Cytomegalovirus infection and antibody protection of the developing placenta

Human cytomegalovirus (HCMV) infection is transmitted from the infected mother to the placenta and fetus. Virus replicates in the decidua, invasive cytotrophoblasts that breach the uterine vasculature and villous cytotrophoblasts underlying syncytiotrophoblasts, then reaches blood vessels in the villus core. Virus replication, fibrosis, and edema result in a hypoxic intrauterine environment and release of cytokines that stimulates compensatory development of the placenta. We employed villous explant cultures to study viral effects on differentiation and test novel approaches to rescue the placenta from infection.

Cytomegalovirus vaccines

An effective cytomegalovirus (CMV) vaccine could prevent the majority of birth defects caused by congenital CMV infections. Candidate vaccines in clinical evaluation include live attenuated, protein subunit, DNA, and viral-vectored approaches. Subunit approaches have focused on the CMV proteins pp65 and IE1 as important inducers of cytotoxic T cells and glycoprotein B (gB) as an important inducer of neutralizing antibodies. A vaccine comprised of recombinant gB protein with MF59 adjuvant reduced the incidence of primary infection by 50%. Recent revelations regarding CMV entry pathways into different cell types suggest a possible course for improvement. A 5-subunit pentameric complex is uniquely required for endothelial and epithelial cell entry. Sera from naturally infected subjects contain high-potency neutralizing activities specific for this complex, whereas the gB/MF59 vaccine fails to induce comparable neutralizing activities. A vaccine's ability to induce salivary antibodies that neutralize epithelial cell entry may be especially important for preventing oral transmission as the first cells infected are presumably epithelial cells of the oral mucosa. In addition, recent evidence suggests that antibodies can inhibit postentry CMV spread between endothelial and epithelial cells. Such activities may serve to limit viral replication in tissues or impair dissemination to the placenta and fetus. Thus, inclusion of epitopes derived from the pentameric complex may provide enhanced efficacy by inducing potent neutralizing/spread-inhibiting antibodies that target virus replication in a broad spectrum of cell types. Next-generation vaccine candidates in preclinical development incorporate peptides, subunits, or multisubunit complexes representing parts or all of the pentameric complex. Approaches include peptides, recombinant proteins, DNA, replication-defective viral vectors, genetically disabled CMV, and inactivated CMV virions. The diversity of novel strategies under development engenders optimism that a successful candidate will emerge.

Prevalence of Chagas disease in pregnant women and congenital transmission of Trypanosoma cruzi in Brazil: a systematic review and meta-analysis

OBJECTIVE

To estimate the prevalence of Chagas disease in pregnant women and the risk of congenital transmission of Trypanosoma cruzi infection in Brazil, through a systematic review and meta-analysis.

METHODS

We searched electronic databases, grey literature and reference lists of included publications to identify epidemiological studies on the prevalence of Chagas disease in pregnant women and on the congenital transmission rate of T. cruzi infection in Brazil published between January 1980 and June 2013. Pooled estimates and 95% confidence intervals (95% CIs) were calculated using fixed- and random-effects models.

RESULTS

Sixteen articles were included - 12 studies on the prevalence of Chagas disease in pregnant women (549,359 pregnant women) and nine on congenital transmission rates (1687 children born to infected mothers). Prevalence of Chagas disease in pregnant women ranged from 0.1% to 8.5%, and congenital transmission rates from 0% to 5.2%. The pooled prevalence of Chagas disease among pregnant women across studies was 1.1% (95% CI: 0.6-2.0); the pooled congenital transmission rate was 1.7% (95% CI: 0.9-3.1). In 2010, 34,629 pregnant women were estimated to be infected with T. cruzi, and 312-1073 children born (mean: 589 cases) with congenital infection.

CONCLUSION

Congenital Chagas disease is a neglected public health problem in Brazil. Systematic congenital Chagas disease control programs through routine prenatal screening for T. cruzi should be widely implemented in Brazil's endemic areas, to identify infected pregnant women and newborns at risk of congenital infection.

