scholarly journals Major tegument protein VP8 of bovine herpesvirus 1 is phosphorylated by viral US3 and cellular CK2 protein kinases

2009 ◽  
Vol 90 (12) ◽  
pp. 2829-2839 ◽  
Author(s):  
Shaunivan L. Labiuk ◽  
Lorne A. Babiuk ◽  
Sylvia van Drunen Littel-van den Hurk

The UL47 gene product, VP8, is one of the major tegument proteins of bovine herpesvirus 1 (BoHV-1) and is subject to phosphorylation. Analysis of protein bands co-immunoprecipitated with VP8 from BoHV-1-infected cells by mass spectroscopy suggested that VP8 interacts with two protein kinases: cellular CK2 and viral US3. CK2 is a highly conserved cellular protein, expressed ubiquitously and known to phosphorylate numerous proteins. The US3 gene product is one of the viral kinases produced by BoHV-1 during infection. Interactions of CK2 and US3 with VP8 were confirmed outside the context of infection when FLAG–VP8 was expressed alone or co-expressed with US3–haemagglutinin tag in Cos-7 cells. Furthermore, VP8 and US3 were found to co-localize in the nucleus during viral infection. To explore the significance of these interactions, an in vitro kinase assay was performed, which demonstrated that VP8 is heavily phosphorylated by CK2. In the presence of the highly specific CK2 kinase inhibitor 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT), phosphorylation of VP8 was significantly reduced. Phosphorylation of VP8 was also inhibited by the presence of kenpaullone, a less specific CK2 inhibitor, but not by protein kinase CK1 or protein kinase C inhibitors. When VP8 and US3 were both included in the kinase assay in the presence of DMAT, phosphorylation of VP8 was again observed. Autophosphorylation of US3 was also detected and was not inhibited by DMAT. Based on these results, it is proposed that VP8 interacts with cellular CK2 and viral US3 in BoHV-1-infected cells, and is in turn subject to kinase activities associated with both of these proteins.

2000 ◽  
Vol 74 (6) ◽  
pp. 2876-2884 ◽  
Author(s):  
Ngan Lam ◽  
Geoffrey J. Letchworth

ABSTRACT The bovine herpesvirus 1 (BHV-1) UL3.5 gene encodes a 126-amino-acid tegument protein. Homologs of UL3.5 are present in some alphaherpesviruses and have 20 to 30% overall amino acid homology that is concentrated in the N-terminal 50 amino acids. Mutant pseudorabies virus lacking UL3.5 is deficient in viral egress but can be complemented by BHV-1 UL3.5 (W. Fuchs, H. Granzow, and T. C. Mettenleiter, J. Virol. 71:8886–8892, 1997). The function of BHV-1 UL3.5 in BHV-1 replication is not known. To get a better understanding of its function, we sought to identify the proteins that interact with the BHV-1 UL3.5 protein. By using an in vitro pull-down assay and matrix-assisted laser desorption ionization mass spectrometry analysis, we identified BHV-1 α-transinducing factor (αBTIF) as a BHV-1 UL3.5-interacting protein. The interaction was verified by coimmunoprecipitation from virus-infected cells using an antibody to either protein, by indirect immunofluorescence colocalization in both virus-infected and transfected cells, and by the binding of in vitro-translated proteins. In virus-infected cells, UL3.5 and αBTIF colocalized in a Golgi-like subcellular compartment late in infection. In transfected cells, they colocalized in the nucleus. Deletion of 20 amino acids from the N terminus of UL3.5, but not 40 amino acids from the C terminus, abolished the UL3.5-αBTIF interaction both in vitro and in vivo. The interaction between UL3.5 and αBTIF may be important for BHV-1 maturation and regulation of αBTIF transactivation activity.


2015 ◽  
Vol 89 (8) ◽  
pp. 4598-4611 ◽  
Author(s):  
Kuan Zhang ◽  
Sharmin Afroz ◽  
Robert Brownlie ◽  
Marlene Snider ◽  
Sylvia van Drunen Littel-van den Hurk

