Antiviral Therapy of CMV Disease in Children

In utero human cytomegalovirus infection is associated with increased levels of putatively protective maternal antibodies in nonprimary infection: evidence for boosting but not protection

BACKGROUND

Although primary maternal cytomegalovirus infections are associated with higher risk of in utero transmission, most fetal infections worldwide result from nonprimary maternal infections. Antibodies directed at glycoprotein B and the gH/gL/pUL128-130-131 pentamer can neutralize virus, and higher levels of antibody directed at several particular pentamer epitopes defined by monoclonal antibodies (mAbs) are associated with reduced risk of fetal cytomegalovirus transmission during primary maternal infection. This had not been explored in maternal nonprimary infection.

METHODS

In a setting where most maternal cytomegalovirus infections are nonprimary, 42 mothers of infants with congenital CMV infections (transmitters) were compared to 75 cytomegalovirus-seropositive mothers whose infants were cytomegalovirus-uninfected (nontransmitters). Control infants were matched by sex, maternal HIV status and gestational age. We measured the ability of maternal antibodies to block three key pentameric epitopes: one in the gH subunit, another straddling UL130/UL131 and the third straddling gH/gL/UL128/UL130. We tested if levels of antibodies directed at these epitopes were higher in nontransmitters compared to transmitters.

RESULTS

Levels of all three putatively protective pentamer-directed antibodies were significantly higher in transmitters compared to nontransmitters. In contrast, antibodies targeting an epitope on glycoprotein B were not different. Total antibody specific for pentamer and for gB were also higher in transmitters.

CONCLUSIONS

We found no evidence that higher levels of any CMV-specific antibodies were associated with reduced risk of congenital CMV infection in nonprimary maternal infection. Instead, we found higher maternal antibody targeting epitopes on CMV pentamer in transmitters than nontransmitters, providing evidence for antibody boosting but not protection.

Symptomatic Cytomegalovirus Infections in the First Year of Life: When Is Antiviral Therapy Conceived to Be Justified?

All infants treated with antiviral medication for symptomatic congenital (diagnosis <3 weeks) and probably postnatal (>3 weeks) cytomegalovirus infection were characterized with the help of a survey covering all German Pediatric hospitals between 2012 and 2013. We found that >50% of infants treated for cytomegalovirus were classified as probably postnatal cytomegalovirus infection, which was associated with preterm birth and underlying diseases of the immune system, heart or lung.

Surgical manifestations of gastrointestinal cytomegalovirus infection in children: Clinical audit and literature review

INTRODUCTION

Gastrointestinal sequelae of cytomegalovirus are rare, usually associated with significant immune compromise, and carry a high morbidity and mortality. Gastrointestinal disease frequently requires surgical intervention for diagnosis and management.

AIM

The aim of the study is to evaluate the incidence, presentation and management of gastrointestinal cytomegalovirus disease in a pediatric population.

METHOD

Between January 2003 and June 2011, a retrospective folder review was conducted of all symptomatic children with proven CMV disease, presenting to the surgical service. Eligible patients were identified using the surgical, histopathology and serology databases.

RESULTS

Thirty-eight patients (1.8/1000 surgical admissions) were identified with a median presenting age of 5months (range 3days-12years). Esophagitis (n=18) and small bowel disease (n=16) predominated, but CMV was seen throughout the gastrointestinal tract. Risk factors included HIV infection (n=21, 55%) and recent gastrointestinal surgery or infection (n=10, 26%). Characteristic multiple jejunoileal perforations were seen in six patients. Compared to upper GIT disease, intestinal involvement was associated with younger age and doubled mortality. In HIV-infected children, median CD4 (%) was lower in intestinal compared to upper gastrointestinal disease. Morbidities included anastomotic breakdowns (5), anastomotic strictures (3), relook laparotomies (10), resistant esophageal strictures (5) and prolonged parenteral nutrition (5). Anti-CMV drugs were given in 63%. Overall mortality was 32% (12/38) and was associated with lower GIT disease.

CONCLUSION

Invasive CMV gastrointestinal disease in our children was predominantly HIV-associated, or followed a major lower gastrointestinal inflammatory insult in infants younger than 6months. Successful therapy requires a high index of suspicion of active CMV disease to allow early implementation of CMV viral load control and aggressive treatment of the underlying immune impairment. Multiple surgical interventions are often required for both tissue diagnosis and management of acute and chronic complications. CMV-viral-load-tailored anti-CMV therapy is supported by recent literature.

Managing infections in pregnancy

PURPOSE OF REVIEW

The management of infection in pregnancy aims mainly at improving the diagnosis and prognosis of congenital infections. Over 400 publications have dealt with this issue over the last 2 years, taking advantage of progress made not only in the epidemiological knowledge of infections but also neonatal treatment and prenatal diagnosis and interventions. The focus remains largely on viral and parasitic infections, namely cytomegalovirus (CMV) and toxoplasmosis, with the appearance of influenza as part of recent and severe outbreaks.

