Diagnosis and treatment of cytomegalovirus iridocyclitis without retinal necrosis.

AIM: To describe the diagnostic and therapeutic management of cytomegalovirus (CMV) anterior uveitis unassociated with retinal necrosis in immunocompetent patients. METHODS: Patients referred between 2001 and 2003 for management of unilateral, chronic, recurrent uveitis associated with secondary glaucoma underwent extensive investigation including laboratory tests for herpes virus infections. Specific antiviral treatment was initiated in all cases and the level of ocular inflammation was evaluated during the follow up. RESULTS: Five patients, three men and two women, were included. Median age was 50 years old (range 30-80 years). Anterior unilateral uveitis without iris atrophy was observed in all cases. Uveitis was chronic in three cases and recurrent in two cases. Glaucoma was observed in all patients with a median intraocular pressure of 30 mm Hg (range 22-43 mm Hg). Five patients responded initially to specific anti-CMV therapy. Even though glaucoma surgery was necessary in two cases, both ocular inflammation and glaucoma were controlled in all cases. Relapses occurred in three cases after cessation of therapy, requiring prolonged maintenance therapy with valganciclovir. CONCLUSIONS: CMV infection and specific antiviral therapy should be considered in all cases of relapsing or chronic iridocyclitis and secondary glaucoma. Maintenance regimens of valganciclovir may be necessary to prevent further relapses.

Viral chemokine receptors and chemokines in human cytomegalovirus trafficking and interaction with the immune system. CMV chemokine receptors.

The ubiquitous, opportunistic pathogen human cytomegalovirus (CMV) encodes several proteins homologous to those of the host organism. Four different CMV genes encode chemokine receptor-like peptides. These genes, UL33, UL78, US27, and US28, are expressed at various stages of infection in vitro. Their functions remain largely unknown. To date, chemokine binding and signalling has only been demonstrated for the US28 gene product. Putative ligands for the other CMV-encoded chemokine receptors are discussed on basis of phylogenetic analysis. The potential roles of these receptors in virus trafficking, persistence, and immune evasion are summarized. Similarly, modulation of expression of the host chemokines IL-8, MCP-1a and RANTES in relation to viral dissemination and persistence is reviewed.

Human cytomegalovirus infection of bone marrow myofibroblasts enhances myeloid progenitor adhesion and elicits viral transmission.

Human cytomegalovirus (CMV) infection of bone marrow transplant recipients can cause pancytopenia, as well as life-threatening interstitial pneumonia. CMV replicates actively in bone marrow stromal cells, whereas it remains latent in hematopoietic progenitors. Our aim was to study the influence of CMV infection on adherence of CD34(+) cells to the myofibroblastic component of human bone marrow and examine transmission of virus from myofibroblasts to CD34(+) cells. We show that smooth actin, but not fibronectin, organization is markedly modified by CMV infection of bone marrow stromal myofibroblasts. Nonetheless, CMV infection led to increased adherence of the CD34(+) progenitor cell line, KG1a, relative to adherence to uninfected myofibroblasts from the same donors. Adherence of CD34(+) cells to infected bone marrow myofibroblasts resulted in transfer of virions and viral proteins through close cell-to-cell contacts. This phenomenon may play a role in the pathophysiology of CMV bone marrow infection and in eventual virus dissemination.

Differentiation-dependent redistribution of heparan sulfate in epithelial intestinal Caco-2 cells leads to basolateral entry of cytomegalovirus.

Human cytomegalovirus (HCMV) causes a broad spectrum of clinical manifestations in immunocompromised patients, including infection of the gastrointestinal tract. To investigate the role of epithelial cells in the gastrointestinal HCMV disease, we used the intestinal epithelial cell line Caco-2, which is permissive for HCMV replication. In differentiated Caco-2 cells, we showed previously that HCMV infection proceeds preferentially from the basolateral membrane, suggesting that receptors for HCMV may be contained predominantly in the basolateral membrane (A. Esclatine et al., 2000, J. Virol. 74, 513-517). Therefore, we examined expression and localization in Caco-2 cells of heparan sulfate (HS) proteoglycan and annexin II, previously implicated in initial events of HCMV infection. We observed that annexin II is expressed in Caco-2 cells, but is not essential for entry of HCMV. We showed that, during the differentiation process, HS, initially present on the entire surface of the membrane of undifferentiated cells, ultimately became sequestered at the basolateral cell surface of fully differentiated cells. We established by biochemical assays that membrane-associated HS proteoglycan mediates both viral attachment to, and subsequent infection of, Caco-2 cells, regardless of the cell differentiation state. Thus, the redistribution of HS is implicated in the basolateral entry of HCMV into differentiated Caco-2 cells.

