Improved prenatal diagnosis of congenital human cytomegalovirus infection by a modified nested polymerase chain reaction

Human Cytomegalovirus-Specific Memory CD4+ T-Cell Response and Its Correlation With Virus Transmission to the Fetus in Pregnant Women With Primary Infection

Background

Primary human cytomegalovirus (HCMV) infection during pregnancy is the major cause of congenital viral sequelae. The HCMV-specific T-cell response may have a role in the prevention of virus transmission to the fetus.

Methods

HCMV-specific memory T cells were investigated in the second month after primary infection onset in 44 pregnant women (15 transmitting the infection to the fetus) and 8 pregnant women with remote infection. Peripheral blood mononuclear cells were stimulated for 12 days with peptide pools of HCMV proteins IE-1, IE-2, and pp65, and subsequently restimulated for 24 hours with the same peptide pools in a cultured enzyme-linked immunospot (ELISPOT) assay.

Results

In pregnant women with primary infection, the cultured ELISPOT assay detected a higher T-cell response to pp65 than to IE-1 or IE-2, whereas in remote infection pp65-, IE-1-, and IE-2-specific T cells were detected at comparable levels. During primary infection, the cultured ELISPOT response was mainly mediated by CD4+ T cells, and was lower than in remote infection. Strikingly, the cultured ELISPOT response to pp65 (but not to IE-1 or IE-2) was significantly higher in nontransmitting mothers. To detect other factors potentially associated with nontransmission, different serological parameters were analyzed. Only immunoglobulin G avidity index was higher in nontransmitting mothers, who showed also a lower DNAemia level. These 2 parameters remained associated with congenital infection in multivariate analysis.

Conclusions

Determination of HCMV-specific T cells by cultured ELISPOT, in pregnant women with primary HCMV infection, in association with avidity index and DNAemia may help to assess the risk of HCMV fetal transmission.

Preexisting antibodies can protect against congenital cytomegalovirus infection in monkeys

Human cytomegalovirus (HCMV) is the most common congenital infection and a known cause of microcephaly, sensorineural hearing loss, and cognitive impairment among newborns worldwide. Natural maternal HCMV immunity reduces the incidence of congenital infection, but does not prevent the disease altogether. We employed a nonhuman primate model of congenital CMV infection to investigate the ability of preexisting antibodies to protect against placental CMV transmission in the setting of primary maternal infection and subsequent viremia, which is required for placental virus exposure. Pregnant, CD4+ T cell-depleted, rhesus CMV-seronegative (RhCMV-seronegative) rhesus monkeys were treated with either standardly produced hyperimmune globulin (HIG) from RhCMV-seropositive macaques or dose-optimized, potently RhCMV-neutralizing HIG prior to intravenous challenge with an RhCMV mixture. HIG passive infusion provided complete protection against fetal loss in both groups. The dose-optimized, RhCMV-neutralizing HIG additionally inhibited placental transmission of RhCMV and reduced viral replication and diversity. Our findings suggest that the presence of durable and potently neutralizing antibodies at the time of primary infection can prevent transmission of systemically replicating maternal RhCMV to the developing fetus, and therefore should be a primary target of vaccines to eliminate this neonatal infection.

Congenital Cytomegalovirus Infection: Prognostic Value of Maternal DNAemia at Amniocentesis

BACKGROUND

Human Cytomegalovirus (HCMV) is the most common cause of childhood hearing loss and can lead to neurodevelopmental delay. To date, few studies have examined the correlation between maternal viremia and congenital HCMV infection. The aim of our study was to ascertain if HCMV DNA in the peripheral blood of pregnant women with primary HCMV infection at the time of amniocentesis may have a prognostic value in terms of congenital infection and neonatal symptomatic disease.

METHODS

We performed a prospective observational study of pregnant women referred to our maternal-fetal medicine division with suspected HCMV infection. Primary infection was diagnosed based on seroconversion for HCMV and/or HCMV immunoglobulin M-positive and low or moderate HCMV immunoglobulin G avidity. At the time of amniocentesis, maternal blood samples were collected and analyzed by means of real-time polymerase chain reaction to determine the presence of viral DNAemia. Fetuses and newborns were evaluated for the presence of congenital infection and symptomatic disease.

RESULTS

A total of 239 pregnant women were enrolled; 32 blood samples (13.4%) were positive, and 207 (86.6%) were negative for HCMV DNA. The overall rate of transmission was 23.4%. Fifteen infected patients (26.8%) were symptomatic. Vertical transmission occurred in 14 women (43.8%) with positive and 42 (20.3%) with negative results for HCMV DNAemia (P = .006; odds ratio, 3.06; 95% confidence interval, 1.41-6.64). Symptomatic infection occurred in 6 (42.9%) infected fetuses or newborns from women with and in 9 (21.4%) from women without viral DNAemia (P = .16).

CONCLUSION

Maternal viremia at amniocentesis is associated with a 3-fold greater chance of congenital infection, but it is not correlated with symptomatic disease.

Reduced frequencies of polyfunctional CMV-specific T cell responses in infants with congenital CMV infection

PURPOSE

CMV infection remains a priority for vaccine development. Vaccination of infants could modify congenital infection and provide lifetime immunity. Properties of CMV-specific T cells associated with control of viral replication in early life have not been fully defined.

