HCMV glycoprotein B subunit vaccine efficacy mediated by nonneutralizing antibody effector functions.

Human cytomegalovirus (HCMV) is the most common congenital infection worldwide, frequently causing hearing loss and brain damage in afflicted infants. A vaccine to prevent maternal acquisition of HCMV during pregnancy is necessary to reduce the incidence of infant disease. The glycoprotein B (gB) + MF59 adjuvant subunit vaccine platform is the most successful HCMV vaccine tested to date, demonstrating ∼50% efficacy in preventing HCMV acquisition in multiple phase 2 trials. However, the mechanism of vaccine protection remains unknown. Plasma from 33 postpartum women gB/MF59 vaccinees at peak immunogenicity was tested for gB epitope specificity as well as neutralizing and nonneutralizing anti-HCMV effector functions and compared with an HCMV-seropositive cohort. gB/MF59 vaccination elicited IgG responses with gB-binding magnitude and avidity comparable to natural infection. Additionally, IgG subclass distribution was similar with predominant IgG1 and IgG3 responses induced by gB vaccination and HCMV infection. However, vaccine-elicited antibodies exhibited limited neutralization of the autologous virus, negligible neutralization of multiple heterologous strains, and limited binding responses against gB structural motifs targeted by neutralizing antibodies including AD-1, AD-2, and domain I. Vaccinees had high-magnitude IgG responses against AD-3 linear epitopes, demonstrating immunodominance against this nonneutralizing, cytosolic region. Finally, vaccine-elicited IgG robustly bound membrane-associated gB on the surface of transfected or HCMV-infected cells and mediated virion phagocytosis, although were poor mediators of NK cell activation. Altogether, these data suggest that nonneutralizing antibody functions, including virion phagocytosis, likely played a role in the observed 50% vaccine-mediated protection against HCMV acquisition.

Intrahost Dynamics of Human Cytomegalovirus Variants Acquired by Seronegative Glycoprotein B Vaccinees.

Human cytomegalovirus (HCMV) is the most common congenital infection worldwide and a frequent cause of hearing loss and debilitating neurologic disease in newborn infants. Thus, a vaccine to prevent HCMV-associated congenital disease is a public health priority. One potential strategy is vaccination of women of child bearing age to prevent maternal HCMV acquisition during pregnancy. The glycoprotein B (gB) plus MF59 adjuvant subunit vaccine is the most efficacious tested clinically to date, demonstrating 50% protection against primary HCMV infection in a phase 2 clinical trial. Yet, the impact of gB/MF59-elicited immune responses on the population of viruses acquired by trial participants has not been assessed. In this analysis, we employed quantitative PCR as well as multiple sequencing methodologies to interrogate the magnitude and genetic composition of HCMV populations infecting gB/MF59 vaccinees and placebo recipients. We identified several differences between the viral dynamics in acutely infected vaccinees and placebo recipients. First, viral load was reduced in the saliva of gB vaccinees, though not in whole blood, vaginal fluid, or urine. Additionally, we observed possible anatomic compartmentalization of gB variants in the majority of vaccinees compared to only a single placebo recipient. Finally, we observed reduced acquisition of genetically related gB1, gB2, and gB4 genotype "supergroup" HCMV variants among vaccine recipients, suggesting that the gB1 genotype vaccine construct may have elicited partial protection against HCMV viruses with antigenically similar gB sequences. These findings suggest that gB immunization had a measurable impact on viral intrahost population dynamics and support future analysis of a larger cohort.IMPORTANCE Though not a household name like Zika virus, human cytomegalovirus (HCMV) causes permanent neurologic disability in one newborn child every hour in the United States, which is more than that for Down syndrome, fetal alcohol syndrome, and neural tube defects combined. There are currently no established effective measures to prevent viral transmission to the infant following HCMV infection of a pregnant mother. However, the glycoprotein B (gB)/MF59 vaccine, which aims to prevent pregnant women from acquiring HCMV, is the most successful HCMV vaccine tested clinically to date. Here, we used viral DNA isolated from patients enrolled in a gB vaccine trial who acquired HCMV and identified several impacts that this vaccine had on the size, distribution, and composition of the in vivo viral population. These results have increased our understanding of why the gB/MF59 vaccine was partially efficacious, and such investigations will inform future rational design of a vaccine to prevent congenital HCMV.