Congenital cytomegalovirus infection is associated with high maternal socio-economic status and corresponding low maternal cytomegalovirus seropositivity

AIMS

Human cytomegalovirus (CMV) is the leading infectious cause of congenital infection in developed countries. Globally, CMV seropositivity has been associated with low socio-economic status (SES); however, Australian data are lacking. Therefore, we examined the association between SES and CMV seroprevalence in children and pregnant women.

METHODS

Three groups were examined: 1, a prospective cohort of Australian children aged 0-15 years (n = 220); 2, a clinic-based sample of pregnant women (n = 778); and 3, a case series of infants and children (n = 219) with symptomatic congenital CMV infection. SES was determined using a postcode-based score from the Australian Bureau of Statistics.Group 1 was recruited from endocrinology clinics and follow-up at Prince of Wales Hospital and Children's Hospital at Westmead. Group 2 was recruited at the Royal Hospital for Women. Congenitally infected infants were identified through the Australian Paediatric Surveillance Unit.

RESULTS

CMV seroprevalence among all children was 20% (95% confidence interval (CI) 15-25%), and there was no association with SES (P = 0.58). Seroprevalence among pregnant women was 57% (53-60%), and higher rates of CMV seropositivity were associated with lower SES (P < 0.001). More congenital CMV cases were reported in the highest socio-economic groups (55%) than the lowest (9%) (P < 0.001).

CONCLUSIONS

A marked socio-economic gradient in CMV seroprevalence is evident in Australian pregnant women and cases of congenital CMV but not in unselected Australian children. These findings highlight the importance of a community-wide approach to CMV awareness and the potential for hygienic measures to reduce the burden of congenital CMV in Australia.

Cytomegalovirus infection among infants in California neonatal intensive care units, 2005-2010

AIM

To assess the burden of congenital and perinatal cytomegalovirus (CMV) disease among infants hospitalized in neonatal intensive care units (NICUs).

METHODS

CMV infection was defined as a report of positive CMV viral culture or polymerase chain reaction at any time since birth in an infant hospitalized in a NICU reporting to California Perinatal Quality Care Collaborative during 2005-2010.

RESULTS

One hundred and fifty-six (1.7 per 1000) infants were reported with CMV infection, representing an estimated 5% of the expected number of live births with symptomatic CMV disease. Prevalence was higher among infants with younger gestational ages and lower birth weights. Infants with CMV infection had significantly longer hospital stays and 14 (9%) died.

CONCLUSIONS

Reported prevalence of CMV infection in NICUs represents a fraction of total expected disease burden from CMV in the newborn period, likely resulting from underdiagnosis and milder symptomatic cases that do not require NICU care. More complete ascertainment of infants with congenital CMV infection that would benefit from antiviral treatment may reduce the burden of CMV disease in this population.

Coxsackievirus B4 myocarditis and meningoencephalitis in newborn twins

Coxsackievirus B4 (CB4) is a picornavirus associated with a variety of human diseases, including neonatal meningoencephalitis, myocarditis and type 1 diabetes. We report the pathological findings in twin newborns who died during an acute infection. The twins were born 1 month premature but were well and neurologically intact at birth. After a week they developed acute lethal neonatal sepsis and seizures. Histopathology demonstrated meningoencephalitis and severe myocarditis, as well as pancreatitis, adrenal medullitis and nephritis. Abundant CB4 sequences were identified in nucleic acid extracted from the brain and heart. In situ hybridization with probes to CB4 demonstrated infection of neurons, myocardiocytes, endocrine pancreas and adrenal medulla. The distribution of infected cells and immune response is consistent with reported clinical symptomatology where systemic and neurological diseases are the result of CB4 infection of select target cells.