METHODS

CMV-specific CD4 and CD8 T cell responses were investigated in infants with congenital CMV infection and compared to adults with primary or chronic infection. PBMC were stimulated with UL83 (pp65) or UL122 (IE-2) peptide pools then stained with antibodies to markers of T cell subset (CD4 or CD8), phenotype (CD45RA, CCR7), or function (MIP1β, CD107, IFNγ, IL2) for flow cytometry analysis.

RESULTS

Detection of CMV pp65-specific CD4 T cells was less common in infants than adults. Responder cells were primarily effector memory (EM, CD45RA-CCR7-) in adults, but mixed memory subsets in infants. Detection of CMV pp65-specific CD8 T cells did not differ between the groups, but infants had lower frequencies of total responding cells and of MIP1β- or CD107-expressing cells. Responder cells were EM or effector memory RA (CD45RA + CCR7-) in all groups. Polyfunctional T cells were less commonly detected in infants than adults. Responses to IE-2 were detected in adults but not infants. All infants had detectable circulating CMV DNA at initial study (versus 60 % of adults with primary infection) despite longer duration of CMV infection.

CONCLUSIONS

Reduced frequencies and altered functional profile of CMV-specific CD4 and CD8 T cell responses were detected in infants compared to adults, and were associated with persistent CMV DNA in peripheral blood.

The pathogenesis of human cytomegalovirus

Human cytomegalovirus (HCMV) is a recognized cause of disease in the fetus, the allograft recipient and AIDS patients. More recently, it has been recognized as a pathogen for those admitted to intensive care units, for the elderly and for the general population. The epidemiology and molecular and cellular pathology of this virus are summarized to provide an overarching model of pathogenesis, able to account for these varying clinical presentations. In brief, HCMV has the potential to spread in the bloodstream to all organs, but only produces overt disease if the viral load increases to high levels. This is normally prevented by a robust immune response, so that the infected individual usually remains asymptomatic. However, this benefit comes at the cost of committing more and more immunological resources to controlling HCMV with time, so that the overall function of the immune system is impaired. Fortunately, recent progress in developing novel antiviral drugs and vaccines suggests the possibility that the diverse effects of HCMV may soon become controllable at the individual and population level, respectively.

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.

Burden of disease associated with human cytomegalovirus and prospects for elimination by universal immunisation

Cytomegalovirus is the most frequent cause of intrauterine infection and the commonest infectious agent to affect allograft recipients, yet the virus is acknowledged rarely as an occupational hazard for women of childbearing age or as a nosocomial infection. The potential role of cytomegalovirus in hastening the death of patients with AIDS, elderly people, individuals admitted to intensive-care units, and the general population is not emphasised. Development of vaccines against this important human pathogen has been delayed by reluctance to initiate proof-of-concept studies, but after recent trials, protection is a distinct possibility. Cytomegalovirus deserves to be eliminated from selected populations by means of universal immunisation as soon as suitable vaccines become licensed. This action should control disease in neonates and transplant recipients and could provide substantial additional benefits if other disease associations prove to be causal.

Overview of the diagnosis of cytomegalovirus infection

Cytomegalovirus (CMV) is recognized as the most common congenital viral infection in humans and an important cause of morbidity and mortality in immunocompromised hosts. This recognition of the clinical importance of invasive CMV disease in the setting of immunodeficiency and in children with congenital CMV infection has led to the development of new diagnostic procedures for the rapid identification of CMV. Diagnosis of acute maternal CMV infection by the presence of immunoglobulin (Ig)M and low-avidity IgG requires confirmation of fetal infection, which is typically performed using polymerase chain reaction (PCR) assays for CMV on amniotic fluid. Viral culture of the urine and saliva obtained within the first two weeks of life continues to be the gold standard for diagnosis of congenitally-infected infants. PCR assays of dried blood spots from newborns have been shown to lack sufficient sensitivity for the identification of most neonates with congenital CMV infection for universal screening purposes. However, saliva PCR assays are currently being assessed as a useful screening method for congenital CMV infection. In the immunocompromised host, newer rapid diagnostic assays, such as phosphoprotein 65 antigenemia and CMV real-time PCR of blood or plasma have allowed for preemptive treatment, reducing morbidity and mortality. However, lack of standardized real-time PCR protocols hinders the comparison of data from different centers and the development of uniform guidelines for the management of invasive CMV infections in immunocompromised individuals.

Congenital cytomegalovirus infection following antenatal negative diagnostic amniotic fluid analysis - a single center experience

OBJECTIVE

To determine the perinatal outcome of confirmed congenital cytomegalovirus (CMV) infection despite a negative prenatal amniotic-fluid analysis.

METHODS

A retrospective cohort study of all neonates diagnosed with congenital CMV infection from January 2006 to December 2011 despite negative results on polymerase chain reaction and shell's vial assays of amniotic fluid. Data were collected on all neonates by physical examination, blood work-up (complete blood count, bilirubin, liver enzymes), fundoscopy, brainstem evoked response (BSER), and brain ultrasound, at birth and during follow-up in the neonatal period.

