Genotypic diversity and mixed infection in newborn disease and hearing loss in congenital cytomegalovirus infection

Human Cytomegalovirus (HCMV) Genetic Diversity, Drug Resistance Testing and Prevalence of the Resistance Mutations: A Literature Review

Human cytomegalovirus (HCMV) is a pathogen with high prevalence in the general population that is responsible for high morbidity and mortality in immunocompromised individuals and newborns, while remaining mainly asymptomatic in healthy individuals. The HCMV genome is 236,000 nucleotides long and encodes approximately 200 genes in more than 170 open reading frames, with the highest rate of genetic polymorphisms occurring in the envelope glycoproteins. HCMV infection is treated with antiviral drugs such as ganciclovir, valganciclovir, cidofovir, foscarnet, letermovir and maribavir targeting viral enzymes, DNA polymerase, kinase and the terminase complex. One of the obstacles to successful therapy is the emergence of drug resistance, which can be tested phenotypically or by genotyping using Sanger sequencing, which is a widely available but less sensitive method, or next-generation sequencing performed in samples with a lower viral load to detect minority variants, those representing approximately 1% of the population. The prevalence of drug resistance depends on the population tested, as well as the drug, and ranges from no mutations detected to up to almost 50%. A high prevalence of resistance emphasizes the importance of testing the patient whenever resistance is suspected, which requires the development of more sensitive and rapid tests while also highlighting the need for alternative therapeutic targets, strategies and the development of an effective vaccine.

Genetic and Functional Characterization of Congenital HCMV Clinical Strains in Ex Vivo First Trimester Placental Model

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection, leading to a variety of symptoms in the unborn child that range from asymptomatic to death in utero. Our objective was to better understand the mechanisms of placental infection by HCMV clinical strains, particularly during the first trimester of pregnancy. We thus characterized and compared the replication kinetics of various HCMV clinical strains and laboratory strains by measuring viral loads in an ex vivo model of first trimester villi and decidua, and used NGS and PCA analysis to analyze the genes involved in cell tropism and virulence factors. We observed that first trimester villi and decidua are similarly permissive to laboratory and symptomatic strains, and that asymptomatic strains poorly replicate in decidua tissue. PCA analysis allowed us to segregate our clinical strains based on their clinical characteristics, suggesting a link between gene mutations and symptoms. All these results bring forth elements that can help better understand the mechanisms that induce the appearance of symptoms or in the congenitally infected newborn.

Distribution of CMV envelope glycoprotein B, H and N genotypes in infants with congenital cytomegalovirus symptomatic infection

Background

Cytomegalovirus (CMV) is the leading cause of congenital infections worldwide and contributes to long-term sequelae in neonates and children. CMV envelope glycoproteins play a vital role in virus entry and cell fusion. The association between CMV polymorphisms and clinical outcomes remains controversial. The present study aims to demonstrate the distribution of glycoprotein B (gB), H (gH) and N (gN) genotypes in congenitally CMV (cCMV) infected symptomatic infants and attempts to figure out the association between viral glycoprotein genotypes and clinical outcomes.

Methods

Genotyping of gB, gH and gN was performed in 42 cCMV symptomatic infants and 149 infants with postnatal CMV (pCMV) infection in Children's hospital of Fudan university. Nested PCR, gene sequencing and phylogenetic analyses were used to identify the genotypes.

Results

Our study demonstrated that: 1. The CMV gB1, gH1 and gN1 were the predominant genotypes among symptomatic cCMV infected infants, while gB1, gH1 and gN3a were more prevalent in pCMV group. gH1 genotype has a significant association with symptomatic cCMV infection (p = 0.006). 2. No significant correlation was found between CMV genotypes and hearing impairment. However, gH1 was more prevalent among cCMV infected infants with moderate/severe hearing loss although without statistical difference (p = 0.130). 3. gB3 was more prevalent among infants with skin petechiae (p = 0.049) and found to be associated with an increased risk of skin petechiae (OR = 6.563). The gN4a subtype was significantly associated with chorioretinitis due to cCMV infection (p = 0.007). 4. Urine viral loads were not significantly associated with different genotypes or hearing impairment among symptomatic cCMV infected infants.

Conclusions

Our findings demonstrated the overall distribution of gB, gH and gN genotypes in infants with symptomatic cCMV infection in Shanghai for the first time. The findings in our study may suggest a possible association between gH1 genotype and early infancy hearing loss. gB3 genotype was associated with a 6.5-fold increased risk of petechiae while gN4a strongly correlated with chorioretinitis due to cCMV infection. No significant correlation was found between urine viral loads and CMV genotypes or hearing impairment in cCMV infected infants.

Cytomegalovirus-A Risk Factor for Childhood Hearing Loss: A Systematic Review

OBJECTIVE

Permanent hearing loss is an important public health issue in children with consequences for language, social, and academic functioning. Early hearing detection, intervention, and monitoring are important in mitigating the impact of permanent childhood hearing loss. Congenital cytomegalovirus (CMV) infection is a leading cause of hearing loss. The purpose of this review was to synthesize the evidence on the association between CMV infection and permanent childhood hearing loss.

DESIGN

We performed a systematic review and examined scientific literature from the following databases: MEDLINE, Ovid MEDLINE(R) Daily and Ovid MEDLINE(R), Embase, and CINAHL. The primary outcome was permanent bilateral or unilateral hearing loss with congenital onset or onset during childhood (birth to 18 years). The secondary outcome was progressive hearing loss. We included studies reporting data on CMV infection. Randomized controlled trials, quasi-experimental studies, nonrandomized comparative and noncomparative studies, and case series were considered. Data were extracted and the quality of individual studies was assessed with the Qualitative Assessment Tool for Quantitative Studies (McMaster University). The quality and strength of the evidence were graded using the Grading of Recommendations Assessment, Development and Evaluation (GRADE). A narrative synthesis was completed.

