Mortality associated with resistant cytomegalovirus among patients with cytomegalovirus retinitis and AIDS

Viral load: We need a new look at an old problem?

The concept of viral load was introduced in the 1980s to measure the amount of viral genetic material in a person's blood, primarily for human immunodeficiency virus (HIV). It has since become crucial for monitoring HIV infection progression and assessing the efficacy of antiretroviral therapy. However, during the coronavirus disease 2019 pandemic, the term "viral load" became widely popularized, not only for the scientific community but for the general population. Viral load plays a critical role in both clinical patient management and research, providing valuable insights for antiviral treatment strategies, vaccination efforts, and epidemiological control measures. As measuring viral load is so important, why don't researchers discuss the best way to do it? Is it simply acceptable to use raw Ct values? Relying solely on Ct values for viral load estimation can be problematic due to several reasons. First, Ct values can vary between different quantitative polymerase chain reaction assays, platforms, and laboratories, making it difficult to compare data across studies. Second, Ct values do not directly measure the quantity of viral particles in a sample and they can be influenced by various factors such as initial viral load, sample quality, and assay sensitivity. Moreover, variations in viral RNA extraction and reverse-transcription steps can further impact the accuracy of viral load estimation, emphasizing the need for careful interpretation of Ct values in viral load assessment. Interestingly, we did not observe scientific articles addressing different strategies to quantify viral load. The absence of standardized and validated methods impedes the implementation of viral load monitoring in clinical management. The variability in cell quantities within samples and the variation in viral particle numbers within infected cells further challenge accurate viral load measurement and interpretation. To advance the field and improve patient outcomes, there is an urgent need for the development and validation of tailored, standardized methods for precise viral load quantification.

Harnessing the Noncanonical Keap1-Nrf2 Pathway for Human Cytomegalovirus Control

Host-derived cellular pathways can provide an unfavorable environment for virus replication. These pathways have been a subject of interest for herpesviruses, including the betaherpesvirus human cytomegalovirus (HCMV). Here, we demonstrate that a compound, ARP101, induces the noncanonical sequestosome 1 (SQSTM1)/p62-Keap1-Nrf2 pathway for HCMV suppression. ARP101 increased the levels of both LC3 II and SQSTM1/p62 and induced phosphorylation of p62 at the C-terminal domain, resulting in its increased affinity for Keap1. ARP101 treatment resulted in Nrf2 stabilization and translocation into the nucleus, binding to specific promoter sites and transcription of antioxidant enzymes under the antioxidant response element (ARE), and HCMV suppression. Knockdown of Nrf2 recovered HCMV replication following ARP101 treatment, indicating the role of the Keap1-Nrf2 axis in HCMV inhibition by ARP101. SQSTM1/p62 phosphorylation was not modulated by the mTOR kinase or casein kinase 1 or 2, indicating ARP101 engages other kinases. Together, the data uncover a novel antiviral strategy for SQSTM1/p62 through the noncanonical Keap1-Nrf2 axis. This pathway could be further exploited, including the identification of the responsible kinases, to define the biological events during HCMV replication. IMPORTANCE Antiviral treatment for human cytomegalovirus (HCMV) is limited and suffers from the selection of drug-resistant viruses. Several cellular pathways have been shown to modulate HCMV replication. The autophagy receptor sequestosome 1 (SQSTM1)/p62 has been reported to interact with several HCMV proteins, particularly with components of HCMV capsid, suggesting it plays a role in viral replication. Here, we report on a new and unexpected role for SQSTM1/p62, in HCMV suppression. Using a small-molecule probe, ARP101, we show SQSTM1/p62 phosphorylation at its C terminus domain initiates the noncanonical Keap1-Nrf2 axis, leading to transcription of genes under the antioxidant response element, resulting in HCMV inhibition in vitro. Our study highlights the dynamic nature of SQSTM1/p62 during HCMV infection and how its phosphorylation activates a new pathway that can be exploited for antiviral intervention.