RECENT FINDINGS

The prevalence of CMV infection is stable. The prediction of foetal infection from primary maternal infection is becoming more accurate and therapeutic approaches are promising, including the development of a vaccine in the near future. The prevalence of toxoplasmosis is decreasing markedly in Europe weakening the effect of preventive measures and questioning the rationale for screening. In addition, the efficacy of prenatal treatment is still under scrutiny, although no appropriate randomized controlled trial (RCT) has been undertaken.

SUMMARY

Accurate dating of maternal primary infection is key to prenatal management including foetal and perinatal surveillance and therapy. Heightened prenatal surveillance following influenza infection in early pregnancy is warranted by an apparent increased risk of nonchromosomal congenital malformations in large epidemiological studies, likely as an effect of maternal hyperthermia.

The immunological underpinnings of vaccinations to prevent cytomegalovirus disease

A universal cytomegalovirus (CMV) vaccination promises to reduce the burden of the developmental damage that afflicts up to 0.5% of live births worldwide. An effective vaccination that prevents transplacental transmission would reduce CMV congenital disease and CMV-associated still births and leave populations less susceptible to opportunistic CMV disease. Thus, a vaccination against this virus has long been recognized for the potential of enormous health-care savings because congenital damage is life-long and existing anti-viral options are limited. Vaccine researchers, industry leaders, and regulatory representatives have discussed the challenges posed by clinical efficacy trials that would lead to a universal CMV vaccine, reviewing the links between infection and disease, and identifying settings where disrupting viral transmission might provide a surrogate endpoint for disease prevention. Reducing the complexity of such trials would facilitate vaccine development. Children and adolescents are the targets for universal vaccination, with the expectation of protecting the offspring of immunized women. Given that a majority of females worldwide experience CMV infection during childhood, a universal vaccine must boost natural immunity and reduce transmission due to reactivation and re-infection as well as primary infection during pregnancy. Although current vaccine strategies recognize the value of humoral and cellular immunity, the precise mechanisms that act at the placental interface remain elusive. Immunity resulting from natural infection appears to limit rather than prevent reactivation of latent viruses and susceptibility to re-infection, leaving a challenge for universal vaccination to improve upon natural immunity levels. Despite these hurdles, early phase clinical trials have achieved primary end points in CMV seronegative subjects. Efficacy studies must be expanded to mixed populations of CMV-naive and naturally infected subjects to understand the overall efficacy and potential. Together with CMV vaccine candidates currently in clinical development, additional promising preclinical strategies continue to come forward; however, these face limitations due to the insufficient understanding of host defense mechanisms that prevent transmission, as well as the age-old challenges of reaching the appropriate threshold of immunogenicity, efficacy, durability and potency. This review focuses on the current understanding of natural and CMV vaccine-induced protective immunity.

Ganciclovir-resistant cytomegalovirus infections among lung transplant recipients are associated with poor outcomes despite treatment with foscarnet-containing regimens

Ganciclovir-resistant cytomegalovirus (CMV) infections are reported infrequently among lung transplant recipients receiving extended valganciclovir prophylaxis. We performed a single-center, retrospective review of ganciclovir-resistant CMV infections in a program that employed valganciclovir prophylaxis for ≥6 months after lung transplant. CMV infections were diagnosed in 28% (170/607) of patients. UL97 mutations were detected in 9.4% (16/170) of CMV-infected patients at a median of 8.5 months posttransplant (range, 5 to 21) and despite prophylaxis for a median of 7 months (range, 4 to 21). UL97 mutations were canonical; 25% (4/16) of strains carried concurrent UL54 mutations. Ganciclovir-resistant CMV was more likely with breakthrough infections (75% [12/16] versus 19% [30/154]; P = 0.00001) and donor positive/recipient negative (D+/R-) serostatus (75% versus 45% [69/154]; P = 0.03). The median whole-blood CMV load was 4.13 log10 copies/cm(3) (range, 2.54 to 5.53), and 93% (14/15) of patients had low-moderate immune responses (Cylex Immunoknow). Antiviral therapy was successful, failed, or eradicated viremia followed by relapse in 12% (2/16), 31% (5/16), and 56% (9/16) of patients, respectively. Eighty-seven percent (14/16) of patients were treated with foscarnet-containing regimens; toxicity developed in 78% (11/14) of these. Median viral load half-life and time to viremia eradication among foscarnet-treated patients were 2.6 and 23 days, respectively, and did not correlate with protection from relapse. Sixty-nine percent (11/16) of patients developed CMV pneumonitis, and 25% (4/16) died of it. Serum viral load was independently associated with death among foscarnet-treated patients (P = 0.04). In conclusion, ganciclovir-resistant CMV infections remained a major cause of morbidity and mortality following lung transplantation. Foscarnet-based regimens often eradicated viremia rapidly but were ineffective in the long term and limited by toxicity.