RESULTS

Sixty-five articles were included in the review. Prevalence of hearing loss at birth was over 33% among symptomatic CMV-infected newborns and less than 15% in asymptomatic infections. This difference in prevalence was maintained during childhood with more than 40% prevalence reported for symptomatic and less than 30% for asymptomatic CMV. Late-onset and progressive hearing loss appear to be characteristic of congenital CMV infections. Definitions of hearing loss, degree of loss, and reporting of laterality varied across studies. All degrees and both bilateral and unilateral loss were reported, regardless of symptomatic and asymptomatic status at birth, and no conclusions about the characteristics of hearing loss could be drawn. Various patterns of hearing loss were reported including stable, progressive, and fluctuating, and improvement in hearing (sometimes to normal hearing) was documented. These changes were reported in children with symptomatic/asymptomatic congenital CMV infection, presenting with congenital/early onset/late-onset hearing loss and in children treated and untreated with antiviral medication.

CONCLUSIONS

Symptomatic and asymptomatic congenital CMV infection should be considered a risk factor for hearing loss at birth and during childhood and for progressive hearing loss. Therefore, CMV should be included as a risk factor in screening and surveillance programs and be taken into account in clinical follow-up of children with hearing loss.

Common Polymorphisms in the Glycoproteins of Human Cytomegalovirus and Associated Strain-Specific Immunity

Human cytomegalovirus (HCMV), one of the most prevalent viruses across the globe, is a common cause of morbidity and mortality for immunocompromised individuals. Recent clinical observations have demonstrated that mixed strain infections are common and may lead to more severe disease progression. This clinical observation illustrates the complexity of the HCMV genome and emphasizes the importance of taking a population-level view of genotypic evolution. Here we review frequently sampled polymorphisms in the glycoproteins of HCMV, comparing the variable regions, and summarizing their corresponding geographic distributions observed to date. The related strain-specific immunity, including neutralization activity and antigen-specific cellular immunity, is also discussed. Given that these glycoproteins are common targets for vaccine design and anti-viral therapies, this observed genetic variation represents an important resource for future efforts to combat HCMV infections.

Congenital Cytomegalovirus Infection

Congenital cytomegalovirus (cCMV) infection is a leading cause of hearing loss and neurological disabilities in children, with the disease burden and disabilities due to cCMV greater than many other well recognized childhood conditions. A minority of infants with cCMV will have symptoms at birth. Infants with symptomatic cCMV are at higher risk for sequelae than those born without symptoms. The majority of infants with cCMV are asymptomatic at birth, but 10%-15% will develop hearing loss. Although clinical symptoms can help predict which infants will have sensorineural hearing loss, among asymptomatic cCMV there are currently no predictors of adverse outcome. The identification of a biomarker to identify those at highest risk of sequelae is highly desirable to target interventions to those who could potentially benefit. Because there is increasing rationale for establishing both targeted and universal screening programs for cCMV in the United States and worldwide, this is an urgent priority.

Human cytomegalovirus multiple-strain infections and viral population diversity in haematopoietic stem cell transplant recipients analysed by high-throughput sequencing

Human cytomegalovirus (HCMV) is an important opportunistic pathogen in allogeneic haematopoietic stem cell transplant (HSCT) recipients. High-throughput sequencing of target-enriched libraries was performed to characterise the diversity of HCMV strains present in this high-risk group. Forty-four HCMV-DNA-positive plasma specimens (median viral input load 321 IU per library) collected at defined time points from 23 HSCT recipients within 80 days of transplantation were sequenced. The genotype distribution for 12 hypervariable HCMV genes and the number of HCMV strains present (i.e. single- vs. multiple-strain infection) were determined for 29 samples from 16 recipients. Multiple-strain infection was observed in seven of these 16 recipients, and five of these seven recipients had the donor (D)/recipient (R) HCMV-serostatus combination D + R + . A very broad range of genotypes was detected, with an intrahost composition that was generally stable over time. Multiple-strain infection was not associated with particular virological or clinical features, such as altered levels or duration of antigenaemia, development of acute graft-versus-host disease or increased mortality. In conclusion, despite relatively low viral plasma loads, a high frequency of multiple-strain HCMV infection and a high strain complexity were demonstrated in systematically collected clinical samples from this cohort early after HSCT. However, robust evaluation of the pathogenic role of intrahost viral diversity and multiple-strain infection will require studies enrolling larger numbers of recipients.

Cytomegalovirus Genetic Diversity Following Primary Infection

BACKGROUND

Infection with multiple cytomegalovirus (CMV) strains (mixed infection) was reported in a variety of hosts. As the virus genetic diversity in primary CMV infection and the changes over time remain incompletely defined, we examined CMV diversity and changes in diversity over time in healthy adolescent females who participated in a phase 2 CMV gB/MF59 vaccine trial.

METHODS

CMV genetic diversity was determined by genotyping of 5 genes-gB (UL55), gH (UL75), gN (UL73), US28, and UL144-in urine, saliva, and plasma samples from 15 study subjects.

RESULTS

At the time of primary infection, 5 of 12 (42%) urine samples had multiple virus strains, and 50% of vaccine recipients were infected with gB1 genotype (vaccine strain). Mixed infection was documented in all 15 subjects within 3 months after primary infection, and the majority had different CMV genotypes in different compartments. Changes in genotypes over time were observed in all subjects.

CONCLUSIONS

Infection with multiple CMV genotypes was common during primary infection and further diversification occurred over time. Infection with gB1 genotype in vaccine recipients suggests a lack of strain-specific protection from the vaccine. As only 5 polymorphic genes were assessed, this study likely underestimated the true genetic diversity in primary CMV infection.

