADsubUS24) exhibited a 20- to 30-fold growth defect, compared to their wild-type parent (BADwt), after infection at a relatively low (0.01 PFU/cell) or high (1 PFU/cell) input multiplicity. Representative virus-encoded proteins and viral DNA accumulated with normal kinetics to wild-type levels after infection with mutant virus when cells received equal numbers of mutant and wild-type infectious units. Further, the proteins were properly localized and no ultrastructural differences were found by electron microscopy in mutant-virus-infected cells compared to wild-type-virus-infected cells. However, virions produced by US24-deficient mutants had a 10-fold-higher genome-to-PFU ratio than wild-type virus. When infections were performed using equal numbers of input virus particles, the expression of immediate-early, early, and late viral proteins was substantially delayed and decreased in the absence of US24 protein. This delay is not due to inefficient virus entry, since two tegument proteins and viral DNA moved to the nucleus equally well in mutant- and wild-type-virus-infected cells. In summary, US24 is a virion protein and virions produced by US24-deficient viruses exhibit a block to the human cytomegalovirus replication cycle after viral DNA reaches the nucleus and before immediate-early mRNAs are transcribed.

scholarly journals Influence of Tegument Proteins of Pseudorabies Virus on Neuroinvasion and Transneuronal Spread in the Nervous System of Adult Mice after Intranasal Inoculation

2004 ◽  
Vol 78 (6) ◽  
pp. 2956-2966 ◽  
Author(s):  
Robert Klopfleisch ◽  
Jens P. Teifke ◽  
Walter Fuchs ◽  
Martina Kopp ◽  
Barbara G. Klupp ◽  
...  
Keyword(s):  
Cell Culture ◽  
Nervous System ◽  
Pseudorabies Virus ◽  
Single Cells ◽  
Wild Type Virus ◽  
Wild Type ◽  
Survival Times ◽  
Intranasal Infection ◽  
Tegument Proteins ◽  
Adult Mice

ABSTRACT Pseudorabies virus (PrV) is a neurotropic alphaherpesvirus that, after intranasal infection of adult mice, enters peripheral neurons and propagates to the central nervous system. In recent years we have analyzed the contribution of virus-encoded glycoproteins to neuroinvasion and transneuronal spread (reviewed in T. C. Mettenleiter, Virus Res. 92:197-206, 2003). We now extend our studies to analyze the role of tegument proteins in these processes. To this end, PrV mutants unable to express the UL11, UL37, UL46, UL47, and UL48 tegument proteins, as well as the corresponding rescued viruses, were intranasally instilled into 6- to 8-week-old CD1 strain mice. First, mean survival times were determined which showed that mice infected with the UL46 deletion mutant succumbed to the disease as early as wild-type PrV-infected animals. Survival times increased in the order: PrV-ΔUL47-, PrV-ΔUL11-, and PrV-ΔUL48-infected animals, a finding which parallels the growth phenotype of these viruses in cell culture. In contrast, none of the PrV-ΔUL37-infected animals died. Upon closer histological examination, all viruses except PrV-ΔUL37 were able to infect the nasal cavity and propagate to first- and second-order neurons as shown by two-color immunofluorescence. However, neuroinvasion was delayed in PrV-ΔUL47, PrV-ΔUL11, and PrV-ΔUL48, a finding that correlated with the extended survival times. Surprisingly, whereas PrV-ΔUL48 and PrV-ΔUL37 replicated to similar titers in cell culture which were ∼500-fold lower than those of wild-type virus, after intranasal infection of mice PrV-ΔUL48 was able to infect areas of the brain like wild-type PrV, although only after a considerably longer time period. In contrast, PrV-ΔUL37 was not able to enter neurons and was restricted to the infection of single cells in the nasal respiratory epithelium. Thus, our data demonstrate the importance of herpesviral tegument proteins in neuronal infection and show a different contribution of tegument proteins to the neuroinvasion phenotype of a neurotropic alphaherpesvirus.