Human cytomegalovirus chemokine receptor gene US28 is transcribed in latently infected THP-1 monocytes.

The human cytomegalovirus (HCMV) US28 gene product, pUS28, is a G protein-coupled receptor that interacts with both CC and CX(3)C chemokines. To date, the role of pUS28 in immune evasion and cell migration has been studied only in cell types that can establish productive HCMV infection. We show that HCMV can latently infect THP-1 monocytes and that during latency US28 is transcribed. We also show that the transcription is sustained during differentiation of the THP-1 monocytes. Since cells expressing pUS28 were previously shown to adhere to immobilized CX(3)C chemokines (C. A. Haskell, M. D. Cleary, and I. F. Charo, J. Biol. Chem. 275:34183-34189, 2000), we hypothesize that latently infected circulating monocytes express pUS28, thereby enabling adhesion of these cells to CX(3)C-exposing endothelium. Consequently, the US28-encoded chemokine receptor may play an important role in dissemination of latent HCMV.

A canarypox vector-expressing cytomegalovirus (CMV) phosphoprotein 65 induces long-lasting cytotoxic T cell responses in human CMV-seronegative subjects.

The major matrix phosphoprotein 65 (pp65) of cytomegalovirus (CMV) is an important target of HLA-restricted cytotoxic T cells (CTL) after natural infection. A canarypox-CMV pp65 recombinant was studied for its ability to induce CMV pp65-specific CTL, helper T lymphocytes, and antibodies in a phase I clinical trial. Twenty-one CMV-seronegative adult volunteers were randomized to receive immunizations at months 0, 1, 3, and 6 with either canarypox-CMV pp65 or placebo. In canarypox-CMV pp65-immunized subjects, pp65-specific CTL were elicited after only 2 vaccinations and were present at months 12 and 26 in all subjects tested. Cell-depletion studies indicated that the CTL were phenotype CD8(+). Peripheral blood mononuclear cells proliferated in response to stimulation with purified pp65, and antibodies specific for pp65 also were detected. Canarypox-CMV pp65 is the first recombinant vaccine to elicit CMV-specific CTL responses, which suggests the potential usefulness of this approach in preventing disease caused by CMV.

High efficient production of Pr55(gag) virus-like particles expressing multiple HIV-1 epitopes, including a gp120 protein derived from an Ugandan HIV-1 isolate of subtype A.

The main goal of this study was to investigate a novel approach for an efficient and reproducible production of Virus-Like Particles (VLPs) expressing multiple HIV-1 epitopes. The HIV-1 Pr55(gag)-based VLPs have been produced in a Baculovirus expression system, using a transfer vector able to support the independent expression of different open reading frames (ORFs). In this regard, the gp120 derived from 94UG018 HIV-1(A) isolate, previously studied in our laboratory, has been packaged into the VLPs together with nef and pol ORFs. In particular, the gp120(UG) sequence shows a 90% homology in the V3 region compared to African HIV-1 strains of the A-clade. This novel approach is extremely effective for the production of VLPs expressing all the epitopes, as confirmed by Western Blot characterization. Furthermore, the resulting HIV-VLP(A)s show the expected density (1.14--1.18 g/ml) on a 10--60% sucrose gradient and the morphology of an immature virion at standard transmission electron microscopy. Our results demonstrate that this strategy is highly efficient for expressing a balanced amount of multiple epitopes and their packaging in VLP structures, without affecting the Pr55(gag) autoassembling capacities. Furthermore, the genetic transposition performed in a modified E. coli represents a methodological improvement, allowing a faster and more reproducible identification of recombinant Baculovirus DNA molecules.

Acyclovir-resistant bilateral keratitis associated with mutations in the HSV-1 thymidine kinase gene.

