Transforming potential of the herpesvirus oncoprotein MEQ: morphological transformation, serum-independent growth, and inhibition of apoptosis

Marek's disease virus (MDV) induces the rapid development of overwhelming T-cell lymphomas in chickens. One of its candidate oncogenes, meq (MDV Eco Q) which encodes a bZIP protein, has been biochemically characterized as a transcription factor. Interestingly, MEQ proteins are expressed not only in the nucleoplasm but also in the coiled bodies and the nucleolus. Its novel subcellular localization suggests that MEQ may be involved in other functions beyond its transcriptional potential. In this report we show that MEQ proteins are expressed ubiquitously and abundantly in MDV tumor cell lines. Overexpression of MEQ results in transformation of a rodent fibroblast cell line, Rat-2. The criteria of transformation are based on morphological transfiguration, anchorage-independent growth, and serum-independent growth. Furthermore, MEQ is able to distend the transforming capacity of MEQ-transformed Rat-2 cells through inhibition of apoptosis. Specifically, MEQ can efficiently protect Rat-2 cells from cell death induced by multiple modes including tumor necrosis factor alpha, C2-ceramide, UV irradiation, and serum deprivation. Its antiapoptotic function requires new protein synthesis, as treatment with a protein synthesis inhibitor, cycloheximide, partially reversed MEQ's antiapoptotic effect. Coincidentally, transcriptional induction of bcl-2 and suppression of bax are also observed in MEQ-transformed Rat-2 cells. Taken together, our results suggest that MEQ antagonizes apoptosis through regulation of its downstream target genes involved in apoptotic and/or antiapoptotic pathways.

Serological characteristics of a membrane glycoprotein gp82 of Marek's disease virus

Marek's disease virus (MDV) is a cell-associated herpesvirus of gallinaceous fowl. Glycoproteins of herpesviruses have been reported to be important in stimulating humoral and cell-mediated immune responses against viral infection. At least eight glycoproteins of MDV have been identified, and glycoprotein B (gB) has been reported to produce protective immunity. In addition to glycoproteins, other cell membrane proteins may also be important for engendering immunity. In an attempt to determine whether the protein is involved in immune responses, we developed three monoclonal antibodies (Mabs) and rabbit polyclonal antibodies specific for MDV membrane protein gp82. Three Mabs (Mab2.1, 3.7, and 5.7) were produced by using TrpEgp82 fusion protein as the immunogen that was expressed by recombinant pATH expression vector pATHgp82 in Escherichia coli. Indirect immunofluorescence assay (IFA), immunoprecipitation, and Western blot analysis were used to determine the characteristics of gp82. All of the Mabs reacted with gp82 protein irrespective of its conformation. The gp82 protein was predominantly anchored on the surface membrane of a chicken embryo fibroblast (CEF) infected with serotype 1 MDV (MDV-1). There was no detectable immunofluorescence staining in the cytoplasm or nucleus in the MDV-1-infected CEFs. These results indicate that gp82 is a membrane protein. The distribution pattern of immunofluorescence staining of gp82 varies between CEFs infected with the low passage MDV-1 isolate Md11, and those infected with a high passage derivative, Md11/75c. In SB-1 (Serotype 2 MDV [MDV-2]) and Turkey herpesvirus (HVT) (serotype 3 MDV [MDV-3]) infected CEFs, gp82 was not detected by immunoprecipitation, Western blot, or IFA using both monoclonal and polyclonal antibodies. These results suggest that gp82 in serotype 2 or 3 has a modified epitope, or that the gene is permanently repressed.

Identification of tumor-specific paclitaxel (Taxol)-responsive regulatory elements in the interleukin-8 promoter