scholarly journals The Human Cytomegalovirus UL44 Protein Is a Substrate for the UL97 Protein Kinase

2003 ◽  
Vol 77 (14) ◽  
pp. 7720-7727 ◽  
Author(s):  
Paula M. Krosky ◽  
Moon-Chang Baek ◽  
Wan Jin Jahng ◽  
Imma Barrera ◽  
Robert J. Harvey ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Human Cytomegalovirus ◽  
Nucleoside Analogs ◽  
Wild Type Virus ◽  
Null Mutant ◽  
Natural Substrate ◽  
Wild Type ◽  
Two Dimensional Gel Electrophoresis ◽  
Infected Cells

ABSTRACT The human cytomegalovirus UL97 protein is an unusual protein kinase that is able to autophosphorylate and to phosphorylate certain exogenous substrates, including nucleoside analogs such as ganciclovir. However, no natural substrate of UL97 in infected cells has been identified. We report here that recombinant UL44 protein became radiolabeled when incubated with recombinant UL97 and [32P]ATP and that both proteins could be coimmunoprecipitated by an antibody that recognizes either protein. Subsequent studies showed that highly purified, recombinant UL97 phosphorylated purified, recombinant UL44. This phosphorylation occurred on serine and threonine residues and was sensitive to inhibition by maribavir and to a mutation that inactivates UL97 catalytic activity. Two-dimensional gel electrophoresis revealed the absence of specific phosphorylated forms of UL44 in immunoprecipitates from lysates of cells infected with a UL97 null mutant virus or with wild-type virus in the presence of maribavir. The results indicate that UL97 is sufficient to phosphorylate UL44 in vitro and is necessary for the normal phosphorylation of UL44 in infected cells. This strongly suggests that UL44 is a natural substrate of UL97.

scholarly journals A Pseudorabies Virus Recombinant Simultaneously Lacking the Major Tegument Proteins Encoded by the UL46, UL47, UL48, and UL49 Genes Is Viable in Cultured Cells

2003 ◽  
Vol 77 (23) ◽  
pp. 12891-12900 ◽  
Author(s):  
Walter Fuchs ◽  
Harald Granzow ◽  
Thomas C. Mettenleiter
Keyword(s):  
Deletion Mutant ◽  
Pseudorabies Virus ◽  
Cultured Cells ◽  
Wild Type Virus ◽  
Rabbit Kidney ◽  
Replication Capacity ◽  
Electron Microscopic ◽  
Tegument Proteins ◽  
Microscopic Studies

ABSTRACT The UL46, UL47, UL48, and UL49 genes, which encode major tegument proteins, are conserved in most alphaherpesvirus genomes. However, the relative importance of each of these proteins for replication of individual alphaherpesviruses appears to be different. Recently, we demonstrated that single deletions of UL47 or UL48 impair maturation and egress of pseudorabies virus (PrV) particles to different extents, whereas deletions of UL46 or UL49 have no significant effects on virus replication in cell culture (W. Fuchs, H. Granzow, B. G. Klupp, M. Kopp, and T. C. Mettenleiter, J. Virol. 76:6729-6742, 2002; M. Kopp, B. G. Klupp, H. Granzow, W. Fuchs, and T. C. Mettenleiter, J. Virol. 76:8820-8833, 2002). To test for possible functional redundancy between the four tegument proteins, a quadruple gene deletion mutant (PrV-ΔUL46-49) was generated and characterized in vitro. Although plaque formation by this mutant was almost abolished and maximum titers were reduced more than 100-fold compared to those of parental wild-type virus, PrV-ΔUL46-49 could be propagated and serially passaged in noncomplementing porcine and rabbit kidney cells. Electron-microscopic studies revealed that nucleocapsid formation and egress of PrV-ΔUL46-49 from the host cell nucleus were not affected, but secondary envelopment of nucleocapsids in the cytoplasm was only rarely observed. The replication defect of PrV-ΔUL46-49 could be fully corrected by reinsertion of the UL46-to-UL49 gene cluster. Plaque sizes and virus titers were only slightly increased after restoration of only UL47 expression, whereas repair of only UL48 resulted in a significant increase in replication capacity to the level of a UL47 deletion mutant. In conclusion, we show that none of the UL46 to UL49 tegument proteins is absolutely required for productive replication of PrV. Moreover, our data indicate that the UL47 and UL48 proteins function independently during cell-to-cell spread and virus egress.

