CLINICAL CHARACTERISTICS AND PROGNOSTIC FACTORS AFFECTING CLINICAL OUTCOMES IN CYTOMEGALOVIRUS RETINITIS WITH OR WITHOUT HIV INFECTION.

PURPOSE: To explore the clinical features and outcomes of cytomegalovirus retinitis (CMVR) in patients with HIV and non-HIV. METHODS: This retrospective cohort study included all patients with CMVR in National Taiwan University Hospital from 2013 to 2018. Demographic data, clinical characteristics, CMVR recurrence, and overall survival were compared between the HIV and non-HIV groups. Generalized estimating equation models were implemented to analyze the risk factors of poor visual prognosis. The Kaplan-Meier survival analysis was performed to investigate recurrence and survival. RESULTS: A total of 66 patients (95 eyes) with CMVR were enrolled, with no significant differences between the HIV (41 patients; 61 eyes) and non-HIV (25 patients; 34 eyes) groups in initial/final visual acuity, lesion area, or viral loads. Poor visual outcome was associated with poor initial visual acuity, retinal detachment, and a higher plasma cytomegalovirus titer. The HIV group had significantly longer survival rate ( P = 0.033) and lower recurrence rate ( P = 0.01) than the non-HIV group, and it also presented with better prognosis in recurrence-free survival analysis ( P = 0.01). CONCLUSION: Patients with CMVR without HIV had higher mortality and recurrence rates than the HIV group. Risk factors of poor visual outcome included poor initial visual acuity, retinal detachment, and a high plasma cytomegalovirus titer.

CMV retinitis and subsequent acute cystoid macular oedema after treatment with vitreous ganciclovir injection: a case report.

BACKGROUND: To report a very rare acute cystoid macular oedema following ganciclovir injection in patients receiving allogeneic haematopoietic stem cell transplantation. CASE PRESENTATION: A 44-year-old male patient experienced vision loss in his left eye eight months after allogeneic stem cell transplantation. Ophthalmologic examination showed posterior retinopathy with retinal haemorrhage, a yellow necrotic border, and a vascular white sheath involved in the superior temporal retina but not the posterior pole. Cytomegalovirus DNA results in both plasma and ocular fluid were positive. All tests combined with the patient's medical history suggested that his ocular disease was cytomegalovirus retinitis. Consequently, he received a weekly ganciclovir vitreous injection. The disease was visibly controlled, and the fundus condition improved after the first three treatments. However, the patient had severe vision loss in his left eye and acute cystic oedema in the macula, while the original lesion was stable two hours after the fourth treatment. The macular oedema subsided significantly on the first day. Over the next week, daily OCT findings indicated that the patient's macular oedema gradually subsided and resolved completely by the second week, and his left eye vision partially improved. CONCLUSION: Macular oedema may occur in patients with cytomegalovirus retinitis, but it rarely occurs during treatment. In this case, the patient's macular oedema appeared and resolved quickly. Macular oedema in patients with cytomegalovirus retinitis receiving vitreous cavity injections of ganciclovir needs to be further studied and discussed.

Atypical cytomegalovirus retinal disease in pyroptosis-deficient mice with murine acquired immunodeficiency syndrome.

