A cost comparison study to review community versus acute hospital models of nursing care delivered to oncology patients

PURPOSE

Ireland's Sláintecare health plan is placing an increased focus on primary care. A community oncology nursing programme was developed to train community nurses to deliver care in the community. While the initial pilot was proven to be clinically safe, no cost evaluation was carried out. This study aims to compare the costs of providing cancer support services in a day-ward versus in the community.

METHODS

183 interventions (40 in day-ward and 143 in community) were timed and costed using healthcare professional salaries and the Human Capital method.

RESULTS

From the healthcare provider perspective, the day-ward was a significantly cheaper option by an average of €17.13 (95% CI €13.72 - €20.54, p < 0.001). From the societal perspective, the community option was cheaper by an average of €2.77 (95% CI -€3.02 - €8.55), although this was a non-significant finding. Sensitivity analyses indicate that the community service may be significantly cheaper from the societal perspective.

CONCLUSIONS

Given the demand for cost-viable options for primary care services, this programme may represent a national option for cancer care in Ireland when viewed from the societal perspective.

Abstract B163: Identification and preclinical characterisation of VER-250840, a potent, selective Chk1 inhibitor with in vivo oral single-agent antitumor activity

On sustaining damage to their DNA, cells employ a sophisticated mechanism of detection and repair, termed the DNA damage response (DDR). As a critical component of the DDR and G2/M checkpoint, Chk1 kinase represents an attractive target for cancer therapy. We have utilized a structure-based drug design approach to identify and develop VER-250840, a novel, orally active inhibitor of the checkpoint kinase, Chk1. VER-250840 exhibited sub-nM potency against Chk1 kinase with exquisite selectivity over an extensive and diverse panel of kinases. In vitro, VER-250840 inhibited Chk1 autophosphorylation with an IC50 of 1.0 nM and increased the number of S-phase tumor cells staining positive for pan-nuclear γH2AX with an EC50 of 7 - 27 nM. Accumulated genomic DNA damage by Chk1 inhibition led to irreversible cell cycle arrest, inhibition of tumor cell proliferation, increased replication stress, and cell death in both 2D culture and multicellular tumor spheroids. In an in vivo A2058 tumor xenograft PD study, VER-250840 demonstrated rapid and sustained inhibition of Chk1 auto-phosphorylation within 30 minutes of oral administration. Doses of 10 mg/kg and higher PO resulted in greater than 90% inhibition of tumor pChk1 (S296) over 24 hours. In SKOV3 in vivo models, VER-250840 inhibited Chk1 auto-phosphorylation, modulated other biomarkers of replication stress and DNA damage, and exhibited moderate antitumor activity with minimal toxicity when administered orally on a 21-day once-daily schedule. Work is ongoing to further optimize in vivo efficacy. In conclusion, VER-250840 demonstrates potent and selective activity as a monotherapy both in vitro and in vivo. From these findings, further evaluation and optimization of this novel kinase inhibitor is justly merited.

Citation Format: Joanne Wayne, Stephen Stokes, Nicolas Foloppe, Helen Browne, Teresa Brooks, Karen Benwell, Lisa Baker, Zoe Daniels, Andrea Fiumana, Christopher Graham, Alba Macias, Daniel Maddox, Sean McKenna, Christopher Northfield, Stuart Ray, Heather Simmonite, Emma Stefaniak, Paul Webb, Mike Wood, Andrew Massey. Identification and preclinical characterisation of VER-250840, a potent, selective Chk1 inhibitor with in vivo oral single-agent antitumor activity [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B163.

Identification of novel, in vivo active Chk1 inhibitors utilizing structure guided drug design

Chk1 kinase is a critical component of the DNA damage response checkpoint especially in cancer cells and targeting Chk1 is a potential therapeutic opportunity for potentiating the anti-tumor activity of DNA damaging chemotherapy drugs. Fragment elaboration by structure guided design was utilized to identify and develop a novel series of Chk1 inhibitors culminating in the identification of V158411, a potent ATP-competitive inhibitor of the Chk1 and Chk2 kinases. V158411 abrogated gemcitabine and camptothecin induced cell cycle checkpoints, resulting in the expected modulation of cell cycle proteins and increased cell death in cancer cells. V158411 potentiated the cytotoxicity of gemcitabine, cisplatin, SN38 and camptothecin in a variety of p53 deficient human tumor cell lines in vitro, p53 proficient cells were unaffected. In nude mice, V158411 showed minimal toxicity as a single agent and in combination with irinotecan. In tumor bearing animals, V158411 was detected at high levels in the tumor with a long elimination half-life; no pharmacologically significant in vivo drug-drug interactions with irinotecan were identified through analysis of the pharmacokinetic profiles. V158411 potentiated the anti-tumor activity of irinotecan in a variety of human colon tumor xenograft models without additional systemic toxicity. These results demonstrate the opportunity for combining V158411 with standard of care chemotherapeutic agents to potentiate the therapeutic efficacy of these agents without increasing their toxicity to normal cells. Thus, V158411 would warrant further clinical evaluation.