scholarly journals The Pseudorabies Virus VP22 Homologue (UL49) Is Dispensable for Virus Growth In Vitro and Has No Effect on Virulence and Neuronal Spread in Rodents

2002 ◽  
Vol 76 (2) ◽  
pp. 774-782 ◽  
Author(s):  
T. del Rio ◽  
H. C. Werner ◽  
L. W. Enquist
Keyword(s):  
Cell Biology ◽  
Pseudorabies Virus ◽  
Polyacrylamide Gel Electrophoresis ◽  
Wild Type Virus ◽  
Cell Fractionation ◽  
Null Mutant ◽  
Wild Type ◽  
Virus Growth ◽  
Simplex Virus

ABSTRACT The tegument of herpesvirus virions is a distinctive structure whose assembly and function are not well understood. The herpes simplex virus type 1 VP22 tegument protein encoded by the UL49 gene is conserved among the alphaherpesviruses. Using cell biology and viral genetics, we provide an initial characterization of the pseudorabies virus (PRV) VP22 homologue. We identified three isoforms of VP22 present in PRV-infected cells that can be resolved by polyacrylamide gel electrophoresis. The predominant form is not phosphorylated and is present in virions, while the other two species are phosphorylated and excluded from virions. VP22 localized to the nucleus by 6 h postinfection, as determined by immunofluorescence and cell fractionation. VP22 immunofluorescence in the nucleus was both diffuse and in punctate structures. The punctate nuclear localization was the most pronounced form of staining and did not localize exclusively to sites of viral DNA replication. Unexpectedly, a VP22 null mutant had no obvious phenotypes during tissue culture infections and was similar to the wild type in all respects. Moreover, the VP22 null mutant was as virulent and neuroinvasive as the wild-type virus after infection of the rodent eye and spread to the brain using both anterograde and retrograde neuronal circuits.

scholarly journals Mutagenesis of the Active-Site Cysteine in the Ubiquitin-Specific Protease Contained in Large Tegument Protein pUL36 of Pseudorabies Virus Impairs Viral Replication In Vitro and Neuroinvasion In Vivo

2008 ◽  
Vol 82 (12) ◽  
pp. 6009-6016 ◽  
Author(s):  
Sindy Böttcher ◽  
Christina Maresch ◽  
Harald Granzow ◽  
Barbara G. Klupp ◽  
Jens P. Teifke ◽  
...  
Keyword(s):  
Active Site ◽  
Pseudorabies Virus ◽  
Wild Type Virus ◽  
Tegument Protein ◽  
Wild Type ◽  
Active Site Cysteine ◽  
Specific Protease ◽  
Ubiquitin Specific Protease

ABSTRACT Herpesviruses specify a ubiquitin-specific protease activity located within their largest tegument protein. Although its biological role is still largely unclear, mutation within the active site abolished deubiquitinating (DUB) activity and decreased virus replication in vitro and in vivo. To further elucidate the role of DUB activity for herpesvirus replication, the conserved active-site cysteine at amino acid position 26 within pUL36 of Pseudorabies virus (PrV) (Suid herpesvirus 1), a neurotropic alphaherpesvirus, was mutated to serine. Whereas one-step growth kinetics of the resulting mutant virus PrV-UL36(C26S) were moderately reduced, plaque size was decreased to 62% of that of the wild-type virus. Ultrastructural analysis revealed large accumulations of unenveloped nucleocapsids in the cytoplasm, but incorporation of the tegument protein pUL37 was not abolished. After intranasal infection with PrV-UL36(C26S) mice showed survival times two times longer than those of mice infected with wild-type or rescued virus. Thus, the DUB activity is important for PrV replication in vitro and for neuroinvasion in mice.