Drip System for Admissions to Resident Teams: Impact on Workload and Education.

OBJECTIVES: Assigning patients to a call team every fourth day (bolus system) caused the maldistribution of patients among resident teams and required additional faculty effort for overflow patient care. We changed to a continuous daily rotation (drip system) and examined the effect on clinical workload among resident teams, resident education, and faculty utilization. METHODS: This is a retrospective study based on the daily records of 7 am team census, the attending physician schedules for a pediatric hospital medicine service with 5 teams, and the measures of resident education, including noon conference attendance, scores on in-service examinations, and duty hour violations. Data from the bolus system (May 2014-June 2015) were compared with the drip system (May 2016-June 2017). RESULTS: Data from 348 bolus days and 338 drip days were analyzed. There was a decrease in interteam variation from 6.2 to 3.9 patients (P < 0.001). There were fewer days with the following: large interteam variation (143 to 25, P < 0.001), days with resident teams at or above capacity (26 to 11, P = 0.01), resident teams below a minimum 7 am census (133 to 18, P < 0.001), and days when additional faculty were pulled for clinical care (61 to 9, P < 0.001). Resident noon conference attendance was unchanged and there was no adverse effect on examination scores or duty hour violations. CONCLUSIONS: Changing from a bolus to a drip model for admissions to inpatient teams resulted in a more even distribution of the workload and a more efficient use of physician resources without negatively affecting resident education.

Role of nucleotide-binding oligomerization domain 1 (NOD1) and its variants in human cytomegalovirus control in vitro and in vivo.

Induction of nucleotide-binding oligomerization domain 2 (NOD2) and downstream receptor-interacting serine/threonine-protein kinase 2 (RIPK2) by human cytomegalovirus (HCMV) is known to up-regulate antiviral responses and suppress virus replication. We investigated the role of nucleotide-binding oligomerization domain 1 (NOD1), which also signals through RIPK2, in HCMV control. NOD1 activation by Tri-DAP (NOD1 agonist) suppressed HCMV and induced IFN-ß. Mouse CMV was also inhibited through NOD1 activation. NOD1 knockdown (KD) or inhibition of its activity with small molecule ML130 enhanced HCMV replication in vitro. NOD1 mutations displayed differential effects on HCMV replication and antiviral responses. In cells overexpressing the E56K mutation in the caspase activation and recruitment domain, virus replication was enhanced, but in cells overexpressing the E266K mutation in the nucleotide-binding domain or the wild-type NOD1, HCMV was inhibited, changes that correlated with IFN-ß expression. The interaction of NOD1 and RIPK2 determined the outcome of virus replication, as evidenced by enhanced virus growth in NOD1 E56K mutant cells (which failed to interact with RIPK2). NOD1 activities were executed through IFN-ß, given that IFN-ß KD reduced the inhibitory effect of Tri-DAP on HCMV. Signaling through NOD1 resulting in HCMV suppression was IKKα-dependent and correlated with nuclear translocation and phosphorylation of IRF3. Finally, NOD1 polymorphisms were significantly associated with the risk of HCMV infection in women who were infected with HCMV during participation in a glycoprotein B vaccine trial. Collectively, our data indicate a role for NOD1 in HCMV control via RIPK2- IKKα-IRF3 and suggest that its polymorphisms predict the risk of infection.

Cytomegalovirus Kinetics Following Primary Infection in Healthy Women.

The kinetics of cytomegalovirus (CMV) DNA in infected asymptomatic hosts are largely unknown. We measured viral load (VL) in 124 fluid samples (oral, urine, vaginal, blood) collected from 21 women who acquired CMV. A quantitative real-time polymerase chain reaction assay of US17, which correlated with clinical assays, was used. VL decreased following primary infection in all fluids. The geometric mean VL of vaginal fluid was significantly higher than that of other sources: oral (3.89; 95% confidence interval [CI], 1.43-10.57), urine (6.36; 95% CI, 2.48-16.32), and whole blood (11.88; 95% CI, 4.12-34.20). Vaginal CMV shedding may provide a route for sexual and possibly perinatal transmission.

Vaccine prevention of maternal cytomegalovirus infection.