Do postmenopausal women with thickened endometrium on trans-vaginal ultrasound in the absence of vaginal bleeding need hysteroscopic assessment? A Pilot Study

We aimed to determine the incidence of endometrial cancer in a cohort of postmenopausal women with thickened endometrium but no bleeding referred for hysteroscopy and determine the risk estimate of cancer using a cut-off of > 11 mm. This retrospective study of asymptomatic postmenopausal women with thickened endometrium on trans-vaginal scan referred for hysteroscopy was performed using data from 2008 to 2010. In total 63 women were identified. 2 cases of endometrial cancer were identified with an incidence of 3.17%. 22 cases had endometrial thickness (ET) > 11 mm of which 2 were malignant giving a risk estimate for endometrial cancer of 9.1%. 61 women had benign pathology, 40.98% had atrophic endometrium and 59.02% had benign polyp. In conclusion, the incidence of endometrial cancer in postmenopausal women with thickened endometrium on transvaginal scan without vaginal bleeding is low and ET of 11 mm or more seems realistic to use as a cut-off for referral for hysteroscopy.

A novel, small molecule inhibitor of Hsc70/Hsp70 potentiates Hsp90 inhibitor induced apoptosis in HCT116 colon carcinoma cells

PURPOSE

The anti-apoptotic function of the 70 kDa family of heat shock proteins and their role in cancer is well documented. Dual targeting of Hsc70 and Hsp70 with siRNA induces proteasome-dependent degradation of Hsp90 client proteins and extensive tumor specific apoptosis as well as the potentiation of tumor cell apoptosis following pharmacological Hsp90 inhibition.

METHODS

We have previously described the discovery and synthesis of novel adenosine-derived inhibitors of the 70 kDa family of heat shock proteins; the first inhibitors described to target the ATPase binding domain. The in vitro activity of VER-155008 was evaluated in HCT116, HT29, BT474 and MDA-MB-468 carcinoma cell lines. Cell proliferation, cell apoptosis and caspase 3/7 activity was determined for VER-155008 in the absence or presence of small molecule Hsp90 inhibitors.

RESULTS

VER-155008 inhibited the proliferation of human breast and colon cancer cell lines with GI(50)s in the range 5.3-14.4 microM, and induced Hsp90 client protein degradation in both HCT116 and BT474 cells. As a single agent, VER-155008 induced caspase-3/7 dependent apoptosis in BT474 cells and non-caspase dependent cell death in HCT116 cells. VER-155008 potentiated the apoptotic potential of a small molecule Hsp90 inhibitor in HCT116 but not HT29 or MDA-MB-468 cells. In vivo, VER-155008 demonstrated rapid metabolism and clearance, along with tumor levels below the predicted pharmacologically active level.

CONCLUSION

These data suggest that small molecule inhibitors of Hsc70/Hsp70 phenotypically mimic the cellular mode of action of a small molecule Hsp90 inhibitor and can potentiate the apoptotic potential of a small molecule Hsp90 inhibitor in certain cell lines. The factors determining whether or not cells apoptose in response to Hsp90 inhibition or the combination of Hsp90 plus Hsc70/Hsp70 inhibition remain to be determined.