Congenital cytomegalovirus infection and brain clefting

BACKGROUND

Human cytomegalovirus, a major cause of permanent neurodevelopmental disability in children, frequently produces intracranial abnormalities, including calcifications and polymicrogyria, in infants with congenital cytomegalovirus infections. This report describes the features of cerebral cortical clefting, including schizencephaly, in children with congenital cytomegalovirus infection.

METHODS

This is a retrospective review of the medical records of infants and children with congenital cytomegalovirus infection evaluated at Primary Children's Medical Center, Salt Lake City, Utah, between 1999 and 2008.

FINDINGS

Twenty-five children with congenital cytomegalovirus infection were identified during this 10-year period; 23 (92%) had computed tomography and 17 (68%) had magnetic resonance imaging. Imaging was obtained at a median age of 6 months (mode 1 month or less). Of 15 children with confirmed congenital infections, 10 (66%) had polymicrogyria or abnormal gyral patterns, five (33%) had cleft cortical dysplasia, and two (13%) had schizencephaly. Of 10 children with suspected congenital cytomegalovirus infection, eight (80%) had polymicrogyria, two (20%) had cleft cortical dysplasia, and one (10%) had bilateral schizencephaly with calcifications. Seventeen of the 25 infants (68%) had intracranial calcifications.

INTERPRETATION

These results indicate that clefting, either as cleft cortical dysplasia or schizencephaly, is an important feature of congenital cytomegalovirus infection.

Frequency of the congenital transmission of Trypanosoma cruzi: a systematic review and meta-analysis

BACKGROUND

Chagas disease is caused by the parasite Trypanosoma cruzi and is endemic in much of Latin America. With increased globalisation and immigration, it is a risk in any country, partly through congenital transmission. The frequency of congenital transmission is unclear.

OBJECTIVE

To assess the frequency of congenital transmission of T. cruzi.

SEARCH STRATEGY

PubMed, Journals@Ovid Full Text, EMBASE, CINAHL, Fuente Academica and BIREME databases were searched using seven search terms related to Chagas disease or T. cruzi and congenital transmission.

SELECTION CRITERIA

The inclusion criteria were the following: Dutch, English, French, Portuguese or Spanish language; case report, case series or observational study; original data on congenital T. cruzi infection in humans; congenital infection rate reported or it could be derived. This systematic review included 13 case reports/series and 51 observational studies.

DATA COLLECTION AND ANALYSIS

Two investigators independently collected data on study characteristics, diagnosis and congenital infection rate. The principal summary measure--the congenital transmission rate--is defined as the number of congenitally infected infants divided by the number of infants born to infected mothers. A random effects model was used.

MAIN RESULTS

The pooled congenital transmission rate was 4.7% (95% confidence interval: 3.9-5.6%). Countries where T. cruzi is endemic had a higher rate of congenital transmission compared with countries where it is not endemic (5.0% versus 2.7%).

CONCLUSIONS

Congenital transmission of Chagas disease is a global problem. Overall risk of congenital infection in infants born to infected mothers is about 5%. The congenital mode of transmission requires targeted screening to prevent future cases of Chagas disease.

Antibody kinetics in infants exposed to Chikungunya virus infection during pregnancy reveals absence of congenital infection

To search for serological evidence of congenital infection in apparently healthy neonates born to women infected with the Chikungunya virus (CHIKV) during pregnancy, monitoring for CHIKV-specific antibodies was performed within the CHIMERE cohort study (Reunion island, 2006-2008). CHIKV-specific antibody kinetics showed no evidence of asymptomatic congenital infection as neonates were tested negative for CHIKV-specific IgM antibodies at birth and 368 infants with CHIKV-specific IgG antibodies seroreversed completely (mean seroreversion time: 7.7 months). Seroreversion time of transplacental CHIKV IgG antibodies was inversely correlated with the stage of pregnancy at which exposure took place and end-term small for gestational infants seroreversed earlier.

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

BACKGROUND

Congenital cytomegalovirus (cCMV) is a common congenital infection and a leading nongenetic cause of sensorineural hearing loss (SNHL). CMV exhibits extensive genetic variability, and infection with multiple CMV strains (mixed infection) was shown to be common in congenital CMV. The role of mixed infections in disease and outcome remains to be defined.