RESULTS

The study group included 10 patients with primary congenital CMV infection during pregnancy. Follow-up time ranged from 1 to 62 months (median, 17 months). Four patients had consistently normal findings throughout follow-up, and three developed mild hepatosplenomegaly (1-32 months). In the remaining four offspring, brain ultrasound preformed after birth revealed lenticular striated vasculopathy (LSV) and in three of them the BSER test showed decreased hearing ability. Treatment with ganciclovir/valganciclovir was administered at age of 2 weeks, 2, 18, and 32 months. The BSER normalized after 9 and 12 months of treatment in two patients for whom follow-up data were available.

CONCLUSION

Negative findings on amniotic-fluid tests for CMV do not rule out neonatal infection with clinical morbidity.

Kinetics of effector functions and phenotype of virus-specific and γδ T lymphocytes in primary human cytomegalovirus infection during pregnancy

The T-cell response to human cytomegalovirus (HCMV) primary infection was analyzed in 27 pregnant women during the first year after primary HCMV infection. Pregnant women with remote HCMV infection were enrolled as controls. Interferon-γ-producing T cells were readily detected at levels comparable (CD4(+)) or higher (CD8(+)) than controls, whereas the CD4(+) and CD8(+) lymphoproliferative response as well as IL-2 production was significantly reduced with respect to controls for at least 9 months after infection. In addition, CD45RA re-expression as well as cytotoxic T lymphocyte activity and perforin expression were the major components of the adaptive CD4(+) and CD8(+) T-cell immune response, while Vδ2(-) γδ T-cell expansion in response to HCMV infection followed kinetics similar to that of CD8(+) T cells. Reduced CD45RA re-expression directly correlated with HCMV transmission to the fetus, thus providing an important prognostic parameter.

Role of prenatal diagnosis and counseling in the management of 735 pregnancies complicated by primary human cytomegalovirus infection: a 20-year experience

BACKGROUND

The burden of congenital human cytomegalovirus (HCMV) infection is well recognized. However, screening for maternal infection remains controversial in view of diagnostic challenges, counseling difficulties, and absence of medical treatment.

OBJECTIVE

To assess the role of prenatal diagnosis and counseling in the management of pregnancy complicated by primary HCMV infection.

STUDY DESIGN

Retrospective study aimed at investigating diagnostic features, options, and pregnancy outcome in 735 women with primary HCMV infection over a period of 20 years (1990-2009).

RESULTS

Overall, 25.6% women were found to be seronegative before the actual pregnancy. However, none were informed about HCMV infection and potential prevention strategies. Diagnosis of primary HCMV infection was achieved by seroconversion in 44.4% cases and by different combinations of virus-specific IgM, low IgG avidity, and DNAemia in 43.9% cases. Non-specific symptoms and/or haematological/biochemical alterations were recalled by 73.5% women. The onset of infection could be established, and counseling adjusted accordingly in >90% cases. The overall rate of vertical transmission was 37.1%, ranging from 5.6% for preconceptional infections to 64.1% for third trimester infections. Amniocentesis was chosen by 43.1% women, whereas pregnancy termination was requested by 15.6%.

CONCLUSIONS

Reference virology centers and ad hoc trained and experienced physicians are required for accurate diagnosis of primary infection in pregnancy and ensuing counseling. Prenatal diagnosis has a central role in the management of pregnancies complicated by primary HCMV infection. HCMV-seronegative women should receive adequate information.

Prognostic markers of symptomatic congenital human cytomegalovirus infection in fetal blood

OBJECTIVE

To identify fetal cord blood prognostic markers of symptomatic congenital human cytomegalovirus infection (HCMV).

DESIGN

Retrospective observational study.

SETTING

Fetal medicine unit in Milan and Medical virology unit in Pavia, Italy.

POPULATION

HCMV-infected and -uninfected fetuses of mothers with primary HCMV infection during the period 1995-2009.

METHODS

Overall, 94 blood samples from as many fetuses of 93 pregnant women experiencing primary HCMV infection were examined for multiple immunological, haematological and biochemical markers as well as virological markers. Congenital HCMV infection was diagnosed by detection of virus in amniotic fluid, and symptomatic/asymptomatic infections were determined by ultrasound scans, nuclear magnetic resonance imaging, histopathology or clinical examination at birth. Blood sample markers were retrospectively compared in symptomatic and asymptomatic fetuses with congenital infection.

MAIN OUTCOME MEASURES

A statistical analysis was performed to determine the value of each parameter in predicting outcome.

RESULTS

Univariate analysis showed that most nonviral and viral markers were significantly different in symptomatic (n = 16) compared with asymptomatic (n = 31) fetuses. Receiver operator characteristics analysis indicated that, with reference to an established cutoff for each marker, the best nonviral factors for differentiation of symptomatic from asymptomatic congenital infection were β(2) -microglobulin and platelet count, and the best virological markers were immunoglobulin M antibody and DNAaemia. β(2) -Microglobulin alone or the combination of these four markers reached the optimal diagnostic efficacy.

CONCLUSIONS

The determination of multiple markers in fetal blood, following virus detection in amniotic fluid samples, is predictive of perinatal outcome in fetuses with HCMV infection.