Abstract C207: Checkpoint abrogation and potentiation of cytotoxic chemotherapeutics with a novel checkpoint kinase 1 inhibitor

Conventional chemotherapeutic agents such as gemcitabine, cisplatin or irinotecan induce DNA damage and activate cell cycle checkpoints. P53 defective tumors lack a functional G1 checkpoint and rely heavily on the S and G2 checkpoints, and the effector kinase Chk1, for protection against this DNA damage. Inhibiting Chk1 potentiates the anti-tumor effects of these cytotoxic chemotherapeutic agents. Targeting Chk1 is a potential therapeutic opportunity for potentiating the anti-tumor efficacy of DNA damaging cytotoxic chemotherapeutic drugs without increasing their toxicity to normal cells. Elaboration of a designed kinase directed fragment core utilizing X-ray structure guided design lead to the identification of a potent pyridone series of Chk1 inhibitors. Further profiling identified V158411 as the lead candidate. X-ray crystallography identified V158411 as being bound to the ATPase site in the kinase domain of Chk1. V158411 potently inhibited Chk1 and Chk2 with IC50s of 4.4 and 4.5nM respectively. The addition of V158411 to gemcitabine or camptothecin treated cells abrogated the cell cycle checkpoints induced by these agents resulting in the expected modulation of cell cycle proteins and increased apoptosis. V158411 potentiated the cytotoxicity of gemcitabine, cisplatin, SN38 and camptothecin in a variety of p53 deficient but not proficient human tumor cell lines in vitro. V158411 could be formulated in a simple aqueous form suitable for i.v. dosing. In nude mice, V158411 was well tolerated as a single agent (MTD &gt;100mg/kg) and in combination with irinotecan. Intravenous administration to rats and mice resulted in low plasma clearances (20mL/min/kg) and long half-lives (2.9–3.7h). In tumor bearing animals, V158411 was detected at high concentrations in the tumor (tumor:plasma AUC ratio of 4.7) with a long tumor elimination half life of 22 hours. No pharmacologically relevant in vivo drug-drug interaction with irinotecan was identified. V158411 potentiated the anti-tumor activity of gemcitabine and irinotecan in a variety of human tumor xenograft models without additional systemic toxicity. These results demonstrate the potential of combining V158411 with standard of care chemotherapeutic agents to potentiate the therapeutic efficacy of these agents without increasing their toxicity to normal cells. Based on this data, the clinical development of V158411 is currently being actively pursued.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C207.

Characterization of the herpes simplex virus (HSV)-1 tegument protein VP1-2 during infection with the HSV temperature-sensitive mutant tsB7

VP1-2, encoded by the UL36 gene of herpes simplex virus (HSV), is a large structural protein, conserved across the family Herpesviridae, that is assembled into the tegument and is essential for virus replication. Current evidence indicates that VP1-2 is a central component in the tegumentation and envelopment processes and that it also possesses important roles in capsid transport and entry. However, any detailed mechanistic understanding of VP1-2 function(s) remains limited. This study characterized the replication of HSV-1 tsB7, a temperature-sensitive mutant restricted at the non-permissive temperature due to a defect in VP1-2 function. A tsB7 virus expressing green fluorescent protein-fused VP16 protein was used to track the accumulation and location of a major tegument protein. After infection at the permissive temperature and shift to the non-permissive temperature, the production of infectious virus ceased. VP1-2 accumulated in altered cytosolic clusters, together with VP16 and other virion proteins. Furthermore, correlating with the results of immunofluorescence, electron microscopy demonstrated abnormal cytosolic capsid clustering and a block in envelopment. As VP1-2 encompasses a ubiquitin-specific protease domain, the occurrence of ubiquitin-conjugated proteins during tsB7 infection was also examined at the non-permissive temperature. A striking overaccumulation was observed of ubiquitin-specific conjugates in cytoplasmic clusters, overlapping and adjacent to the VP1-2 clusters. These results are discussed in relation to the possible functions of VP1-2 in the assembly pathway and the nature of the defect in tsB7.

Human cytomegalovirus (HCMV)-infected endothelial cells and macrophages are less susceptible to natural killer lysis independent of the downregulation of classical HLA class I molecules or expression of the HCMV class I homologue, UL18

A number of reports have suggested that human cytomegalovirus (HCMV)-infected fibroblasts are resistant to natural killer (NK) lysis, and that the HCMV-encoded human leucocyte antigen (HLA) class I homologue UL18 may be responsible for this effect. While fibroblasts are easy to infect in vitro, their role in HCMV pathogenesis in vivo is unclear. Here, we have established systems to address NK recognition of infected endothelial cells and macrophages, two important HCMV cellular reservoirs in vivo. The HCMV-infected endothelial cells exhibited increased resistance to NK killing, and, in most experiments, infected macrophages demonstrated a decreased susceptibility to NK lysis. Infection with the mutant HCMV strain RV670, lacking the genes US1-9 and US11 that are responsible for downregulation of HLA class I molecules, also led to decreased NK susceptibility. Furthermore, reduced NK susceptibility was independent of the expression of the HLA class I homologue UL18, since cells infected with the UL18Delta HCMV strain were also less susceptible to NK killing. These results suggest that HCMV-induced resistance to NK cytotoxicity in endothelial cells and macrophages is independent of known pathways that interfere with the expression of cellular HLA class I A, B and C surface antigens and the HCMV encoded class I homologue UL18.