METHODS

Genotyping of envelope glycoproteins, UL55 (gB), UL73 (gN) and UL75 (gH), was performed on saliva specimens of 79 infants from the ongoing CMV and Hearing Multicenter Screening (CHIMES) Study and on blood and urine specimens of 52 infants who participated in natural history studies at the University of Alabama at Birmingham. Genotyping of UL144 and US28 was also performed in the CHIMES cohort. The association of individual genotypes and mixed infection with clinical findings at birth and SNHL was examined.

RESULTS

Thirty-seven of 131 infants (28%) were symptomatic at birth and 26 (20%) had SNHL at birth. All known genotypes of UL55, UL75, UL73 and US28 were represented, and no particular genotype was associated with symptomatic infection or SNHL. UL144 subtype C was more common in symptomatic infants but not associated with SNHL. Mixed infection was observed in 59 infants (45%) and not associated with symptoms (P = 0.43) or SNHL at birth (P = 0.82). In the cohort of 52 infants with long-term hearing outcome, mixed infection at birth was not predictive of SNHL.

CONCLUSIONS

Mixed infection is common in infants with congenital CMV but is neither associated with symptomatic infection nor associated with SNHL.

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.

Polymicrogyria and congenital parvovirus b19 infection

Fetal parvovirus B19 infection causes anemia, hydrops, and pregnancy loss but is generally not considered teratogenic. Nevertheless, disturbances of neuronal migration have been described with congenital parvovirus infection. We evaluated a term infant with congenital parvovirus disease and polymicrogyria. We compared this case with four other reports of central nervous system disease after birth to parvovirus-infected mothers. After an extensive diagnostic evaluation, this infant was found to have congenital parvovirus disease with severe anemia and nonimmune hydrops as well as extensive polymicrogyria. Although rare, this report and literature review suggest that parvovirus B19 has the potential to disrupt normal neurodevelopment. We suggest that infants with severe congenital parvovirus infection have close developmental surveillance and if symptomatic undergo neuroimaging to assess for disorders of neuromigration.

Congenital cytomegalovirus infection as a cause of sensorineural hearing loss in a highly immune population

BACKGROUND

The burden of congenital cytomegalovirus (CMV)-associated sensorineural hearing loss (SNHL) in populations with CMV seroprevalence approaching 100% is unknown. The purpose of this study was to assess the rate, associated factors, and predictors of SNHL in CMV-infected infants identified by newborn screening in a highly seropositive maternal population.

METHODS

Newborns with positive saliva CMV-DNA that was confirmed by virus isolation in the first 2 weeks of life were enrolled in a prospective follow-up study to monitor hearing outcome.

RESULTS

Of 12,195 infants screened, 121 (1%) were infected with CMV and 12 (10%) had symptomatic infection at birth. Hearing function could be assessed in 102/121 children who underwent at least one auditory brainstem evoked response testing at a median age of 12 months. SNHL was observed in 10/102 (9.8%; 95% confidence interval: 5.1-16.7) children. Median age at the latest hearing evaluation was 47 months (12-84 months). Profound loss (>90 dB) was found in 4/5 children with bilateral SNHL while all 5 children with unilateral loss had moderate to severe deficit. The presence of symptomatic infection at birth (odds ratio, 38.1; 95% confidence interval: 1.6-916.7) was independently associated with SNHL after adjusting for intrauterine growth restriction, gestational age, gravidity, and maternal age. Among 10 infants with SNHL, 6 (60%) were born to mothers with nonprimary CMV infection.

CONCLUSIONS

Even in populations with near universal immunity to CMV, congenital CMV infection is a significant cause of SNHL demonstrating the importance of CMV as a major cause of SNHL in children worldwide. As in other populations, SNHL is more frequently observed in symptomatic CMV infection.