Paclitaxel (Taxol) is a novel chemotherapeutic drug that is effective against breast and ovarian cancers. Although the primary target of paclitaxel is microtubules, its efficacy exceeds that of conventional microtubule-disrupting agents, suggesting that it may have additional cellular effects. Previously, we demonstrated that paclitaxel can induce interleukin-8 (IL-8) gene expression at the transcriptional level in subsets of human ovarian cancer lines. In this as well as the previous report, we present evidence that this ability is not linked to the lipopolysaccharide pathway of IL-8 gene induction. The present study identifies the cis-acting elements and trans-acting factors involved in this induction by transfecting DNA constructs containing the 5'-flanking region of the IL-8 gene linked to the chloramphenicol acetyltransferase reporter gene into paclitaxel-responsive and nonresponsive ovarian cancer cells (responsiveness refers to the IL-8 response). Paclitaxel only activated the IL-8 promoter in responsive cells. The AP-1 and NF-kappaB binding sites in the IL-8 promoter are required for activation by paclitaxel; in contrast, a C/EBP site required for IL-8 promoter activation in other cell types is not involved. Gel shift assays demonstrate that paclitaxel causes a marked increase in protein binding to the NF-kappaB and AP-1 consensus binding sequences in the paclitaxel-responsive ovarian cells, but not the nonresponsive cells. The induction of NF-kappaB and AP-1 binding is reduced by the addition of protein kinase C inhibitors and cyclic AMP effector, respectively. These results demonstrate a molecular mechanism for cell-specific paclitaxel-induced IL-8 gene expression which may have clinical relevance.

Marek's disease virus EcoRI-Q gene (meq) and a small RNA antisense to ICP4 are abundantly expressed in CD4+ cells and cells carrying a novel lymphoid marker, AV37, in Marek's disease lymphomas

Mature lymphomas produced in Rhode Island Red (RIR) chickens infected with the RB1B strain of Marek's disease virus (MDV) were examined for the presence of viral DNA and RNA and expression of viral antigens. In situ hybridization showed that all tumours examined contained viral DNA in areas of lymphoid infiltration. In 3/5 tumours, there was a correlation between the number and distribution of cells expressing the Marek's disease EcoRI-Q gene (meq) and those that carried the lymphoid cell marker AV37. Expression of the MDV-specific phosphoprotein pp38 was infrequent in lymphomas but abundant in a splenic tumour which also expressed the viral glycoprotein gB. Northern blot analysis of lymphocyte fractions purified by immunoaffinity showed that CD4+ and AV37+ fractions from lymphomas expressed meq and the small RNA antisense to ICP4 (SAR). The results are consistent with the notion that transformed cells are CD4+ cells, carrying the AV37 marker and expressing meq and SAR.

A simple immunoperoxidase plaque assay to detect and quantitate Marek's disease virus plaques

We report an immunoperoxidase-based staining technique that can be used to rapidly and accurately detect and quantitate Marek's disease virus (MDV) plaques. Monolayer cultures were fixed and incubated with a monoclonal antibody specific for MDV. After washing, a second antibody of horseradish peroxidase-conjugated goat anti-mouse IgG was applied, incubated for 1 hr, and washed with phosphate-buffered saline. After the cultures were incubated with diaminobenzidine, CoCl2, and H2O2, the plaques appeared as black spots and were easily seen and counted. Significantly more immunoperoxidase-stained serotype 1 MDV plaques could be counted at 4 days postinoculation than were seen in unstained cultures. With serotype 2 MDV-infected cells, the difference in plaque counts was less dramatic. Nevertheless, at 3 days postinoculation, significantly more stained serotype 2 plaques were seen than unstained plaques. Immunoperoxidase staining of turkey herpesvirus plaques did not increase the sensitivity of viewing plaques. Similar numbers of stained and unstained plaques were seen at 2 days postinoculation. We also demonstrated that we could count serotype-specific MDV plaques in a mixed infection that contained all three serotypes.

Synthesis and biological evaluation of the 1,5-diarylpyrazole class of cyclooxygenase-2 inhibitors: identification of 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benze nesulfonamide (SC-58635, celecoxib)

A series of sulfonamide-containing 1,5-diarylpyrazole derivatives were prepared and evaluated for their ability to block cyclooxygenase-2 (COX-2) in vitro and in vivo. Extensive structure-activity relationship (SAR) work was carried out within this series, and a number of potent and selective inhibitors of COX-2 were identified. Since an early structural lead (1f, SC-236) exhibited an unacceptably long plasma half-life, a number of pyrazole analogs containing potential metabolic sites were evaluated further in vivo in an effort to identify compounds with acceptable pharmacokinetic profiles. This work led to the identification of 1i (4-[5-(4-methylphenyl)-3-(trifluoromethyl)- H-pyrazol-1-yl]benzenesulfonamide, SC-58635, celecoxib), which is currently in phase III clinical trials for the treatment of rheumatoid arthritis and osteoarthritis.