Viral shedding, and distribution of cytomegalovirus glycoprotein H (UL75), glycoprotein B (UL55), and glycoprotein N (UL73) genotypes in congenital cytomegalovirus infection

BACKGROUND

Children with congenital CMV infection (cCMV) shed virus in urine and saliva for prolonged periods of time. Outcome of cCMV varies from asymptomatic infection with no sequelae in most cases, to severe longterm morbidity. The factors associated with asymptomatic cCMV are not well defined. We evaluated the viral shedding in a cohort of infants with cCMV identified on newborn screening. In addition, we describe the distribution of viral genotypes in our cohort of asymptomatic infants and previous cohorts of cCMV children in the literature.

METHODS

Study population consisted of 40 children with cCMV identified in screening of 19,868 infants, a prevalence of 2/1000. The viral shedding was evaluated at 3 and 18 months of age by real-time CMV-PCR of saliva and plasma, and CMV culture of urine. CMV positive saliva samples were analyzed for genotypes for CMV envelope glycoproteins gB (UL55), and gH (UL75) by genotype specific real-time PCR, and gN (UL73) by cloning and sequencing RESULTS: At 3 months age 40/40 saliva and urine samples, and 19/40 plasma samples were positive for CMV. At 18 months age all urine samples tested (33/33), 9/37 of saliva samples, and 2/34 plasma samples were positive for CMV. The genotype distribution did not differ from the published data CONCLUSIONS: The urinary virus shedding is more persistent than salivary shedding in children with cCMV. The genotype distribution was similar to previous literature and does not explain the low disease burden of cCMV in our population.

Association of CMV genomic mutations with symptomatic infection and hearing loss in congenital CMV infection

Background

Congenital cytomegalovirus (cCMV) infection is the most common congenital infection and a leading cause of long-term neurological and sensory sequelae, the most common being sensorineural hearing loss (SNHL). Despite extensive research, clinical or laboratory markers to identify CMV infected children with increased risk for disease have not been identified. This study utilizes viral whole-genome next generation-sequencing (NGS) of specimens from congenitally infected infants to explore viral diversity and specific viral variants that may be associated with symptomatic infection and SNHL.

Methods

CMV DNA from urine specimens of 30 infants (17 asymptomatic, 13 symptomatic) was target enriched and next generation sequenced resulting in 93% coverage of the CMV genome allowing analysis of viral diversity.

Results

Variant frequency distribution was compared between children with symptomatic and asymptomatic cCMV and those with (n = 13) and without (n = 17) hearing loss. The CMV genes UL48A, UL88, US19 and US22 were found to have an increase in nucleotide diversity in symptomatic children; while UL57, UL20, UL104, US14, UL115, and UL35 had an increase in diversity in children with hearing loss. An analysis of single variant differences between symptomatic and asymptomatic children found UL55 to have the highest number, while the most variants associated with SNHL were in the RL11 gene family. In asymptomatic infants with SNHL, mutations were observed more frequently in UL33 and UL20.

Conclusion

CMV genomes from infected newborns can be mapped to 93% of the genome at a depth allowing accurate and reproducible analysis of polymorphisms for variant and gene discovery that may be linked to symptomatic and hearing loss outcomes.

Prevalence of cytomegalovirus DNAemia and genotypic distribution among childbearing mothers and neonates in Taiwan

BACKGROUND

Congenital cytomegalovirus (CMV) infection is the leading cause of neurologic disabilities and sensorineural hearing loss in children. However, in Taiwan, there is limited information on the genotypic diversity and prevalence of perinatal CMV infection in both mothers and neonates. The aim of this study was to screen samples from both mothers and umbilical cord blood for CMV at the time of delivery and to determine the CMV genotypic distribution.

METHODS

Between June 2012 and July 2015, residual maternal and umbilical cord blood samples were collected from consenting participants admitted to the Chang Bing Show Chwan Memorial Hospital in central Taiwan. The blood samples were screened for CMV DNA using real-time PCR assay, and the genotypic classification of the CMV UL55, UL144, and US28 genes was determined by sequencing and phylogenetic analysis.

RESULTS

A total of 1282 mother-neonate paired samples were enrolled in the study, 95.3% of whom were Taiwanese. CMV DNA was detectable in 6.2% of the maternal blood samples, with a significantly higher rate noted in non-Taiwanese mothers (11.7%,p=0.027). For the 1,282 umbilical cord blood samples, CMV DNA was detectable in 5.3% of the samples. The presence of CMV DNA in maternal blood was positively associated with the presence of CMV DNA in umbilical cord blood (p=0.01). In addition, the UL55, UL144, and US28 genotypic distribution was similar between mothers and neonates.

CONCLUSION

The prevalence of CMV DNAemia in childbearing mothers and neonates is similar and their genotypic distribution implies potential CMV infection during pregnancy.

Distribution of the CMV glycoprotein gH/gL/gO and gH/gL/pUL128/pUL130/pUL131A complex variants and associated clinical manifestations in infants infected congenitally or postnatally

Human cytomegalovirus (CMV) is a major cause of morbidity in fetuses following intrauterine infection. The glycoprotein (g) envelope trimeric gH/gL/gO and pentameric gH/gL/pUL128/pUL130/pUL131A complexes are required for CMV entry into fibroblasts and endothelial/epithelial cells, respectively, and both are targets for neutralizing antibodies. The role of sequence variability among viral strains in the outcome of congenital CMV infection is controversial. Variation in the CMV UL75 gene encoding glycoprotein H (gH), the UL115 (gL), the UL74 (gO), and the UL128 locus (UL128L) encoding three structural proteins (pUL128, pUL130, and pUL131A) was determined in 82 newborns with congenital CMV infection and 113 infants with postnatal or unproven congenital CMV infection. Genotyping was performed by sequencing analysis of PCR-amplified fragments and the PCR-restriction fragment length polymorphism (RFLP) method, and the viral load was measured by quantitative real-time PCR. The obtained results demonstrated that (1) different CMV variants and mixed CMV infections can be detected in newborns infected congenitally; (2) the gH1 genotype, UL130 variant 6, and UL131A variant 1 were associated with some signs/symptoms within cohort of pediatric patients, mainly consisting of infants with symptomatic CMV infection. The results revealed that pUL130, pUL131A, and gH polymorphisms seemed to be associated with the outcome of CMV infection in infants.