PURPOSE: To evaluate the contribution of molecular methods for the diagnosis of an acyclovir-resistant HSV-1 bilateral keratitis in an AIDS patient and to report a new point mutation in the nucleotide sequence of the thymidine kinase (tk) gene involved. METHODS: A 31 year old HIV-positive female presented with severe, active, bilateral and sight-threatening keratitis of 6 months duration, which was treated unsuccessfully with acyclovir. After corneal biopsy, samples were analysed by standard virological procedures, in situ hybridization, and PCR. The tk gene was cloned and subsequently sequenced. RESULTS: Conventional virological methods remained inconclusive. However, in situ hybridization and PCR rapidly confirmed the diagnosis of HSV-1 keratitis. The tk gene sequence revealed the presence of five variations previously described in two reference strains, but also a new point mutation at nucleotide position 431 which leads to an amino-acid change at position 144 that supported the hypothesis of a putatively altered functional form of the enzyme. Intravenous foscarnet treatment in an induction regimen was effective and cicatrization occurred within 3 weeks. CONCLUSIONS: PCR and in situ hybridization are effective and powerful techniques when other virological procedures are non-contributive, particularly in immunocompromised patients previously treated with antiviral drugs. The new point mutation identified in the tk gene may be associated with resistance to acyclovir.

Identification of MK-944a: a second clinical candidate from the hydroxylaminepentanamide isostere series of HIV protease inhibitors.

Recent results from human clinical trials have established the critical role of HIV protease inhibitors in the treatment of acquired immune-deficiency syndrome (AIDS). However, the emergence of viral resistance, demanding treatment protocols, and adverse side effects have exposed the urgent need for a second generation of HIV protease inhibitors. The continued exploration of our hydroxylaminepentanamide (HAPA) transition-state isostere series of HIV protease inhibitors, which initially resulted in the identification of Crixivan (indinavir sulfate, MK-639, L-735,524), has now yielded MK-944a (L-756,423). This compound is potent, is selective, and competitively inhibits HIV-1 PR with a K(i) value of 0.049 nM. It stops the spread of the HIV(IIIb)-infected MT4 lymphoid cells at 25.0-50.0 nM, even in the presence of alpha(1) acid glycoprotein, human serum albumin, normal human serum, or fetal bovine serum. MK-944a has a longer half-life in several animal models (rats, dogs, and monkeys) than indinavir sulfate and is currently in advanced human clinical trials.

Drug discovery, drug development and the emerging world of pharmacogenomics: prospecting for information in a data-rich landscape.

Drug development is a very expensive and inefficient process. Currently, it takes on average 15 years and costs approximately US $500 million to bring a new drug to market, with the pharmaceutical industry spending more than US $20 billion in identifying and developing drugs in 1998. Twenty-two percent of this total was spent on screening assays and toxicity testing. Yet the rapidly accelerating advances in high-throughput technologies, including screening and robotics, combinatorial chemistry, and genomics makes this an extremely data-rich environment. Add to that the new paradigms of pharmacogenomics and 'customized medicine', and the question is, are we helping or hurting our cause? Clearly, interpreting this flood of data and turning it into useful information is our next great hurdle. By extending the pharmacogenomic paradigm to the drug discovery process, this paper intends to put the scope of the problem into context.

Cytomegalovirus: virological facts for clinicians.

Human cytomegalovirus (HCMV) is a complex DNA virus encoding more than 200 viral proteins. This highly adapted opportunist agent has developed several ways to evade the immune system. Among all clinical features due to HCMV, retinitis occurs especially in severely immunosuppressed patients, particularly during the end phase of HIV infection. Highly active antiretroviral therapy (HAART) has significantly reduced the incidence of this complication. However, in this HAART era, we observe the emergence of new clinical patterns in patients presenting with cicatricial HCMV retinitis. These patterns could be potentially related to immune mechanisms directed against viral antigens expressed at the surface of retinal cells that are still latently infected without any viral replication. We used a model of human retinal pigment epithelial (RPE) cells to evaluate virus-host interactions in the presence of different cytokines in the eye which play a major role in immunological or infectious conditions. Two different enzymatic pathways seem to be particularly involved during infection. Lack of tryptophan and production of nitric oxide seem to block HCMV replication in RPE cells. We propose a model to explain some of the mechanisms involved during severe immunosuppression and also after immune recovery.

Entry of human cytomegalovirus into retinal pigment epithelial and endothelial cells by endocytosis.