Nucleolar and nuclear localization properties of a herpesvirus bZIP oncoprotein, MEQ

Marek's disease virus (MDV) is one of the most oncogenic herpesviruses and induces T lymphomas in chickens within weeks after infection. Only a limited number of viral transcripts are detected in MDV tumor samples and cell lines. One of the major transcripts encodes MEQ, a 339-amino-acid bZIP protein which is homologous to the Jun/Fos family of transcription factors. The C-terminal half of MEQ contains proline-rich repeats and, when fused to the DNA-binding domain of a yeast transcription factor, Gal4 (residues 1 to 147), exhibits transactivation function. MEQ can dimerize with itself and with c-Jun. The MEQ-c-Jun heterodimers bind to an AP-1-like enhancer within the MEQ promoter region with greater affinity than do homodimers of either protein, and they transactivate MEQ expression. Here we show that MEQ is expressed in the nucleus but, interestingly, with a predominant fraction in the nucleoli and coiled bodies. This makes MEQ the first bZIP protein to be identified in the nucleoli. MEQ contains two stretches of basic residues, designated basic region 1 (BR1) and basic region 2 (BR2). Using a series of deletion mutants, we have mapped the primary nuclear localization signal (NLS) and the sole nucleolar localization signal (NoLS) to the BR2 region. BR1 was shown to provide an auxiliary signal in nuclear translocation. To demonstrate that BR2 is an authentic NoLS, BR2 was fused to cytoplasmic v-Raf (delta gag) kinase. The BR2-Raf fusion protein was observed to migrate into the nucleoplasm and the nucleolus. The BR2 region can be further divided into two long arginine-lysine stretches, BR2N and BR2C, which are separated by the five amino acids Asn-Arg-Asp-Ala-Ala (NRDAA). We provide evidence that the requirement for nuclear translocation is less stringent than that for nucleolar translocation, as either BR2N or BR2C alone is sufficient to translocate the cytoplasmic v-Raf (delta gag) into the nucleus, but only in combination can they translocate v-Raf (delta gag) into the nucleolus. Our studies demonstrate that MEQ is both a nuclear and nucleolar protein, adding MEQ to the growing list of transactivators which localize to the nucleolus.

Retroviral insertional mutagenesis of a herpesvirus: a Marek's disease virus mutant attenuated for oncogenicity but not for immunosuppression or in vivo replication

Our earlier studies have shown that retrovirus insertion into herpesvirus is an efficient process that engenders recombinant herpesviruses with altered biological properties. The RM1 clone is derived from the JM strain of Marek's disease virus (MDV) through retrovirus insertional mutagenesis and contains sequences of reticuloendotheliosis virus inserted at the junction of the internal repeat and unique short regions of the genome. In previous studies, the RM1 clone appeared attenuated for oncogenicity but caused marked atrophy of the thymic lobes. The present studies represent a detailed analysis of the biological characteristics of the RM1 clone in order to better understand mechanisms of oncogenicity and gene function of MDV. RM1 was almost fully attenuated for oncogenicity but retained other in vivo properties of virulent viruses such as thymic and bursal atrophy, early immunosuppression, early cytolytic infection followed by efficient replication, and contact spread--all normally absent in attenuated strains. This suggests that, for serotype 1 MDV, oncogenicity is not tightly linked with immunodepression or viral replication and that these properties may be controlled by different genes or mechanisms. The mutation was stable through serial passage of the virus in chickens as determined by molecular analysis. None of the mutant viruses demonstrated expansion of the 132-bp repeat region of the genome, indicating that such expansion is not required for attenuation. Chickens vaccinated with RM1 clones were protected against challenge with virulent MDV, and levels of protection exceeded those of other attenuated serotype 1 vaccine viruses. Thus, attenuation by selective mutation may be an advantageous strategy for development of serotype 1 Marek's disease vaccines.