The Natural History and Rehabilitative Outcomes of Hearing Loss in Congenital Cytomegalovirus: A Systematic Review

OBJECTIVE

The purpose of this study was to examine the literature regarding the natural history and rehabilitative outcomes of sensorineural hearing loss from congenital cytomegalovirus infections.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

A systematic search was performed in PubMed, PsychINFO, CINAHL, and Web of Science to identify peer-reviewed research. Eligible studies were those containing original peer-reviewed research in English addressing either the natural history or rehabilitative outcomes of sensorineural hearing loss (SNHL) in congenital cytomegalovirus (cCMV).

STUDY APPRAISAL AND SYNTHESIS METHODS

Two investigators independently reviewed all articles and extracted data. Bias was assessed using the Cochrane Collaboration's tool and the Newcastle-Ottawa Assessment Scale.

RESULTS

Thirty-six articles were reviewed. Universal screening identifies 0.2 to 1% of newborns with cCMV infection. SNHL ranged from 8 to 32% of infants and was more prevalent in symptomatic versus asymptomatic cases. Nine to 68% of hearing loss occurs in a late or delayed fashion. In 7 to 71% of cases hearing loss is progressive. Cochlear implantation (CI) is a viable option for patients with cCMV associated hearing loss and leads to improvements in hearing and language. There is limited literature comparing rehabilitation outcomes in cCMV and non-cCMV CI recipients.

CONCLUSION

Late onset and progressive hearing loss is seen in children who develop hearing loss from cCMV. Frequent audiologic follow-up is necessary considering the natural history of cCMV hearing loss. Universal screening should be pursued due to the number of asymptomatic children, at birth, who develop late onset/delayed hearing loss. CI is an effective means of improving speech and language in this population.

Development of highly efficient protocols for extraction and amplification of cytomegalovirus DNA from dried blood spots for detection and genotyping of polymorphic immunomodulatory genes

Congenital cytomegalovirus (CMV) infection is a major cause of birth defects ranging from developmental disorders to stillbirth. Most newborns affected by CMV do not present with symptoms at birth but are at risk of sequelae at later stages of their childhood. Stored dried blood spots (DBS) taken at birth can be used for retrospective diagnosis of hereditary diseases, but detection of pathogens is challenged by potentially low pathogen concentrations in the small blood volume available in a DBS. Here we test four different extraction methods for optimal recovery of CMV DNA from DBS at low to high CMV titers. The recovery efficiencies varied widely between the different extractions (from 3% to 100%) with the most efficient method extracting up to 113-fold more CMV DNA than the least efficient and 8-fold more than the reference protocol. Furthermore, we amplified four immunomodulatory CMV genes from the extracted DNA: the UL40 and UL111A genes which occur as functional knockouts in some circulating CMV strains, and the highly variable UL146 and US28 genes. The PCRs specifically amplified the CMV genes at all tested titers with sufficient quality for sequencing and genotyping. In summary, we here report an extraction method for optimal recovery of CMV DNA from DBSs that can be used for both detection of CMV and for genotyping of polymorphic CMV genes in congenital CMV infection.

Salivary cytomegalovirus excretion in children in daycare centers and home care facilities in Japan

Cytomegalovirus (CMV) is the most common cause of congenital viral infection in developed countries. The incidence of in utero infection is high in pregnant women who are CMV antibody negative. An important infection route is in contact with children who attend daycare centers (DCCs). However, there are few reports on CMV excretion in children at DCCs in Japan. Saliva samples were collected twice during a 6-month interval from children attending one of two DCCs (DCC1 and DCC2 groups) and from those receiving home care (HC group). The samples were used to quantitatively evaluate CMV using real-time polymerase chain reaction and to determine glycoprotein B (gB) genotypes. The percentage of subjects who demonstrated CMV excretion in either the first or second sample collection was higher in the DCC groups than in the HC group, with incidences in the DCC1, DCC2, and HC groups of 53.4% (n = 47 of 88), 23.9% (n = 16 of 67), and 12.7% (n = 7 of 55), respectively. Compared with the DCC2 group, the DDC1 group had a higher incidence of CMV excretion and included more subjects with a high number of viral copies. In both DCC groups, the incidence of CMV excretion was highest in children younger than 3 years of age. In all three groups, the predominant genotypes were gB1 and gB3. Based on the higher incidence of CMV excretion in the DCC groups compared with the HC group, it is considered that CMV infection is acquired mainly in DCCs in children under the age of 3.

Subversion of Immune Response by Human Cytomegalovirus

Human cytomegalovirus (HCMV) is the most common cause of congenital infections and is an important pathogen in immunocompromised individuals. Despite a robust host immune system, HCMV able to replicate, evade host defenses, establish latency for life. A significant portion of HCMV genome dedicated to encode gene products for modulation of host immune response. Growing number of HCMV gene products are being recognized to play role in immune evasion. Information on viral immune evasion mechanisms by which HCMV persists in host will be useful in devising antiviral intervention strategies and development of new vaccines. This minireview provides a brief overview of immune evasion strategy adapted by HCMV by utilizing its gene products in modulation of host immune response.

Prevalence, Magnitude, and Genotype Distribution of Urinary Cytomegalovirus (CMV) Shedding Among CMV-Seropositive Children and Adolescents in the United States

Background

There are limited nationally representative data on correlates of cytomegalovirus (CMV) shedding among children and adolescents. In addition, the genotype distribution of CMV infections has not been well characterized among general populations in the United States.

