Cytomegalovirus retinitis secondary to chronic viremia in phagocytic leukocytes

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.

Cytomegalovirus retinitis after intravitreous triamcinolone in an immunocompetent patient

PURPOSE

To report the case of a 75-year-old man with diabetes who developed cytomegalovirus (CMV) retinitis after intravitreous injection of triamcinolone acetonide (IVTA).

DESIGN

Observational case report.

METHODS

Review of medical records.

RESULTS

A 75-year-old man with diabetic macular edema developed arcuate retinal whitening after IVTA. A presumptive diagnosis of viral retinitis was made, and a vitrectomy was performed. Polymerase chain reaction of the vitreous was positive for CMV DNA. An infectious disease consultant found no signs of systemic CMV infection, and laboratory examination revealed that the patient was HIV negative. The patient responded well to intravitreal ganciclovir and oral valganciclovir, but when therapy was discontinued, the retinitis recurred and CMV DNA was again detected in the vitreous. The retinitis once again responded to antiviral therapy.

CONCLUSIONS

CMV retinitis can occur after local immunosuppression with IVTA. Clinicians should be aware of this rare complication of IVTA.

Branch retinal artery occlusion (BRAO) combined with branch retinal vein occlusion (BRVO) and optic disc neovascularization associated with HIV and CMV retinitis

Two vaso-occlusive events, branch retinal artery occlusion (BRAO) and branch retinal vein occlusion (BRVO), were observed in the retina of an HIV-infected patient with cytomegalovirus (CMV) retinitis who developed neovascularization of the disc (NVD). Although BRVO and reversible NVD have been reported in association with CMV retinitis, we have seen no reports of concomitant BRAO. CMV damages endothelial cells and causes an occlusive vasculitis. In HIV-infected individuals, damaged endothelial cells and rheologic problems result in increased blood viscosity. HIV infection has also been associated systemically with elevated levels of cytokines, including tumor necrosis factor alpha (TNF-alpha). In vitro, TNF-alpha exerts effects that decrease fibrinolytic potential; this activity in the circulation of a patient with AIDS may lead to vascular occlusive events. In the patient reported here, the retinal changes were not reversed by induction therapy with ganciclovir and the NVD did not regress.

Biphasic viremia and viral gene expression in leukocytes during acute cytomegalovirus infection of mice

Circulating leukocytes are important in dissemination of cytomegalovirus (CMV) infection in humans. In the mouse model of murine CMV infection (MCMV), it has been shown that infection peaks on days 5 to 7 after experimental infection, when 0.01 to 0.1% of the circulating leukocytes contain viral DNA. In our laboratory, MCMV DNA was detected by in situ hybridization predominantly in the mononuclear cells on day 6 after acute infection. Infectious virus was recovered from day 6 mononuclear fractions in 16 of 16 mice compared with that from day 6 polymorphonuclear fractions in 4 of 16 mice. An eclipse phenomenon was noted in the blood leukocytes by quantitative blot hybridization: the amount of MCMV DNA present was small on day 2, diminished on days 3 and 4, and then increased markedly on days 5 and 6 in both the mononuclear and polymorphonuclear fractions immediately following viral augmentation in the liver and spleen. MCMV immediate-early and glycoprotein B (late) transcripts were present in pooled mononuclear fractions only on day 6 of acute infection but not in pooled polymorphonuclear fractions. Collectively, these data demonstrate that (i) circulating leukocytes, predominantly mononuclear, are involved in dissemination of MCMV; (ii) a primary viremia with dissemination of MCMV to reticuloendothelial organs (liver and spleen) occurs and is followed by viral amplification and a subsequent, more intense secondary viremia; and (iii) immediate-early viral mRNA and glycoprotein B mRNA transcripts are detectable only during peak infection on day 6 in mononuclear leukocytes but not in polymorphonuclear leukocytes.

