Fatal reactivation of postnatal cytomegalovirus infection with rapid emergence of ganciclovir resistance in an infant after allogeneic stem cell transplantation

Bilateral cytomegalovirus retinitis in a healthy infant

Purpose

To report a case of bilateral cytomegalovirus (CMV) retinitis in an otherwise healthy infant.

Methods

A four-month-old, healthy, male infant was evaluated for visual inattention.

Results

This full-term infant with a normal birth weight and an uneventful gestational period was referred with symptoms of visual inattention, fever, and agitation one week prior to admission. Ocular involvements were detected in the form of bilateral pan uveitis with diffuse bilateral retinitis and vasculitis with hemorrhage in the peripheral retina and posterior pole. CMV DNA was detected in the patient's ocular sample and cerebrospinal fluid by polymerase chain reaction (PCR). He was treated with intravitreal and systemic ganciclovir. Unfortunately, the infant died because of CMV encephalitis. Therefore, bilateral CMV retinitis (CMVR), which was probably transmitted from the mother, was diagnosed in this immunocompetent infant.

Conclusions

The present case highlights the possibility of CMVR in immunocompetent infant associated with systemic CMV infection, even during the postnatal period. Therefore, a high index of clinical suspicion and prompt treatment may be life-saving in similar cases.

Rationally designed chemokine-based toxin targeting the viral G protein-coupled receptor US28 potently inhibits cytomegalovirus infection in vivo

The use of receptor-ligand interactions to direct toxins to kill diseased cells selectively has shown considerable promise for treatment of a number of cancers and, more recently, autoimmune disease. Here we move the fusion toxin protein (FTP) technology beyond cancer/autoimmune therapeutics to target the human viral pathogen, human cytomegalovirus (HCMV), on the basis of its expression of the 7TM G protein-coupled chemokine receptor US28. The virus origin of US28 provides an exceptional chemokine-binding profile with high selectivity and improved binding for the CX3C chemokine, CX3CL1. Moreover, US28 is constitutively internalizing by nature, providing highly effective FTP delivery. We designed a synthetic CX3CL1 variant engineered to have ultra-high affinity for US28 and greater specificity for US28 than the natural sole receptor for CX3CL1, CX3CR1, and we fused the synthetic variant with the cytotoxic domain of Pseudomonas Exotoxin A. This novel strategy of a rationally designed FTP provided unparalleled anti-HCMV efficacy and potency in vitro and in vivo.

Absence of intraocular infections after hematopoietic stem cell transplantation at a single center: the experience with current preventive regimens

PURPOSE

To investigate the prevalence of intraocular infections after allogeneic stem cell transplantation (allo-SCT).

METHODS

The study design was a single institutional retrospective noncomparative cohort of 135 consecutive patients in 2006 and 2007 who underwent allo-SCT for hematological malignancy. The primary outcome was the development of intraocular infections after allo-SCT and secondary outcome consisted of development of other ocular disorders during follow-up.

RESULTS

The most frequent ocular sequel to allo-SCT included ocular graft-versus-host disease (GvHD), which developed in 37/135 patients (27%). Intraocular infection occurred in 1 of 135 patients (0.7%). This patient developed infectious chorioretinitis together with osteomyelitis, endocarditis, and brain abscess with fungus Scedosporium and was successfully treated with a combination of voriconazole, amphotericine B, and surgical interventions. Viral and/or bacterial intraocular infections were not observed at all.

CONCLUSIONS

Intraocular infections after allo-SCT are currently uncommon due to systematic use of preemptive treatment regimens, frequent controls, and early treatment of systemic infections.

Improved detection of mutated human cytomegalovirus UL97 by pyrosequencing

Ganciclovir (GCV) resistance frequently occurs upon prolonged treatment of ongoing active human cytomegalovirus (HCMV) infection in individuals with immature or compromised immune functions (e.g., recipients of solid-organ and hematopoietic stem cell transplants). Using pyrosequencing (PSQ), we established fast and sensitive detection of GCV resistance-associated mutations occurring in the HCMV open reading frame UL97. These mutations have been repeatedly associated with clinical treatment failure. We designed four PSQ assays and evaluated them by analyzing mixtures of plasmids or bacterial artificial chromosome-derived viruses containing UL97 wild-type and mutant sequences. A minimum level of 6% mutant sequence variants could be detected in these mixtures. In order to further evaluate the novel PSQ assays, we tested clinical specimens from patients with active HCMV infections. The results were compared with those obtained by conventional dideoxy chain terminator sequencing. As the PSQ method was more sensitive in detecting minor HCMV mutant fractions in a wild-type population, it is suggested that pyrosequencing is a useful tool for the early detection of emerging GCV-resistant HCMV in GCV-treated patients.

Dynamics of the emergence of a human cytomegalovirus UL97 mutant strain conferring ganciclovir resistance in a pediatric stem-cell transplant recipient

Stem-cell transplant recipients are at risk of developing ganciclovir-resistant human cytomegalovirus (HCMV) infection caused by mutations in the viral UL97 gene. Knowledge of the relative proportions of coexisting HCMV wild-type and mutant strains may contribute to a better understanding of the dynamics of in vivo mutant strain selection under ganciclovir. Currently, genotype resistance screening for UL97 is routinely performed by restriction fragment length polymorphism detection and sequencing. We present here the longitudinal course of a pediatric recipient of an allogeneic stem-cell transplant infected with a ganciclovir-resistant HCMV strain. EDTA-treated blood samples were analyzed longitudinally. The patient acquired a primary HCMV infection shortly before transplantation and reactivated the virus following allogeneic hematopoietic stem cell transplantation, thus receiving an intensive antiviral treatment schedule. Three different methods for UL97 mutation analysis, restriction fragment length polymorphism detection, sequencing, and a new, real-time PCR approach were performed. In conclusion, for our pediatric patient, during peak viral load, the UL97 wild-type strain predominates, while during clinical deterioration with low viral load, the predominant mutant strain persists.

Antiviral treatment of cytomegalovirus infection and resistant strains

This review discusses the management of resistant cytomegalovirus and prevention strategies for fatal therapy failures. Five drugs, ganciclovir/valganciclovir, cidofovir, foscarnet and fomivirsen, have been approved so far for the treatment of human cytomegalovirus (HCMV) diseases. Except for fomivirsen, all of the approved drugs share the same target molecule, the viral DNA polymerase. The emergence of drug-resistant HCMV has also been reported for all of them. For optimal care of patients, the clinical virologist has to provide the most meaningful assays for monitoring of therapy and early detection of emerging drug-resistant HCMV. Additionally, a quantitative drug monitoring would be helpful. New antiviral agents are urgently needed with less adverse effects, good oral bioavailability and possibly novel targets or mechanisms of action to avoid cross-resistance and to improve the ability to suppress the selection of resistant virus strains by combination therapy. Compounds like maribavir, leflunomide and artesunate, which exhibit anti-HCMV activity in vitro and in patients need to be evaluated in clinical studies. Besides these, new therapy approaches like immunotherapy or new diagnostic techniques like pyrosequencing have to be considered in the future.