Methods

This study characterized urinary CMV shedding among CMV immunoglobulin G-positive 6- to 19-year-olds in the US household population using data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). Multivariable Poisson regression was used to estimate adjusted prevalence ratios (aPR) and corresponding 95% confidence intervals (CIs). Analyses were weighted and multiple imputation was performed to handle missing data (with the exception of CMV genotypes).

Results

Prevalence of urinary CMV shedding was significantly lower among 9- to 11-year-olds (20.6%; aPR = 0.61; 95% CI, 0.44-0.83) and 12- to 19-year-olds (7.0%; aPR = 0.21; 95% CI, 0.14-0.30) compared with 6- to 8-year-olds (34.4%). Among CMV shedders, the youngest age group also had the highest urinary CMV viral loads. The prevalence of urinary CMV shedding among obese individuals was significantly lower compared with lean individuals (aPR = 0.68; 95% CI, 0.47-0.99). Among CMV shedders, glycoprotein B (gB)1 (51%) was the most prevalent gB variant, followed by gB2 (29%), gB3 (21%), and gB4 (13%); glycoprotein H (gH)2 (60%) was more prevalent than gH1 (48%). Multiple (≥2) gB (14%) and multiple gH (7%) infections were detected among CMV shedders.

Conclusions

This study underscores the importance of young children even above the age of 5 years as a potential source of CMV transmission. The detection of multiple CMV strains among CMV shedders may have implications for the transmission of viral diversity as well as vaccine development.

Genotyping of Cytomegalovirus from Symptomatic Infected Neonates in Iraq

Among all other viruses, human cytomegalovirus (HCMV) is the most frequent cause of congenital infection worldwide. Strain variation in HCMV may predict severity or outcome of congenital HCMV disease. Previous studies have associated a particular genotype with specific sequelae or more severe illness, but the results were contradictory. There are no previous studies addressing the genotype of HCMV in Iraq. Therefore, the present study is aimed at molecular detection and genotyping of HCMV isolated from symptomatic congenitally/perinatally infected neonates. This prospective study comprised 24 serum samples from symptomatic neonates with congenital/perinatal infection. Viral DNA was extracted from these serum samples; nested polymerase chain reaction was used to amplify the HCMV gB (UL55) gene. Polymerase chain reaction products of the second round of amplification were subjected to direct Sanger sequencing. Bioedit and MEGA5 software (EMBL-EBI, Hinxton, Cambridgeshire, UK) were used for alignment and construction of a phylogenetic tree. Human cytomegalovirus DNA was detected in 23 of 24 samples (95.8%). According to the phylogenetic analysis, three genotypes of the virus were identified; gB1, gB2, and gB3 genotypes. However, the gB4 genotype was not detected. Human cytomegalovirus gB3 was the most frequent genotype: 14 of 24 (58.33%) among symptomatic infected infants, followed by gB1 (6/24; 25%) and gB2 (4/24; 16.67%). A mixed HCMV infection with gB3/gB1 was detected in only one case. Human cytomegalovirus gB3 was the most predominant genotype among symptomatic congenitally/perinatally HCMV-infected neonates. No association was found between B3 genotype and specific clinical presentation. Jaundice was the most common clinical feature among symptomatically infected neonates, followed by hepatosplenomegaly.

Brain-resident memory CD8+ T cells induced by congenital CMV infection prevent brain pathology and virus reactivation

Congenital HCMV infection is a leading infectious cause of long-term neurodevelopmental sequelae. Infection of newborn mice with mouse cytomegalovirus (MCMV) intraperitoneally is a well-established model of congenital human cytomegalovirus infection, which best recapitulates the hematogenous route of virus spread to brain and subsequent pathology. Here, we used this model to investigate the role, dynamics, and phenotype of CD8⁺ T cells in the brain following infection of newborn mice. We show that CD8⁺ T cells infiltrate the brain and form a pool of tissue-resident memory T cells (T_RM cells) that persist for lifetime. Adoptively transferred virus-specific CD8⁺ T cells provide protection against primary MCMV infection in newborn mice, reduce brain pathology, and remain in the brain as T_RM cells. Brain CD8⁺ T_RM cells were long-lived, slowly proliferating cells able to respond to local challenge infection. Importantly, brain CD8⁺ T_RM cells controlled latent MCMV and their depletion resulted in virus reactivation and enhanced inflammation in brain.

Novel decay dynamics revealed for virus-mediated drug activation in cytomegalovirus infection

Human cytomegalovirus (CMV) infection is a substantial cause of morbidity and mortality in immunocompromised hosts and globally is one of the most important congenital infections. The nucleoside analogue ganciclovir (GCV), which requires initial phosphorylation by the viral UL97 kinase, is the mainstay for treatment. To date, CMV decay kinetics during GCV therapy have not been extensively investigated and its clinical implications not fully appreciated. We measured CMV DNA levels in the blood of 92 solid organ transplant recipients with CMV disease over the initial 21 days of ganciclovir therapy and identified four distinct decay patterns, including a new pattern exhibiting a transient viral rebound (Hump) following initial decline. Since current viral dynamics models were unable to account for this Hump profile, we developed a novel multi-level model, which includes the intracellular role of UL97 in the continued activation of ganciclovir, that successfully described all the decline patterns observed. Fitting the data allowed us to estimate ganciclovir effectiveness in vivo (mean 92%), infected cell half-life (mean 0.7 days), and other viral dynamics parameters that determine which of the four kinetic patterns will ensue. An important clinical implication of our results is that the virological efficacy of GCV operates over a broad dose range. The model also raises the possibility that GCV can drive replication to a new lower steady state but ultimately cannot fully eradicate it. This model is likely to be generalizable to other anti-CMV nucleoside analogs that require activation by viral enzymes such as UL97 or its homologues.

