Identification of two protein binding sites within the varicella-zoster virus major immediate early gene promoter.

Binding sites for cellular proteins in the promoter of the varicella-zoster virus (VZV) major immediate early (IE) gene were investigated. Protein binding was detected at sequence motifs possessing homology to the CCAAT element and an ATF/AP-1-like binding site, and recognition of the ATF/AP-1 site was apparently facilitated by occupation of the CCAAT site. Gene expression directed by the VZV major IE promoter was stimulated by the adenovirus 5, 289 amino acid EIA gene product. The implications of the results for VZV gene expression and replication are discussed.     

The immediate early proteins of varicella-zoster virus

Stable, relatively high-titer varicella-zoster virus (VZV) stocks as well as a high-titer anti-VZV serum prepared in inbred guinea pigs have allowed the identification of VZV immediate early proteins using the classic inhibitor approach. VZV infection was initiated in the presence of cycloheximide. Following the removal of cycloheximide, actinomycin D and radiolabel were added. After the labeling period, extracts were immunoprecipitated with anti-VZV guinea pig serum and subjected to polyacrylamide gel electrophoresis and fluorography or autoradiography. Four immediate early proteins of mol wts 185,000, 69,000, 43,000, and 34,000 were identified. The largest three were phosphoproteins.     

Regulation of pseudorabies virus gG glycoprotein gene promoter independently of pseudorabies immediate early IE180 protein

The pseudorabies virus (PRV) glycoprotein known as gG is generally regarded as an early protein, and the immediate early IE180 protein regulates its expression during infection. This study, however, provides evidence that although induction by IE180 is observed, the expression of a marker protein (EGFP), or gG itself, under the control of the gG promoter, can also occur independently of the expression of IE180. This result was demonstrated both with transient transfection assays using plasmids and with viral infections. In transient transfections, the expression under control of the gG promoter depends on the cell type and surprisingly, can be 1.3-fold higher than the expression under the control of the IE180 promoter in Hela Tet-Off cells. Recombinant PRV S3 was constructed by replacing gE in the PRV genome with a chimeric transgene, expressing EGFP under the control of the gG promoter. In PK15 cells infected with NIA-3 wild-type virus or with S3 recombinant virus, expression of gG PRV mRNA (or EGFP mRNA) under the control of the gG promoter in the presence of cycloheximide was detected by RT-PCR. This again indicates that some basal expression was produced in infected cells independently of IE180. This expression was augmented by IE180 protein in both plasmid transfections and viral infections.     

Human T cells recognize multiple epitopes of an immediate early/tegument protein (IE62) and glycoprotein I of varicella zoster virus.

Infection with varicella zoster virus (VZV) elicits persistent cell-mediated immunity directed against the immediate early (IE62) protein and the glycoprotein I (gp I) in most healthy subjects. In these experiments, synthetic peptides corresponding to residues of the IE62 protein and gp I were used to identify linear amino acid sequences of these immunogenic VZV proteins that were recognized by peripheral blood T lymphocytes from VZV-immune individuals of known major histocompatibility complex (MHC) type. All of 12 VZV-immune donors had T-cell proliferative responses, defined as a stimulation index (SI) greater than or equal to 2.0, to at least two of ten synthetic IE62 peptides; the mean number of IE62 peptides recognized by T cells from VZV-immune donors was seven. Five of the ten IE62 peptides stimulated T cells from 75% to 83% of the VZV-immune donors; the other five IE62 peptides were recognized by T cells from 42% to 67% of the subjects. All VZV-immune donors also had T proliferation responses to at least two of ten synthetic gp I peptides; the mean number of peptides recognized was six. Six of the ten gp I peptides were recognized by T cells from 67% to 92% of the VZV-immune donors; the frequency of donors responding to the other gp I peptides ranged from 42% to 58%. None of five nonimmune donors demonstrated T-cell proliferation to any of the IE62 or gp I peptides. A combination of two IE62 peptides provided epitopes that could be recognized by T cells from all twelve VZV-immune donors, regardless of DR type. Similarly, one gp I peptide in combination with either of two other gp I peptides induced proliferation of T cells from all immune subjects. Memory T cells with specificity for multiple short amino acid sequences of the IE62 protein and gp I were detected in subjects who had had primary VZV infection more than 20 years earlier. These observations indicate that natural VZV infection elicits a diverse cell-mediated immune response to viral proteins that is not restricted to only one or two immunodominant regions. Although the usefulness of peptide vaccines remains to be established, multiple epitopes of the IE62 protein and gp I were identified that could be presented by antigen-presenting cells (APC) and recognized by T cells from most subjects in an "outbred" human population.     

