Central nervous system disorders in infants with congenital cytomegalovirus infection

Epidemiological characteristics of human cytomegalovirus infection and glycoprotein H genotype in Chinese children

BACKGROUND

Human cytomegalovirus (HCMV) is a common pathogen that causes many diseases in young children. HCMV glycoprotein H (gH) genotypes may be associated with the type and severity of some diseases. In this study, systematic surveillance was conducted on the prevalence of HCMV infections and HCMV gH genotypes in children.

METHODS

Urine samples were collected from children admitted to the inpatient wards and outpatient departments between January 2015 and December 2016 in the Children's Hospital, Zhejiang University School of Medicine (Hangzhou, China), and these were tested by real-time PCR for HCMV DNA detection and HCMV gH genotyping.

RESULTS

During the study period, a total of 32,542 urine samples were collected and analyzed using real-time PCR to confirm HCMV infection, and 5286 (16.2%) cases were positive for HCMV DNA. From our results, children aged less than one year were the most susceptible population to HCMV. Based on the data obtained from gH probes combined with real-time PCR assay, 964 HCMV-positive samples were genotyped for gH. Among them, 584 (60.6%) were positive for gH1 subtype, 307 (31.8%) for gH2 subtype, and 73 (7.6%) for both gH1 and gH2 subtypes. The gH2 rate of 42.9% indicated HCMV infection was the highest subtype in the group aged ≤28 days while gH1 rate of 77% was the highest in the group aged >3 years. The highest gH2 rate (36.4%) and lowest gH1 rate (50.0%) were detected in children with HCMV viremia, whereas the highest gH1 rates (65.0%) and lowest gH2 rates (28.8%) were found in children with HCMV hepatitis.

CONCLUSION

The findings of our study show that children less than 1-year-old are the major population among HCMV-infected children. gH1 is the predominant genotype of HCMV in China, which occurs more frequently than gH2 genotype in the case of HCMV hepatitis. However, the opposite tendency is observed in HCMV viremia, where the gH2 genotype is predominant.

Effect of cytomegalovirus infection and leukocyte immunoglobulin like receptor B1 polymorphisms on receptor expression in peripheral blood mononuclear cells

Leukocyte immunoglobulin like receptor B1 (LILRB1) plays a significant role in a number of infectious, autoimmune, cardiovascular, and oncologic disorders. LILRB1 expression varies between individuals and may be associated with polymorphisms on the regulatory region of the LILRB1 gene, as well as to previous cytomegalovirus infection. In this study, the contribution of these two factors to LILRB1 expression in peripheral blood mononuclear cells of healthy young adults was analyzed. LILRB1 expression in NK cells, T cells, B cells and monocytes was significantly stronger in individuals who had had cytomegalovirus infection than in those who had not (P < 0.001, P < 0.001, P < 0.01, and P < 0.001, respectively). Overall, no differences in LILRB1 expression were observed between individuals with and without GAA haplotypes of the LILRB1 regulatory region. However, when analyzed according to cytomegalovirus infection status, significant differences in LILRB1+ NK cells were observed. A higher proportion of LILRB1+ cells was found in GAA+ than in GAA- individuals who had not been infected (P < 0.01), whereas GAA- individuals had a larger proportion of LILRB1+ cells than GAA+ individuals who were cytomegalovirus positive (P < 0.01). In conclusion, cytomegalovirus infection has a major effect on LILRB1 expression in NK and other mononuclear cells and polymorphisms in the LILRB1 regulatory region appear to have a modulatory influence over this effect.

Prenatal Cerebellar Disruptions: Neuroimaging Spectrum of Findings in Correlation with Likely Mechanisms and Etiologies of Injury

There is increasing evidence that the cerebellum is susceptible to prenatal infections and hemorrhages and that congenital morphologic anomalies of the cerebellum may be caused by disruptive (acquired) causes. Starting from the neuroimaging pattern, this report describes a spectrum of prenatal cerebellar disruptions including cerebellar agenesis, unilateral cerebellar hypoplasia, cerebellar cleft, global cerebellar hypoplasia, and vanishing cerebellum in Chiari type II malformation. The neuroimaging findings, possible causative disruptive events, and clinical features of each disruption are discussed. Recognition of cerebellar disruptions and their differentiation from cerebellar malformations is important in terms of diagnosis, prognosis, and genetic counselling.