Pyroptosis is a caspase-dependent programmed cell death pathway that initiates and sustains inflammation through release of pro-inflammatory cytokines interleukin (IL)-1ß and IL-18 following formation of gasdermin D (GSDMD)-mediated membrane pores. To determine the possible pathogenic contributions of pyroptosis toward development of full-thickness retinal necrosis during AIDS-related human cytomegalovirus retinitis, we performed a series of studies using an established model of experimental murine cytomegalovirus (MCMV) retinitis in mice with retrovirus-induced immunosuppression (MAIDS). Initial investigations demonstrated significant transcription and translation of key pyroptosis-associated genes within the ocular compartments of MCMV-infected eyes of mice with MAIDS. Subsequent investigations compared MCMV-infected eyes of groups of wildtype MAIDS mice with MCMV-infected eyes of groups of caspase-1-/- MAIDS mice, GSDMD-/- MAIDS mice, or IL-18-/- MAIDS mice to explore a possible contribution of pyroptosis towards the pathogenesis of MAIDS-related MCMV retinitis. Histopathologic analysis revealed typical full-thickness retinal necrosis in 100% of MCMV-infected eyes of wildtype MAIDS mice. In sharp contrast, none (0%) of MCMV-infected eyes of MAIDS mice that were deficient in either caspase-1, GSDMD, or IL-18 developed full-thickness retinal necrosis but instead exhibited an atypical pattern of retinal disease characterized by thickening and proliferation of the retinal pigmented epithelium layer with relative sparing of the neurosensory retina. Surprisingly, MCMV-infected eyes of all groups of deficient MAIDS mice harbored equivalent intraocular amounts of infectious virus as seen in MCMV-infected eyes of groups of wildtype MAIDS mice despite failure to develop full-thickness retinal necrosis. We conclude that pyroptosis plays a significant role in the development of full-thickness retinal necrosis during the pathogenesis of MAIDS-related MCMV retinitis. This observation may extend to the pathogenesis of AIDS-related HCMV retinitis and other AIDS-related opportunistic virus infections.

Extralesional microvascular and structural macular abnormalities in cytomegalovirus retinitis.

To evaluate extralesional microvascular and structural changes of the macula using optical coherence tomography angiography (OCTA) and structural OCT in cytomegalovirus retinitis (CMVR). An observational study of CMVR patients were performed. Complete ophthalmic examination, serial color fundus photography, structural OCT and OCTA were performed at baseline and follow-up visits for up to 12 months. The structural OCT was analyzed to evaluate macular areas within, bordering and beyond the CMVR lesions. Extralesional retinal capillary plexus of the macula were evaluated by OCT angiography and compared with the unaffected fellow eyes. Thirteen eyes from 13 patients were enrolled. At baseline, macular areas without CMVR lesions showed decreased vessel density (VD) of both the superficial (P = 0.0002) and deep (P < 0.0001) retinal capillary plexus in eyes with CMVR as compared with the corresponding macular areas of the unaffected fellow eyes. The decrease of VD persisted through the follow-up period for up to 12 months after adjusting for degree of vitreous haze. Structural macular OCT characteristics at the borders and beyond the lesions included intraretinal hyperreflective dots, cystoid macular edema, subretinal fluid and selective ellipsoid zone (EZ) loss. The selective EZ loss found in 6 of 12 eyes showed recovery in 4 eyes after receiving anti-viral treatment. In CMVR eyes, there were microvascular and microstructural abnormalities in the macular area without clinically visible CMVR lesions. Our results provided interesting insights into CMV infection of the retina.

Ocular cytomegalovirus latency exacerbates the development of choroidal neovascularization.

Age-related macular degeneration (AMD) is a complex, multifactorial, progressive disease which represents a leading cause of irreversible visual impairment and blindness in older individuals. Human cytomegalovirus (HCMV), which infects 50-80% of humans, is usually acquired during early life and persists in a latent state for the life of the individual. In view of its previously described pro-angiogenic properties, we hypothesized that cytomegalovirus might be a novel risk factor for progression to an advanced form, neovascular AMD, which is characterized by choroidal neovascularization (CNV). The purpose of this study was to investigate if latent ocular murine cytomegalovirus (MCMV) infection exacerbated the development of CNV in vascular endothelial growth factor (VEGF)-overexpressing VEGF-Ahyper mice. Here we show that neonatal infection with MCMV resulted in dissemination of virus to various organs throughout the body including the eye, where it localized principally to the choroid in both VEGF-overexpressingVEGF-Ahyper and wild-type(WT) 129 mice. By 6 months post-infection, no replicating virus was detected in eyes and extraocular tissues, although virus DNA was still present in all eyes and extraocular tissues of both VEGF-Ahyper and WT mice. Expression of MCMV immediate early (IE) 1 mRNA was detected only in latently infected eyes of VEGF-Ahyper mice, but not in eyes of WT mice. Significantly increased CNV was observed in eyes of MCMV-infected VEGF-Ahyper mice compared to eyes of uninfected VEGF-Ahyper mice, while no CNV lesions were observed in eyes of either infected or uninfected WT mice. Protein levels of several inflammatory/angiogenic factors, particularly VEGF and IL-6, were significantly higher in eyes of MCMV-infected VEGF-Ahyper mice, compared to uninfected controls. Initial studies of ocular tissue from human cadavers revealed that HCMV DNA was present in four choroid/retinal pigment epithelium samples from 24 cadavers. Taken together, our data suggest that ocular HCMV latency could be a significant risk factor for the development of AMD. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

[A comparative study of retinal nerve fiber layer thickness in AIDS patients with different fundus diseases].

