Onset of valganciclovir resistance in two infants with congenital cytomegalovirus infection

Decoding human cytomegalovirus for the development of innovative diagnostics to detect congenital infection

Cytomegalovirus is the most common cause of congenital infectious disease and the leading nongenetic etiology of sensorineural hearing loss. Although most infected neonates are asymptomatic at birth, congenital cytomegalovirus infection is responsible for nearly 400 infant deaths annually in the United States and may lead to significant long-term neurodevelopmental impairments in survivors. The resulting financial and social burdens of congenital cytomegalovirus infection have led many medical centers to initiate targeted testing after birth, with a growing advocacy to advance universal newborn screening. While no cures or vaccines are currently available to eliminate or prevent cytomegalovirus infection, much has been learned over the last five years regarding disease pathophysiology and viral replication cycles that may enable the development of innovative diagnostics and therapeutics. This Review will detail our current understanding of congenital cytomegalovirus infection, while focusing our discussion on routine and emerging diagnostics for viral detection, quantification, and long-term prognostication. IMPACT: This review highlights our current understanding of the fetal transmission of human cytomegalovirus. It details clinical signs and physical findings of congenital cytomegalovirus infection. This submission discusses currently available cytomegalovirus diagnostics and introduces emerging platforms that promise improved sensitivity, specificity, limit of detection, viral quantification, detection of genomic antiviral resistance, and infection staging (primary, latency, reactivation, reinfection).

An Update on Current Antiviral Strategies to Combat Human Cytomegalovirus Infection

Human cytomegalovirus (HCMV) remains an essential global concern due to its distinct life cycle, mutations and latency. As HCMV is a herpesvirus, it establishes a lifelong persistence in the host through a chronic state of infection. Immunocompromised individuals are at risk of significant morbidity and mortality from the virus. Until now, no effective vaccine has been developed to combat HCMV infection. Only a few antivirals targeting the different stages of the virus lifecycle and viral enzymes are licensed to manage the infection. Therefore, there is an urgent need to find alternate strategies to combat the infection and manage drug resistance. This review will provide an insight into the clinical and preclinical antiviral approaches, including HCMV antiviral drugs and nucleic acid-based therapeutics.

Ganciclovir-resistant cytomegalovirus retinitis in a 4-month-old infant

We present a case of ganciclovir-resistant cytomegalovirus retinitis (CMV) in a 4-month-old boy with congenital CMV infection. This case highlights the potential utility of a combination of intermittent viral load monitoring and retinal examinations in cases of congenital CMV with retinitis.

Death from human cytomegalovirus infection in a girl with congenital thymic dysplasia

We report the case of a girl with congenital thymic dysplasia and refractory disseminated Human Cytomegalovirus (CMV) infection diagnosed by autopsy. Additionally, she was diagnosed with T-cell lymphopenia immunodeficiency and received antiviral therapy with ganciclovir (GCV) /valganciclovir (V-GCV) and enhanced foscarnet. The CMV viral load (VL) monitoring was elevated with retinitis, interstitial pneumonia, and hepatitis. The phenotype of T-cell lymphopenia was uncertain, which limited any alternative therapy by whole-exome sequencing (WES) and lymphocyte subset panel until autopsy. The girl died of progressive respiratory failure and septic shock at ten months of age. Severe disseminated CMV infection typically develops in infants with primary maternal infections and occurs earlier during gestation and in people with a weakened host immune system. Individuals with CMV infection with initial immunodeficiency are associated with a poor prognosis, which is similar to patients with secondary immunodeficiency. This case describes the difficult treatment and prognosis of CMV infection in patients with congenital immunodeficiency, highlighting the importance of early aggressive anti-CMV antiviral therapy in immunodeficiencies, VL monitoring, drug resistance and the role of T-cells in CMV infection.

Congenital cytomegalovirus infection diagnostics and management

PURPOSE OF THE REVIEW

Congenital cytomegalovirus infection (cCMV) is the most frequent congenital infection and a leading nongenetic cause of sensorineural hearing loss (SNHL) and brain disease. The purpose of this review is to highlight recent developments in the diagnosis and management of children with cCMV.