Herpes simplex virus nucleocapsids mature to progeny virions by an envelopment --> deenvelopment --> reenvelopment pathway

Herpes simplex virus (HSV) nucleocapsids acquire an envelope by budding through the inner nuclear membrane, but it is uncertain whether this envelope is retained during virus maturation and egress or whether mature progeny virions are derived by deenvelopment at the outer nuclear membrane followed by reenvelopment in a cytoplasmic compartment. To resolve this issue, we used immunogold electron microscopy to examine the distribution of glycoprotein D (gD) in cells infected with HSV-1 encoding a wild-type gD or a gD which is retrieved to the endoplasmic reticulum (ER). In cells infected with wild-type HSV-1, extracellular virions and virions in the perinuclear space bound approximately equal amounts of gD antibody. In cells infected with HSV-1 encoding an ER-retrieved gD, the inner and outer nuclear membranes were heavily gold labeled, as were perinuclear enveloped virions. Extracellular virions exhibited very little gold decoration (10- to 30-fold less than perinuclear virions). We conclude that the envelope of perinuclear virions must be lost during maturation and egress and that mature progeny virions must acquire an envelope from a post-ER cytoplasmic compartment. We noted also that gD appears to be excluded from the plasma membrane in cells infected with wild-type virus.

Effects of targeting herpes simplex virus type 1 gD to the endoplasmic reticulum and trans-Golgi network

Glycoprotein D (gD) of herpes simplex virus type 1 (HSV-1) was modified to encode targeting signals known to localize proteins to either the endoplasmic reticulum (ER) or the trans-Golgi network. These motifs conferred the predicted targeting properties on gD in transfected cells as judged by immunofluorescence staining, and the exclusion of targeted gD from the cell surface was confirmed by the fact that these molecules exhibited substantially reduced activity in cell-cell fusion assays. Recombinant viruses expressing Golgi-targeted forms of gD grew to wild-type levels in noncomplementing cells, exhibited unaltered particle/infectivity ratios, and were found to contain wild-type levels of gD, whereas a recombinant expressing ER-retained gD was helper cell dependent and, when grown on noncomplementing cells, produced virions of low specific infectivity with greatly reduced levels of gD. These data imply that HSV-1 acquires its final membrane from a post-ER compartment and lend support to the view that the virus undergoes de-envelopment and reenvelopment steps during virus egress.

Glycoproteins gB, gD, and gHgL of herpes simplex virus type 1 are necessary and sufficient to mediate membrane fusion in a Cos cell transfection system

Herpes simplex virus type 1 glycoproteins gB, gD, and gHgL were expressed by transient transfection of Cos cells. Polykaryocyte formation above the background level seen in untransfected controls was observed only if all three components were expressed. Thus, gB, gD, and gHgL are necessary and sufficient to induce membrane fusion.

Site-directed and linker insertion mutagenesis of herpes simplex virus type 1 glycoprotein H

The gH-gL complex of herpes simplex virus type 1 (HSV-1) is essential for virion infectivity and virus-induced cell fusion, but functional domains of the gH molecule remain to be defined. We have addressed this question by mutagenesis. A set of linker insertion mutants in HSV-1 gH was generated and tested in transient assays for their ability to complement a gH-negative virus. Insertions at three sites in the C-terminal third of the external domain affected the ability of gH to function in cell-cell fusion and virus entry, while insertions at six sites in the N-terminal half of the external domain induced conformational changes in gH such that it was not recognized by monoclonal antibody LP11, although expression at the cell surface was unchanged. A recombinant virus in which a potential integrin-binding motif, RGD, in gH was changed to the triplet RGE entered cells as efficiently as the wild type, indicating that HSV-1 entry is not mediated by means of the gH-RGD motif binding to cell surface integrins. Furthermore, mutagenesis of the glycosylation site which is positionally conserved in all herpesvirus gH sequences in close proximity to the transmembrane domain generated a recombinant virus that grew in vitro with wild-type single-step kinetics.