Guidelines on CMV congenital infection

Congenital cytomegalovirus (CMV) infection occurs in 0.6-0.7% of all newborns and is the most prevalent infection-related cause of congenital neurological handicap. Vertical transmission occurs in around 30% of cases, but the fetus is not always affected. Symptomatic newborns at birth have a much higher risk of suffering severe neurological sequelae. Detection of specific IgG and IgM and IgG avidity seem to be the most reliable tests to identify a primary infection but interpretation in a clinical context may be difficult. If a seroconversion is documented or a fetal infection is suspected by ultrasound markers, an amniocentesis should be performed to confirm a vertical transmission. In the absence of a confirmed fetal infection with fetal structural anomalies, a pregnancy termination should be discouraged. Fetal prognosis is mainly correlated to the presence of brain damage. Despite promising results with the use of antiviral drugs and CMV hyperimmune globulin (HIG), results have to be interpreted with caution. Pregnant women should not be systematically tested for CMV during pregnancy. Managing CMV screening should be restricted to pregnancies where a primary infection is suspected or among women at high risk. The magnitude of congenital CMV disease and the value of interventions to prevent its transmission or to decrease the sequelae need to be established before implementing public health interventions. In this paper, aspects of CMV infection in the pregnant woman and her infant are reviewed.

Cytomegalovirus-specific, high-avidity IgG with neutralizing activity in maternal circulation enriched in the fetal bloodstream

BACKGROUND

Cytomegalovirus (CMV) is the major cause of congenital infection and disease leading to permanent birth defects. In about 35-40% of pregnant women with primary CMV infection, virus crosses the placenta, resulting in the birth of congenitally infected babies. In contrast, this happens in only 1-3% of seropositive women with strong CMV-specific humoral immunity. Whether CMV reaches the fetus and disseminates depends on the level of high-avidity antibodies in the maternal circulation and the passive immunity of the fetus.

OBJECTIVES AND STUDY DESIGN

To identify CMV infection in uncomplicated deliveries based on detection of viral DNA in placental biopsy specimens at term. To quantify CMV-specific IgG avidity, neutralizing titer, IgG1 concentration, and characterize the immunoblot profiles for CMV proteins in paired samples of placental and cord blood sera.

RESULTS

In accord with earlier reports, CMV DNA was detected in 39% (11/28) of placentas with mean- to high-avidity CMV-specific IgG. In seropositive women, the concentration of antiviral antibodies, specifically IgG1, increased in the fetal bloodstream, and CMV neutralizing titers in maternal and fetal blood were comparable.

CONCLUSIONS

CMV-specific, high-avidity neutralizing antibodies from maternal circulation are transcytosed to the fetal bloodstream, contribute to suppression of viral replication in the placenta and could prevent congenital disease.

Measurement of the sensitivity of different commercial assays in the diagnosis of CMV infection in pregnancy

To evaluate the performance of different commercial assays for the detection of recent cytomegalovirus (CMV) in pregnancy, the sensitivity and specificity of assays for CMV-specific IgM antibodies were compared. Routine specimens from pregnant women were screened for CMV IgM using the Abbott AxSYM assay. Sera that were reactive according to AxSYM were further tested for IgM by other commercial assays. In selected IgM positive samples a CMV IgG avidity assay (Radim) and virus isolation from urine (shell vial) were also performed. The positivity rate for IgM anti-CMV by AxSYM was relatively high (140 out of 492, combining reactive and grayzone results). Only 26 of the 140 samples were positive for IgM according to Radim. The IgG avidity was low in 16 of the 43 samples tested, and the Radim and DiaSorin IgM assays were negative in 5 of them; 2 of the latter cases were also positive for viral isolation according to a shell vial method. There are differences in the sensitivity of the commercially available tests for CMV antibodies. CMV screening in pregnancy is performed as a first step by immunoassays and the choice of highly sensitive IgM test associated with further serological and virological methods could help to identify early primary infections.

Clinical predictive value of real-time PCR quantification of human cytomegalovirus DNA in amniotic fluid samples

The aim of this study was to evaluate the diagnostic reliability and prognostic significance of the quantification of cytomegalovirus (CMV) DNA in amniotic fluid (AF). We retrospectively reviewed the results for 282 amniotic fluid samples that had been tested for CMV by a quantitative real-time PCR. We observed three cases in which no CMV genomes were detected in the AF but in which the children were nevertheless congenitally infected. Hence, we conclude that a negative result by PCR for CMV in AF cannot rule out the possibility of congenital infection. No false-positive PCR results were observed. A correlation between the CMV viral load in AF and the fetal and neonatal outcomes could not be demonstrated in our study. Instead, a correlation was found between the CMV viral load and the gestational age at the time of amniocentesis.

Human cytomegalovirus-specific memory CD8+ and CD4+ T cell differentiation after primary infection

BACKGROUND

The development of human cytomegalovirus (HCMV)-specific T cell immunity after primary infection and its correlation with virus transmission to the fetus were investigated.

METHODS

The membrane phenotype (CCR7 and CD45RA expression) of and intracellular cytokine (interferon [IFN]-gamma and interleukin-2) production by HCMV-specific T cells (stimulated with HCMV-infected dendritic cells) were investigated in 21 immunocompetent pregnant women (12 transmitters and 9 nontransmitters) and in 5 nonpregnant subjects during the first year after infection.