Multipotent mesenchymal stromal cells are fully permissive for human cytomegalovirus infection

Congenital human cytomegalovirus (HCMV) infection is a leading infectious cause of birth defects. Previous studies have reported birth defects with multiple organ maldevelopment in congenital HCMV-infected neonates. Multipotent mesenchymal stromal cells (MSCs) are a group of stem/progenitor cells that are multi-potent and can self-renew, and they play a vital role in multi-organ formation. Whether MSCs are susceptible to HCMV infection is unclear. In this study, MSCs were isolated from Wharton's jelly of the human umbilical cord and identified by their plastic adherence, surface marker pattern, and differentiation capacity. Then, the MSCs were infected with the HCMV Towne strain, and infection status was assessed via determination of viral entry, replication initiation, viral protein expression, and infectious virion release using western blotting, immunofluorescence assays, and plaque forming assays. The results indicate that the isolated MSCs were fully permissive for HCMV infection and provide a preliminary basis for understanding the pathogenesis of HCMV infection in non-nervous system diseases, including multi-organ malformation during fetal development.

Effects of cytomegalovirus infection in human neural precursor cells depend on their differentiation state

Cytomegalovirus (CMV) is the most common cause of congenital infection in developed countries and a major cause of neurological disability in children. Although CMV can affect multiple organs, the most important sequelae of intrauterine infection are related to lesions of the central nervous system. However, little is known about the pathogenesis and the cellular events responsible for neuronal damage in infants with congenital infection. Some studies have demonstrated that neural precursor cells (NPCs) show the greatest susceptibility to CMV infection in the developing brain. We sought to establish an in vitro model of CMV infection of the developing brain in order to analyze the cellular events associated with invasion by this virus. To this end, we employed two cell lines as a permanent source of NPC, avoiding the continuous use of human fetal tissue, the human SK-N-MC neuroblastoma cell line, and an immortalized cell line of human fetal neural origin, hNS-1. We also investigated the effect of the differentiation stage in relation to the susceptibility of these cell lines by comparing the neuroblastoma cell line with the multipotent cell line hNS-1. We found that the effects of the virus were more severe in the neuroblastoma cell line. Additionally, we induced hNS-1 to differentiate and evaluated the effect of CMV in these differentiated cells. Like SK-N-MC cells, hNS-1-differentiated cells were also susceptible to infection. Viability of differentiated hNS-1 cells decreased after CMV infection in contrast to undifferentiated cells. In addition, differentiated hNS-1 cells showed an extensive cytopathic effect whereas the effect was scarce in undifferentiated cells. We describe some of the effects of CMV in neural stem cells, and our observations suggest that the degree of differentiation is important in the acquisition of susceptibility.

Cytomegalovirus infection in infants admitted to a neonatal intensive care unit

OBJECTIVES

To determine the incidence of congenital cytomegalovirus (CMV) infection and the frequency of postnatal infection in a neonatal intensive care unit (NICU).

METHODS

Urine samples of 135 infants who were admitted to the NICU during a 6 month period were evaluated to detect CMV using a nested PCR assay. A breast milk sample was obtained to determine viral excretion. Clinical characteristics of infected and non-infected infants were compared.

RESULTS

Congenital CMV infection was confirmed in two (1.48%) infants. Post-natal infection was documented in four of 36 (11.1%) infants that were evaluated. CMV excretion was detected in 43 of 116 mothers. Gestational age of infants born to mothers who excreted CMV was shorter than that of infants of mothers with negative results (33.1 versus 34.2 weeks; p = 0.07).

CONCLUSIONS

CMV excretion in breast milk is frequent and is associated to congenital and postnatal infection. Further studies are necessary to assess the impact of CMV infection during pregnancy and neonatal outcomes.