Glycaemic and insulin responses of diabetic patients to traditional Malaysian meals and the effect of guar gum

The aims of the project were to determine the glycaemic and insulin responses of non-insulin dependent diabetic patients (NIDDM) to 3 traditional Malaysian meals compared to oral glucose, and to determine whether guar gum would affect these responses. Patients with NIDDM were tested with 75 g oral glucose and three common breakfast meals of the three main ethnic groups of Malaysia. When compared with the oral glucose group, significantly by lower blood glucose responses were seen at 90 and 120 minutes post prandial for nasi lemak (p<0.05) and at 60, 75 and 90 minutes for mee sup (p<0.05). No significant difference was seen for roti telur. There was no significant difference in plasma glucose at any time point of the study when the three test meals were compared with each other. Addition of 5g granulated guar gum mixed with water taken prior to the glucose significantly lowered the plasma glucose at 60, 120 and 150 minutes postprandially (p<0.05). Similarly for the test meals, guar gum significantly lowered plasma glucose concentration between 15 and 45 minutes (p<0.03) postprandial for nasi lemak and between 15 and 30 minutes (p<0.03) for mee sup but not with roti telur. With addition of guar gum, there was no significant change of insulin responses with the three meals but a significant increase was seen at 30 minutes (p<0.02) after ingestion of glucose.

Protection and synergism by recombinant fowl pox vaccines expressing genes from Marek's disease virus

Recombinant fowl poxviruses (rFPV) were constructed to express genes from serotype 1 Marek's disease virus (MDV) coding for glycoproteins B (gB1), C (gC), and D (gD) and tegument proteins UL47 and UL48, as well as genes from serotypes 2 and 3 MDV coding for glycoprotein B (gB2 and gB3). These rFPVs, alone and in various combinations, including combinations of fowl poxvirus (FPV)/gBs with turkey herpesvirus (HVT), were evaluated for ability to protect maternal antibody-positive (ab+) and -negative (ab-) chickens against challenge with highly virulent MDV isolates. The protective efficacy was also compared with that of prototype Marek's disease (MD) vaccines. No protection was induced in ab+ chickens by rFPV expressing gC, gD, UL47, or UL48. In contrast, the rFPV/gB1 construct protected about 23% of ab+ chickens against MDV challenge compared with 26% for cell-associated HVT. Levels of protection by rFPV/gBs of different MDV serotypes was highest for gB1, intermediate for gB2, and lowest for gB3. When rFPV/gB1 was combined with cell-associated HVT, protection was enhanced by an average of 138% compared with the best component monovalent vaccine, and the mean level of protection was 59% compared with 67% for the HVT+SB-1 bivalent vaccine. Relatively high protection (50%) and enhancement (200%) were also observed between rFPV/gB1 and cell-free HVT. These results suggest a specific synergistic interaction between rFPV/gB1 and HVT, possibly analogous to that previously described between serotypes 2 and 3 viruses. Levels of protection by rFPV/ gB1 alone or by bivalent rFPV/gB1+cell-associated HVT were similar to those of conventional cell-associated MD vaccines. However, the bivalent rFPV/gB1+cell-free HVT vaccine was clearly more protective than cell-free HVT alone and, thus, may be the most protective, entirely cell-free MD vaccine thus far described.

Taxol-dependent transcriptional activation of IL-8 expression in a subset of human ovarian cancer

Taxol is important in the treatment of both primary and drug-resistant ovarian cancer. Although Taxol is known to stabilize microtubules and block cell mitosis, the effectiveness of this drug exceeds that of other antimitotic agents, suggesting it may have an additional mode of action. Stimulated by murine macrophage studies indicating cytokine induction by Taxol, we have investigated proinflammatory cytokine expression in a series of cell lines and recent explants of human ovarian cancer. Taxol induced secretion of interleukin (IL) 8 but not IL-6, IL-1alpha, or IL-1beta in 4 of 10 samples. Induction was dependent on transcriptional activation, and, in contrast to murine macrophage studies, was apparently independent of an active lipopolysaccharide signaling pathway. Confluent cultures secreted as much IL-8 as proliferating cells. Taxol did not induce IL-8 in breast carcinoma, endometrial stromal, or T-lymphocyte or monocyte cultures. We propose that the local expression of this chemokine in vivo may elicit a host response similar in effectiveness to that of cytokine gene therapy. These data are the first to suggest that a chemotherapeutic agent may have a direct effect on transcription of cytokine and/or growth factor genes in ovarian cancer, and that this effect may not be restricted to proliferating tumor cells.