The URNA Genes of Herpesvirus Saimiri (Strain C488) Are Dispensable for Transformation of Human T Cells In Vitro

1999 ◽  
Vol 73 (12) ◽  
pp. 10551-10555 ◽  
Author(s):  
Armin Ensser ◽  
André Pfinder ◽  
Ingrid Müller-Fleckenstein ◽  
Bernhard Fleckenstein
Keyword(s):  
Cell Culture ◽  
Herpesvirus Saimiri ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Human T Cell ◽  
Human T Cells ◽  
Small Nuclear Rnas ◽  
T Cell Lines

ABSTRACT The herpesvirus saimiri strain C488 genome contains five genes for small nuclear RNAs, termed herpesvirus saimiri URNAs (or HSURs). Using a cosmid-based approach, all HSURs were precisely deleted from the genome. The mutant virus replicated at levels that were similar to those of wild-type viruses in OMK cells. Although the HSURs are expressed in wild-type virus-transformed human T-cell lines, the deletion does not affect viral transformation in cell culture.

scholarly journals Essential Function of the Pseudorabies Virus UL36 Gene Product Is Independent of Its Interaction with the UL37 Protein

2004 ◽  
Vol 78 (21) ◽  
pp. 11879-11889 ◽  
Author(s):  
Walter Fuchs ◽  
Barbara G. Klupp ◽  
Harald Granzow ◽  
Thomas C. Mettenleiter
Keyword(s):  
Gene Product ◽  
Pseudorabies Virus ◽  
Rabbit Kidney ◽  
Tegument Protein ◽  
Wild Type ◽  
Coding Region ◽  
Ordered Structures ◽  
Ca 50 ◽  
Essential Function ◽  
Full Length Clone

ABSTRACT The large tegument protein encoded by the UL36 gene of pseudorabies virus (PrV) physically interacts with the product of the adjacent UL37 gene (B. G. Klupp, W. Fuchs, H. Granzow, R. Nixdorf, and T. C. Mettenleiter, J. Virol. 76:3065-3071, 2002). To analyze UL36 function, two PrV recombinants were generated by mutagenesis of an infectious PrV full-length clone in Escherichia coli: PrV-ΔUL36F exhibited a deletion of virtually the complete UL36 coding region, whereas PrV-UL36BSF contained two in-frame deletions of 238 codons spanning the predicted UL37 binding domain. Coimmunoprecipitation experiments confirmed that the mutated gene product of PrV-UL36BSF did not interact with the UL37 protein. Like the previously described PrV-ΔUL37 (B. G. Klupp, H. Granzow, and T. C. Mettenleiter, J. Virol. 75:8927-8936, 2001) but in contrast to PrV-ΔUL36F, PrV-UL36BSF was able to replicate in rabbit kidney (RK13) cells, although maximum virus titers were reduced ca. 50-fold and plaque diameters were reduced by ca. 45% compared to wild-type PrV. PrV-ΔUL36F was able to productively replicate after repair of the deleted gene or in a trans-complementing cell line. Electron microscopy of infected RK13 cells revealed that PrV-UL36BSF and phenotypically complemented PrV-ΔUL36F were capable of nucleocapsid formation and egress from the nucleus by primary envelopment and deenvelopment at the nuclear membrane. However, reenvelopment of nucleocapsids in the cytoplasm was blocked. Only virus-like particles without capsids were released efficiently from cells. Interestingly, cytoplasmic nucleocapsids of PrV-UL36BSF but not of PrV-ΔUL36F were found in large ordered structures similar to those which had previously been observed with PrV-ΔUL37. In summary, our results demonstrate that the interaction between the UL36 and UL37 proteins is important but not strictly essential for the formation of secondary enveloped, infectious PrV particles. Furthermore, UL36 possesses an essential function during virus replication which is independent of its ability to bind the UL37 protein.

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