ABSTRACTThe major tegument protein of bovine herpesvirus 1 (BoHV-1), VP8, is essential for virus replication in cattle. VP8 is phosphorylatedin vitroby casein kinase 2 (CK2) and BoHV-1 unique short protein 3 (US3). In this study, VP8 was found to be phosphorylated in both transfected and infected cells but was detected as a nonphosphorylated form in mature virions. This suggests that phosphorylation of VP8 is strictly controlled during different stages of the viral life cycle. The regulation and function of VP8 phosphorylation by US3 and CK2 were further analyzed. Anin vitrokinase assay, site-directed mutagenesis, and liquid chromatography-mass spectrometry were used to identify the active sites for US3 and CK2. The two kinases phosphorylate VP8 at different sites, resulting in distinct phosphopeptide patterns. S16is a primary phosphoreceptor for US3, and it subsequently triggers phosphorylation at S32. CK2 has multiple active sites, among which T107appears to be the preferred residue. Additionally, CK2 consensus motifs in the N terminus of VP8 are essential for phosphorylation. Based on these results, a nonphosphorylated VP8 mutant was constructed and used for further studies. In transfected cells phosphorylation was not required for nuclear localization of VP8. Phosphorylated VP8 appeared to recruit promyelocytic leukemia (PML) protein and to remodel the distribution of PML in the nucleus; however, PML protein did not show an association with nonphosphorylated VP8. This suggests that VP8 plays a role in resisting PML-related host antiviral defenses by redistributing PML protein and that this function depends on the phosphorylation of VP8.IMPORTANCEThe progression of VP8 phosphorylation over time and its function in BoHV-1 replication have not been characterized. This study demonstrates that activation of S16initiates further phosphorylation at S32by US3. Additionally, VP8 is phosphorylated by CK2 at several residues, with T107having the highest level of phosphorylation. Evidence for a difference in the phosphorylation status of VP8 in host cells and mature virus is presented for the first time. Phosphorylation was found to be a critical modification, which enables VP8 to attract and to redistribute PML protein in the nucleus. This might promote viral replication through interference with a PML-mediated antiviral defense. This study provides new insights into the regulation of VP8 phosphorylation and suggests a novel, phosphorylation-dependent function for VP8 in the life cycle of BoHV-1, which is important in view of the fact that VP8 is essential for virus replicationin vivo.


2006 ◽  
Vol 18 (2) ◽  
pp. 213 ◽  
Author(s):  
M. Givens ◽  
M. Marley ◽  
P. Galik ◽  
K. Riddell ◽  
D. Stringfellow

Lactoferrin is an iron-binding glycoprotein found in milk, saliva, tears, and other exocrine secretions. It is known to have in vitro antiviral effects against human, feline, and canine herpesviruses. In addition, lactoferrin is known to be safe in cell culture. Bovine herpesvirus-1 (BHV-1) is a likely contaminant of in vitro embryo production. Further, trypsin treatment is not completely effective in removing the virus from these embryos. We hypothesized that a nontoxic concentration of lactoferrin might prevent replication of BHV-1 within in vitro embryo production systems. Thus, the specific objectives of this research were to determine if lactoferrin from bovine milk would inhibit BHV-1 in cell culture and to determine if in vitro-produced embryos could develop normally when cultured in lactoferrin. Two-fold dilutions of lactoferrin (from 10 to 0.625 mg/mL) were added to Madin Darby bovine kidney cells, followed in 15 min by the addition 104 PFU/mL of BHV-1 (Colorado strain). Samples of cell lysate were taken at Day 2 and virus was quantified by plaque assay. The percent of virus inhibited by the antiviral agent at each concentration was determined by comparison to equivalent samples from temporal control cultures in which no compound was added before or after inoculation (Percentage of virus inhibited = [Quantity of virus in the control sample - Quantity of virus in the compound sample]/Quantity of virus in the control sample � 100). Next, the effect of lactoferrin was determined on in vitro-produced embryos. Cumulus oocyte complexes were received from an abattoir, matured in transit, placed in fertilization drops for 6 h, and then placed in culture drops containing lactoferrin (10, 5, and 2.5 mg/mL). At Day 3.5, embryos > 4 cell stage were placed into fresh culture drops containing lactoferrin. On Day 7.5, blastocyst development was noted and the developed embryos were stained to count viable cells. Blastocyst development rate and nucleated cell count of the treated embryos were compared to those of the controls using Chi square test, and ANOVA and Tukey-Kramer HSD, respectively. Lactoferrin (10 mg/mL) inhibited 2 to 5 logs of virus. At concentrations of 5 and 2.5 mg/mL, 1 to 3 logs of virus were inhibited, and concentrations of 1.25 and 0.625 mg/mL inhibited 0 to 2 logs of virus. Lactoferrin did not affect the nucleated cell count of the treated embryos. In addition, unlike 10 and 5 mg/mL, 2.5 mg/mL of lactoferrin did not affect blastocyst development. These preliminary results indicate that lactoferrin from bovine milk can significantly inhibit BHV-1 in cell culture. Furthermore, supplementation of in vitro culture with 2.5 mg/mL of lactoferrin does not affect blastocyst development or cell count of in vitro-produced embryos.