Objective: To investigate the characteristics of retinal nerve fiber layer (RNFL) thickness in AIDS patients with normal fundus, HIV-related microvascular retinopathy (MVR), and cytomegalovirus retinitis (CMVR). Methods: In this cross-sectional study, 111 patients were diagnosed with AIDS from 2012 to 2017 by infectious disease physicians in Beijing You'an Hospital. There were 105 males and 6 females, aged 20-65 years. According to the results of ophthalmic examination, the patients were divided into three groups: 31 patients in the active-stage CMVR group, 47 patients in the MVR group, and 33 patients with normal fundus in the control group. RNFL thickness was measured by optical coherence tomography in all patients. At the same time, visual acuity, intraocular pressure, and fundus were examined, and AIDS-related systemic examination (CD4(+) T lymphocyte count, HAART treatment status, and blood cytomegalovirus DNA level) was performed. The measurement data were compared by t-test, variance analysis or rank sum test. The counting data were compared by chi square test or Fisher exact probability method. Results: In the control group, the thickness of RNFL in the superior quadrant in the left and right eyes was 145 (79, 231) µm and 142 (46, 179) µm, respectively; the difference was statistically significant (Z=-2.481, P=0.013). The RNFL thickness of the diseased and healthy eyes in the MVR group was 116 (91, 138) µm and 122 (82, 192) µm, respectively, with no significant difference (Z=-0.861, P=0.389); the best corrected visual acuity was 0.0 (0.0, 0.2) and 0.0 (0.0, 0.2), respectively, with no significant difference (Z=-0.378, P=0.705). In the CMVR group, the best corrected visual acuity of the diseased and healthy eyes was (0.23±0.48) and (0.02±0.82), respectively, and the difference was statistically significant (t=-2.944, P=0.003); the RNFL thickness was 133 (61, 219) µm and 121 (69, 146), respectively, in the whole optic disc, with statistically significant difference (Z=-2.385, P=0.017), 104 (41, 374) µm and 82 (55, 121) µm, respectively, in the nasal quadrant, and 99 (14, 173) µm and 72 (36, 111) µm, respectively, in the temporal quadrant, with statistically significant difference (Z=-2.045, -2.543; P=0.041, 0.011). The RNFL thickness in the CMVR group, the MVR group, and the control group was 149 (61, 350) µm, 126 (71, 304) µm, and 113 (87, 149) µm, respectively, with statistically significant difference (H=20.908, P=0.000). Conclusions: The fundus of AIDS patients had different characteristics on optical coherence tomography. In active CMVR patients, the thickness of RNFL was generally thickened. In MVR patients, the average thickness of RNFL was thicker than that in the normal control group.(Chin J Ophthalmol, 2020, 56:258-265).

Autophagy protects against retinal cell death in mouse model of cytomegalovirus retinitis.