BACKGROUND: Congenital infection with cytomegalovirus (CMV) is an important cause of hearing, cognitive, and motor impairments in newborns. METHODS: In this phase 2, placebo-controlled, randomized, double-blind trial, we evaluated a vaccine consisting of recombinant CMV envelope glycoprotein B with MF59 adjuvant, as compared with placebo. Three doses of the CMV vaccine or placebo were given at 0, 1, and 6 months to CMV-seronegative women within 1 year after they had given birth. We tested for CMV infection in the women in quarterly tests during a 42-month period, using an assay for IgG antibodies against CMV proteins other than glycoprotein B. Infection was confirmed by virus culture or immunoblotting. The primary end point was the time until the detection of CMV infection. RESULTS: We randomly assigned 234 subjects to receive the CMV vaccine and 230 subjects to receive placebo. A scheduled interim analysis led to a stopping recommendation because of vaccine efficacy. After a minimum of 1 year of follow-up, there were 49 confirmed infections, 18 in the vaccine group and 31 in the placebo group. Kaplan-Meier analysis showed that the vaccine group was more likely to remain uninfected during a 42-month period than the placebo group (P=0.02). Vaccine efficacy was 50% (95% confidence interval, 7 to 73) on the basis of infection rates per 100 person-years. One congenital infection among infants of the subjects occurred in the vaccine group, and three infections occurred in the placebo group. There were more local reactions (pain, erythema, induration, and warmth) and systemic reactions (chills, arthralgias, and myalgias) in the vaccine group than in the placebo group. CONCLUSIONS: CMV glycoprotein B vaccine has the potential to decrease incident cases of maternal and congenital CMV infection. (ClinicalTrials.gov number, NCT00125502.)

Awareness of and behaviors related to child-to-mother transmission of cytomegalovirus.

OBJECTIVE: Congenital cytomegalovirus (CMV) infection is a common cause of hearing loss and intellectual disability. We assessed CMV knowledge and the frequency of women's behaviors that may enable CMV transmission to inform strategies for communicating prevention messages to women. METHODS: We analyzed survey responses from 4184 participants (2181 women, 2003 men) in the 2010 HealthStyles survey, a national mail survey designed to be similar to the United States population. RESULTS: Only 7% of men and 13% of women had heard of congenital CMV. Women with children under age 19 (n=918) practiced the following risk behaviors at least once per week while their youngest child was still in diapers: kissing on the lips (69%), sharing utensils (42%), sharing cups (37%), and sharing food (62%). Women practiced protective, hand cleansing behaviors most of the time or always after: changing a dirty diaper (95%), changing a wet diaper (85%), or wiping the child's nose (65%), but less commonly after handling the child's toys (26%). CONCLUSIONS: Few women are aware of CMV and most regularly practice behaviors that may place them at risk when interacting with young children. Women should be informed of practices that can reduce their risk of CMV infection during pregnancy.

Prevention of maternal and congenital cytomegalovirus infection.

Congenital cytomegalovirus (CMV) infection is an important cause of hearing impairment, mental retardation, and cerebral palsy. Principal sources of infection during pregnancy are young children and intimate contacts. Prevention of maternal and congenital CMV infection depends on counseling women regarding the sources of infection and hygienic measures that might prevent infection. There is currently insufficient evidence to support use of antiviral treatment or passive immunization for postexposure prophylaxis of pregnant women or as a maternal treatment aimed at preventing fetal infection. Vaccines for CMV are under development but it will be a number of years before one is licensed.

Glycoprotein B vaccine is capable of boosting both antibody and CD4 T-cell responses to cytomegalovirus in chronically infected women.

Traditionally, vaccines have been utilized to generate immune responses to a pathogen in a naive population. In the setting of congenital cytomegalovirus (CMV) infection, a vaccine that, when administered to women already infected with CMV, could boost the mother's immunity to CMV would most likely be beneficial in diminishing in utero transmission of CMV. However, the ability to boost an immune response in a population of individuals seropositive for a pathogen of interest is not well studied. This study examines the ability of a recombinant CMV glycoprotein B vaccine with MF59 adjuvant to boost both antibody (neutralizing and enzyme-linked immunosorbent assay end point dilution titer) and CD4+ T-cell responses in previously CMV-seropositive women by way of natural infection. These data suggest that this vaccine is capable of boosting immunity in a population of CMV-infected women and warrants additional evaluation to determine whether these boosted responses may prevent mother to child transmission of CMV.