2009 ◽  
Vol 21 (1) ◽  
pp. 173 ◽  
Author(s):  
A. Bielanski ◽  
A. Lalonde ◽  
J. Algire

Bovine herpesvirus-1 (BHV-1) causes a variety of economically important respiratory and reproductive problems, the latter including vulvovaginitis, endometritis and infertility. For that reason, several countries have eradicated the disease and others have schemes in progress to achieve freedom. Although there is a considerable amount of information about the risk of BHV-1 transmission through contaminated semen used for artificial insemination, there is no available evidence to indicate whether the resulting embryos, when used for embryo transter (ET), can lead to the transmission of BHV-1 to recipients and offspring. For this experiment, bull semen contaminated in vitro with BHV-1 at 102 TCID50 mL–1 (Colorado strain) and then cryopreserved was used for insemination (2 times at estrus) of BHV-1 seronegative, superovulated heifers (N = 18). Embryos were collected postmortem 7 days post-insemination and were washed according to the IETS recommendations (however without trypsin treatment) or left unwashed. On 4 occasions, washed embryos were transferred to BHV-1 seronegative recipients. The remaining embryos and other samples collected from the reproductive tract were tested for BHV-1 presence using the standard virus isolation test. In total, out of 144 unfertilized oocytes and embryos collected, 9 were ET quality. Most of the embryos were degenerated (N = 79) or unfertilized (N = 56). The 4 heifers, which each received a single morula-stage embryo, maintained seronegative status, but did not become pregnant. BHV-1 was detected in 43% (23/53) unwashed and 0% (0/57) of washed embryos, 78% (14/18) of follicular fluid samples, 89% (16/18) of oviductal epithelial cells, 78% (14/18) of endometrium, and 89% (16/18) of corpora lutea tissues. Results herein suggest that BHV-1 can be transmitted by infected semen to embryo donors. The resulting unwashed embryos may remain infectious. However, whether BHV-1 uninfected offspring can be produced by ET of BHV-1 contaminated embryos that are washed according to the IETS guidelines, remains to be determined.


2006 ◽  
Vol 87 (8) ◽  
pp. 2149-2154 ◽  
Author(s):  
Benoît Muylkens ◽  
François Meurens ◽  
Frédéric Schynts ◽  
Frédéric Farnir ◽  
Aldo Pourchet ◽  
...  

Vaccines used in control programmes of Bovine herpesvirus 1 (BoHV-1) utilize highly attenuated BoHV-1 strains marked by a deletion of the glycoprotein E (gE) gene. Since BoHV-1 recombinants are obtained at high frequency in experimentally coinfected cattle, the consequences of recombination on the virulence of gE-negative BoHV-1 were investigated. Thus, gE-negative BoHV-1 recombinants were generated in vitro from several virulent BoHV-1 and one mutant BoHV-1 deleted in the gC and gE genes. Four gE-negative recombinants were tested in the natural host. All the recombinants were more virulent than the gE-negative BoHV-1 vaccine and the gC- and gE-negative parental BoHV-1. The gE-negative recombinant isolated from a BoHV-1 field strain induced the highest severe clinical score. Latency and reactivation studies showed that three of the recombinants were reexcreted. Recombination can therefore restore virulence of gE-negative BoHV-1 by introducing the gE deletion into a different virulence background.


1998 ◽  
Vol 72 (4) ◽  
pp. 3029-3036 ◽  
Author(s):  
S. X. Wu ◽  
X. P. Zhu ◽  
G. J. Letchworth

ABSTRACT Nine glycoproteins (gB, gC, gD, gE, gG, gH, gI, gK, and gL) have been identified in bovine herpesvirus 1 (BHV-1). gM has been identified in many other alpha-, beta-, and gammaherpesviruses, in which it appears to play a role in membrane penetration and cell-to-cell fusion. We sought to express BHV-1 open reading frame UL10, which encodes gM, and specifically identify the glycoprotein. We corrected a frameshift error in the published sequence and used the corrected sequence to design coterminal peptides from the C terminus. These were expressed as glutathione S-transferase fusion proteins inEscherichia coli. The fusion protein containing the 63 C-terminal amino acids from the corrected gM sequence engendered antibodies that immunoprecipitated a 30-kDa protein from in vitro translation reactions programmed with the UL10 gene. Proteins immunoprecipitated by this antibody from virus-infected cells ran at 36 and 43 kDa in reducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 43 and 48 kDa in nonreducing SDS-PAGE. Only the larger of the pair was present in virions. A 7-kDa protein was released from gM by reducing agents. The 7-kDa protein was not recognized in Western blots probed with the anti-gM antibody but reacted specifically with antibodies prepared against BHV-1 UL49.5, previously reported to be a 9-kDa protein associated with an unidentified 39-kDa protein (X. Liang, B. Chow, C. Raggo, and L. A. Babiuk, J. Virol. 70:1448–1454, 1996). This is the first report of a small protein covalently bound to any herpesvirus gM. Similar patterns of hydrophobic domains and cysteines in all known gM and UL49.5 homologs suggest that these two proteins may be linked by disulfide bonds in all herpesviruses.


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