BACKGROUND: Extensive death of uninfected bystander neuronal cells is an important component of the pathogenesis of cytomegalovirus retinitis (CMV). Our previous results have shown that there is a functional relationship between autophagy and apoptosis during MCMV infection of retinal pigment epithelium (RPE). The purpose of this study was to determine whether autophagy plays a significant role in the death of retinal cells during MCMV retinitis. METHODS: The retinas of adult BALB/c mice were infected with MCMV via supraciliary injection. Rapamycin, a mTOR inhibitor, was injected to MCMV-infected BALB/c mice intraperitoneally. Immunohistochemistry and western blot were performed to observe the spread pattern of virus in retinas and the levels of targeted proteins. Plaque assay was performed to determine the virus titer in different groups. Since Atg5 is a key gene regulating autophagy, we bred Atg5flox/flox; Nestin-Cre mice to deeply elucidate the role of autophagy during MCMV retinitis. Atg5flox/flox; Nestin-Cre mice were genotyped and infected with MCMV. Immunohistochemistry was performed to observe the type of virus-infected cells and apoptosis in retinas during MCMV retinitis. RESULTS: In MCMV mouse model, MCMV infection in outer nuclear layer (ONL) and inner nuclear layer (INL) in the retinas caused cleaved caspase 3 positive apoptosis, which is not co-localized with early antigen (EA) positive virus infected cells in rapamycin treated group. Rapamycin treatment increased the levels of LC3B-II by inhibiting mTOR and decreased the levels of cleaved caspase-3 during MCMV retinitis. However, virus propagation was not affected by rapamycin. In Atg5flox/flox; Nestin-Cre mice, RPE and glial cells were the main targets of viral infection, and number of EA positive retinal cells and TUNEL positive retinal cells was significantly increased compared to Atg5flox/+; Nestin-Cre mice though there was no difference of virus propagation between Atg5flox/flox; Nestin-Cre mice and Atg5flox/+; Nestin-Cre mice. CONCLUSIONS: Autophagy protects retinal cells from MCMV infection induced apoptosis through mTOR-mediated signaling pathway.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY FINDINGS IN MACULA-INVOLVING CYTOMEGALOVIRUS RETINITIS.

PURPOSE: To evaluate the microstructural features of cytomegalovirus (CMV) retinitis by spectral domain optical coherence tomography (OCT). METHODS: Subjects were patients with macula-involving CMV retinitis with OCT imaging. The leading edge of retinitis in the macula was identified based on fundus imaging, and OCT findings were longitudinally evaluated in three areas: within the area of active retinitis, at the leading edge of retinitis, and just beyond the leading edge of retinitis. RESULTS: Optical coherence tomography imaging of macular CMV retinitis identified vitreous cells in 10 eyes (100%), posterior vitreous detachment in four eyes (40%), broad-based vitreomacular traction in one eye (10%), epiretinal membrane in eight eyes (80%), and lamellar hole-associated epiretinal proliferation associated with an atrophic hole in one eye (10%). Retinal architectural disruption, disruption of inner retinal layers, disruption of the external limiting membrane, and ellipsoid zone abnormalities were noted within the area of retinitis in all eyes and decreased in frequency and severity at and beyond the leading edge of retinitis, although all 10 eyes (100%) exhibited one of these abnormalities, especially outer retinal microabnormalities, beyond the leading edge of retinitis. CONCLUSION: Microstructural abnormalities were frequently noted on OCT of CMV retinitis, including within the retina beyond the leading edge of retinitis identified by corresponding fundus imaging. Outer retinal abnormalities were noted more frequently than inner retinal abnormalities beyond the leading edge of retinitis. These findings provide insight into the effects of CMV retinitis on retinal microstructure and potentially on vision and highlight the potential utility of OCT for monitoring microprogression of macula-involving CMV retinitis.

OPTICAL COHERENCE TOMOGRAPHY FINDINGS IN CYTOMEGALOVIRUS RETINITIS: A Longitudinal Study.