Cytomegalovirus retinitis in the highly active anti-retroviral therapy era

Cytomegalovirus (CMV) retinitis is an opportunistic infection that has traditionally affected those who have HIV/AIDS or immunosuppressed individuals. CMV retinitis previously infected one-third of AIDS patients in the pre-highly active antiretroviral therapy (HAART) era, but since HAART, Western countries have seen an 80% decrease in the incidence of the disease. More recently, CMV retinitis has been reported in patients who are immunosuppressed, often due to chemotherapy or immunomodulatory medications. The diagnosis of CMV retinitis is often suspected based on clinical findings, with polymerase chain reaction for confirmation of CMV, especially in atypical cases. Highly active antiretroviral therapy and anti-CMV medications (systemic or local) remain the mainstay of treatment. However, for those who are not responsive to HAART, CMV retinitis remains a challenge, and can still lead to significant vision loss. Moreover, a regimen of anti-CMV medications can sometimes lead to viral resistance or organ toxicity. Complications such as immune recovery retinitis and rhegmatogenous retinal detachments continue to threaten the vision of patients who develop CMV retinitis. These complications can arise following initiation of treatment or if patients show disease progression. Proper vision screening for CMV retinitis in immunosuppressed patients at-risk is necessary for early detection and treatment.

The Synthesis and Anti-Cytomegalovirus Activity of Piperidine-4-Carboxamides

Treatment options for human cytomegalovirus (CMV) remain limited and are associated with significant adverse effects and the selection of resistant CMV strains in transplant recipients and congenitally infected infants. Although most approved drugs target and inhibit the CMV DNA polymerase, additional agents with distinct mechanisms of action are needed for the treatment and prevention of CMV. In a large high throughput screen using our CMV-luciferase reporter Towne, we identified several unique inhibitors of CMV replication. Here, we synthesize and test in vitro 13 analogs of the original NCGC2955 hit (1). Analogs with no activity against the CMV-luciferase at 10 µM and 30 µM (2–6, 10–14) were removed from further analysis. Three analogs (7–9) inhibited CMV replication in infected human foreskin fibroblasts. The EC₅₀ of (1) was 1.7 ± 0.6 µM and 1.99 ± 0.15 µM, based on luciferase and plaque assay, respectively. Compounds 7, 8, and 9 showed similar activities: the EC₅₀ values of 7 were 0.21 ± 0.06 µM (luciferase) and 0.55 ± 0.06 (plaque), of 8: 0.28 ± 0.06 µM and 0.42 ± 0.07, and of 9: 0.30 ± 0.05 µM (luciferase) and 0.35 ± 0.07 (plaque). The CC₅₀ for 7, 8, and 9 in non-infected human foreskin fibroblasts was > 500µM, yielding a selectivity index of >1500. Compounds 1, 7, and 8 were also tested in CMV-infected primary human hepatocytes and showed a dose–response against CMV by luciferase activity and viral protein expression. None of the active compounds inhibited herpes simplex virus 1 or 2. Compounds 7 and 8 inhibited mouse CMV replication in vitro. Both inhibited CMV at late stages of replication; 7 reduced virus yield at all late time points, although not to the same degree as letermovir. Finally, the activity of analog 8 was additive with newly identified CMV inhibitors (MLS8969, NFU1827, MSL8554, and MSL8091) and with ganciclovir. Further structural activity development should provide promising anti-CMV agents for use in clinical studies.

Continuous High-Dose (6 mg) vs. Low-Dose (3 mg) Intravitreal Ganciclovir for Cytomegalovirus Retinitis After Haploidentical Hematopoietic Stem Cell Transplantation: A Randomized Controlled Study

Purpose: To evaluate the safety and efficacy of continuous high-dose (6 mg) intravitreal ganciclovir injections (IVG) for cytomegalovirus (CMV) retinitis (CMVR) after haploidentical hematopoietic stem cell transplantation (Haplo-HSCT), and to explore factors that may influence the treatment procedure.

Design: Prospective, randomized, single-blinded, positive-controlled, interventional, comparative study.

Methods: A total of 22 patients with CMVR (32 eyes) were randomized to either high-dose group (IVG 6 mg weekly) or low-dose group (IVG 3 mg given twice weekly for 2 weeks as induction phase and weekly thereafter as maintenance phase). Patients who were recorded any positive CMV DNAemia or other active CMV diseases and needed systemic anti-CMV treatment during the study period were excluded. The vision outcome, variables of the treatment procedure, and incidence of complication and CMVR recurrence were analyzed and compared. Logistic regression was applied to determine the factors that may have an impact on the treatment process at baseline.