Antibiotic Use and Outcomes in Young Children Hospitalized With Uncomplicated Community-Acquired Pneumonia.

Background: We aimed to compare children aged 36 months or younger hospitalized with uncomplicated community-acquired pneumonia (CAP) who are not treated with antibiotics to those treated with antibiotics in terms of clinical features and outcome measures. Methods: Administrative data and medical record review were used to identify patients from 3 to 36 months of age hospitalized from 2011 to 2019 with uncomplicated CAP. Patients were considered treated if they received antibiotics for >2 inpatient days and/or at discharge, and not treated if they received ≤2 inpatient days and no antibiotics at discharge. Untreated patients were compared to treated patients based on demographic features, clinical and laboratory results, and outcomes of interest, including illness severity, length of stay, and 30-day hospital readmissions. Results: Three hundred twenty-two CAP cases were included; 266 (83%) received antibiotics for >48 hours and/or at discharge. Fifty-six patients received ≤2 inpatient days of antibiotics and no antibiotics at discharge; the majority received no inpatient antibiotics. There were no differences between the 2 groups in illness severity, length of stay, or hospital readmissions. The proportion of patients treated with antibiotics decreased from 88% (2011-2013) to 66% during the most recent years studied (2017-2019). Conclusions: There was no difference in outcome of uncomplicated CAP in previously healthy children <36 months of age between those treated and not treated with antibiotics. Additional tools are needed to facilitate identification of viral CAP in young children and decrease unnecessary antibiotic use.

Antibody binding to native cytomegalovirus glycoprotein B predicts efficacy of the gB/MF59 vaccine in humans.

Human cytomegalovirus (CMV) is the most common infectious cause of infant brain damage and posttransplant complications worldwide. Despite the high global burden of disease, vaccine development to prevent infection remains hampered by challenges in generating protective immunity. The most efficacious CMV vaccine candidate tested to date is a soluble glycoprotein B (gB) subunit vaccine with MF59 adjuvant (gB/MF59), which achieved 50% protection in multiple historical phase 2 clinical trials. The vaccine-elicited immune responses that conferred this protection have remained unclear. We investigated the humoral immune correlates of protection from CMV acquisition in populations of CMV-seronegative adolescent and postpartum women who received the gB/MF59 vaccine. We found that gB/MF59 immunization elicited distinct CMV-specific immunoglobulin G (IgG)-binding profiles and IgG-mediated functional responses in adolescent and postpartum vaccinees, with heterologous CMV strain neutralization observed primarily in adolescent vaccinees. Using penalized multiple logistic regression analysis, we determined that protection against primary CMV infection in both cohorts was associated with serum IgG binding to gB present on a cell surface but not binding to the soluble vaccine antigen, suggesting that IgG binding to cell-associated gB is an immune correlate of vaccine efficacy. Supporting this, we identified gB-specific monoclonal antibodies that differentially recognized soluble or cell-associated gB, revealing that there are structural differences in cell-associated and soluble gB are relevant to the generation of protective immunity. Our results highlight the importance of the native, cell-associated gB conformation in future CMV vaccine design.

Cytomegalovirus shedding and delayed sensorineural hearing loss: results from longitudinal follow-up of children with congenital infection.

BACKGROUND: The pathogenesis of cytomegalovirus (CMV)-related hearing loss is not well understood. OBJECTIVE: To evaluate the relationship between persistent CMV shedding and delayed sensorineural hearing loss in children born with congenital CMV. METHODS: Serial audiologic assessments and CMV cultures of urine and saliva were performed on 580 children who had been diagnosed with congenital CMV infection. RESULTS: Prevalence of CMV culture-positivity in any specimen decreased to approximately 50% by the third birthday and approximately 5% after the seventh birthday. Intermittent shedding occurred in 28% of children. Seventy-seven children had hearing loss at birth and 38 children developed delayed hearing loss by the end of follow-up. In multivariate analyses, delayed hearing loss was strongly associated with symptomatic infection at birth (OR = 5.9, 95% CI: 1.8-18.9) and modestly associated with older age at last culture-positive visit (OR = 1.6, 95% CI: 1.1-2.0, comparing 1-year age differences) Observed rates of delayed hearing loss were 0.79 per 100 person-years for children asymptomatic at birth and 4.29 per 100 person-years for children symptomatic at birth. Between the ages of 6 months and 8 years, we would expect delayed hearing loss to occur in 6.9% of asymptomatic children and in 33.7% of symptomatic children. CONCLUSIONS: The strongest risk factor for delayed hearing loss was CMV-related symptoms at birth, but many asymptomatic children also developed delayed hearing loss. Longer duration of CMV shedding may also be a predictor of delayed hearing loss.