Identification and characterization of a Marek's disease virus gene encoding DNA polymerase

DNA sequence analysis revealed a gene encoding the Marek's disease virus (MDV) DNA polymerase (pol) within the BamHI-E fragment of the long unique region of the virus genome. Identification is based on an extensive amino acid homology between the MDV open reading frame and the DNA pol (UL30) of the herpes simplex virus. We describe here a 3540-base-pair fragment of the MDV DNA encoding 1180 amino acids with a M(r) of 133,920 daltons as the viral DNA pol gene, with the analysis of transcription and translation. In Northern blot hybridization, a transcript of 4.0 kb was detected in GA-MDV-infected duck embryo fibroblast (DEF) cells. An antiserum was generated in rabbit using TryE-pol fusion protein expressed in E. coli. This antiserum specifically immunoprecipitated a protein of 135 kD from lysates of MDV-GA-infected DEF cells. MDV DNA pol showed extensive homology to five distantly related herpesviruses: equine herpesvirus (EHV), varicella-zoster virus (VZV), herpes simplex virus type 1 (HSV-1), Epstein-Barr virus (EBV), and human cytomegalovirus (HCMV). Comparison of amino acid sequences among the herpesviruses highlights nine highly conserved regions. Three of the conserved regions are in the N-terminus in the 3'-5' exonuclease domains and the remaining six are in the C-terminus in the catalytic domains. The predicted structural characters are in good agreement with the published data on a number of human herpesvirus DNA pol. The identification of MDV DNA pol gene may lead to a better understanding of MDV replication.

Characteristics of CVI988/Rispens and R2/23, two prototype vaccine strains of serotype 1 Marek's disease virus

Studies were focused on two attenuated serotype 1 Marek's disease (MD) vaccine viruses, CVI988/Rispens (passage 42) and R2/23 (passage 105). Both serotype 1 vaccine viruses provided much higher levels of protection than the prototype MD vaccine, turkey herpesvirus (HVT); the best protection was generally provided by CVI988/Rispens when compared with other vaccines. The efficacy of neither serotype 1 vaccine was improved by mixture with viruses of other serotypes (synergism). No differences between the two serotype 1 vaccines were revealed by cross-neutralization tests, thus excluding preferential in vivo neutralization by maternal antibodies as an explanation for differences in protective efficacy. Neither vaccine strain induced MD lesions or reduced growth rates in 8- or 18-week trials. Neither virus depressed humoral or cellular immune responses to antigenic challenge at 3 or 15 days after vaccination. Both virus strains exhibited altered characteristics during serial backpassage; R2/23 acquired increased oncogenic potential, and CVI988/Rispens acquired the potential for increased viremia titers, accompanied by an increased frequency of both histologic nerve lesions and gross thymic atrophy. During backpassage trials, contact spread was not observed for R2/23 and, surprisingly, seemed relatively limited for CVI988/Rispens. Studies on these two serotype 1 strains generally support the safety and efficacy of the serotype 1 class of MD vaccines.

Mutational analysis of the proteolytic cleavage site of glycoprotein B (gB) of Marek's disease virus

The Marek's disease virus (MDV) glycoprotein B (gB) precursor, gp100, is proteolytically cleaved into two disulfide-linked subunits, gp60 and gp49. In the gB homologs of most other herpesviruses, a tetrapeptide, Arg-Xaa-Arg-Arg, is immediately upstream from the predicted cleavage site. We have investigated the specificity of the proteolytic cleavage in gp100 by introducing mutations within its predicted cleavage site (Arg-Leu-Arg-Arg) and expressed these mutants in recombinant fowlpox virus (FPV). The results show that all three Arg residues at the predicted cleavage site play an important role in the specific proteolytic cleavage of gp100. Furthermore, we demonstrated that the cleavage of gp100 is not necessary for transport of gB to the cell surface.