Results: Compared to the low-dose group, the high-dose group resulted in a median of two less intravitreal injections (4 vs. 6 times, respectively, P = 0.016), while the rate of vision stability or improvement (81.2 vs. 87.5%), the incidence of complication (6.2 vs. 18.8%), and CMVR recurrence (12.5% vs. 6.2%) were similar (all P > 0.05). No drug-related toxicity was observed. Initial aqueous CMV-DNA load (OR: 6.872, 95% CI: 1.335–35.377, P = 0.021) and extension of lesion (OR: 0.942, 95% CI: 0.897 to .991, P = 0.020), but not dosing regimen (P = 0.162), were predictors of the treatment duration.

Conclusions: Continuous high-dose regimen was well tolerated and resulted in less intravitreal injections, with similar vision outcomes and safety profiles. The clinical course of CMVR after Haplo-HSCT was determined by its own nature at baseline and could not be modified by treatment protocols under consistent immune background.

Management of cytomegalovirus corneal endotheliitis

Background

Cytomegalovirus (CMV) can manifest as corneal endotheliitis in immunocompetent individuals. Early diagnosis is prudent to prevent endothelial cell loss, which could ultimately lead to corneal decompensation. CMV DNA was first detected in an eye with corneal endotheliitis in 2006; since then, clinical evidence from numerous case reports and case series have accumulated.

Main text

In this narrative review, we identified several drugs, including ganciclovir, valganciclovir, and their combination in oral, intravenous, intravitreal, and topical forms in different concentrations, together with the judicious use of topical steroids, have reported variable success. There has yet to be any prospective comparative study evaluating the efficacy and safety of these assorted forms of treatment; clinical evidence is based on case reports and case series. CMV endotheliitis presenting with corneal edema can masquerade as other corneal diseases and thus poses a great challenge especially in post-keratoplasty eyes. Heightened awareness is needed before and after keratoplasty to start prompt prophylaxis and treatment.

Conclusion

There is no consensus on the management of CMV endotheliitis. Further studies are much needed to elucidate the optimal treatment modality, regime, and duration in the treatment and prophylaxis of CMV endotheliitis.

Global estimate of phenotypic and genotypic ganciclovir resistance in cytomegalovirus infections among HIV and organ transplant patients; A systematic review and meta-analysis

Human cytomegalovirus (CMV), an opportunistic pathogen belonging to Herpesviridae family, is considered as one of the major causes of morbidity and mortality among wide variety of patients, particularly in transplant recipients and HIV positive patients. As this virus can be resistant to treatment, frequency of CMV in patients who receive organ transplantation and people suffering from AIDS was studied between 1980 and 2019. Medline (via PubMed), Embase, Web of Science, and the Iranian Database were reviewed, and Comprehensive Meta-Analysis (V2.0, Biostat) software analyzed all data. Finally, we used Cochran's Q-statistic to encounter heterogeneity between different studies. Meta-analyses indicated, GCV resistance was 14.1% (95% CI 11.2-17.7); however, in patients suffering from AIDS and organ transplantation were 19.5% (95% CI 14.7-25.4) and 11.4% (95% CI 8.1-15.8), respectively. There were increasing rates in the prevalence of GCV resistance in CMV among transplant recipients, and HIV positive patients. Therefore, evaluation of these refractory infections is beneficial.

[Modern ethiotropic chemotherapy of human cytomegalovirus infection: clinical effectiveness, molecular mechanism of action, drug resistance, new trends and prospects. Part 1.]