High levels of circulating cytomegalovirus DNA reflect visceral organ disease in viremic immunosuppressed patients other than marrow recipients

Although viremia is a hallmark of disseminated cytomegalovirus (CMV) infection, not all viremic patients have visceral organ CMV disease. We used blot hybridization with a cloned subgenomic probe to quantitate viral DNA in blood leukocytes of 60 viremic patients (25 with solid organ transplants, 20 with AIDS, and 15 marrow recipients) who had different clinical manifestations of CMV infection. The results are expressed as pg of viral DNA/10 micrograms of leukocyte DNA. Patients with AIDS or with solid organ transplants who had CMV visceral organ disease had the largest amounts of viral DNA in their granulocytes (median 632 and 237 pg, respectively). These amounts were significantly greater than those in similar viremic patients without CMV visceral disease (17 and 21 pg; P < 0.005 and 0.002, respectively). All patients in the study with > 150 pg of CMV DNA in their granulocytes had visceral CMV disease. The amounts of viral DNA in granulocytes of AIDS and organ transplant patients with CMV retinitis were low (median 22 pg). Marrow transplant patients were unique in that the amounts of CMV DNA in granulocytes were low whether CMV visceral organ disease was present (17 pg) or absent (14 pg). We conclude that high levels of circulating CMV DNA in viremic AIDS and solid organ transplant patients reflect viral involvement of visceral organs but not the retina. In marrow recipients, the severity of CMV disease, even when fatal, is not reflected quantitatively in peripheral blood leukocytes.

Human immunodeficiency virus type 1 antigenaemia is enhanced in patients with disseminated cytomegalovirus infection and deficient T lymphocytes

We have studied 61 patients with the acquired immunodeficiency syndrome (AIDS) regarding the relationships between disseminated cytomegalovirus (CMV) infection with CMV retinitis, HIV1 antigenaemia and CD4+ and CD8+ T-cell deficiency. HIV1 p24 antigenaemia was present in all patients with CMV retinitis (at a high concentration), but in only 28% of patients without retinitis (at a low concentration). Compared to patients without retinitis, those patients who developed retinitis had lower CD4+ and CD8+ prior to and during AIDS. CMV may contribute to deficiencies of T lymphocytes in patients with AIDS.

Role of primary and secondary maternal viremia in transplacental guinea pig cytomegalovirus transfer

The modulation of the outcome of intrauterine guinea pig cytomegalovirus (GPCMV) infection by maternal viremia was investigated in the guinea pig model. Virus assay and in situ hybridization were used to study GPCMV infection of maternal blood, placentas, and fetuses following inoculation of pregnant guinea pigs by the subcutaneous, intracardiac, or intranasal route. Animals were inoculated in early gestation and were evaluated every 7 to 10 days throughout pregnancy. Although placental and fetal infections occurred in all groups examined, transfer of GPCMV to placentas and fetuses was most efficient in mothers inoculated subcutaneously. Primary viremia was followed by virus clearance from blood and by an episode of secondary viremia in the three groups of mothers examined. Placental and fetal infections in animals infected subcutaneously or intracardially were first detected at the time of primary viremia, persisted throughout gestation, and increased during secondary viremia. In contrast, placental and fetal infections in animals inoculated intranasally were demonstrated primarily during secondary viremia. Fetal infection was detected in all mothers with detectable primary and secondary viremia but in only 33% of mothers that experienced only primary viremia. These results suggest that secondary maternal viremia is associated with increased placental and fetal GPCMV infections.

Cytomegalovirus retinitis

Cytomegalovirus retinitis is a frequent and serious complication of various conditions, including diseases characterized by impaired immunity, such as the acquired immunodeficiency syndrome. Due to recent advances in the treatment of cytomegalovirus retinitis, accurate diagnosis and management have become increasingly important. In this review, the authors present the epidemiology, clinical features, diagnostic testing, treatment with complications, and prognosis of cytomegalovirus retinitis. A differential diagnosis is presented and the characteristic ocular lesions are illustrated.

Disseminated cytomegalovirus infection. Molecular analysis of virus and leukocyte interactions in viremia

Viremia is a hallmark of disseminated cytomegalovirus (CMV) infection and disease. Using conventional virus culture and a subgenomic cloned CMV DNA probe to detect viral DNA within leukocytes, we studied the virus-cell interactions involved in immunocompromised patients with viremic CMV infection. CMV was recovered by culture in 17/17 samples enriched for polymorphonuclear leukocytes. Viral DNA was detected by dot-blot hybridization in 16/17 (94%). In contrast, samples enriched for mononuclear cells yielded infectious CMV in culture in only 7/15 (47%) instances; nonetheless, viral DNA was present in 16/17 samples probed. The quantity of CMV DNA in polymorphonuclear cells was significantly greater than in mononuclear leukocytes (mean 13.1 vs. 9.1 estimated viral genome equivalents per 100 cells, respectively), and CMV was always recovered from these cells regardless of the amount of viral DNA present. Yet, when the amounts of CMV DNA were virtually identical in granulocytes and mononuclear cells (6.3 and 7.1 genomic equivalents, respectively) collected simultaneously, infectious CMV could not be recovered from mononuclear cells. Although several interpretations are possible, these data are consistent with the view that CMV exists within granulocytes in a mature infectious form during viremia. The virus interactions with mononuclear cells appear to be more complex, particularly in those cells that contain CMV DNA but do not yield infectious virus.

