Cytomegalovirus treatment options in immunocompromised patients

Investigation into the use of gamma irradiated Cytodex-1 microcarriers to produce a human cytomegalovirus (HCMV) vaccine candidate in epithelial cells

V160 is a viral vaccine candidate against human cytomegalovirus (HCMV) that is manufactured using Adult Retinal Pigment Epithelial cells (ARPE-19) grown on Cytodex-1 microcarriers. The microcarriers are generally hydrated, washed, and autoclaved prior to use, which can be limiting at large production scales. To minimize microcarrier preparation and sterilization, the use of gamma irradiated Cytodex-1 was investigated. Similar ARPE-19 cell growth was observed on heat-sterilized and gamma irradiated Cytodex-1; however, significantly reduced virus production was observed in cultures exposed to gamma irradiated Cytodex-1. Additional experiments suggest that infection inhibition is not exclusive to ARPE-19 but is most directly linked to HCMV V160, as evidenced by similar inhibition of V160 with Vero cells and no inhibition of Measles virus with either cell type. These observations suggest a putative impact on HCMV infection from the presence of extractable(s)/leachable(s) in the gamma irradiated microcarriers. Thorough aseptic rinsing of gamma irradiated Cytodex-1 prior to use can mitigate this impact and enable comparable process performance to heat-sterilized Cytodex-1. Though not fully a "ready-to-use" product for the HCMV V160 production process, utilization of Cytodex-1 microcarriers was possible without requiring heat sterilization, suggesting a potential path forward for large scale production of V160.

Lessons from Acquired Natural Immunity and Clinical Trials to Inform Next-Generation Human Cytomegalovirus Vaccine Development

Human cytomegalovirus (HCMV) infection, the most common cause of congenital disease globally, affecting an estimated 1 million newborns annually, can result in lifelong sequelae in infants, such as sensorineural hearing loss and brain damage. HCMV infection also leads to a significant disease burden in immunocompromised individuals. Hence, an effective HCMV vaccine is urgently needed to prevent infection and HCMV-associated diseases. Unfortunately, despite more than five decades of vaccine development, no successful HCMV vaccine is available. This review summarizes what we have learned from acquired natural immunity, including innate and adaptive immunity; the successes and failures of HCMV vaccine human clinical trials; the progress in related animal models; and the analysis of protective immune responses during natural infection and vaccination settings. Finally, we propose novel vaccine strategies that will harness the knowledge of protective immunity and employ new technology and vaccine concepts to inform next-generation HCMV vaccine development.

Polymorphic Forms of Human Cytomegalovirus Glycoprotein O Protect against Neutralization of Fibroblast Entry by Antibodies Targeting Epitopes Defined by Glycoproteins H and L

Human cytomegalovirus (CMV) utilizes different glycoproteins to enter into fibroblast and epithelial cells. A trimer of glycoproteins H, L, and O (gH/gL/gO) is required for entry into all cells, whereas a pentamer of gH/gL/UL128/UL130/UL131A is selectively required for infection of epithelial, endothelial, and some myeloid-lineage cells, but not of fibroblasts. Both complexes are of considerable interest for vaccine and immunotherapeutic development but present a conundrum: gH/gL-specific antibodies have moderate potency yet neutralize CMV entry into all cell types, whereas pentamer-specific antibodies are more potent but do not block fibroblast infection. Which cell types and neutralizing activities are important for protective efficacy in vivo remain unclear. Here, we present evidence that certain CMV strains have evolved polymorphisms in gO to evade trimer-specific neutralizing antibodies. Using luciferase-tagged variants of strain TB40/E in which the native gO is replaced by gOs from other strains, we tested the effects of gO polymorphisms on neutralization by monoclonal antibodies (mAbs) targeting four independent epitopes in gH/gL that are common to both trimer and pentamer. Neutralization of fibroblast entry by three mAbs displayed a range of potencies that depended on the gO type, a fourth mAb failed to neutralize fibroblast entry regardless of the gO type, while neutralization of epithelial cell entry by all four mAbs was potent and independent of the gO type. Thus, specific polymorphisms in gO protect the virus from mAb neutralization in the context of fibroblast but not epithelial cell entry. No influence of gO type was observed for protection against CMV hyperimmune globulin or CMV-seropositive human sera, suggesting that antibodies targeting protected gH/gL epitopes represent a minority of the polyclonal neutralizing repertoire induced by natural infection.