Physical interaction between two varicella zoster virus gene regulatory proteins, IE4 and IE62

Transfection assays demonstrate that the varicella zoster virus (VZV) immediate-early 62 (IE62) protein is a major transactivator of VZV gene expression, whereas a second immediate-early protein, IE4, can act as a major coactivator of transactivation mediated through IE62. To test whether IE62 and IE4 interact physically, we performed several protein-protein interaction assays. Coimmunoprecipitation analyses using VZV-infected cell lysates as well as purified protein mixtures demonstrate that IE62 and IE4 form stable complexes in solution under stringent salt conditions. Enzyme-linked immunosorbent assay protein-protein interaction assays and maltose-binding protein capture assays demonstrate that IE62 binds IE4 in a concentration- and dose-dependent manner. Far Western blot analyses show that IE4 binds to an undermodified form of IE62, and the use of calf intestinal phosphatase and protein kinases suggests that the interaction with IE4 is dependent on the phosphorylation state of IE62. An IE4 binding domain on IE62 has been mapped using a set of truncated IE62 fusion peptides. Collectively, these results imply a direct and specific physical interaction between IE4 and less-phosphorylated forms of IE62. These data have implications for virion assembly, as well as for the regulation of gene expression in VZV-infected cells.     

水痘-带状疱疹病毒疫苗株ORF62碱基突变及ORF62编码IE62反式激活力的分析

目的 分析水痘-带状疱疹病毒(VZV)疫苗株(vOka)ORF62碱基突变及ORF62编码即刻早期蛋白(IE62)对VZV基因启动子的反式激活力.方法 分别以vOka及其亲本株(pOka)基因组DNA为模板,PCR扩增获得ORF62全序列,克隆到高效表达质粒pCAGGS中构建vOka和pOka ORF62表达质粒;采用双脱氧核苷酸链末端终止法对表达质粒中ORF62测序;应用基因转染瞬时表达技术比较vOka和pOka IE62在MeWo和CV1细胞中对VZV基因启动子的反式激活力差别.结果 成功构建vOka和pOka ORF62表达质粒pCAG-vOka62和pCAG-pOka62;测序结果发现,与pOka比较,vOka ORF62至少有9个碱基突变,其中106262、107136和107262位点碱基突变后分别产生Sma Ⅰ、BssH Ⅱ和Nae Ⅰ酶切位点.vOka IE62在MeWo细胞中对ORF4、ORF10和ORF61启动子的反式激活力低于pOka IE62,但在CV1细胞中对ORF9启动子的反式激活力高于poka IE62.结论 利用vOka ORF62碱基突变产生的酶切位点可鉴别vOka和pOka,vOka和poka IE62对VZV基因启动子的反式激活力差别可能与转染细胞类型有关.     

Subcellular localization of the major immediate early protein (IE1) of human cytomegalovirus at early times after infection

The immediate early (IE) 1 protein of human cytomegalovirus was investigated by subcellular fractionation and immunocolloidal gold electron microscopy. The IE1 protein is phosphorylated and detected on intracytoplasmic membranes at early times after infection. An electron microscopy study confirmed that the IE1 antigen was an intracytoplasmic membrane-associated protein at early times after infection. The IE1 antigen as well as the IE2 antigen was also detected in the nucleus. However, the IE1 antigen was not detected on the plasma membrane surface of infected cells. The role of this viral protein in the immune response is discussed.     