RESULTS

IFN-gamma-producing CD4+ and CD8+ T cells were readily detected during the first month, and their levels did not significantly change with time. CCR7 expression was negligible during both the early and the late stage of infection. Among CCR7- cells, those reexpressing CD45RA progressively increased until they reached median levels of 33% (range, 7%-51%) and 51% (range, 22%-76%) for HCMV-specific CD4+ and CD8+ T cells, respectively, similar to those observed in subjects with remote infection. CD45RA reexpression correlated with HCMV disappearance from blood. The level of HCMV-specific CD45RA+ T cells during the first months after infection was significantly lower in mothers who were transmitters than in those who were nontransmitters.

CONCLUSIONS

After primary infection, circulating HCMV-specific effector T cells revert to the CD45RA+ phenotype, which appears to be associated with control of viremia and vertical transmission. Thus, these cells may represent long-lived true memory lymphocytes in the HCMV-specific pool.

Molecular epidemiology of primary human cytomegalovirus infection in pregnant women and their families

The source of human cytomegalovirus (HCMV) infection was investigated in 29 pregnant women with primary HCMV infection by comparing DNA sequences of UL146, UL144 and a portion of UL55 gene of HCMV strains circulating within each family. Thirteen families were identified in which the pregnant woman, the husband and/or a child were shedding HCMV. In three of these families, both the woman and the husband suffered from a concomitant primary HCMV infection. Phylogenetic analysis of UL146, UL144, and UL55 genes indicated that strains circulating within each family were identical, whereas strains from different families appeared to be distinct. However, identical UL146, UL144, and UL55 DNA sequences were observed sporadically among unrelated strains. A child rather than the husband was the virus source for the great majority of pregnant women. No association was observed between UL144 polymorphisms and intrauterine transmission.

Congenital cytomegalovirus infection following primary maternal infection in the third trimester

OBJECTIVE

To determine the effect of primary cytomegalovirus (CMV) infection in the third trimester on fetal outcome.

DESIGN

Observational study.

SETTING

Four perinatal departments in tertiary hospitals in Israel.

POPULATION

Twenty-eight women with primary CMV infection acquired after 25 weeks of gestation.

METHODS

Prenatal evaluation included amniocentesis and ultrasonographic examinations. Maternal infection was determined from seroconversion and presence of low avidity anti-CMV immunoglobulin G after 25 weeks of gestation. Fetal CMV infection was diagnosed from CMV isolated or CMV DNA amplified from the amniotic fluid. Neonatal infection was established from CMV presence in their urine or anti-CMV IgM was in their peripheral blood immediately after birth. All liveborn neonates underwent cerebral ultrasonography, hearing assessment, and psychomotor development evaluation. Infected neonates were followed up for a median of 36 months (range 6-36 months).

MAIN OUTCOME MEASURES

Intrauterine CMV infection and neonatal CMV disease throughout follow up.

RESULTS

Vertical transmission of CMV was documented in 21 (75%) of the 28 pregnancies. None of the 20 live infected newborn had symptomatic congenital infection. One pregnancy was terminated at 34 weeks following evidence of prenatal infection. Most of the patients (75%) had CMV serology test due to clinical signs of CMV disease.

CONCLUSIONS

Although CMV infection during the third trimester of pregnancy is highly transmissible, sequelae were not found among infected offspring.

New advances in the diagnosis of congenital cytomegalovirus infection

Although the diagnosis of congenital CMV infection is still complex, important goals have been achieved in recent years, among which are: the availability of more reliable IgM tests for screening pregnant women whose pre-pregnancy serological status for CMV is unknown, tests to determine the avidity index of anti-CMV IgG, allowing the diagnosis of a primary CMV infection and innovative and traditional virological tests to detect the virus in amniotic fluid. When a woman is found to be IgM-positive, further diagnostic evaluation focused on determining whether this is due to a primary infection should be carried out. Maternal primary infections that were difficult to determine until a few years ago unless documented by seroconversions can now be readily diagnosed from the presence of low/moderate avidity anti-CMV antibody which persists for approximately 18-20 weeks after primary infection. In mothers at risk of transmitting the virus prenatal diagnosis can be performed between 21 and 22 weeks of gestation, and the amniotic fluid represents the pathological material of choice to determine intrauterine virus transmission. At birth or in the first 2/3 weeks of life, it is essential to use appropriate tests for diagnosis of CMV congenital infection.

Detection of HCMV DNA in placenta, amniotic fluid and fetuses of seropositive women by nested PCR

Human cytomegalovirus (HCMV) is the most common viral cause of intrauterine infection throughout the world. Its distribution patterns in different clinical samples are poorly understood. This study was performed to determine the frequency of CMV DNA positivity in maternal/fetus sera, placentas and amniotic fluid, together with maternal/fetus serology. Clinical specimens were obtained from 92 pregnant women who delivered by cesarean section. 98% of women and their neonates were HCMV IgG positive and 5.4% of these mothers were IgM positive, while no IgM was detected in neonates of IgM positive mothers. Among the IgG positive mothers, IgM was detected in 3.3% of their fetuses. 5.4% and 3.3% of maternal and fetal sera were HCMV DNA positive, respectively. The three neonates who were positive for HCMV DNA in sera were also positive for HCMV IgM and the PCR of their amnions was positive (p < 0.0001). 9.8% of placenta samples and 4.3% of amniotic fluid specimens were positive for HCMV DNA while among these placenta samples, two amnions were PCR positive (p = 0.046). Our results showed that there is not always a correlation between placenta and amnion infections. This may be due to reactivation of HCMV leading to placenta infection, as all affected placentas do not pass infection to fetuses and amniotic fluids. Detection of HCMV DNA in amnion and fetus plasma and the existence of fetus IgM against HCMV can also occur without clinical symptoms.