Cytomegalovirus antivirals and development of improved animal models

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Cytomegalovirus infection in pregnancy: review of the literature

The aim of this review is to summarize the principles of cytomegalovirus (CMV) infection in pregnancy.In particular, the aim of this review is to evaluate:Incidence and mother-to-child transmissionThe value of screening of pregnant womenDiagnosis of CMV maternal infectionDiagnosis of fetal infection (evaluate the value of ultrasound examination and amniocentesis and evaluate whether the amniotic viral load of mothers with primary cytomegalovirus infection correlate with fetal or neonatal outcomes)Diagnosis of infection in newbornsTherapy in pregnancy, postnatal therapy and prevention.

[Aicardi-Goutieres syndrome: a Mendelian mimic of congenital infection]

In 1988, we have drawn attention to the consistent finding of raised levels of interferon-alpha (IFN) in the cerebro-spinal fluid (CSF) and serum of infants affected with a severe genetically determined encephalopathy. These encephalopathies called Aicardi-Goutières syndrome (AGS) are characterized by calcifications of the basal ganglia, white matter demyelination and elevated levels of lymphocytes in the cerebrospinal fluid. These features mimic those of acquired in utero viral infection, so that AGS is sometimes mistaken for the sequelae of congenital infection. This diagnostic distinction has obvious importance, given that AGS is an autosomal recessive disorder whose true nature is often only recognized upon the birth of a second affected child. Recent molecular advances have shown that AGS can be caused by mutations in any one of at least five genes. The relationship between the involved disrupted nuclease pathways and the production of IFN leading to CNS damage in AGS is discussed.

Significant performance variation among PCR systems in diagnosing congenital toxoplasmosis in São Paulo, Brazil: analysis of 467 amniotic fluid samples

INTRODUCTION

Performance variation among PCR systems in detecting Toxoplasma gondii has been extensively reported and associated with target genes, primer composition, amplification parameters, treatment during pregnancy, host genetic susceptibility and genotypes of different parasites according to geographical characteristics.

PATIENTS

A total of 467 amniotic fluid samples from T. gondii IgM- and IgG-positive Brazilian pregnant women being treated for 1 to 6 weeks at the time of amniocentesis (gestational ages of 14 to 25 weeks).

METHODS

One nested-B1-PCR and three one-round amplification systems targeted to rDNA, AF146527 and the B1 gene were employed.

RESULTS

Of the 467 samples, 189 (40.47%) were positive for one-round amplifications: 120 (63.49%) for the B1 gene, 24 (12.69%) for AF146527, 45 (23.80%) for both AF146527 and the B1 gene, and none for rDNA. Fifty previously negative one-round PCR samples were chosen by computer-assisted randomization analysis and re-tested (nested-B1-PCR), during which nine additional cases were detected (9/50 or 18%).

DISCUSSION

The B1 gene PCR was far more sensitive than the AF146527 PCR, and the rDNA PCR was the least effective even though the rDNA had the most repetitive sequence. Considering that the four amplification systems were equally affected by treatment, that the amplification conditions were optimized for the target genes and that most of the primers have already been reported, it is plausible that the striking differences found among PCR performances could be associated with genetic diversity in patients and/or with different Toxoplasma gondii genotypes occurring in Brazil.

CONCLUSION

The use of PCR for the diagnosis of fetal Toxoplasma infections in Brazil should be targeted to the B1 gene when only one gene can be amplified, preferably by nested amplification with primers B22/B23.

Procalcitonin in preterm infants during the first few days of life: introducing an age related nomogram

OBJECTIVE

To determine normal concentrations of procalcitonin in preterm infants shortly after birth and to assess its accuracy in detecting bacterial infection.

METHODS

Blood samples of 100 preterm infants were prospectively drawn during the first 4 days of life for determination of procalcitonin concentration. Infants were classified into four groups according to their sepsis status.