Emergence of antiviral resistance during oral valganciclovir treatment of an infant with congenital cytomegalovirus (CMV) infection

Congenital infection with human cytomegalovirus (CMV) is a major cause of morbidity, including sensorineural hearing loss (SNHL), in newborns. Antiviral therapy with ganciclovir (GCV) and its oral prodrug, valganciclovir (VAL-GCV) are increasingly being administered to infected infants, toward the goal of improving neurodevelopmental and auditory outcomes. In this case report, we describe a symptomatic congenitally infected infant treated with VAL-GCV in whom GCV resistance was suspected, based on a 50-fold increase in viral load after 6 weeks of oral therapy. Analyses of CMV sequences from both blood and urine demonstrated populations of viruses with M460V and L595F mutations in the UL97 phosphotransferase gene. In contrast, analysis of viral DNA retrieved from the newborn dried blood spot demonstrated wild-type UL97 sequences. DNAemia resolved after the discontinuation of VAL-GCV. Long-term VAL-GCV therapy in congenitally infected infants can select for resistant viral variants, and anticipatory virological monitoring may be warranted.

Is HCMV Vaccine an Unmet Need? The State of Art of Vaccine Development

Congenital HCMV infection is the most frequent congenital infection, with an incidence of 0.2–2.5% among all live births. About 11% of infected newborns show symptoms at birth, including hepato-splenomegaly, thrombocytopenia, neurologic involvement, hearing impairment and visual deficit. Moreover, 5–25% of the asymptomatic congenital HCMV-infected neonates will develop sequelae over months or even years. The relevant social burden, the economic costs of pre-natal screening, post-natal diagnosis, follow-up and possible therapy, although still limited, are the major factors to be considered. Several types of vaccines have been explored in order to develop an effective and safe HCMV vaccine: live attenuated, subunit, vectored, peptide, DNA, and subviral ones, but none are available for use. This review illustrates the different vaccine types studied to date, focusing on the possible vaccination strategy to be implemented once the HCMV vaccine is available, in terms of target population.

Antiviral therapy of two patients with chromosomally-integrated human herpesvirus-6A presenting with cognitive dysfunction

BACKGROUND

Human herpesvirus 6 (HHV-6) is a neurotropic virus implicated in central nervous system (CNS) dysfunction, multiple sclerosis, seizures and encephalitis. Inherited or "chromosomally integrated" HHV-6 (CIHHV-6) is a condition characterized by high DNA loads and germ line transmission of HHV-6 genomes, which are integrated into the telomere.

OBJECTIVES

We previously reported that integrated HHV-6 can be reactivated by trichostatin A in vitro. Therefore, we hypothesized that a broad array of neurological symptoms of CIHHV-6 patients may respond to antiviral drug treatment.

STUDY DESIGN

The patients have been treated with antiviral drugs and monitored for viral load, late mRNA, and clinical improvement.

RESULTS

Antiviral therapy of two CIHHV patients resulted in successful clinical resolution. However, both patients relapsed on multiple occasions within 4-6 months of cessation of antiviral therapy.

CONCLUSIONS

Successful antiviral drug treatment suggests that clinical symptoms of these patients were due to symptomatic reactivation of CIHHV-6. Alternatively, some CIHHV-6 patients may have a reduced resistance to community-acquired HHV-6 strains due to tolerance leading to persistent infections.

Cytomegalovirus antivirals and development of improved animal models

INTRODUCTION

Cytomegalovirus (CMV) is a ubiquitous pathogen that establishes a lifelong asymptomatic infection in healthy individuals. Infection of immunesuppressed individuals causes serious illness. Transplant and AIDS patients are highly susceptible to CMV leading to life-threatening end-organ disease. Another vulnerable population is the developing fetus in utero, where congenital infection can result in surviving newborns with long-term developmental problems. There is no vaccine licensed for CMV and current antivirals suffer from complications associated with prolonged treatment. These include drug toxicity and emergence of resistant strains. There is an obvious need for new antivirals. Candidate intervention strategies are tested in controlled preclinical animal models but species specificity of human CMV precludes the direct study of the virus in an animal model.

AREAS COVERED

This review explores the current status of CMV antivirals and development of new drugs. This includes the use of animal models and the development of new improved models such as humanized animal CMV and bioluminescent imaging of virus in animals in real time.

EXPERT OPINION

Various new CMV antivirals are in development, some with greater spectrum of activity against other viruses. Although the greatest need is in the setting of transplant patients, there remains an unmet need for a safe antiviral strategy against congenital CMV. This is especially important as an effective CMV vaccine remains an elusive goal. In this regard, greater emphasis should be placed on suitable preclinical animal models and greater collaboration between industry and academia.

Congenital cytomegalovirus infection manifesting as neonatal persistent pulmonary hypertension: report of two cases

Various neonatal symptoms can lead to a diagnosis of congenital CMV infection. We report two cases of persistent pulmonary hypertension in relation with congenital CMV infection following maternal primary infection and reinfection, respectively. Both infants had severe refractory hypoxemia, requiring high-frequency ventilation, inhaled nitric oxide and inotropic support. One of them required extracorporeal membrane oxygenation for five days. Ganciclovir therapy was attempted in the two cases on day 12 postnatal. One of the infant died on day 15 postnatal. The other survived and is developing uneventfully at 15 months of age.

CONCLUSION

Neonatal persistent pulmonary hypertension can be the consequence of congenital CMV infection. Intensive respiratory support and IV ganciclovir are indicated in case of life-threatening condition.