PURPOSE: To evaluate the vitreal, retinal, and choroidal features using spectral domain optical coherence tomography (SD-OCT) in eyes affected by cytomegalovirus (CMV) retinitis. METHODS: Patients diagnosed with either active or inactive CMV retinitis were included in the study. Complete ophthalmic examination, serial color fundus photography, and SD-OCT (with and without enhanced depth imaging function) were performed for all the subjects at baseline and follow-up visits. The SD-OCT images were analyzed by two independent graders to evaluate the structural changes in areas of CMV retinitis. Prevalence data for vitreal, retinal, and choroidal SD-OCT features were collected. RESULTS: Twelve eyes from 9 patients (6 males, mean age: 52.7 ± 10.3 years) were enrolled. Nine eyes were diagnosed with active CMV retinitis at baseline. Active disease SD-OCT characteristic findings included nebulous vitritis (100%), posterior hyaloid thickening (83.3%), epiretinal membrane (100%), and retinal swelling (100%). Two distinct patterns of chorioretinal involvement were observed in active retinitis: 1) full-thickness retinitis (Full thickness retinitis) (n = 7 eyes) with choriocapillaris alterations and retinal pigment epithelial thickening and 2) cavernous retinitis (n = 3 eyes) characterized by inner retinal hyperreflectivity, large empty spaces in outer nuclear layer, and bridges of retinal tissue but retinal pigment epithelium and choriocapillaris sparing. Patients with cavernous retinitis develop retinal detachment during follow-up. Eyes with Full thickness retinitis developed choriocapillaris atrophy and choroidal thinning and retinal scars as the lesions healed. CONCLUSION: There are two distinct patterns of chorioretinal involvement in CMV retinitis. SD-OCT is a useful tool in the diagnosis, management, and prediction of the outcome of CMV retinitis.

Cytomegalovirus retinitis in a patient with secondary acute lymphosarcoma leukemia undergoing allogeneic hematopoietic stem-cell transplantation: A rare case report: a care-compliant article.

RATIONALE: Cytomegalovirus (CMV) retinitis is a common opportunistic infection in immunocompromised patients, which may lead to blindness. CMV retinitis is not an uncommon infectious disease in patients with immune regulatory abnormalities, for example, human immunodeficiency virus (HIV) patients. However, CMV retinitis in a patient with acute lymphosarcoma leukemia (ALL) undergoing allogeneic hematopoietic stem-cell transplantation (HSCT) phase is very rare. PATIENT CONCERNS: A case of CMV retinitis in a patient receiving immunosuppressive therapy as a part of ALL allogeneic HSCT is described including the pathogenesis, clinical signs, and therapy. DIAGNOSES: CMV retinitis. INTERVENTIONS: Ganciclovir intravitreal injection at weekly intervals for 4 weeks. OUTCOMES: Patient's vision had improved and the load of CMV deoxyribonucleic acid (DNA) in the aqueous humor declined. The CMV retinitis and perivascular of retina infiltration regressed. LESSONS: We propose that the concentration of CMV DNA load in the aqueous humor could be useful in making the diagnosis and in selecting the optimal treatment in this kind of CMV retinitis.

COMPARISON OF VISUAL PROGNOSIS AND CLINICAL FEATURES OF CYTOMEGALOVIRUS RETINITIS IN HIV AND NON-HIV PATIENTS.

PURPOSE: To compare the visual prognosis and clinical features of cytomegalovirus (CMV) retinitis between HIV and non-HIV patients. METHODS: Retrospective cross-sectional study on patients diagnosed with CMV retinitis. Depending on the presence of HIV infection, best-corrected visual acuity (VA) and clinical feature of CMV retinitis were analyzed. The clinical characteristics associated with poor visual prognosis after antiviral treatment were also identified. RESULTS: A total of 78 eyes (58 patients) with CMV retinitis were included in this study: 21 eyes and 57 eyes in HIV and non-HIV patients, respectively. Best-corrected VA was not significantly different between HIV and non-HIV patients. The rate of foveal involvement, retinal detachment, involved zone, and mortality did not significantly differ between the two groups. Visual acuity after antiviral treatment was significantly worse (pretreatment logarithm of the minimal angle of resolution best-corrected VA, 0.54 ± 0.67 [Snellen VA, 20/63]; posttreatment logarithm of the minimal angle of resolution best-corrected VA, 0.77 ± 0.94 [Snellen VA, 20/125]; P = 0.014). Poor visual prognosis was significantly associated with Zone 1 involvement, retinal detachment, and a poor general condition. CONCLUSION: The overall visual prognosis and the clinical features of CMV retinitis do not differ between HIV and non-HIV patients. The visual prognosis of CMV retinitis still remains quite poor despite advancements in antiviral treatment. This poor prognosis after antiviral treatment is associated with retinal detachment during follow-up, Zone 1 involvement, and the poor general condition of the patient.

Treatment outcomes of reduced-dose intravitreal ganciclovir for cytomegalovirus retinitis.