Identification and characterization of Marek's disease virus genes homologous to ICP27 and glycoprotein K of herpes simplex virus-1

We have identified two Marek's Disease Virus (MDV) genes within the EcoRI-B fragment of MDV-GA genomic DNA. EcoRI-B is 11.3-kb long and maps within the long unique region of MDV genomes. A 3.2-kb fragment of EcoRI-B has been sequenced and contains two open reading frames, ORF53 and ORF54. ORF53 (MDV gK), a homolog to HSV-1 glycoprotein K (gK), is 1062 nucleotides long and encodes 354 amino acids (39.5 kDa). ORF54, designated MDV ICP27, based on significant similarity to HSV-1 ICP27, is 1419 nucleotides long and encodes 473 amino acids (54.5 kDa). In Northern blot hybridization, two overlapping transcripts (2.9 and 1.6 kb) were detected in MDV-infected DEF cells treated with cycloheximide, suggesting that both transcripts belong to the immediate-early gene family. Amino acid sequence analysis of MDV gK shows some common glycoprotein features, including a putative N-terminal signal sequence, four N-linked glycosylation sites, and four potential transmembrane domains. Comparison of the predicted amino acid sequence of MDV ICP27 with that of HSV-1 ICP27 and VZV ORF4 shows a high degree of conservation within the C-terminus. The C-terminal region of HSV-1 ICP27 has been demonstrated to be critical to its function. A conserved zinc finger metal-binding motif C(442)-X4-C(447)-X13-H(461)-C(467) was also found in the C-terminus of MDV ICP27. Furthermore, MDV ICP27 upstream sequences contain four copies of consensus sequence elements similar to the tegument protein target sequence TAATGARAT. TrpE-ICP27 fusion protein was expressed in Escherichia coli, and rabbit antisera were generated using purified fusion protein. A 55-kDa protein has been detected in both MDV-GA- and Md11-infected cells using immunoblot analysis.

Identification and characterization of a Marek's disease virus gene homologous to glycoprotein L of herpes simplex virus

We have identified three Marek's disease virus (MDV) open reading frames (ORFs) within the BamHI D fragment of MDV genome. The predicted polypeptides are homologous to UL1 (glycoprotein L, gL), UL2 (uracil-DNA glycosylase), and UL3 (nuclear localizing phosphoprotein) of herpes simplex virus type 1 (HSV-1). Comparison of the deduced amino acid sequences of these three ORFs with HSV-1 counterparts revealed overall identities of 18, 43, and 49%, respectively. In spite of the low overall amino acid identity with HSV-1 gL, the first open reading frame was identified as a gL homolog of HSV-1 based not only on the gene arrangement but also on a limited amino acid conservation among gL homologs of alpha-herpesviruses. To characterize the expression of the MDV gL gene, an antiserum to a hydrophilic region of the gene expressed in a bacterial expression vector was produced. Immunoprecipitation with this antiserum revealed a 25,000-Da polypeptide in MDV-infected cells. Furthermore, the 25,000-Da polypeptide migrated as a 18,000-Da polypeptide following PNGase F treatment. This result is consistent with the predicted molecular weight of MDV gL, considering the two potential N-glycosylation sites and the predicted N-terminal signal sequence. A recombinant fowlpox virus expressing the MDV gL gene was generated to characterize this glycoprotein. Unlike gL in MDV-infected cells, gL expressed by recFPV-gL was highly sensitive to Endo H, indicating that it was probably retained in the endoplasmic reticulum and was not properly processed to a mature form. Therefore, similar to HSV-1 coexpression and complex formation of MDV gL and gH may be required for proper processing and transport of gL to the cell surface.

The glycoprotein B genes of Marek's disease virus serotypes 2 and 3: identification and expression by recombinant fowlpox viruses