Modern chemotherapy of cytomegalovirus (CMV) infections has a very limited arsenal of first-line drugs. These are preparations of ganciclovir (GCV) belonging to the class of modified nucleosides and its metabolic precursor ganciclovir valine ester. After three-step phosphorylation, GCV, as a structural analogue of the natural nucleotide, competes with it for binding to DNA polymerase and, due to its structural features, inhibits its activity. However, with prolonged use of GCV, mainly under conditions of immunosuppression, the virus develops drug resistance associated in most cases with changes in pUL97 catalyzing the first stage of GCV phosphorylation, as well as in the catalytic subunit of DNA polymerase. When variants of viruses resistant to GCV appear, second-line drugs are used: pyrophosphate analog of foscarnet and nucleotide cidofovir. Resistance to second-line drugs is due to mutations in the pol-gene and in a number of cases leads to multiresistance, which makes it impossible to use traditional anti-CMV drugs. In addition, the use of all of the above drugs is accompanied by the development of severe side effects. All of the above determines the need to search for new compounds that can effectively inhibit the reproduction of the virus, harmless to the macroorganism, convenient to use, overcoming the drug resistance barrier in viruses.As a result of the search in international databases (PubMed, MedLine, eLIBRARY.RU, ClinicalTrials.gov, etc.), the main trends in the search for new anti-CMV agents were identified. In the first part of the review, we concentrated on compounds that are modifications of known antiviral agents currently used in clinical practice, the most promising for the development of drug anti-CMV drugs.

Digitoxin Suppresses Human Cytomegalovirus Replication via Na+, K+/ATPase α1 Subunit-Dependent AMP-Activated Protein Kinase and Autophagy Activation

Host-directed therapeutics for human cytomegalovirus (HCMV) requires elucidation of cellular mechanisms that inhibit HCMV. We report a novel pathway used by cardiac glycosides to inhibit HCMV replication: induction of AMP-activated protein kinase (AMPK) activity and autophagy flux through the Na⁺,K⁺/ATPase α1 subunit. Our data illustrate an intricate balance between the autophagy regulators AMPK, mammalian target of rapamycin (mTOR), and ULK1 during infection and treatment with the cardiac glycoside digitoxin. Both infection and digitoxin induced AMPK phosphorylation, but ULK1 was differentially phosphorylated at unique sites leading to opposing effects on autophagy. Suppression of autophagy during infection occurred via ULK1 phosphorylation at Ser757 by enhanced mTOR activity. Digitoxin continuously phosphorylated AMPK, leading to ULK1 phosphorylation at Ser317, and suppressed mTOR, resulting in increased autophagy flux and HCMV inhibition. In ATG5-deficient human fibroblasts, digitoxin did not inhibit HCMV, supporting autophagy induction as a mechanism for virus inhibition. Drug combination studies with digitoxin and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) further confirmed the role of autophagy activation in HCMV inhibition. Individually, each compound phosphorylated AMPK, but their combination reduced autophagy rather than inducing it and was antagonistic against HCMV, resulting in virus replication. The initial ULK1 activation by digitoxin was counteracted by AICAR, which prevented the downstream interaction of Beclin1 and phosphatidylinositol 3-kinase class III (PI3K-CIII), further supporting digitoxin-mediated HCMV inhibition through autophagy. Finally, the α1 subunit was required for autophagy induction, since in α1-deficient cells neither AMPK nor autophagy was activated and HCMV was not inhibited by digitoxin. In summary, induction of a novel pathway (α1-AMPK-ULK1) induces autophagy as a host-directed strategy for HCMV inhibition.IMPORTANCE Infection with human cytomegalovirus (HCMV) creates therapeutic challenges in congenitally infected children and transplant recipients. Side effects and selection of resistant mutants with the limited drugs available prompted evaluation of host-directed therapeutics. We report a novel mechanism of HCMV inhibition by the cardiac glycoside digitoxin. At low concentrations that inhibit HCMV, digitoxin induced signaling through the α1 subunit of the Na⁺,K⁺/ATPase pump and the cellular kinase AMPK, resulting in binding and phosphorylation of ULK1 (Ser317) and autophagy activation. HCMV suppressed autophagy through ULK1 phosphorylation (Ser757) by activating the mTOR kinase. The pump-autophagy pathway was required for HCMV inhibition, since in α1- or ATG5-deficient cells the virus was not inhibited. Furthermore, the AMPK activator AICAR antagonized digitoxin activity against HCMV, a phenomenon resulting from opposing effects downstream in the autophagy pathway, at the Beclin1 stage. In summary, autophagy may provide a strategy for harnessing HCMV replication.