Enhancer stimulation unmasks latent gene transfer after adenovirus-mediated gene delivery into human vascular smooth muscle cells

Recombinant adenoviral vectors are being used increasingly for gene transfer studies in mammalian cells and gene therapy protocols in humans. High adenoviral titers are often required for successful transduction of vascular smooth muscle cells (VSMCs), defined as uptake and detectable expression of the foreign gene, but the relative contributions of efficiency of viral uptake and control of transcription are poorly understood. To explore the extent to which a lack of detectable gene expression may be due to inefficient transcription of a successfully transferred gene, we have used a replication-deficient adenovirus expressing beta-galactosidase (RAd35 beta-Gal), under the control of the human cytomegalovirus major immediate-early promoter (CMV-IEP), which contains cAMP and nuclear factor-kappa B response elements, to investigate constitutive and inducible gene expression after gene transfer into human VSMCs. Histochemical staining with 5-bromo-4-chloro-3-indolyl beta-D-galactopyranoside (X-gal), a quantitative spectrophotometric assay, SDS-PAGE, Western blotting, and Northern analysis were used to evaluate beta-galactosidase expression in infected cells. After infection with RAd35 beta-Gal at 30, 100, and 1000 plaque-forming units per cell (pfu/cell), expression of beta-galactosidase was augmented up to 17-, 19-, and 23-fold, respectively, in human VSMCs treated with forskolin and phorbol ester compared with unstimulated cells. After infection, the proportion of detectably transduced cells was increased by enhancer stimulation from 58% to 100% at 100 pfu/cell and from 9% to 62% at 10 pfu/cell, indicating quiescent viral DNA in unstimulated cells. At high adenoviral titers (1000 pfu/cell), the recombinant gene became the most abundant protein in cell extracts. These findings demonstrate that in human VSMCs, limited constitutive expression from the CMV-IEP, rather than failure of translocation of adenoviral DNA, may be responsible for the apparent failure of transduction at a low multiplicity of infection.

An endoplasmic reticulum-retained herpes simplex virus glycoprotein H is absent from secreted virions: evidence for reenvelopment during egress

Although it is generally accepted that one of the first steps of herpesvirus egress is the acquisition of an envelope by nucleocapsids budding into the inner nuclear membrane, later events in the pathway are not well understood. We tested the hypothesis that the virus then undergoes de-envelopment, followed by reenvelopment at membranes outside the endoplasmic reticulum (ER), by constructing a recombinant virus in which the expression of an essential glycoprotein, gH, is restricted to the inner nuclear membrane-ER by means of the ER retention motif, KKXX. This targeting signal conferred the predicted ER localization properties on gH in recombinant virus-infected cells, and gH and gL polypeptides failed to become processed to their mature forms. Cells infected with the recombinant virus released particles with 100-fold less infectivity than those released by cells infected with the wild-type parent virus, yet the number of enveloped virus particles released into the medium was unaltered. These particles contained normal amounts of gD and VP16 but did not contain detectable amounts of gH, and these data are consistent with a model of virus exit whereby naked nucleocapsids in the cytoplasm acquire their final envelope from a subcellular compartment other than the ER-inner nuclear membrane.

Analysis of the contributions of herpes simplex virus type 1 membrane proteins to the induction of cell-cell fusion

The contributions of a set of herpes simplex virus type 1 membrane proteins towards the process of cell-cell fusion were examined with a series of deletion mutants into which a syncytial mutation had been introduced at codon 855 of the glycoprotein B (gB) gene. Analysis of the fusion phenotypes of these recombinant viruses in Vero cells revealed that while gC, gG, US5, and UL43 are dispensable for syncytium formation at both high and low multiplicities of infection, gD, gHgL, gE, gI, and gM were all required for the fusion of cellular membranes. These data confirm that the requirements for virion entry and cell-cell fusion are not identical. gD and gHgL, like gB, are essential for both processes. gG, gI, and gM, on the other hand, are dispensable for virus penetration, yet play a role in cell-to-cell spread by the direct contact route, at least on an SC16 gBANG background.