BACKGROUND: Cytomegalovirus retinitis (CMVR) is one of the most common opportunistic infection in immunocompromised individuals. Intravitreal ganciclovir injection has been used successfully but no standard regimen was established. Risks of drug toxicity, endophthalmitis, and injection-related complications increased with number and frequency of injection. The aim of this study is to evaluate the outcomes of reduced-dose intravitreal ganciclovir (2 mg/0.04 mL) for the treatment of CMVR. METHODS: A prospective observational cohort study involving 67 eyes of 49 patients with CMVR was performed. Induction therapy involved intravenous ganciclovir (10 mg/kg/day) for 2 weeks unless contraindicated or patients refused. Patients were then treated with reduced-dose intravitreal ganciclovir every week for 4 weeks, and then every other week until the lesion healed. The patients' demographic data were recorded, and vision parameters were examined every visit. RESULTS: Twenty eyes (29.9 %) presented with initial visual acuities less than 6/60. The majority of patients were diagnosed with CMVR in zones 1 or 2 (63 eyes, 94 %), and, at least, one quadrant of the retina was involved (56 eyes, 83.6 %). Forty-one eyes (61.2 %) completely resolved after treatment within the 6-month follow-up. There was no significant difference in healing time, whether or not patients received induction treatment with intravenous ganciclovir (111.00 ± 12.96 vs 105.00 ± 28.32 days, p = 0.8). Five eyes (12.2 %) of patients with healed CMVR had visual acuities less than 6/60. CONCLUSIONS: Reduced-dose intravitreal ganciclovir is a safe and effective treatment option. It provides comparable results to other weekly regimens. Induction with intravenous ganciclovir is not crucial in a resolution of retinitis, although it may be necessary to reduce systemic cytomegalovirus loads and mortality rates. TRIAL REGISTRATION: The trial was registered with Thai Clinical Trials Registry (TCTR) on 16 March 2016 - TCTR20160316001 .

Cytomegalovirus Retinitis in Three Pediatric Cases with Acute Lymphoblastic Leukemia: Case Series and Review of the Literature.

Cytomegalovirus (CMV) retinitis is typically diagnosed in patient with AIDS and those who underwent allogeneic hematopoietic cell transplant. However, it may develop in patients with acute lymphoblastic leukemia (ALL) who have not undergone hematopoietic cell transplantation. To increase awareness of CMV retinitis in this group, we describe 3 patients ages 3, 9, and 12, with ALL who developed CMV retinitis. The diagnosis of CMV retinitis was made on the basis of ophthalmological findings suggesting typical retinal lesions. In 2 cases, CMV DNAemia was present, while in 1 patient CMV DNA was detected only in vitreous fluid using the PCR technique. All cases were treated with intravenous ganciclovir for 2 or 3 weeks as induction therapy, followed by oral valganciclovir prophylaxis. Initially, active retinitis lesions resolved in all cases; however, in 1 patient CMV retinitis relapsed 3 times during follow-up. In this case, by using foscarnet therapy, satisfactory responses were achieved and the progression of CMV retinitis lesions stopped and eventually regressed.

Cytomegalovirus retinitis in HIV/AIDS patients.

UNLABELLED: Human immunodeficiency virus (HIV) has the ability to affect any organ in the body. In 70% of HIV-infected patients ocular manifestations were observed, which in the vast majority reflect the systemic disease and may be the first sign of a disseminated infection. AIM: The purpose of this paper is to determine the prevalence and the clinical aspects of cytomegalovirus retinitis in HIV/AIDS (Acquired Immunodeficiency Syndrome) patients. METHOD: The study is retrospective, conducted in the Ophthalmology Office of "Matei Bals" Infectious Diseases Hospital in Bucharest during the period August 1, 2007 - August 1, 2013. Each patient was examined thoroughly at the slit lamp biomicroscope by using a lens of 90D and a 20D lens using the indirect microscope after administration of topical mydriatics. RESULTS: 131 patients were followed for HIV / AIDS with posterior segment ocular involvement. 36.64% of the 131 patients having affected the posterior segment have been diagnosed with CMV retinitis. CONCLUSIONS: Doctors should be aware of the existence of ocular damage in HIV/AIDS and to emphasize the importance of regular ophthalmologic examination of patients with HIV/AIDS.