Ulcerated Lesions of the Oral Mucosa: Clinical and Histologic Review

Ulcerated lesions of the oral cavity have many underlying etiologic factors, most commonly infection, immune related, traumatic, or neoplastic. A detailed patient history is critical in assessing ulcerative oral lesions and should include a complete medical and medication history; whether an inciting or triggering trauma, condition, or medication can be identified; the length of time the lesion has been present; the frequency of episodes in recurrent cases; the presence or absence of pain; and the growth of the lesion over time. For multiple or recurrent lesions the presence or history of ulcers on the skin, genital areas, or eyes should be evaluated along with any accompanying systemic symptoms such as fever, arthritis, or other signs of underlying systemic disease. Biopsy may be indicated in many ulcerative lesions of the oral cavity although some are more suitable for clinical diagnosis. Neoplastic ulcerated lesions are notorious in the oral cavity for their ability to mimic benign ulcerative lesions, highlighting the essential nature of biopsy to establish a diagnosis in cases that are not clinically identifiable or do not respond as expected to treatment. Adjunctive tests may be required for final diagnosis of some ulcerated lesions especially autoimmune lesions. Laboratory tests or evaluation to rule out systemic disease may be also required for recurrent or severe ulcerations especially when accompanied by other symptoms. This discussion will describe the clinical and histopathologic characteristics of a variety of ulcerated lesions found in the oral cavity.

Review article: cytomegalovirus and inflammatory bowel disease

BACKGROUND

The association between ulcerative colitis and cytomegalovirus (CMV) has been recognised for over 50 years; and the role of CMV in ulcerative colitis in general, and steroid resistance in particular, remains a topic of ongoing controversy. The outcome for patients with CMV reactivation appears worse than that for patients without reactivation, but it is not entirely clear whether CMV is a contributor or a bystander and if treatment with anti-virals alters the course of inflammatory bowel disease (IBD).

AIM

To review the role of CMV associated with IBD, including epidemiology, clinical features, diagnosis and management strategies.

METHODS

By reviewing literature available on CMV associated with IBD in adult patients. A PubMed literature search was performed using the following terms individually or in combination: CMV colitis, cytomegalovirus colitis, IBD and CMV, CMV treatment.

RESULTS

Cytomegalovirus reactivation is common in patients with severe colitis, with a reported prevalence of 4.5-16.6%, and as high as 25% in patients requiring colectomy for severe colitis. The outcome for this group of patients appears worse than that for patients without reactivation; however, reported remission rates following treatment with anti-viral therapy are as high as 71-86%.

CONCLUSIONS

Evidence, although not conclusive, supports testing for CMV colonic disease in cases of moderate to severe colitis, by processing biopsies for haematoxylin and eosin staining with immunohistochemistry and/or, CMV DNA real-time polymerase chain reaction; and if present treating with ganciclovir.

Identification and HLA-tetramer-validation of human CD4+ and CD8+ T cell responses against HCMV proteins IE1 and IE2

Human cytomegalovirus (HCMV) is an important human pathogen. It is a leading cause of congenital infection and a leading infectious threat to recipients of solid organ transplants as well as of allogeneic hematopoietic cell transplants. Moreover, it has recently been suggested that HCMV may promote tumor development. Both CD4+ and CD8+ T cell responses are important for long-term control of the virus, and adoptive transfer of HCMV-specific T cells has led to protection from reactivation and HCMV disease. Identification of HCMV-specific T cell epitopes has primarily focused on CD8+ T cell responses against the pp65 phosphoprotein. In this study, we have focused on CD4+ and CD8+ T cell responses against the immediate early 1 and 2 proteins (IE1 and IE2). Using overlapping peptides spanning the entire IE1 and IE2 sequences, peripheral blood mononuclear cells from 16 healthy, HLA-typed, donors were screened by ex vivo IFN-γ ELISpot and in vitro intracellular cytokine secretion assays. The specificities of CD4+ and CD8+ T cell responses were identified and validated by HLA class II and I tetramers, respectively. Eighty-one CD4+ and 44 CD8+ T cell responses were identified representing at least seven different CD4 epitopes and 14 CD8 epitopes restricted by seven and 11 different HLA class II and I molecules, respectively, in total covering 91 and 98% of the Caucasian population, respectively. Presented in the context of several different HLA class II molecules, two epitope areas in IE1 and IE2 were recognized in about half of the analyzed donors. These data may be used to design a versatile anti-HCMV vaccine and/or immunotherapy strategy.

A model of human cytomegalovirus infection in severe combined immunodeficient mice

Animal models for the evaluation of therapies against human cytomegalovirus (HCMV) are limited due to the species-specific replication of CMV. Models utilizing human fetal tissues implanted into SCID mice have been used but tend to be labor intensive and require human tissues. We therefore developed a model using HCMV-infected human foreskin fibroblasts (HFF) seeded onto a biodegradable gelatin matrix (Gelfoam). Infected HFFs are then implanted subcutaneously into SCID mice. We next evaluated two antivirals in this model. Treatment from days 0 to 5 with ganciclovir (GCV) produced a marginally significant reduction in viral titer while treatment from days 0 to 14 resulted in a more significant reduction in viral titers of 1.47 log(10)pfu/ml (P<0.0001). Viral titers were similarly reduced in a group receiving GCV treatment from days 7 to 14 post-implantation (1.50 log(10)pfu/ml, P<0.0001). Cidofovir therapy from days 7 to 14 reduced viral titers by almost 2 log(10)pfu/ml (from 3.51+/-0.31 log(10)pfu/ml in untreated animals to 1.56+/-0.40 log(10)pfu/ml in treated animals, P<0.0001). These results indicate that the Gelfoam-HCMV SCID mouse model is suitable for the in vivo evaluation of new antivirals against HCMV and is simpler and more convenient than previous models.