Cytomegalovirus seroprevalence and childhood sources of infection: A population-based study among pre-adolescents in the United States.

BACKGROUND: Among pre-adolescents, the importance of different sources of cytomegalovirus (CMV) infection is unclear. OBJECTIVE: To assess the importance of several CMV sources among pre-adolescent children. STUDY DESIGN: We used data from a United States population-based sample conducted from 1988 to 1994: 4-10-year-old participants (n=3386) of the Third National Health and Nutrition Examination Survey. We tested available sera for CMV-specific-IgG and assessed CMV prevalence differences by surrogates for exposure to childhood CMV sources (maternal CMV serostatus, breast-feeding, older sibling CMV serostatus, and child care center attendance). RESULTS: CMV infection was more prevalent (70%) among Mexican American children with foreign-born householders than among children with native-born householders (31% non-Hispanic White, 39% non-Hispanic Black, and 37% Mexican American children). Child's serostatus was associated with their mother's (prevalence difference range (PDR)=33-40%) and older sibling's serostatus (PDR=39-50%). Breast-feeding was associated with CMV in some racial/ethnic and householder groups (PDR=-5.1% to 22.7%). There was little difference in CMV seroprevalence by child care center attendance (PDR=-6.5% to -0.4%). CONCLUSIONS: This study expands understanding of CMV by identifying the importance of householder nativity and demonstrating the importance of family transmission among the general population of pre-adolescents.

Maternal and fetal cytomegalovirus infection: diagnosis, management, and prevention.

Congenital cytomegalovirus infection is a major cause of central nervous system and sensory impairments that affect cognition, motor function, hearing, language development, vestibular function, and vision. Although the importance of congenital cytomegalovirus infection is readily evident, the vast majority of maternal and fetal infections are not identified, even in developed countries. Multiple studies of prenatal cytomegalovirus infections have produced a body of knowledge that can inform the clinical approach to suspected or proven maternal and fetal infection. Reliable diagnosis of cytomegalovirus infection during pregnancy and accurate diagnosis of fetal infection are a reality. Approaches to preventing the transmission of cytomegalovirus from mother to fetus and to the treatment of fetal infection are being studied. There is evidence that public health approaches based on hygiene can dramatically reduce the rate of primary maternal cytomegalovirus infections during pregnancy. This review will consider the epidemiology of congenital cytomegalovirus infection, the diagnosis and management of primary infection during pregnancy, and approaches to preventing maternal infection.

Seroprevalence of cytomegalovirus infection in the United States, 1988-1994.

BACKGROUND: Cytomegalovirus (CMV) is a leading cause of congenital illness and disability, including hearing loss and mental retardation. However, there are no nationwide estimates of CMV seroprevalence among pregnant women or the overall population of the United States. METHODS: To determine CMV prevalence in a representative sample of the US population, we tested serum samples for CMV-specific immunoglobulin G from participants aged > or =6 years (n=21,639) in the third National Health and Nutrition Examination Survey (1988-1994). RESULTS: The prevalence of CMV infection was 58.9% in individuals > or =6 years old. CMV seroprevalence increased gradually with age, from 36.3% in 6-11-year-olds to 90.8% in those aged > or =80 years. CMV seroprevalence differed by race and/or ethnicity as follows: 51.2% in non-Hispanic white persons, 75.8% in non-Hispanic black persons, and 81.7% in Mexican Americans. Racial and/or ethnic differences in CMV seroprevalence persisted when controlling for household income level, education, marital status, area of residence, census region, family size, country of birth, and type of medical insurance. Among women, racial and/or ethnic differences were especially significant; between ages 10-14 years and 20-24 years, seroprevalence increased 38% for non-Hispanic black persons, 7% for non-Hispanic white persons, and <1% for Mexican Americans. CONCLUSIONS: On the basis of these results, we estimate that each year in the United States approximately 340,000 non-Hispanic white persons, 130,000 non-Hispanic black persons, and 50,000 Mexican American women of childbearing age experience a primary CMV infection. Given the number of women at risk and the significance of congenital disease, development of programs for the prevention of CMV infection, such as vaccination or education, is of considerable public health importance.