Polymorphisms and features of cytomegalovirus UL144 and UL146 in congenitally infected neonates with hepatic involvement

Human cytomegalovirus is a significant agent of hepatic involvement in neonates. In this study, we investigated the polymorphisms and features of the viral genes UL144 and UL146 as well as their significance to congenital hepatic involvement. In 79 neonates with congenital cytomegalovirus infection and hepatic involvement, full length UL144 and UL146 were successfully amplified in 73.42% and 60.76% of cases, respectively. Sequencing indicated that both genes were hypervariable. Notably, UL144 genotype B was highly associated with aspartate aminotransferase (P = 0.028) and lactate dehydrogenase (P = 0.046). Similarly, UL146 genotype G1 and G13 were significantly associated with CMV IgM (P = 0.026), CMV IgG (P = 0.034), alanine aminotransferase (P = 0.019), and aspartate aminotransferase (P = 0.032). In conclusion, dominant UL144 (genotype B) and UL146 (genotype G1 and G13) genotypes are associated with elevated levels of enzymes and CMV IgM and IgG of cytomegalovirus infection.

Diagnosis, gB genotype distribution and viral load of symptomatic congenitally infected CMV patients in Cuba

OBJECTIVE

Cytomegalovirus (CMV) is the leading cause of viral congenital infection. Some viral factors have been proposed to be CMV pathogenicity markers. The objective of this study was to investigate the frequency of congenital CMV infection in symptomatic patients and the possible association with the CMV glycoprotein B (gB) genotype and viral load.

STUDY DESIGN

A total of 361 newborns (NB) and 158 pregnant women (PW) with clinically suspected CMV infection were enrolled. Studied samples included urine, saliva, serum, vaginal swabs and amniotic fluid. CMV infection was diagnosed by multiplex nested PCR. CMV gB genotyping was performed on infected samples, followed by viral load determination.

RESULTS

Overall, 18.7% of the tested patients were positive for CMV infection, 19.7% of NB were congenitally infected and 16.5% of PW showed active CMV infection. gB-2 was the most prevalent genotype detected (39/97 patients). gB CMV mixed infections were detected in 12 patients. gB-2 was associated with mono-infections (P<0.01). Mixed infections showed higher levels of viral load compared with gB mono-infection (P=0.03). Hepatomegaly, splenomegaly, jaundice, sepsis-like syndrome and malformations were the most prevalent clinical findings. gB-4 was more frequently associated with sepsis-like syndrome than other gB genotypes (P=0.04, odds ratio=4.3, confidence interval: 0.9 to 21.6). The difference in medians of CMV load was statistically significant among patients presenting different clinical signs (P=0.04).

CONCLUSIONS

This study showed that CMV is a frequent cause of congenital infection in symptomatic Cuban patients. Despite gB2 being the most frequently detected, gB-4 was the only genotype associated with clinical features (sepsis-like syndrome in NB). No other associations among specific genotypes and clinical characteristics were found. Further studies are needed to clarify the role that viral load and genotype play in the outcome of congenital infection.

Distribution of Cytomegalovirus Genotypes among Neonates Born to Infected Mothers in Islamabad, Pakistan

Background

Congenital cytomegalovirus (cCMV) infection contributes to considerable long-term sequelae in neonates and children all over the world. The association between viral genotypes and severity of clinical cytomegalovirus (CMV) infection is yet to be defined. The objective of this study was to find the impact of active CMV infection during pregnancy and the clinical significance of genotypes in neonates with congenital cytomegalovirus infections in Pakistan.

Methods

A total of 409 blood samples from pregnant women seeking health care services at the two antenatal hospitals of Islamabad during January to December 2012 were tested by ELISA and nested-PCR. Pregnant women with active infection (detected as IgM positive, PCR positive or positive on both assays) were followed until delivery, to detect the outcome of overt cCMV infection in neonates. Genetic characterization of CMV strains was performed by sequence analysis of envelope glycoproteins: gB, gN and gH to detect the contributing CMV genotypes.

Results

The seroprevalence of anti-CMV IgG and IgM was 97.5% (399 out of 409) and 12.7% (52 out of 409), respectively, while 20% (82/409) pregnant women were found positive for CMV DNA by PCR. Logistic regression analysis showed a significant association of active infection with parity [OR = 2.56, 95% CI = 1.82–2.62, p = 0.04], febrile illness [OR = 1.84, 95% CI = 1.76–3.65, p = 0.01] and jaundice [OR = 22.5, 95% CI = 4.53–85.02, p = 0.002]. We were able to isolate virus in 41 out of 70 neonates; 36.6% (15 out of 41) of them were symptomatic at birth while 63.4% (26 out of 41) were asymptomatic. The most prominent clinical feature observed in symptomatic neonates was hepatosplenomegaly (26.6%; 4 out of 15). All three genotypes gB, gN and gH were found with the highest frequency of gB1 genotype, found in 75% infants with hepatic damage. Phylogenetic analysis of Pakistani strains showed 96%-100% homology to their prototype strains.

Conclusions

Active CMV infection during pregnancy is a major cause of congenital CMV infection with comparable distribution of all three genotypes: gB, gN and gH in symptomatic and asymptomatic neonates. Our findings emphasize to conduct a comprehensive large scale survey and introduction of country wide routine screening at maternity clinics for early diagnosis of CMV to reduce its associated devastating outcomes.

Combined genetic variants of human cytomegalovirus envelope glycoproteins as congenital infection markers

Background

Human cytomegalovirus (HCMV) is still considered to be the main viral cause of birth defects and long-term neurological and sensory sequelae following congenital infection.

Several Authors sustain a key role of HCMV envelope glycoproteins, such as gB, gN and gO - mainly involved in cell targeting, viral penetration and spread - as putative virulence factors. The genes coding for these glycoproteins possess hypervariable regions, resulting in a number of genetic variants in circulating clinical strains. Considering that the genetic polymorphisms underlying the specific differences between gB, gN and gO genotypes can influence the ability of HCMV to preferentially target specific host cells, it is very likely that they play an important role in defining HCMV infection outcome.