Cytomegalovirus Retinitis in a Patient Treated with Anti--Tumor Necrosis Factor Alpha Antibody Therapy for Rheumatoid Arthritis

BACKGROUND

Anti-tumor necrosis factor alpha (anti-TNF- alpha ) antibodies have been used for the treatment of chronic inflammatory diseases such as rheumatoid arthritis (RA) and psoriasis arthritis. Such antibody therapies result in a severe interference with the patient's immune system. Increased rates of upper respiratory tract infection, reactivation of latent tuberculosis, and other systemic infectious diseases have been reported among patients receiving anti-TNF- alpha antibodies.

METHODS

As a note of caution, we describe a 57-year-old woman who received therapy with anti-TNF- alpha antibodies for RA refractory to methotrexate. After almost 2 years of treatment, she developed a severe cytomegalovirus (CMV) retinitis of the right eye.

RESULTS

Laboratory assays revealed an immune status with nearly total loss of the cellular immune response and partial reduction of the humoral immune response. Intravenous treatment with ganciclovir, followed by oral administration of valganciclovir, resulted in an ophthalmological remission. Cessation of immunosuppressive therapy led to partial immunological reconstitution in the patient. Six months after discontinuation of immunosuppressive therapy, CMV retinitis of the left eye occurred but was treated successfully with a second course of oral valganciclovir.

CONCLUSION

In the light of this first reported case of a serious CMV infection following therapy with anti-TNF- alpha antibodies, CMV infection should be considered in symptomatic patients.

Mechanism of action of the ribopyranoside benzimidazole GW275175X against human cytomegalovirus

New human cytomegalovirus (HCMV) therapies with novel mechanisms of action are needed to treat drug-resistant HCMV that arises during therapy with currently approved agents. 2-Bromo-5,6-dichloro-1-beta-D-ribofuranosyl-1H-benzimidazole (BDCRB) is an effective anti-HCMV agent with a novel mechanism of action, but problems with in vivo stability preclude clinical development. A D-ribopyranosyl derivative of BDCRB, GW275175X, displays similar antiviral activity without the in vivo stability problems. We present an initial description of the activity of GW275175X against HCMV, other herpesviruses, and selected nonherpesviruses. In addition, we show that it acts as a DNA maturation inhibitor like the parent compound, BDCRB, rather than via the mechanisms of action of 1263W94 or any anti-HCMV drugs approved for marketing. GW275175X is a promising candidate for clinical development as an anti-HCMV agent.

Gastrointestinal Infections Caused by Cytomegalovirus

Cytomegalovirus (CMV) is an important human pathogen, causing a variety of syndromes ranging from asymptomatic infections to life-threatening end-organ disease. Infections of the gastrointestinal tract are an especially common form of disease caused by CMV and are usually manifest as luminal infections, such as esophagitis or colitis. Solid organ disease caused by CMV is also known to occur, with hepatitis being the most common syndrome. The large majority of cases of tissue-invasive disease caused by CMV have been reported to occur in immunocompromised hosts. Patients at highest risk for serious CMV-mediated disease are commonly HIV infected, recipients of transplants, or are receiving potent immunosuppressive medications. Intriguingly, several recent reports have discussed the previously underappreciated role of serious forms of CMV-mediated disease occurring in immunocompetent patients. This paper reviews several recent reports addressing important aspects related to the diagnosis, treatment, and management of CMV infections of the gastrointestinal tract.

Potential antiviral therapeutics for smallpox, monkeypox and other orthopoxvirus infections

We assessed the activities of 24 different antiviral compounds against smallpox (two strains of variola major and one of variola minor), monkeypox, vaccinia and cowpox viruses by a neutral red uptake assay. To establish assay parameters, we examined viral replication and its inhibition at various times postinfection and at several multiplicities of infection. Drugs were selected to target a range of functions involved in viral replication. Eight compounds (cidofovir, cyclic HPMPC (cHPMPC), HPMPA, ribavirin, tiazofurin, carbocyclic 3-deazaadenosine, 3-deazaneplanocin A and DFBA (1-(2,4-difluorobenzyloxy)adenosine perchlorate)-a derivative of adenosine N1-oxide) inhibited the replication of all three variola strains and the other orthopoxviruses at drug concentrations within a pharmacologically achievable range. Two others (methisazone and bis-POM-PMEA) showed a lesser degree of antiviral effect, while the remainder were inactive. To examine possible naturally occurring drug resistance among a large number of variola isolates obtained from different geographical regions and at different times, we examined the sensitivity of 35 different strains of variola as well as other orthopoxviruses to a subset of three of the most active compounds: cidofovir, cHPMPC, and ribavirin. Preliminary data indicate that nearly all isolates appear to have similar drug sensitivities. These findings are currently being verified and expanded.