The "silent" global burden of congenital cytomegalovirus

Human cytomegalovirus (CMV) is a leading cause of congenital infections worldwide. In the developed world, following the virtual elimination of circulating rubella, it is the commonest nongenetic cause of childhood hearing loss and an important cause of neurodevelopmental delay. The seroprevalence of CMV in adults and the incidence of congenital CMV infection are highest in developing countries (1 to 5% of births) and are most likely driven by nonprimary maternal infections. However, reliable estimates of prevalence and outcome from developing countries are not available. This is largely due to the dogma that maternal preexisting seroimmunity virtually eliminates the risk for sequelae. However, recent data demonstrating similar rates of sequelae, especially hearing loss, following primary and nonprimary maternal infection have underscored the importance of congenital CMV infection in resource-poor settings. Although a significant proportion of congenital CMV infections are attributable to maternal primary infection in well-resourced settings, the absence of specific interventions for seronegative mothers and uncertainty about fetal prognosis have discouraged routine maternal antibody screening. Despite these challenges, encouraging results from prototype vaccines have been reported, and the first randomized phase III trials of prenatal interventions and prolonged postnatal antiviral therapy are under way. Successful implementation of strategies to prevent or reduce the burden of congenital CMV infection will require heightened global awareness among clinicians and the general population. In this review, we highlight the global epidemiology of congenital CMV and the implications of growing knowledge in areas of prevention, diagnosis, prognosis, and management for both low (50 to 70%)- and high (>70%)-seroprevalence settings.

Pathogenesis and treatment of human immunodeficiency virus-associated cytomegalovirus retinitis

In the era of HAART, human cytomegalovirus (HCMV) retinitis remains the leading opportunistic ocular infection and the major cause of blindness in patients with AIDS. The virus has been subjected to selection and presented with the opportunity to occupy a niche to which it is highly adapted in order to escape from host immune recognition and establish persistent infection in the retina. The imbalance between host immune protection and viral immune evasion results in retinitis progression. Moreover, a synergistic interaction between HCMV and HIV in the pathogenesis of retinitis has been proposed. HAART has had a major beneficial impact on the prognosis for HIV-infected individuals. Both HAART and specific anti-HCMV treatment contribute to therapeutic success against HCMV retinitis in AIDS patients. The improved prognosis for AIDS patients with respect to the development of HCMV retinitis has been welcomed; however, we should bear in mind the occurrence of HIV drug resistance, relapse of retinitis and immune recovery uveitis after treatment, which mean that this complication of HIV infection remains a threat.

Viral infection and neural stem/progenitor cell's fate: implications in brain development and neurological disorders

Viral infections in the prenatal (during pregnancy) and perinatal period have been a common cause of brain malformation. Besides the immediate neurological dysfunctions, virus infections may critically affect CNS development culminating in long-term cognitive deficits. Most of these neurotropic viruses are most damaging at a critical stage of the host, when the brain is in a dynamic stage of development. The neuropathology can be attributed to the massive neuronal loss induced by the virus as well as lack of CNS repair owing to a deficit in the neural stem/progenitor cell (NSPC) pool or aberrant formation of new neurons from NSPCs. Being one of the mitotically active populations in the post natal brain, the NSPCs have emerged as the potential targets of neurotropic viruses. The NSPCs are self-renewing and multipotent cells residing in the neurogenic niches of the brain, and, therefore, hampering the developmental fate of these cells may adversely affect the overall neurogenesis pattern. A number of neurotropic viruses utilize NSPCs as their cellular reservoirs and often establish latent and persistent infection in them. Both HIV and Herpes virus infect NSPCs over long periods of time and reactivation of the virus may occur later in life. The virus infected NSPCs either undergoes cell cycle arrest or impaired neuronal or glial differentiation, all of which leads to impaired neurogenesis. The disturbances in neurogenesis and CNS development following neurotropic virus infections have direct implications in the viral pathogenesis and long-term neurobehavioral outcome in infected individuals.