In the present study, we analysed HCMV gB, gN and gO gene polymorphisms in viral strains isolated from paediatric patients with congenital or post-natal infection, to investigate whether specific genetic variants may be associated with congenital infection.

Methods

The restriction fragment polymorphisms of genes coding for HCMV gB (UL55), gN (UL73) and gO (UL74) were investigated by analysing viral DNA extracted from 40 urine samples of as many paediatric patients with congenital or post-natal HCMV infection. Randomly selected samples were subjected to DNA sequencing and phylogenetic analysis. Statistical analysis was performed using Fisher’s exact test to assess the significance of single and combined glycoprotein genotypes frequency distribution. Statistical significance was considered at a P <0.05.

Results

While gB genomic variants were quite homogeneously represented in both paediatric groups, the gN4 genotype significantly prevailed in congenitally infected children (89.5 %) vs post-natally infected children (47.6 %), with a predominance of the gN4c variant (47.4 %). A similar trend was observed for gO3 (52.6 % vs 19 %).

Concerning genotypes association, a statistically significant (P = 0.037) gN4-gO3 combination was found specifically in the congenitally infected group.

Conclusions

The results indicate that the gN4 (mostly the gN4c variant) and gO3 combined genotypes could provide useful markers of congenital infection and represent suitable candidate molecules for prophylactic vaccine preparations.

Cytomegalovirus Genotype Distribution Among Congenitally and Postnatally Infected Patients: Association of Particular Glycoprotein (g)B and gN Types With Symptomatic Disease

Background. Human cytomegalovirus is a leading cause of congenital infection, and there are limited data on prognosis markers in disease development. We aimed to study 3 virology targets (glycoprotein [g]B, gN, and UL144) to assess their correlation with congenital infection and various organ system involvement.

Methods. Forty-eight congenital cases and 58 postnatally infected children were included (2003–2014). Genotyping for the 3 targets and distribution among the cohorts were investigated, and the relationship between the gB, gN, and UL144 types with clinical manifestations in congenital infection was also studied.

Results. All of the genotypes were similarly represented among cohorts, and the most prevalent were the UL144B, gB1, and gN1 genotypes. The gB2 genotype was associated with abnormal image findings by ultrasound and/or magnetic resonance in congenital infection (odds ratio [OR], 6.2; 95% confidence interval [CI], 1.1–34.3; P = .036); the gN1 genotype was associated with an elevated risk of developing neurological disorders (OR, 7.0; 95% CI, 1.1–45.9; P = .043). Both gN1 and gB2 were independent factors for symptomatic infection. Statistical analyses showed no association between any UL144 genotype and disease severity.

Conclusions. All of the genotypes can be involved in congenital infection, although the gB2 and gN1 genotypes might be associated with a more serious illness.

Strain Variation and Disease Severity in Congenital Cytomegalovirus Infection: In Search of a Viral Marker

The wide spectrum of congenital cytomegalovirus (CMV) disease and known differences in the biology and in vitro growth of CMV strains continue to drive studies in search for specific viral genetic determinants that may predict severity of congenital CMV disease. Several CMV genes have been studied in detail in congenitally infected children, but the complexity of the viral genome and differences in the definition of symptomatic disease versus asymptomatic CMV infection continue to raise questions related to what constitutes a pathogenic CMV strain.

High-throughput analysis of human cytomegalovirus genome diversity highlights the widespread occurrence of gene-disrupting mutations and pervasive recombination

Human cytomegalovirus is a widespread pathogen of major medical importance. It causes significant morbidity and mortality in the immunocompromised and congenital infections can result in severe disabilities or stillbirth. Development of a vaccine is prioritized, but no candidate is close to release. Although correlations of viral genetic variability with pathogenicity are suspected, knowledge about strain diversity of the 235kb genome is still limited. In this study, 96 full-length human cytomegalovirus genomes from clinical isolates were characterized, quadrupling the available information for full-genome analysis. These data provide the first high-resolution map of human cytomegalovirus interhost diversity and evolution. We show that cytomegalovirus is significantly more divergent than all other human herpesviruses and highlight hotspots of diversity in the genome. Importantly, 75% of strains are not genetically intact, but contain disruptive mutations in a diverse set of 26 genes, including immunomodulative genes UL40 and UL111A. These mutants are independent from culture passaging artifacts and circulate in natural populations. Pervasive recombination, which is linked to the widespread occurrence of multiple infections, was found throughout the genome. Recombination density was significantly higher than in other human herpesviruses and correlated with strain diversity. While the overall effects of strong purifying selection on virus evolution are apparent, evidence of diversifying selection was found in several genes encoding proteins that interact with the host immune system, including UL18, UL40, UL142 and UL147. These residues may present phylogenetic signatures of past and ongoing virus-host interactions.

IMPORTANCE

Human cytomegalovirus has the largest genome of all viruses that infect humans. Currently, there is a great interest in establishing associations between genetic variants and strain pathogenicity of this herpesvirus. Since the number of publicly available full-genome sequences is limited, knowledge about strain diversity is highly fragmented and biased towards a small set of loci. Combined with our previous work, we have now contributed 101 complete genome sequences. We have used these data to conduct the first high-resolution analysis of interhost genome diversity, providing an unbiased and comprehensive overview of cytomegalovirus variability. These data are of major value to the development of novel antivirals and a vaccine and to identify potential targets for genotype-phenotype experiments. Furthermore, they have enabled a thorough study of the evolutionary processes that have shaped cytomegalovirus diversity.