Efficacy and Mechanism of Action of Low Dose Emetine against Human Cytomegalovirus

Infection with human cytomegalovirus (HCMV) is a threat for pregnant women and immunocompromised hosts. Although limited drugs are available, development of new agents against HCMV is desired. Through screening of the LOPAC library, we identified emetine as HCMV inhibitor. Additional studies confirmed its anti-HCMV activities in human foreskin fibroblasts: EC₅₀−40±1.72 nM, CC₅₀−8±0.56 μM, and selectivity index of 200. HCMV inhibition occurred after virus entry, but before DNA replication, and resulted in decreased expression of viral proteins. Synergistic virus inhibition was achieved when emetine was combined with ganciclovir. In a mouse CMV (MCMV) model, emetine was well-tolerated, displayed long half-life, preferential distribution to tissues over plasma, and effectively suppressed MCMV. Since the in vitro anti-HCMV activity of emetine decreased significantly in low-density cells, a mechanism involving cell cycle regulation was suspected. HCMV inhibition by emetine depended on ribosomal processing S14 (RPS14) binding to MDM2, leading to disruption of HCMV-induced MDM2-p53 and MDM2-IE2 interactions. Irrespective of cell density, emetine induced RPS14 translocation into the nucleus during infection. In infected high-density cells, MDM2 was available for interaction with RPS14, resulting in disruption of MDM2-p53 interaction. However, in low-density cells the pre-existing interaction of MDM2-p53 could not be disrupted, and RPS14 could not interact with MDM2. In high-density cells the interaction of MDM2-RPS14 resulted in ubiquitination and degradation of RPS14, which was not observed in low-density cells. In infected-only or in non-infected emetine-treated cells, RPS14 failed to translocate into the nucleus, hence could not interact with MDM2, and was not ubiquitinated. HCMV replicated similarly in RPS14 knockdown or control cells, but emetine did not inhibit virus replication in the former cell line. The interaction of MDM2-p53 was maintained in infected RPS14 knockdown cells despite emetine treatment, confirming a unique mechanism by which emetine exploits RPS14 to disrupt MDM2-p53 interaction. Summarized, emetine may represent a promising candidate for HCMV therapy alone or in combination with ganciclovir through a novel host-dependent mechanism.

Infection with human Cytomegalovirus (HCMV) is a growing and pressing problem, creating ongoing management and therapeutic challenges. Despite the availability of DNA polymerase inhibitors, development of new strategies for HCMV therapy is needed. We report for the first time on the efficacy of an old drug (emetine) against HCMV in vitro and mouse CMV in vivo, using exceedingly low drug doses. We also provide evidence for a specific host-dependent anti-CMV mechanism of emetine in vitro, thus uncovering a cellular function that can be further studied for drug development. Our work provides a novel direction for HCMV therapeutics through repurposing of an old agent, at substantially lower doses, and inhibiting HCMV indirectly through host activities critical for virus replication.

Late emergence of A594V and L595W mutations related to ganciclovir resistance in a patient with HCMV retinitis and long-term HIV progression

The emergence of ganciclovir (GCV) resistance during the treatment of human cytomegalovirus (HCMV) infection is a serious clinical challenge, and is associated with high morbidity and mortality. In this case report, we describe the emergence of two consecutive mutations (A594V and L595W) related to GCV resistance in a patient with HCMV retinitis and long-term HIV progression after approximately 240 days of GCV use. Following the diagnosis of retinitis, the introduction of GCV did not result in viral load reduction. The detected mutations appeared late in the treatment, and we propose that other factors (high initial HCMV load, previous GCV exposure, low CD4+ cell count), in addition to the presence of resistance mutations, may have contributed to the treatment failure of HCMV infection in this patient.