PURPOSE: Human retinal pigment epithelial (RPE) cells and endothelial cells (HUVECs) are targets of human cytomegalovirus (HCMV) infection in vivo with significantly protracted replication in vitro compared with that in fibroblasts. This study analyzes the kinetics and mechanisms of HCMV entry into both cell types. METHODS: RPE cells were obtained from donor eyes. HUVECs were isolated from human umbilical cords. HCMV entrance was followed by electron microscopy and immunofluorescence in the presence of lysosomotropic agents and cytochalasin B. RESULTS: Human cytomegalovirus entered into RPE cells and HUVECs as early as 5 minutes after virus- cell contact. Entry was mediated by endocytosis, whereas HCMV enters fibroblasts through fusion. Most internalized viral particles and dense bodies appeared to be degraded within vacuoles. Viral entry, transport of viral proteins to the nucleus, and onset of viral transcription (immediate early [IE] protein expression) were significantly blocked by cytochalasin B. Lysosomotropic agents did not significantly reduce IE expression in RPE cells or HUVECs. CONCLUSIONS: This study shows that HCMV penetrates these highly specialized relevant cells via endocytosis. The low level of infection and the delay in the onset of HCMV expression seen in these cells compared with fibroblasts may be related to the sequestration and degradation of incoming viral particles in endocytic vacuoles.

Managed care of children with special health care needs: the ABC Program.

Families of children voluntarily enrolled in a managed care program for children with special health care needs receiving SSI and Medicaid benefits and their case managers were surveyed regarding care satisfaction, quality, and access. Claims data were used to compare the cost and utilization of health care before and during program enrollment. Families rated health care quality improved in 43%, unchanged as "excellent" in 50% of cases. The care received was seen as more nearly complete and of higher quality when the provider was based in the hospital or the hospital's community clinics as compared with "private" community pediatricians. Hospitalization decreased, but no decrease in cost was demonstrated. A carefully planned and implemented managed care program can improve patient perception of quality among chronically ill children.

Implication of gammadelta T cells in the human immune response to cytomegalovirus.

In normal individuals, gammadelta T cells account for less than 6% of total peripheral T lymphocytes and mainly express T-cell receptor (TCR) Vdelta2-Vgamma9 chains. We have previously observed a dramatic expansion of gammadelta T cells in the peripheral blood of renal allograft recipients only when they developed cytomegalovirus (CMV) infection. This increase was long lasting (more than 1 year), was associated with an activation of gammadelta T cells, and concerned only Vdelta1 or Vdelta3 T-cell subpopulations. Analysis of gammadelta TCR junctional diversity revealed that CMV infection in these patients was accompanied by (a) a marked restriction of CDR3 size distribution in Vdelta3 and, to a lesser extent, in Vdelta1 chains; and (b) a selective expansion of Vdelta1 cells bearing recurrent junctional amino acid motifs. These features are highly suggestive of an in vivo antigen-driven selection of gammadelta T-cell subsets during the course of CMV infection. Furthermore, Vdelta1 and Vdelta3 T cells from CMV-infected kidney recipients were able to proliferate in vitro in the presence of free CMV or CMV-infected fibroblast lysates but not uninfected or other herpes virus-infected fibroblast lysates. This in vitro expansion was inhibited by anti-gammadelta TCR mAb's. These findings suggest that a population of gammadelta T cells might play an important role in the immune response of immunosuppressed patients to CMV infection.

Nonpeptide oxytocin antagonists: analogs of L-371,257 with improved potency.

Structure-activity studies on the oxytocin antagonist 1 (L-371,257; Ki = 9.3 nM) have led to the identification of a related series of compounds containing an ortho-trifluoroethoxyphenylacetyl core which are orally bioavailable and have significantly improved potency in vitro and in vivo, e.g., compound 8 (L-374,943; Ki = 1.4 nM).

Kinetics of transcription of human cytomegalovirus chemokine receptor US28 in different cell types.

In permissive cells, human cytomegalovirus encodes the protein US28, a functional CC chemokine receptor. US28 polyadenylated mRNA could be detected by RT-PCR as early as 2 h post-infection. US28 mRNA appeared after major IE1 transcripts (UL123), but before transcripts of the early genes pp65 (UL83) and gB (UL55), and the late gene pp150 (UL32). This temporal appearance indicates that US28 is transcribed earlier than previously reported. Furthermore, US28 mRNA could be detected in semi- and non-permissive cells.

Role of IFN-gamma-induced indoleamine 2,3 dioxygenase and inducible nitric oxide synthase in the replication of human cytomegalovirus in retinal pigment epithelial cells.