The nucleotide sequences of the glycoprotein B (gB) genes of Marek's disease virus (MDV) serotypes 2 and 3 were determined (gB-2 and gB-3, respectively). The genomic locations of these genes coincide with that of the gB gene of serotype 1 MDV (gB-1). Alignment with gB-1 (Ross et al., 1989, J. Gen. Virol. 70, 1789-1804) revealed predicted amino acid identities of 83 and 82% for gB-2 and gB-3, respectively. Excluding the predicted N-terminal signal sequences, 8 of 9 potential N-linked glycosylation sites and all 10 cysteine residues in gB-1 are conserved in both gB-2 and gB-3. In addition, the putative proteolytic cleavage sites for processing of precursors (gp100s) to gp60s and gp49s are conserved among the three gB homologs. Fowlpox virus (FPV) recombinants expressing either the gB-2 or the gB-3 gene were constructed. We detected expression of authentic gB-2 and gB-3 complexes in cells infected with these FPV recombinants. Digestion of immunoprecipitated gB-1 and gB-3 with endoglycosidases revealed that both gp60s are modified by the additions of O-glycans and complex carbohydrates after cleavage of gp100s, while gp100s and gp49s contain only high-mannose carbohydrates. We confirm that the size differences between gB-1 and gB-3 complexes are due to different carbohydrate modifications.

Nucleotide and predicted amino acid sequences of Marek's disease virus homologues of herpes simplex virus major tegument proteins

The DNA sequence of an 8.4 kbp BamHI-EcoRI fragment of Marek's disease virus (MDV) strain GA was determined. Three of the predicted polypeptides are homologous to UL47, UL48 and UL49 encoding the major tegument proteins of herpes simplex virus type 1 (HSV-1), and four are homologous to HSV-1 UL45, UL46, UL49.5 and UL50. These seven genes are found in the long unique region of the MDV genome and are collinear with homologues in HSV-1 and varicella-zoster virus (VZV). Northern blot analysis revealed different transcriptional patterns from those of HSV-1 and VZV. MDV homologues of UL49.5, UL49 and UL47 lack a poly(A) signal immediately downstream of their coding regions. Amino acid conservation between MDV and HSV-1, and between MDV and VZV is as high as that between HSV-1 and VZV. The MDV homologue of UL48 shows 60% similarity to its HSV-1 counterpart. Amino acid sequence comparison reveals that the MDV homologue of UL48 lacks an acidic carboxyl terminus. This homologue, like the VZV homologue of UL48, may be involved in the trans-activation of immediate early genes and may function as an important component of the structural proteins.

Characterization of a monoclonal antibody against a nuclear antigen associated with serotype-1 Marek's disease virus-infected and transformed cells

A monoclonal antibody (MAb), 2BN90, was characterized on a panel of Marek's disease virus (MDV) isolates representing three antigenically related serotypes and lymphoblastoid cell lines established from Marek's disease (MD) tumors. It was reactive with all serotype 1 isolates, including CV1988, in both enzyme-linked immunosorbent assay (ELISA) and immunofluorescence (IF) test. The MAb immunoprecipitated and immunoblotted a 40-kilodalton protein, which was found to be phosphorylated by metabolic labeling with 32P inorganic phosphate, and localized to the cell nucleus using the IF test. It reacted with MDV-transformed lymphoblastoid cell lines, and the percentage of reactive cells was enhanced after treatment with iododeoxyuridine. MAb 2BN90 may be useful as a type-specific antibody of choice for serotyping MDV serotype 1 strains and as a probe for studying the role of pp40 in MDV infection and transformation.

Recombinant fowlpox viruses expressing the glycoprotein B homolog and the pp38 gene of Marek's disease virus

Two Marek's disease virus (MDV) genes, one homologous to the glycoprotein B gene of herpes simplex virus and encoding the B antigen complex and the other encoding a 38-kDa phosphorylated protein (pp38), were inserted into the fowlpox virus (FPV) genome under the control of poxvirus promoters. Randomly selected nonessential regions of FPV were used for insertion, and the vaccinia virus 7.5 kDa polypeptide gene promoter or a poxvirus synthetic promoter was used for expression of MDV genes. Gene expression in cells infected with these recombinants was highly influenced by the promoter (the synthetic promoter being more effective) but was only slightly influenced by the insertion site and by the transcription direction of the insert relative to the direction of the flanking FPV sequences. Cells infected with an FPV recombinant expressing the MDV gB gene reacted positively with a monoclonal antibody specific to this glycoprotein in an immunofluorescence assay. Immunoprecipitation of infected cell lysates showed three glycoproteins identical to those associated with the B antigen complex of MDV (100, 60, and 49 kDa). Cells infected with a recombinant expressing the pp38 gene reacted positively with an anti-pp38 monoclonal antibody in an immunofluorescence assay. The generated protein was phosphorylated and had a molecular weight similar to that of the native pp38 protein. Sera from chickens immunized with an FPV recombinant expressing the MDV glycoprotein B gene reacted with MDV-infected cells.