In vitro combination of anti-cytomegalovirus compounds acting through different targets: role of the slope parameter and insights into mechanisms of Action

Conventional therapy for human cytomegalovirus (CMV) relies on inhibition of the viral DNA polymerase. Ganciclovir (GCV) is the first-line therapy, but when GCV-resistant strains emerge, alternative therapies are extremely limited and are associated with significant toxicities. Combination of anti-CMV agents that act on different targets or stages of virus replication has not been well studied, mostly because of the limited number of anti-CMV agents. We report our investigation of combinations of agents that inhibit CMV by targeting the viral DNA polymerase, cellular kinases, or other cell/virus mechanisms yet to be discovered. The selected compounds differed by the slopes of their dose-response curve: compounds with a slope of 1 (GCV) representing one target or noncooperativity and compounds with high slopes indicating positive cooperativity. Analysis of anti-CMV drug combinations using the Bliss model (which accounts for the slope parameter) distinguished between combinations with synergistic, antagonistic, and additive activities. The combination of GCV and foscarnet was slightly synergistic; strong synergism was found when GCV was used with artemisinin-derived monomers or dimers or the MEK inhibitor U0126. The combination of GCV and cardiac glycosides (digoxin, digitoxin, and ouabain) was additive. The monomeric artemisinin artesunate was synergistic when combined with U0126 or the multikinase inhibitor sunitinib. However, the combination of artemisinin-derived dimers (molecular weights, 606 and 838) and U0126 or sunitinib was antagonistic. These results demonstrate that members of a specific drug class show similar patterns of combination with GCV and that the slope parameter plays an important role in the evaluation of drug combinations. Lastly, antagonism between different classes of CMV inhibitors may assist in target identification and improve the understanding of CMV inhibition by novel compounds.

Wnt modulating agents inhibit human cytomegalovirus replication

Infection with human cytomegalovirus (HCMV) continues to be a threat for pregnant women and immunocompromised hosts. Although limited anti-HCMV therapies are available, development of new agents is desired. The Wnt signaling pathway plays a critical role in embryonic and cancer stem cell development and is targeted by gammaherpesviruses, Epstein-Barr virus (EBV), and Kaposi's sarcoma-associated herpesvirus (KSHV). HCMV infects stem cells, including neural progenitor cells, during embryogenesis. To investigate the role of Wnt in HCMV replication in vitro, we tested monensin, nigericin, and salinomycin, compounds that inhibit cancer stem cell growth by modulating the Wnt pathway. These compounds inhibited the replication of HCMV Towne and a clinical isolate. Inhibition occurred prior to DNA replication but persisted throughout the full replication cycle. There was a significant decrease in expression of IE2, UL44, and pp65 proteins. HCMV infection resulted in a significant and sustained decrease in expression of phosphorylated and total lipoprotein receptor-related protein 6 (pLRP6 and LRP6, respectively), Wnt 5a/b, and β-catenin and a modest decrease in Dvl2/3, while levels of the negative regulator axin 1 were increased. Nigericin decreased the expression of pLRP6, LRP6, axin 1, and Wnt 5a/b in noninfected and HCMV-infected cells. For all three compounds, a correlation was found between expression levels of Wnt 5a/b and axin 1 and HCMV inhibition. The decrease in Wnt 5a/b and axin 1 expression was more significant in HCMV-infected cells than noninfected cells. These data illustrate the complex effects of HCMV on the Wnt pathway and the fine balance between Wnt and HCMV, resulting in abrogation of HCMV replication. Additional studies are required to elucidate how HCMV targets Wnt for its benefit.

Comparison of treatment regimens for cytomegalovirus retinitis in patients with AIDS in the era of highly active antiretroviral therapy

PURPOSE

To describe the outcomes of different treatment approaches for cytomegalovirus (CMV) retinitis in the era of highly active antiretroviral therapy (HAART).

DESIGN

Prospective cohort study, the Longitudinal Study of the Ocular Complications of AIDS.

PARTICIPANTS

A total of 250 patients with CMV retinitis and a CD4+ T-cell count <100 cells/μl (n = 221) at enrollment or incident retinitis (n = 29) during cohort follow-up.

METHODS

The effects of systemic therapy (vs. intraocular therapy only) on systemic outcomes and the effect of intraocular therapies (ganciclovir implants, intravitreal injections) on ocular outcomes were evaluated.

MAIN OUTCOME MEASURES

Mortality, CMV dissemination, retinitis progression, and treatment side effects.