Serine protein kinase associated with varicella-zoster virus ORF 47.

Varicella-zoster virus (VZV) ORF 47 lies in the unique long region of the VZV genome. Sequence homology studies have demonstrated that gene 47 possessed conserved protein kinase motifs. In this study, we investigated the properties of the ORF 47 product. First, a rabbit antiserum was raised against a protein generated from the fusion of the most antigenic ORF 47 domain with Escherichia coli beta-galactosidase. The high-titer antiserum reacted specifically with ORF 47 polypeptides translated in vitro. When incubated with VZV-infected cell lysate, the antiserum immunoprecipitated a phosphoprotein of M(r) 54,000, a size comparable with the predicted molecular mass. The precipitated viral protein was phosphorylated in a protein kinase assay; subsequent phosphoamino acid analysis indicated that the phosphotransferase associated with the ORF 47 protein was a serine protein kinase. Synthesis of the ORF 47 product in VZV-infected cell culture increased in the first and second days and plateaued after the third day of infection. The protein kinase activity associated with VZV ORF 47 had several distinctive biochemical properties: (i) its phosphotransferase activity was enhanced more by manganese than by magnesium, (ii) it utilized both ATP and GTP as donors of phosphate, and (iii) it phosphorylated both acidic and basic substrates. In summary, this report lends support to the computer homology data which predicted that VZV ORF 47 would encode a serine protein kinase.     

Detection of immediate early protein ICP27/IE63 and thymidine kinase in the course of reactivation of latent herpes simplex virus 1 infection

We followed the kinetics of reactivation of latent Herpes simplex virus 1 (HSV-1) infection established in rabbits by corneal route. The corresponding trigeminal ganglia (TG) were cultured and the culture medium was examined at daily intervals for release of infectious virus. Sections from the cultured TG fragments were stained with antisera against non-structural proteins such as the immediate early (IE) protein ICP27 and the early (E) proteins thymidine kinase (TK), the large subunit of ribonucleotide reductase (RR1), the ori-binding protein OBP and with a human serum obtained from volunteers immunized with an experimental subunit HSV-1 envelope (env) vaccine containing late structural proteins gB1, gC1, gD1 and gG1 (env antiserum). By indirect immunofluorescence (IF) test, ICP27 was detected in a few neurons from day 1 post explantation (p.e.), while TK was observed in neurons from day 2 p.e. Fluorescence with the human env antiserum was seen at day 3 p.e. The RR1 and OBP antisera stained productively infected Vero cells from 3 and 4 hrs post inoculation (p.i.), respectively. However, these sera showed no IF in cultured ganglion fragments at any interval examined. Our results showed the same cascade of HSV-1 IE and E protein expression during productive infection and reactivation in vitro.     

Enzyme immunofiltration staining assay for immediate diagnosis of herpes simplex virus and varicella-zoster virus directly from clinical specimens.

A simple, sensitive, 30-min assay for the detection of herpes simplex virus (HSV) and varicella-zoster virus (VZV) antigens in clinical specimens is described. The assay utilizes a filter manifold, biotinylated monoclonal antibodies, streptavidin-horseradish peroxidase conjugate, and the substrate aminoethylcarbazole. The method stains infected cells and cell debris a bright red and is easily interpreted with a dissecting microscope. Reconstruction experiments indicated that as few as two virus-infected cells per swab could be detected. This was equivalent to an infectivity titer of 29 to 160 50% tissue culture infective doses per infected cell and 250 times more sensitive than an enzyme immunofiltration assay which detects a soluble reaction product. Clinical swab specimens collected from ocular, oral, skin, and genital lesions were cultured for virus, and the remaining cell debris was immobilized on glass fiber filters and stained for the presence of virus antigens. Of 71 HSV culture-positive specimens, 66 (93%) were positive for HSV antigens. All of nine VZV culture-positive specimens were positive for VZV antigens. Of 98 culture-negative specimens, 7 were positive for either HSV (n = 3) or VZV (n = 4) antigens.