Detection of cytomegalovirus in human placental cells by polymerase chain reaction

Human cytomegalovirus (HCMV) is the most common cause of viral intrauterine infection. Progress in rapid, specific, and dependable detection of HCMV has recently been achieved by the use of DNA hybridization techniques and other molecular methods. We examined 21 placentas after delivery for the presence of HCMV DNA by polymerase chain reaction (PCR). To test the reliability of the PCR for the detection of HCMV DNA in clinical specimens, two simple PCR assays and a real-time quantitative PCR were used. PCR analysis of villous and decidual cells showed that HCMV DNA was present in 16 placentas (76.2%). Transmission of HCMV infection to chorionic villi was confirmed in 11 organs (52.4%), and congenital infections in newborns were detected in 9 cases (42.8%). These results suggest that HCMV genome detection in placentas at later gestational ages is common. Our results demonstrated that detection of HCMV DNA in placental tissues by DNA amplification provides a specific and sensitive method for diagnosis of intrauterine HCMV infection.

Epidemiology, pathogenesis and prevention of congenital cytomegalovirus infection

Cytomegalovirus is the most common cause of congenital infection. Congenital cytomegalovirus infection can follow both primary and recurrent maternal infections. It is associated with a significant burden of disease and death. The determinants of mother-to-child transmission and the pathogenesis of symptomatic fetal infection remain poorly understood. For a long time, congenital cytomegalovirus infection has been a neglected disease. Recently, the Institute of Medicine has recognized that the development of a vaccine against congenital cytomegalovirus infection is a public health priority, which should stimulate research in this area. The development of antiviral therapies to prevent symptoms in infected newborns also represents an important area of research.

Use of serial maternal urine cytomegalovirus PCR to detect primary CMV infection in seronegative pregnant women

The aim of the study was to determine if serial maternal urine polymerase chain reaction (PCR) tests can detect primary CMV infection during pregnancy. This was a prospective study conducted from 1 January 1999 to 31 December 1999 in an antenatal clinic setting of a teaching hospital. The study group included women who were CMV IgG negative and aged <30 years or had a pre-school child. They were invited to self-collect urine samples monthly and send them to the laboratory by post. Cord bloods were tested for CMV IgG to detect seroconversion. An anxiety questionnaire was sent to all study participants. At first attendance, 1549 (42%) women were CMV IgG negative. Of the 696 eligible women, 609 (88%) participated in the urine PCR study. PCR was performed on 2263 urine samples (median of 4/pregnancy). Primary CMV infection was identified in one woman by urine PCR at 36 weeks (baby CMV negative). Cord blood samples were available from 152/609 infants (25%). Seroconversion was noted in only one woman. Replies to the questionnaire were received from 264/609 women (43%): 214 (81%) had little or no anxiety, and 220 (83%) felt reassured by their study participation. Serial urine PCR is a feasible method of detecting primary maternal CMV infection during pregnancy which has potential for evaluation in further studies.

Human cytomegalovirus proteins pp65 and immediate early protein 1 are common targets for CD8+ T cell responses in children with congenital or postnatal human cytomegalovirus infection

Recombinant modified vaccinia Ankara- and peptide-based IFN-gamma ELISPOT assays were used to detect and measure human CMV (HCMV)-specific CD8(+) T cell responses to the pp65 (UL83) and immediate early protein 1 (IE1; UL123) gene products in 16 HCMV-infected infants and children. Age at study ranged from birth to 2 years. HCMV-specific CD8(+) T cells were detected in 14 (88%) of 16 children at frequencies ranging from 60 to >2000 spots/million PBMC. Responses were detected as early as 1 day of age in infants with documented congenital infection. Nine children responded to both pp65 and IE1, whereas responses to pp65 or IE1 alone were detected in three and two children, respectively. Regardless of the specificity of initial responses, IE1-specific responses predominated by 1 year of age. Changes in HCMV epitopes targeted by the CD8(+) T cell responses were observed over time; epitopes commonly recognized by HLA-A2(+) adults with latent HCMV infection did not fully account for responses detected in early childhood. Finally, the detection of HCMV-specific CD8(+) T cell responses was temporally associated with a decrease in peripheral blood HCMV load. Taken altogether, these data demonstrate that the fetus and young infant can generate virus-specific CD8(+) T cell responses. Changes observed in the protein and epitope-specificity of HCMV-specific CD8(+) T cells over time are consistent with those observed after other primary viral infections. The temporal association between the detection of HCMV-specific CD8(+) T cell responses and the reduction in blood HCMV load supports the importance of CD8(+) T cells in controlling primary HCMV viremia.