RECENT FINDINGS

Progress is being made in the efforts to identify more infants with cCMV, especially those with asymptomatic infection. Largely due to efforts by various advocacy/parent groups, a number of states in the United States and many hospital systems have implemented hearing targeted CMV screening and mandated education of pregnant women about CMV.

SUMMARY

cCMV is an important cause of SNHL and neurologic morbidity worldwide. Early identification of infected children is critical to improve outcomes by providing timely interventions and guidance for long-term follow up. The fact that most infants with cCMV have no abnormal clinical findings, and the need to obtain samples for diagnosis within the first 2-3 weeks of life, makes it challenging to identify a majority of infants with cCMV without universal newborn CMV screening.

Detection of antiviral drug resistance in patients with congenital cytomegalovirus infection using long-read sequencing: a retrospective observational study

BACKGROUND

Congenital human cytomegalovirus (cCMV) infection can cause sensorineural hearing loss and neurodevelopmental disabilities in children. Ganciclovir and valganciclovir (GCV/VGCV) improve long-term audiologic and neurodevelopmental outcomes for patients with cCMV infection; however, antiviral drug resistance has been documented in some cases. Long-read sequencing can be used for the detection of drug resistance mutations. The objective of this study was to develop full-length analysis of UL97 and UL54, target genes with mutations that confer GCV/VGCV resistance using long-read sequencing, and investigate drug resistance mutation in patients with cCMV infection.

METHODS

Drug resistance mutation analysis was retrospectively performed in 11 patients with cCMV infection treated with GCV/VGCV. UL97 and UL54 genes were amplified using blood DNA. The amplicons were sequenced using a long-read sequencer and aligned with the reference gene. Single nucleotide variants were detected and replaced with the reference sequence. The replaced sequence was submitted to a mutation resistance analyzer, which is an open platform for drug resistance mutations.

RESULTS

Two drug resistance mutations (UL54 V823A and UL97 A594V) were found in one patient. Both mutations emerged after 6 months of therapy, where viral load increased. Mutation rates subsided after cessation of GCV/VGCV treatment.

CONCLUSIONS

Antiviral drug resistance can emerge in patients with cCMV receiving long-term therapy. Full-length analysis of UL97 and UL54 via long-read sequencing enabled the rapid and comprehensive detection of drug resistance mutations.

The Effect of (Val)ganciclovir on Hearing in Congenital Cytomegalovirus: A Systematic Review

OBJECTIVE

To search for existing evidence of a beneficial effect of (val)ganciclovir on hearing in children with congenital cytomegalovirus (cCMV) infection and to identify future research questions.

STUDY DESIGN

Systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, searches were performed in PUBMED, EMBASE, and WEB OF SCIENCE on December 15, 2021.

METHODS

Studies providing ear-specific hearing results after treating children with cCMV-related hearing loss with (val)ganciclovir were retained. A meta-analysis [Peto odds ratio (OR), Review Manager 5.3] was performed to compare hearing outcome between treated and untreated children. The National Institutes of Health tool was used for quality assessment and heterogeneity was assessed with I² statistics.

RESULTS

Eighteen studies with a total of 682 treated patients were included for the systematic review. Our meta-analysis showed that treating symptomatic children with hearing loss resulted in more hearing improvement [Peto OR 7.72, 95% confidence interval (CI) 3.08-19.34] and less hearing deterioration (Peto OR 0.23, 95% CI 0.10-0.57). Relative to an improvement and deterioration rate of 9.4% and 28.2% in an untreated group, the rate of the treated group was 44.5% and 6.3%, respectively.

CONCLUSIONS

There is sufficient evidence in literature to support treatment with (val)ganciclovir of children with symptomatic cCMV and hearing loss. However, still today, there is insufficient evidence of the potential beneficial role of (val)ganciclovir on hearing outcome of children with isolated hearing loss, late-onset hearing loss, and asymptomatic cCMV. The urgent need for future prospective, randomized clinical trials still exists. A standardization of definitions and treatment protocols would create uniformity in future studies. Laryngoscope, 2022.