Role of Bax in death of uninfected retinal cells during murine cytomegalovirus retinitis.

PURPOSE: Extensive death of uninfected bystander neuronal cells is an important component of the pathogenesis of cytomegalovirus retinitis. Our previous results have shown that caspase 3-dependent and -independent pathways are involved in death of uninfected bystander cells during murine cytomegalovirus (MCMV) retinitis and also that Bcl-2, an important inhibitor of apoptosis via the Bax-mediated mitochondrial pathway, is downregulated during this process. The purpose of this study was to determine whether Bax-mediated mitochondrial damage has a significant role in the death of uninfected retinal cells. METHODS: BALB/c mice, Bax(-/-) mice, or Bax(+/+) mice were immunosuppressed with methylprednisolone and infected with 5 × 10(3) plaque-forming units (PFU) of the K181 strain of MCMV via the supraciliary route. Injected eyes were analyzed by plaque assay, electron microscopy, hematoxylin and eosin (H&E) staining, TUNEL assay, Western blot (for caspase 3, caspase 12, Bax, receptor interacting protein-1 [RIP1] and receptor interacting protein-3 [RIP3]), as well as immunohistochemical staining for MCMV early antigen and cleaved caspase 3. RESULTS: Significantly more Bax was detected in mitochondrial fractions of MCMV-infected eyes than in mitochondrial fractions of mock-infected control eyes. Furthermore, the level of cleaved caspase 3 was significantly lower in MCMV-infected Bax(-/-) eyes than in MCMV-infected Bax(+/+) eyes. However, more caspase 3-independent cell death of uninfected bystander retinal cells and more cleaved RIP1 were observed in Bax(-/-) than in Bax(+/+) eyes. CONCLUSIONS: During MCMV retinitis, Bax is activated and has an important role in death of uninfected bystander retinal cells by caspase 3-dependent apoptosis. Although the exact mechanism remains to be deciphered, active Bax might also prevent death of some types of uninfected retinal cells by a caspase 3-independent pathway.

Decrease of murine cytomegalovirus-induced retinitis by intravenous delivery of immediate early protein-3-specific siRNA.

PURPOSE: Retinitis induced by both human and murine cytomegaloviruses following immunosuppression is characterized by progressive loss of retinal architecture, due to necrosis of virus-infected cells as well as widespread apoptosis of uninfected bystander cells. Because small inhibitory RNA molecules (siRNA) can reduce murine cytomegalovirus (MCMV) gene expression and thereby inhibit virus replication in vitro, we tested siRNAs directed against MCMV immediate early protein-3 (IE-3) to determine if MCMV-induced retinitis could be alleviated in vivo. METHODS: Immunosuppressed Balb/c mice (2.0 mg methylprednisolone acetate every 3 days beginning on day -2) were infected with 5 × 10(3) pfu of the K181 strain of MCMV via the supraciliary route. At day 2 post infection, mice were treated with various doses of IE-3-specific siRNA ranging from 0.1 nmol to 10 nmol, in a volume of 20 µL PBS via tail vein injection. Injected eyes were collected at various times post inoculation and subjected to plaque assay for virus titer, MCMV antigen staining, H&E staining, TUNEL assay, and Western blot for MCMV IE-3 protein. RESULTS: Small but significant amounts of fluorescently labeled IE-3-specific siRNA localized to the RPE layer 48 hours after intravenous injection. IE-3-specific siRNA significantly reduced virus titers at all concentrations tested (ranging from 0.1 nmol to 10 nmol), but the most potent effect of siRNA was observed at a dose of 1 nmol. We also observed that IE-3-specific siRNA produced a substantial decrease in MCMV titers and a substantial reduction in bystander cell apoptosis over the time course of virus infection. CONCLUSIONS: Systemic administration of IE-3-specific siRNA could alleviate MCMV retinitis by inhibiting virus replication and subsequent death of uninfected retinal cells.