Protection against Marek's disease by a fowlpox virus recombinant expressing the glycoprotein B of Marek's disease virus

Fowlpox virus (FPV) recombinants expressing the glycoprotein B and the phosphorylated protein (pp38) of the GA strain of Marek's disease virus (MDV) were assayed for their ability to protect chickens against challenge with virulent MDV. The recombinant FPV expressing the glycoprotein B gene elicited neutralizing antibodies against MDV, significantly reduced the level of cell-associated viremia, and, similar to the conventional herpesvirus of turkeys, protected chickens against challenge with the GA strain and the highly virulent RB1B and Md5 strains of MDV. The recombinant FPV expressing the pp38 gene failed to either elicit neutralizing antibodies against MDV or protect the vaccinated chickens against challenge with MDV.

Clinical panel assessment of photodamaged skin treated with isotretinoin using photographs

BACKGROUND AND DESIGN

Evaluation of the treatment of photodamaged skin requires adequate efficacy criteria. This study tested the ability of five independent dermatologists to distinguish the effect of topical treatment with isotretinoin cream (0.05% for 3 months, then 0.1% for 6 months) in 326 patients compared with vehicle for 9 months in 325 patients using high-quality, reproducible photographic slides. Panelists were blinded to the patient's identity, treatment group, and time of the photograph (baseline or end of treatment). A computer randomly projected the baseline photograph to one side of a split screen and the end-of-treatment photograph to the other.

OBSERVATIONS

Isotretinoin was significantly better than vehicle for overall appearance, fine wrinkles, and discrete pigmentation by multivariate analysis of the combined results for all panelists. Univariate analysis for each panelist also indicated statistically significant superiority of isotretinoin over vehicle for overall appearance (four panelists), fine wrinkles (five panelists), and discrete pigmentation (three panelists).

CONCLUSION

The clinical panel detected significantly better improvement in photodamaged-skin treated with isotretinoin than in such skin treated with vehicle. The panel provided an independent assessment of the effects of treatment uninfluenced by physical findings during treatment or information provided by the patients treated.

Structural polypeptides of type II avian adenoviruses analyzed by monoclonal and polyclonal antibodies

Polypeptides of hemorrhagic enteritis virus (HEV) of turkeys and marble spleen disease virus (MSDV) of pheasants were analyzed by immune precipitation and immunoblot assays. A total of 11 polypeptides ranging in molecular weight from 14,000 to 97,000 were detected in lysates of HEV-infected turkey cells analyzed by immunoblot assay using a polyclonal antibody against HEV. Identical patterns were observed with preparations of MSDV. Five monoclonal antibodies (MAbs) against HEV were chosen based on their virus neutralization activity and used for identification of neutralizing epitopes of these two viruses. Three MAbs precipitated a single 97,000-molecular-weight hexon polypeptide in an immune precipitation assay.

Structural analysis and transcriptional mapping of the Marek's disease virus gene encoding pp38, an antigen associated with transformed cells

The gene encoding a Marek's disease virus (MDV) pp38 phosphoprotein has been identified, sequenced, and localized to the BamHI H fragment to the left of the putative MDV origin of replication. The open reading frame was defined by sequencing of a lacZ-pp38 fusion protein gene from a lambda gt11 expression library. The entire open reading frame is 290 amino acids long and codes for a protein with a calculated molecular weight of 31,169, compared with the size of 38 kDa of the phosphorylated form estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. S1 nuclease protection analysis showed that the pp38 gene is transcribed leftward as an unspliced mRNA. On the basis of transcriptional mapping studies, the pp38 transcript is predicted to be about 1.8 kb in length without a poly(A) sequence. Its promoter-enhancer region overlaps that of the major rightward BamHI H 1.8-kb transcript implicated in tumor induction. This region contains Oct-1, Sp1, and CCAAT motifs as well as the putative origin of replication. The pp38 protein is the only presently known antigen that is consistently associated with the transformation state. It may play a significant role in MDV transformation.