Cytomegalovirus retinitis and response to therapy with ganciclovir

A 15-month prospective study of 109 patients with the acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC) was conducted. Cytomegalovirus (CMV) retinitis developed in 18 of these patients; they were treated with ganciclovir. Five other patients with CMV retinitis who were not part of the prospective study were also treated with ganciclovir. CMV retinitis frequently involved the peripheral retina. All 23 patients treated with ganciclovir showed clinical regression of retinitis, although breakthrough recurrence of CMV retinitis occurred in seven patients (30.4%) while on maintenance therapy with ganciclovir. During treatment, neutropenia (less than 1000 leukocytes/mm3) developed in three patients (13%). Ganciclovir is an effective means of therapy for CMV retinitis, but it must be given chronically to prevent reactivation. Breakthrough recurrences while on maintenance therapy are not uncommon, but can be successfully treated with more aggressive treatment with ganciclovir. In addition, the prognosis for survival of AIDS patients being treated with ganciclovir is improved when compared with that of untreated patients.

Bilateral acute retinal necrosis (BARN). Identification of the presumed infectious agent

We describe histopathologic features of an enucleated eye of a patient suffering bilateral acute retinal necrosis (BARN). Retinal tissue was found focally degenerated, and the choroid massively enlarged by lymphoid-like agranular cells. An association of the disease with a viral infection could be demonstrated by (a) the presence of virus particles of the herpesvirus type in retinal tissue, (b) the transmission of the infected principle to human embryo fibroblast cultures, and (c) the visualization of CMV-antigens by immunofluorescence microscopy in such infected cultures. Slow growth of the virus in vitro and the presence of CMV-antigens after infection indicate that the herpesvirus involved in BARN was of the type CMV. On the basis of these findings we propose a guideline for therapy.

Cyclosporin A treatment for chronic uveitis associated with retinitis

A chronic bilateral non-granulomatous uveitis triggered by a chlamydial infection developed in a patient with HLA-B 27. Cyclosporin A was administered as an ultimate remedy. It had a rapid curative effect against the inflammation. Probable cytomegalovirus (CMV) retinitis, however, was observed 2 months after the onset of this treatment. Retinitis healed after discontinuation of Cyclosporin A therapy.

Cytomegalovirus retinitis: a manifestation of the acquired immune deficiency syndrome (AIDS)

Two homosexual males with the "gay bowel syndrome' experienced an acute unilateral loss of vision. Both patients had white intraretinal lesions, which became confluent. One of the cases had a depressed cell-mediated immunity; both patients ultimately died after a prolonged illness. In one patient cytomegalovirus was cultured from a vitreous biopsy. Autopsy revealed disseminated cytomegalovirus in both patients. Widespread retinal necrosis was evident, with typical nuclear and cytoplasmic inclusions of cytomegalovirus. Electron microscopy showed herpes virus, while immunoperoxidase techniques showed cytomegalovirus. The altered cell-mediated response present in homosexual patients may be responsible for the clinical syndromes of Kaposi's sarcoma and opportunistic infection by Pneumocystis carinii, herpes simplex, or cytomegalovirus.

Bilateral cytomegalovirus panuveitis after high-dose corticosteroid therapy

A 30-year-old previously healthy woman who recieved immunosuppressive doses of corticosteroids developed an unusual culture-proved cytomegalovirus panuveitis bilaterally. The atypical clinical course was marked by bilateral exudative detachements with minimal evidence of retinitis. Any patient receiving blood transfusions and immunosuppressive doses of corticosteroids is potentially at risk for developing ocular cytomegalovirus infection, and the clinical presentation of the ocular infection may be atypical.

Retinal aneurysms in adult cytomegalovirus retinitis

We observed aneurysms of the retinal arteries, capillaries, and venules occurring in a patient with cytomegalovirus retinitis. These aneurysms were caused by involvement of the retinal vascular endothelium resulting in focal weaknesses in the vascular walls. The clinical appearance of this retinitis superficially resembled retinal branch vein occlusion.