RESULTS

Regimens containing systemic anti-CMV therapy were associated with a 50% reduction in mortality (adjusted hazard ratio [HR], 0.5; 95% confidence interval [CI], 0.3-0.7; P = 0.006), a 90% reduction in new visceral CMV disease (adjusted HR, 0.1; 95% CI, 0.04-0.4; P = 0.004), and among those with unilateral CMV retinitis at presentation, an 80% reduction in second eye disease (adjusted HR, 0.2; 95% CI, 0.1-0.5; P = 0.0005) when compared with those using only intraocular therapy (implants or injections). Compared with systemic treatment only, regimens containing intravitreal injections had greater rates of retinitis progression (adjusted HR, 3.4; P = 0.004) and greater visual field loss (for loss of one half of the normal field, adjusted HR, 5.5; P < 0.01). Intravitreal implants were not significantly better than systemic therapy (adjusted HR for progression, 0.5; P = 0.26; adjusted HR for loss of one half of the visual field, 0.5; P = 0.45), but the sample size was small. Hematologic and renal side effect rates were similar between those groups with and without systemic anti-CMV therapy. The rate of endophthalmitis was 0.017 per eye-year (EY) (95% CI, 0.006-0.05) among those treated with intravitreal injections and 0.01 per EY (95% CI, 0.002-0.04) among those treated with an implant.

CONCLUSIONS

In the HAART era, systemic anti-CMV therapy, while there is immune compromise, seems to provide benefits in terms of longer survival and decreased CMV dissemination.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Human cytomegalovirus inhibition by cardiac glycosides: evidence for involvement of the HERG gene

Infection with human cytomegalovirus (HCMV) continues to be a major threat for pregnant women and the immunocompromised population. Although several anti-HCMV therapies are available, the development of new anti-HCMV agents is highly desired. There is growing interest in identifying compounds that might inhibit HCMV by modulating the cellular milieu. Interest in cardiac glycosides (CG), used in patients with congestive heart failure, has increased because of their established anticancer and their suggested antiviral activities. We report that the several CG--digoxin, digitoxin, and ouabain--are potent inhibitors of HCMV at nM concentrations. HCMV inhibition occurred prior to DNA replication, but following binding to its cellular receptors. The levels of immediate early, early, and late viral proteins and cellular NF-κB were significantly reduced in CG-treated cells. The activity of CG in infected cells correlated with the expression of the potassium channel gene, hERG. CMV infection upregulated hERG, whereas CG significantly downregulated its expression. Infection with mouse CMV upregulated mouse ERG (mERG), but treatment with CG did not inhibit virus replication or mERG transcription. These findings suggest that CG may inhibit HCMV by modulating human cellular targets associated with hERG and that these compounds should be studied for their antiviral activities.

Artemisinin-derived dimer diphenyl phosphate is an irreversible inhibitor of human cytomegalovirus replication

We previously reported that among a series of artemisinin-derived monomers and dimers, dimer diphenyl phosphate (838) was the most potent inhibitor of human cytomegalovirus (CMV) replication. Our continued investigation of a prototypic artemisinin monomer (artesunate [AS]) and dimer (838) now reveals that both compounds have specific activity against CMV but do not inhibit lytic replication of human herpesvirus 1 or 2 or Epstein-Barr virus. AS and 838 inhibited CMV replication during the first 24 h of the virus replication cycle, earlier than the time of ganciclovir (GCV) activities and prior to DNA synthesis. Neither compound inhibited virus entry. Quantification of DNA replication and virus yield revealed a similar level of inhibition by GCV, but AS and 838 had a 10-fold-higher inhibition of virus yield than of DNA replication, suggesting that artemisinins could inhibit CMV through multiple steps: a predominant early inhibition and possibly an additional step following DNA replication. During the strong early CMV inhibition, the transcription of immediate-early genes was not significantly downregulated, and viral protein expression was reduced only after 48 h. AS and GCV were reversible CMV inhibitors, but the inhibition of CMV replication by 838 was irreversible. Combinations of GCV and 838 as well as GCV and AS were highly synergistic. Finally, treatment with 838, but not AS, prior to CMV infection demonstrated strong anti-CMV activity. These findings illustrate the unique activities of dimer 838, including early and irreversible CMV inhibition, possibly by tight binding to its target.