Detection of cytomegalovirus infection during a vaccine clinical trial in healthy young women: seroconversion and viral shedding.

BACKGROUND: An antibody method based on absorption of serum with cytomegalovirus (CMV) glycoprotein B (gB) was developed for detection of infection during clinical trials of CMV gB vaccine. Previous study showed that this method detected the antibody response to infection and was negative with vaccine induced immunity. OBJECTIVES: In an ongoing efficacy trial of CMV gB vaccine the ability of the gB-absorbed CMV IgG assay to detect CMV infection was assessed and compared with viral culture results. STUDY DESIGN: Two hundred and ninety two healthy, seronegative young women in a phase II, double-blind, placebo-controlled, clinical trial of recombinant CMV gB vaccine (sanofi pasteur) with MF59 adjuvant (Chiron) were randomized to receive CMV gB vaccine or placebo (1:1) on a 0, 1 and 6 month schedule. Participants were screened every 3 months for CMV infection using the gB-absorbed CMV IgG assay, and a subgroup was also screened for infection with viral cultures. Viral culture (urine, vaginal swab and saliva) was used to confirm CMV infection in all subjects with a positive gB-absorbed CMV IgG result. RESULTS: Evidence of CMV infection (gB-absorbed CMV IgG levels>or=5.0 AU/ml) was found in 23/292 (7.88%) study participants. The gB-absorbed CMV IgG levels of their first positive serum ranged from 15.7 to 251.0 AU/ml with a mean of 77.0 AU/ml and a median of 44.9 AU/ml. Cytomegalovirus was isolated from all 23 of them from culture specimens collected after their first positive gB-absorbed CMV IgG. The time to first CMV positive culture from first positive gB-absorbed CMV IgG ranged from 0 to 12 weeks with a median of 2 weeks. CONCLUSIONS: The gB-absorbed CMV IgG assay detects CMV infection in CMV gB vaccine clinical trials earlier and more rapidly than virus culture and does not reveal whether subjects received CMV gB vaccine or placebo.

Congenital cytomegalovirus infection following first trimester maternal infection: symptoms at birth and outcome.

BACKGROUND: The relationship between gestational age at time of maternal cytomegalovirus (CMV) infection and outcome of fetal infection is not well defined because the timing of maternal infection is usually not known. OBJECTIVE: To determine whether congenital cytomegalovirus (CMV) infection following primary maternal infection during the first trimester of pregnancy is more likely to lead to central nervous system (CNS) sequelae than fetal infection due to maternal infection later in pregnancy. STUDY DESIGN: Using serum collected during pregnancy from mothers of newborns with congenital CMV infection, maternal infection was categorized as first trimester (<13 weeks) or later based on dates and results of IgG and IgM assays for CMV antibody. Outcome of congenital CMV infection was assessed by longitudinal fotlow-up of the infected cohort. RESULTS: Sensorineural hearing loss was found in 8/34 (24%) of children in the first trimester group, compared with 1/40 (2.5%) in the later infection group (P=0.01, relative risk, 9.6). Considering any CNS sequela (hearing loss, mental retardation, cerebral palsy, seizures, chorioretinitis) 11/34 (32%) first trimester cases were affected compared with 6/40 (15%) in the later infection group (P=0.07, relative risk 2.2). None of the later group had more than one sequela, compared with 4 (12%) of the first trimester group (P=0.04). CONCLUSIONS: Children with congenital CMV infection following first trimester maternal infection are more likely to have CNS sequelae, especially sensorineural hearing loss, than are those whose mothers were infected later in pregnancy. However, some degree of CNS impairment can follow even late gestational infection.