Human Cytomegalovirus Infection Dysregulates the Localization and Stability of NICD1 and Jag1 in Neural Progenitor Cells

Human cytomegalovirus (HCMV) infection of the developing fetus frequently results in major neural developmental damage. In previous studies, HCMV was shown to downregulate neural progenitor/stem cell (NPC) markers and induce abnormal differentiation. As Notch signaling plays a vital role in the maintenance of stem cell status and is a switch that governs NPC differentiation, the effect of HCMV infection on the Notch signaling pathway in NPCs was investigated. HCMV downregulated mRNA levels of Notch1 and its ligand, Jag1, and reduced protein levels and altered the intracellular localization of Jag1 and the intracellular effector form of Notch1, NICD1. These effects required HCMV gene expression and appeared to be mediated through enhanced proteasomal degradation. Transient expression of the viral tegument proteins of pp71 and UL26 reduced NICD1 and Jag1 protein levels endogenously and exogenously. Given the critical role of Notch signaling in NPC growth and differentiation, these findings reveal important mechanisms by which HCMV disturbs neural cell development in vitro. Similar events in vivo may be associated with HCMV-mediated neuropathogenesis during congenital infection in the fetal brain.

IMPORTANCE

Congenital human cytomegalovirus (HCMV) infection is the leading cause of birth defects that primarily manifest as neurological disabilities. Neural progenitor cells (NPCs), key players in fetal brain development, are the most susceptible cell type for HCMV infection in the fetal brain. Studies have shown that NPCs are fully permissive for HCMV infection, which causes neural cell loss and premature differentiation, thereby perturbing NPC fate. Elucidation of virus-host interactions that govern NPC proliferation and differentiation is critical to understanding neuropathogenesis. The Notch signaling pathway is critical for maintaining stem cell status and functions as a switch for differentiation of NPCs. Our investigation into the impact of HCMV infection on this pathway revealed that HCMV dysregulates Notch signaling by altering expression of the Notch ligand Jag1, Notch1, and its active effector in NPCs. These results suggest a mechanism for the neuropathogenesis induced by HCMV infection that includes altered NPC differentiation and proliferation.

Mixed infections with distinct cytomegalovirus glycoprotein B genotypes in Polish pregnant women, fetuses, and newborns

The purpose of this investigation was to describe a distribution of cytomegalovirus (CMV) single and multiple genotypes among infected pregnant women, their fetuses, and newborns coming from Central Poland, as well as congenital cytomegaly outcome. The study involved 278 CMV-seropositive pregnant women, of whom 192 were tested for viral DNAemia. Human cytomegalovirus (HCMV) genotyping was performed for 18 of 34 pregnant women carrying the viral DNA and for 12 of their 15 offspring with confirmed HCMV infections. Anti-HCMV antibodies levels were assessed by chemiluminescence immunoassay (CLIA) and enzyme-linked fluorescence assay (ELFA) tests. Viral DNA loads and genotypes were determined by real-time polymerase chain reaction (PCR) assays for the UL55 gene. In the pregnant women, we identified HCMV gB1, gB2, gB3, and gB4 genotypes. Single gB2, gB3, or gB4 genotypes were observed in 14 (77.8 %) women, while multiple gB1–gB2 or gB2–gB3 genotypes were observed in four (22.2 %). Maternal HCMV genotypes determined the genotypes identified in their fetuses and newborns (p ≤ 0.050). Half of them were infected with single HCMV gB1, gB2, or gB3 genotypes and the other half with multiple gB1–gB2 or gB2–gB3 genotypes. Single and multiple genotypes were observed in both asymptomatic and symptomatic congenital cytomegaly, although no gB3 genotype was identified among asymptomatic cases. In Central Poland, infections with single and multiple HCMV strains occur in pregnant women, as well as in their fetuses and neonates, with both asymptomatic and symptomatic infections. HCMV infections identified in mothers seem to be associated with the viral genotypes in their children.

Cytomegalovirus alpha-chemokine genotypes are associated with clinical manifestations in children with congenital or postnatal infections

Human cytomegalovirus (HCMV) is the leading cause of congenital infections. The aim of our study was to determine the prevalence of genotypes based on the highly polymorphic UL146 and UL147 HCMV genes and the relationship between the genotype and symptoms or viral load. We analyzed samples from 121 infants with symptomatic HCMV infection, including 32 congenitally infected newborns. The G7 and G5 genotypes were predominant in postnatal infection, whereas the G1 genotype was prevalent in congenital infection. Central nervous system (CNS) damage and hepatomegaly were detected more frequently among children infected with the G1 genotype than in those infected by other genotypes. An association between the viral genotype and viruria level was found. There was a strong correlation between HCMV genotypes determined through the UL146 and UL147 sequences (ĸ=0.794). In conclusion, we found that certain vCXCL genotypes are associated with clinical sequelae following HCMV infection.

Cytomegalovirus glycoprotein H genotype distribution and the relationship with hearing loss in children

Cytomegalovirus (CMV) is a leading cause of congenital infection and a leading infectious cause of hearing loss in children. The ORF UL75 gene encodes envelope glycoprotein H (gH), which is essential for CMV entry into host cells and the target of the immune response in humans. However, the distribution of gH variants and the relationship between the viral genotype, viral load, and sequelae in children infected with CMV is debated. The UL75 genetic variation of CMV isolates from 42 newborns infected congenitally with CMV and 93 infants with postnatal or unproven congenital CMV infection was analyzed. Genotyping was performed by analysis of PCR-amplified fragments, and the viral load was measured by quantitative real-time PCR. There were no differences in the distribution of gH genotypes in the children infected congenitally and postnatally. Mixed-genotype infections with both gH1 and gH2 variants were detected in approximately 25% of the examined patients. No relationship between UL75 gene polymorphisms and the symptoms at birth was observed. The results suggest that the infection with gH2 genotype diminishes the risk of hearing loss in children (P = 0.010). In addition, sensorineural hearing loss was associated with CMV gH1 genotype infection in infants (P = 0.032) and a high viral load in urine (P = 0.005). In conclusion, it was found that the gH genotype does not predict clinical sequelae in newborn infants following congenital CMV infection. However, these results suggest that the gH genotype might be associated with hearing loss in children.