An artemisinin-derived dimer has highly potent anti-cytomegalovirus (CMV) and anti-cancer activities

We recently reported that two artemisinin-derived dimers (dimer primary alcohol 606 and dimer sulfone 4-carbamate 832-4) are significantly more potent in inhibiting human cytomegalovirus (CMV) replication than artemisinin-derived monomers. In our continued evaluation of the activities of artemisinins in CMV inhibition, twelve artemisinin-derived dimers and five artemisinin-derived monomers were used. Dimers as a group were found to be potent inhibitors of CMV replication. Comparison of CMV inhibition and the slope parameter of dimers and monomers suggest that dimers are distinct in their anti-CMV activities. A deoxy dimer (574), lacking the endoperoxide bridge, did not have any effect on CMV replication, suggesting a role for the endoperoxide bridge in CMV inhibition. Differences in anti-CMV activity were observed among three structural analogs of dimer sulfone 4-carbamate 832-4 indicating that the exact placement and oxidation state of the sulfur atom may contribute to its anti-CMV activity. Of all tested dimers, artemisinin-derived diphenyl phosphate dimer 838 proved to be the most potent inhibitor of CMV replication, with a selectivity index of approximately 1500, compared to our previously reported dimer sulfone 4-carbamate 832-4 with a selectivity index of about 900. Diphenyl phosphate dimer 838 was highly active against a Ganciclovir-resistant CMV strain and was also the most active dimer in inhibition of cancer cell growth. Thus, diphenyl phosphate dimer 838 may represent a lead for development of a highly potent and safe anti-CMV compound.

Pathogenesis and treatment of human immunodeficiency virus-associated cytomegalovirus retinitis

In the era of HAART, human cytomegalovirus (HCMV) retinitis remains the leading opportunistic ocular infection and the major cause of blindness in patients with AIDS. The virus has been subjected to selection and presented with the opportunity to occupy a niche to which it is highly adapted in order to escape from host immune recognition and establish persistent infection in the retina. The imbalance between host immune protection and viral immune evasion results in retinitis progression. Moreover, a synergistic interaction between HCMV and HIV in the pathogenesis of retinitis has been proposed. HAART has had a major beneficial impact on the prognosis for HIV-infected individuals. Both HAART and specific anti-HCMV treatment contribute to therapeutic success against HCMV retinitis in AIDS patients. The improved prognosis for AIDS patients with respect to the development of HCMV retinitis has been welcomed; however, we should bear in mind the occurrence of HIV drug resistance, relapse of retinitis and immune recovery uveitis after treatment, which mean that this complication of HIV infection remains a threat.

Cytomegalovirus retinitis and the acquired immunodeficiency syndrome--bench to bedside: LXVII Edward Jackson Memorial Lecture

PURPOSE

To update information on cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) and to integrate information on its pathogenesis and clinical outcomes.

DESIGN

Literature review.

METHODS

Selected articles from the medical literature, particularly large epidemiologic studies, including the Johns Hopkins Cytomegalovirus Retinitis Cohort Study, the Longitudinal Study of the Ocular Complications of AIDS, and the Cytomegalovirus Retinitis and Viral Resistance Study, were reviewed. Clinical information is discussed in light of knowledge on CMV, its pathogenesis, and its interactions with human immunodeficiency virus (HIV).

RESULTS

Cytomegalovirus uses several mechanisms to evade the immune system and establish latent infection in immunologically normal hosts. With immune deficiency, such as late-stage AIDS, CMV reactivates, is disseminated to the eye, and establishes a productive infection, resulting in retinal necrosis. HIV and CMV potentiate each other: CMV accelerates HIV disease, and CMV retinitis is associated with increased mortality. Randomized clinical trials have demonstrated the efficacy of treatments for CMV retinitis. Systemically administered treatment for CMV retinitis decreases AIDS mortality. Highly active antiretroviral therapy (HAART) effectively suppresses HIV replication, resulting in immune recovery, which, if sufficient, controls retinitis without anti-CMV therapy. Resistant CMV, detected in the blood, correlates with resistant virus in the eye and is associated with worse clinical outcomes, including mortality. Host factors, including host genetics and access to care, play a role in the development of CMV retinitis.

CONCLUSIONS

Clinical outcomes of CMV retinitis in patients with AIDS are dependent on characteristics of the virus and host and on HIV-CMV interactions.