Accuracy of the serological ELISA test compared with the polymerase chain reaction for the diagnosis of cytomegalovirus infection in pregnancy

CONTEXT

The most frequently used methods for detecting antibodies are the indirect immunofluorescence test and the enzymatic immunoassay (ELISA). The polymerase chain reaction is a molecular biology technique in which the production of large amounts of specific DNA fragments is induced from very low concentrations of complex substrates aloowing the detection of very low amounts of viral particles.

OBJECTIVE

To assess the accuracy of serological/ELISA tests in comparison with the polymerase chain reaction in maternal blood to diagnose cytomegalovirus infection.

DESIGN

A descriptive study was performed.

SETTING

High-risk outpatient clinic of Campinas University (Unicamp).

PARTICIPANTS

We selected 243 pregnant women. All of them had been indicated for blood sampling because of suspicions of cytomegalovirus infection and also because of other infections.

MAIN MEASUREMENTS

The group was tested for cytomegalovirus. Serological tests were run and compared to the polymerase chain reaction, which was considered to be the gold standard. Status analyses were done using Fisher's exact test, via the SAS software.

RESULTS

The previous cytomegalovirus infection rate was 94.6%. The main reasons for inclusion in the study were fetal nervous system malformation (25.5%), maternal toxoplasmosis (25.5%) and Rh isoimmunization (14.8%). Only two women were included because of positive serological immunoglobulin M test for cytomegalovirus. The sensitivity and specificity of the serological tests were 94% and 6% for immunoglobulin G.

CONCLUSION

Serological tests had lower sensitivity in comparison with the polymerase chain reaction test when diagnosing cytomegalovirus infection. The consequences of positive polymerase chain reaction and negative immunoglobulin M in women remain unknown.

Epstein-Barr virus-associated lymphoepithelioma-like carcinoma of the esophagus

Epstein-Barr virus (EBV)-associated lymphoepithelioma-like carcinoma (LELC) rarely occurs in the esophagus. We report a case of such tumor arising in the esophagus of a 64-year-old Taiwanese woman. No tumors were detected outside the esophagus including nasopharynx by thorough clinical studies. She underwent subtotal esophagectomy. Light microscopy disclosed a poorly differentiated carcinoma morphologically reminiscent of nasopharyngeal undifferentiated carcinoma (lymphoepithelioma). Immunohistochemical stain for latent membrane protein-1 showed positivity on the tumor cells. The infiltrating lymphocytes were chiefly composed of CD8-positive cytotoxic T cells. EBV DNA was demonstrated by both nested polymerase chain reaction (PCR) in the main tumor and metastatic lymph node, and localization in the tumor cells by in situ PCR in situ hybridization (ISH). However, the result of EBV-encoded small RNA-1 ISH was negative. Our case suggests that LELC of the esophagus may be associated with EBV in the endemic area. Due to its distinct histological features, the association with EBV, and possible prognostic implication, LELC of the esophagus should be precisely diagnosed and discerned from the usual poorly differentiated carcinoma.

Prenatal diagnosis of congenital human cytomegalovirus infection in amniotic fluid by nucleic acid sequence-based amplification assay

Nucleic acid sequence-based amplification assays for detection of human cytomegalovirus (HCMV) immediate-early and pp67 mRNA in 65 amniotic fluid samples tested for prenatal diagnosis of congenital HCMV infection showed sensitivity, specificity, and negative and positive predictive values >90%.

Genomes of the endothelial cell-tropic variant and the parental Toledo strain of human cytomegalovirus are highly divergent

The low-passage Toledo strain of human cytomegalovirus (HCMV) and fresh clinical HCMV isolates have been reported to share the capacity to propagate efficiently in endothelial cell cultures. In the laboratory, however, repeated attempts to adapt the Toledo strain to growth in endothelial cells have been unsuccessful. Southern blot analysis of the entire viral genome and restriction length polymorphism analysis of multiple genome regions amplified by PCR demonstrated that the reported endothelial cell-tropic viral variant of the Toledo strain and the parental Toledo strain are highly divergent. In fact, the restriction profile of the genome of the endothelial cell-tropic variant seems highly distinct from that of the parental strain. In conclusion, the degree of dissimilarity between the two genomes suggests that the endothelial cell-tropic variant of the Toledo strain could have originated from a recombination event.

Diagnosis and management of human cytomegalovirus infection in the mother, fetus, and newborn infant

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection and mental retardation. HCMV infection, while causing asymptomatic infections in most immunocompetent subjects, can be transmitted during pregnancy from the mother with primary (and also recurrent) infection to the fetus. Hence, careful diagnosis of primary infection is required in the pregnant woman based on the most sensitive serologic assays (immunoglobulin M [IgM] and IgG avidity assays) and conventional virologic and molecular procedures for virus detection in blood. Maternal prognostic markers of fetal infection are still under investigation. If primary infection is diagnosed in a timely manner, prenatal diagnosis can be offered, including the search for virus and virus components in fetal blood and amniotic fluid, with fetal prognostic markers of HCMV disease still to be defined. However, the final step for definite diagnosis of congenital HCMV infection is detection of virus in the blood or urine in the first 1 to 2 weeks of life. To date, treatment of congenital infection with antiviral drugs is only palliative both prior to and after birth, whereas the only efficacious preventive measure seems to be the development of a safe and immunogenic vaccine, including recombinant, subunit, DNA, and peptide-based vaccines now under investigation. The following controversial issues are discussed in the light of the most recent advances in the field: the actual perception of the problem; universal serologic screening before pregnancy; the impact of correct counseling on decision making by the couple involved; the role of prenatal diagnosis in ascertaining transmission of virus to the fetus; the impact of preconceptional and periconceptional infections on the prevalence of congenital infection; and the prevalence of congenitally infected babies born to mothers who were immune prior to pregnancy compared to the number born to mothers undergoing primary infection during pregnancy.