An analysis of the in vitro and in vivo phenotypes of mutants of herpes simplex virus type 1 lacking glycoproteins gG, gE, gI or the putative gJ

Mutants of herpes simplex virus type 1 (HSV-1) lacking glycoproteins gG, gE, gI or the putative gJ were constructed by inserting a lacZ expression cassette within the US4, US8, US7 and US5 genes respectively. Revertant viruses were then constructed by rescue with a wild-type DNA fragment. Each of these mutant viruses, by comparison with the parental virus HSV-1 SC16, exhibited normal particle to infectivity ratios, and had no discernible phenotypic abnormalities in baby hamster kidney-21 cells following high or low multiplicity infections. Infection of mice by scarification of the ear with these mutant viruses showed the following. (i) Interruption of the US5 (gJ) gene has no effect on the ability of HSV-1 to multiply at the inoculation site or its ability to enter or multiply in the peripheral or central nervous system (CNS). This shows that the US5 gene provides a convenient site for the insertion of foreign genes for both in vitro and in vivo studies. (ii) Disruption of the US4 (gG) gene results in marginal attenuation in the mouse ear model. (iii) Disruption of the US7 (gI) or US8 (gE) genes results in pronounced attenuation; virus was rapidly cleared from the inoculation site and was barely detectable in sensory ganglia or in the CNS. The failure of gI-negative or gE-negative viruses to replicate efficiently at the inoculation site in vivo led to the investigation of virus behaviour in epithelial cells in vitro. Viruses lacking gE or gI adsorbed to and entered these cells at normal rates compared with the parental virus, but formed minute plaques. This is consistent with a failure of cell-to-cell spread by the cell contact route. This was confirmed by measurement of the rate of increase in infectious centre numbers following low multiplicity infections. The view that gE and gI influence interactions between cells at the plasma membrane was reinforced by showing that the introduction of disrupted gE or gI genes into a syncytial, but otherwise syngeneic, background resulted in a non-syncytial phenotype. We conclude that the gE-gI complex plays a part, at least in some cell types, in the interactions at the cell surface that allow transmission of the virus from infected to uninfected cells by cell contact. In syncytial strains this leads to uncontrolled membrane fusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Treatment with coumarin to prevent or delay recurrence of malignant melanoma

Both coumarin (1,2-benzopyrone) and warfarin (4-hydroxycoumarin) have been shown to prevent the recurrence of malignant melanoma. Their action is macrophage-dependent and the dosage is critical. In 1984 a multicentre, prospective, randomised, double-blind trial of coumarin, given as a daily 50-mg dose for 2 years after surgery in patients with high-risk melanoma, was started. the patients had lesions greater than 1.70 mm thick and TNM stage IB or stage II disease. To date there are 4 recurrences in the coumarin-treated group of 13 patients, and 10 recurrences in the placebo-treated group of 14 patients (P < 0.01). There were no toxic effects.

Analysis of protective immune responses to the glycoprotein H-glycoprotein L complex of herpes simplex virus type 1

A recombinant vaccinia virus expressing both glycoprotein H (gH) and glycoprotein L (gL) of herpes simplex virus type 1 (HSV-1) was used to examine the protective response to gH-gL in immunized mice and to compare these responses with those induced by the highly protective immunogen, glycoprotein D (gD). Weak levels of HSV-1-specific neutralizing antibody were obtained in response to the gH-gL complex, virus clearance from the site of challenge was marginally enhanced compared to that observed following immunization with gH alone, and gH-gL was found to protect mice against acute infection in the ganglia, although not as efficiently as gD.

Construction and characterization of a human cytomegalovirus mutant with the UL18 (class I homolog) gene deleted

The UL18 open reading frame of human cytomegalovirus (HCMV) (which encodes a product homologous to major histocompatibility complex class I heavy chains) has been disrupted by insertion of the beta-galactosidase gene under control of the major HCMV early promoter. The recombinant virus delta UL18 showed no phenotypic differences from wild-type HCMV in terms of single-step growth curves or particle/infectivity ratios, indicating that the UL18 gene product is dispensable for the growth of HCMV in human fibroblasts in vitro. The synthesis of the mature cellular class I heterodimer is shut down in cells infected at a high multiplicity with wild-type HCMV, and a similar effect was seen in delta UL18-infected fibroblasts, suggesting that although the UL18 gene product can associate with beta 2 microglobulin, it is not directly involved in the disruption of class I assembly.