RESULTS

Mean (SD) gestational age and birth weight were 32 (2.9) weeks and 1682 (500) g respectively. A total of 283 procalcitonin concentrations from healthy infants were plotted to construct nomograms of physiologically raised procalcitonin concentration after birth, stratified by two groups to 24-30 and 31-36 weeks gestation. The peak 95th centile procalcitonin concentration was plotted at 28 hours of age; values return to normal after 4 days of life. Only 12 infants were infected, and 13 of their 16 procalcitonin concentrations after birth were higher than the 95th centile, whereas samples taken at birth were lower. In a multivariable analysis, gestational age, premature rupture of membrane, and sepsis status influenced procalcitonin concentration independently, but maternal infection status did not.

CONCLUSIONS

The suggested neonatal nomograms of preterm infants are different from those of term infants. Procalcitonin concentrations exceeding the 95th centile may be helpful in detecting congenital infection, but not at birth.

Diagnostic value of CD45RO expression on circulating T lymphocytes of fetuses and newborn infants with pre-, peri- or early post-natal infections

We examined the expression of the CD45RO antigen, which characterizes the antigen primed/memory phenotype of T lymphocytes, as a marker for congenital infection in blood samples of newborns and fetuses. CD45RO expression on T cells was determined by triple-colour fluorescence flow cytometry. In total 537 blood samples of newborns and infants up to an age of 3 months and 89 fetal blood samples from gestational weeks 19-31 were analysed. Of the newborns and infants, 74 had a clinically, serologically and/or antigenically evident infection, and four of the fetuses had a confirmed intra-uterine infection. In 35 infants with acute predominantly bacterial infections such as sepsis or pneumonia, 17 (48.6%) had elevated CD45RO(bright) expression. In 39 infants with proven pre-, peri- or early post-natal infections with toxoplasmosis, cytomegalovirus (CMV), rubella, herpes simplex virus (HSV) or human herpes virus type 6 (HHV6), 25 (64.1%) exhibited enhanced CD45RO(bright) expression. Three of four fetuses with confirmed intra-uterine infection (three with CMV, one with parvovirus B19) exhibited elevated CD45RO(bright) expression. The specificity of the CD45RO assay for detecting microbial infections was 94.6% for newborns and infants up to 3 months and 90.6% for fetuses. It is concluded that elevated numbers of CD45RO(bright) T cells in infants up to 3 months of age strongly suggest an infection. However, the sensitivity of the CD45RO assay is not sufficient to enable the test to be used as a general marker for prescreening infants to detect pre-, peri- or early post-natally acquired infections.

Ruminant pestiviruses

The ruminant pestiviruses, bovine virus diarrhoea virus (BVDV) and border disease virus (BDV) are highly successful and important pathogens which infect ruminant species worldwide. Although the serological relationships among ruminant pestiviruses require further clarification, there is growing evidence for two antigenic groups, one of which predominates in cattle and one in sheep. The success of pestiviruses stems from the ability of the non-cytopathic (NCP) biotype of the virus to cross the placenta and establish a persistent infection (PI) in the developing foetus. This biotype should be regarded as the 'normal' biotype with the cytopathic (CP) biotype being an abnormal virus that is usually isolated only from PI animals dying from mucosal disease. Recent molecular evidence points to CP viruses arising from their NCP counterparts by recombination events that include the insertion of host RNA and/or the duplication of viral RNA sequences. However, the biological mechanism through which CP viruses kill cells remains unknown. Virtually all CP and NCP viruses cause only mild, transient clinical symptoms in healthy adult animals and stimulate a protective immune response. Despite the urgent requirement for a safe, effective vaccine, there is still no commercial vaccine that has been shown to immunize dams so that foetal infection is prevented. In the absence of an effective vaccine, reliable diagnostic techniques are essential to implement effective control measures. There is now a range of monoclonal antibody-based enzyme-linked immunosorbent assays for identifying PI or convalescent animals. These tests are specific, rapid, sensitive and reliable but may themselves become redundant as they are superceded by ever-increasing molecular biology-based techniques.