An in vitro model of human CMV infection of primary retinal pigment epithelial (RPE) cells was used to study the effects of cytokines on CMV replication in these cells, which are targets of CMV infection in vivo. IFN-gamma and IFN-beta were potent inhibitors of CMV replication in RPE cells, while TNF-alpha, IL-1beta, or TGF-beta2 did not affect viral replication. Inhibition by IFN-gamma, and to a lesser extent IFN-beta, was almost completely reversed by addition of L-tryptophan to the culture medium, strongly implicating the indoleamine 2,3 dioxygenase (IDO) pathway. Polyadenylated IDO mRNA accumulation was detected as early as 2 h after IFN stimulation. Furthermore, CMV blocked the production of nitric oxide by the inducible form of nitric oxide synthase. This inhibition depended on a functional viral genome. However, exogenous nitric oxide significantly inhibited viral protein expression in RPE cells. Thus, CMV infection blocks the inducible nitric oxide synthase pathway activated by IFN-gamma and IL-1beta, but cannot counteract the IFN-induced IDO pathway, which ultimately controls its replication in primary human RPE cells.

Human cytomegalovirus escape from immune detection.

Human cytomegalovirus (CMV) has devised numerous means of escaping immune surveillance. The CMV genome encodes at least 4 genes involved in downregulating surface expression of HLA class I molecules. In addition, it sequesters CC chemokines, induces Fc receptors, interferes with induction of HLA class II antigens, and can inhibit natural killer cell activity. CMV can efficiently block the presentation of immediate early antigens, the first viral proteins to be produced. Together, these mechanisms probably contribute to the ability of CMV to persist in its host and may play a role in the immunopathology of CMV disease.

Chemokine sequestration by viral chemoreceptors as a novel viral escape strategy: withdrawal of chemokines from the environment of cytomegalovirus-infected cells.

Human cytomegalovirus (HCMV), a betaherpesvirus, has developed several ways to evade the immune system, notably downregulation of cell surface expression of major histocompatibility complex class I heavy chains. Here we report that HCMV has devised another means to compromise immune surveillance mechanisms. Extracellular accumulation of both constitutively produced monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor-superinduced RANTES (regulated on activation, normal T cell expressed and secreted) was downregulated in HCMV-infected fibroblasts in the absence of transcriptional repression or the expression of polyadenylated RNA for the cellular chemokine receptors CCR-1, CCR-3, and CCR-5. Competitive binding experiments demonstrated that HCMV-infected cells bind RANTES, MCP-1, macrophage inflammatory protein (MIP)-1beta, and MCP-3, but not MCP-2, to the same receptor as does MIP-1alpha, which is not expressed in uninfected cells. HCMV encodes three proteins with homology to CC chemokine receptors: US27, US28, and UL33. Cells infected with HCMV mutants deleted of US28, or both US27 and US28 genes, failed to downregulate extracellular accumulation of either RANTES or MCP-1. In contrast, cells infected with a mutant deleted of US27 continues to bind and downregulate those chemokines. Depletion of chemokines from the culture medium was at least partially due to continuous internalization of extracellular chemokine, since exogenously added, biotinylated RANTES accumulated in HCMV-infected cells. Thus, HCMV can modify the chemokine environment of infected cells through intense sequestering of CC chemokines, mediated principally by expression of the US28-encoded chemokine receptor.

Development of orally active oxytocin antagonists: studies on 1-(1-[4-[1-(2-methyl-1-oxidopyridin-3-ylmethyl)piperidin-4-yloxy]-2- methoxybenzoyl]piperidin-4-yl)-1,4-dihydrobenz[d][1,3]oxazin-2-one (L-372,662) and related pyridines.

The previously reported oxytocin antagonist L-371,257 (2) has been modified at its acetylpiperidine terminus to incorporate various pyridine N-oxide groups. This modification has led to the identification of compounds with improved pharmacokinetics and excellent oral bioavailability. The pyridine N-oxide series is exemplified by L-372,662 (30), which possessed good potency in vitro (Ki = 4.1 nM, cloned human oxytocin receptor) and in vivo (intravenous AD50 = 0.71 mg/kg in the rat), excellent oral bioavailability (90% in the rat, 96% in the dog), good aqueous solubility (>8.5 mg/mL at pH 5.2) which should facilitate formulation for iv administration, and excellent selectivity against the human arginine vasopressin receptors. Incorporation of a 5-fluoro substituent on the central benzoyl ring of this class of oxytocin antagonists enhanced in vitro and in vivo potency but was detrimental to the pharmacokinetic profiles of these compounds. Although lipophilic substitution around the pyridine ring of compound 30 gave higher affinity in vitro, such substituents were a metabolic liability and caused shortfalls in vivo. Two approaches to prevent this metabolism, addition of a cyclic constraint and incorporation of trifluoromethyl groups, were examined. The former approach was ineffective because of metabolic hydroxylation on the constrained ring system, whereas the latter showed improvement in plasma pharmacokinetics in some cases.