The UL16 gene of human cytomegalovirus encodes a glycoprotein that is dispensable for growth in vitro

The UL16 gene of human cytomegalovirus (HCMV) encodes a predicted translation product with features characteristic of glycoproteins (signal and anchor sequences and eight potential N-linked glycosylation sites). Antisera were raised against the UL16 gene product expressed in Escherichia coli as a beta-galactosidase fusion protein. The antisera detected a 50-kDa glycoprotein in HCMV-infected cells that was absent from purified virions. The UL16 glycoprotein was synthesized at early times after infection and accumulated to the highest levels at late times after infection. A recombinant HCMV in which UL16 coding sequences were interrupted by a lacZ expression cassette was constructed by insertional mutagenesis. Analysis of the phenotype of the recombinant virus indicated that the UL16 gene product is nonessential for virus infectivity and growth in tissue culture.

A novel herpes simplex virus glycoprotein, gL, forms a complex with glycoprotein H (gH) and affects normal folding and surface expression of gH

A glycoprotein encoded by the UL1 gene of herpes simplex virus type 1 (HSV-1) was detected in infected cells with antipeptide sera. The UL1 gene has previously been implicated in virus-induced cell fusion (S. Little and P. A. Schaffer, Virology 112:686-697, 1981). Two protein species, a 30-kDa precursor form and a 40-kDa mature form of the glycoprotein, both of which were modified with N-linked oligosaccharides, were observed. This novel glycoprotein is the 10th HSV-1 glycoprotein to be described and was named glycoprotein L (gL). A complex was formed between gL and gH, a glycoprotein known to be essential for entry of HSV-1 into cells and for virus-induced cell fusion. Previously, it had been reported that gH expressed in the absence of other viral proteins was antigenically abnormal, not processed, and not expressed at the cell surface (U.A. Gompels and A. C. Minson, J. Gen. Virol. 63:4744-4755, 1989; A. J. Forrester, V. Sullivan, A. Simmons, B. A. Blacklaws, G. L. Smith, A. A. Nash, and A. C. Minson, J. Gen. Virol. 72:369-375, 1991). However, gH coexpressed with gL by using vaccinia virus recombinants was antigenically normal, processed normally, and transported to the cell surface. Similarly, gL was dependent on gH for proper posttranslational processing and cell surface expression. These results suggest that it is a hetero-oligomer of gH and gL which is incorporated into virions and transported to the cell surface and which acts during entry of virus into cells.

A complex between the MHC class I homologue encoded by human cytomegalovirus and beta 2 microglobulin

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that persists in the host and can cause severe disease in the immunocompromised individual or in the fetus. Analysis of the nucleotide sequence of the virus genome has revealed the presence of an open reading frame whose predicted translation product has homology with the heavy chain of the major histocompatibility complex (MHC) class I molecule of higher eukaryotes, and the observed sequence homology was given additional significance by the independent observation that HCMV virions can bind beta 2 microglobulin (beta 2m), the light chain of the MHC class I molecule. We expressed both the HCMV class I homologue and the human beta 2m gene in recombinant vaccinia viruses. We show that the coexpressed gene products associate, that the transport of beta 2m to the cell surface is dependent on coexpression of the class I homologue and that the viral gene product is therefore functionally related to its cellular counterpart. We observe also that, in HCMV-infected cells, no synthesis of mature cellular class I molecules occurs, while messenger RNA levels remain unaltered, and we speculate that one function of the viral homologue may be to sequester beta 2m, thus preventing the maturation of cellular class I molecules and rendering the infected cell unrecognizable by cytotoxic T cells.

Prevention of early recurrence of high risk malignant melanoma by coumarin. Irish Melanoma Group

Coumarin (1,2-benzopyrone) as a daily oral dose of 50 mg was evaluated in a multicentre prospectively randomized, double-blind, placebo-controlled trial to prevent early recurrence of malignant melanoma TNM Stage IB (Breslow thickness greater than 1.70 mm) and Stage II. Intake for the trial started in 1984 and was stopped prematurely, after review, in 1987. There were two recurrences in 13 treated patients and 10 in 14 controls which was significant (P 0.01). The sites of the metastases differed in each group, being local and in bone in the treated group, and in lymph nodes, skin and lung in the control group. There were no toxic effects associated with coumarin treatment and all patients without recurrence are now receiving coumarin.