Diagnosis and management of human cytomegalovirus infection in the mother, fetus, and newborn infant

Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection and mental retardation. HCMV infection, while causing asymptomatic infections in most immunocompetent subjects, can be transmitted during pregnancy from the mother with primary (and also recurrent) infection to the fetus. Hence, careful diagnosis of primary infection is required in the pregnant woman based on the most sensitive serologic assays (immunoglobulin M [IgM] and IgG avidity assays) and conventional virologic and molecular procedures for virus detection in blood. Maternal prognostic markers of fetal infection are still under investigation. If primary infection is diagnosed in a timely manner, prenatal diagnosis can be offered, including the search for virus and virus components in fetal blood and amniotic fluid, with fetal prognostic markers of HCMV disease still to be defined. However, the final step for definite diagnosis of congenital HCMV infection is detection of virus in the blood or urine in the first 1 to 2 weeks of life. To date, treatment of congenital infection with antiviral drugs is only palliative both prior to and after birth, whereas the only efficacious preventive measure seems to be the development of a safe and immunogenic vaccine, including recombinant, subunit, DNA, and peptide-based vaccines now under investigation. The following controversial issues are discussed in the light of the most recent advances in the field: the actual perception of the problem; universal serologic screening before pregnancy; the impact of correct counseling on decision making by the couple involved; the role of prenatal diagnosis in ascertaining transmission of virus to the fetus; the impact of preconceptional and periconceptional infections on the prevalence of congenital infection; and the prevalence of congenitally infected babies born to mothers who were immune prior to pregnancy compared to the number born to mothers undergoing primary infection during pregnancy.

Prenatal diagnosis of congenital cytomegalovirus infection by detection of immunoglobulin M antibodies to the 70-kd heat shock protein in fetal serum

OBJECTIVE

Antibodies to the 70-kd heat shock protein were evaluated as biomarkers for cytomegalovirus infection.

STUDY DESIGN

Fetal sera that was obtained by cordocentesis at 22 to 25 weeks of gestation from 53 mothers with a confirmed primary cytomegalovirus infection and 28 mothers (control group) without cytomegalovirus infection who had been screened for Rh incompatibility, were assayed by enzyme-linked immunosorbent assay for immunoglobulin M and G anti-70-kd heat shock protein antibodies.

RESULTS

Eighteen of 53 fetuses (34.0%) from cytomegalovirus-positive mothers were infected, which was determined by culture or polymerase chain reaction. Anti-70-kd heat shock protein immunoglobulin M was detected in 17 of 18 sera (94.4%) from cytomegalovirus-infected fetuses, in 3 of 35 sera (8.6%) from uninfected fetuses, and in 0 of 28 sera from the control group (P <.0001). The level of antibody reactivity was correlated positively with fetal disease. Anti-70-kd heat shock protein immunoglobulin G was detected in sera from 52 of 53 fetuses (98.1%) from cytomegalovirus-infected mothers.

CONCLUSION

The anti-70-kd heat shock protein immunoglobulin M assay may be of value in the assessment of fetal cytomegalovirus infection in pregnant women with a primary cytomegalovirus infection.

Diagnosis and outcome of preconceptional and periconceptional primary human cytomegalovirus infections

Primary human cytomegalovirus (HCMV) infection occurring in pregnant women within 3 months before (preconceptional) or within 4 weeks after (periconceptional) the last menstrual period represents an as-yet-undefined risk to the fetus. One (9.1%) of 11 newborns born to 12 women with preconceptional infection was subclinically infected (1 aborted fetus was not examined for infection). Of 20 pregnancies in women with periconceptional infection, 7 were terminated before 12 weeks of gestation (aborted fetus was not examined), 1 was terminated at 23 weeks after prenatal diagnosis of congenital infection, and 12 continued to term. Of those 12, 3 resulted in newborns who were congenitally infected. Thus, in the periconceptional group, intrauterine transmission occurred in 4 (30.8%) of 13 pregnancies for which the virologic outcome was known. One newborn was symptomatic at birth, and disseminated HCMV infection was diagnosed in an aborted fetus. Periconceptional primary HCMV infection seems to bear a higher risk of unfavorable outcome than preconceptional infection, and counseling should be adjusted accordingly.

Detection of Epstein-Barr virus genome within thymic epithelial tumours in Taiwanese patients by nested PCR, PCR in situ hybridization, and RNA in situ hybridization

Epstein-Barr virus (EBV) is known to be associated with a variety of tumours, including Burkitt's lymphoma, nasopharyngeal carcinoma, and some carcinomas of other organs with similar lymphoepithelioma-like features. The association between EBV and thymic epithelial tumours is inconclusive, as reports in this regard are not entirely consistent and the methods employed are of different sensitivity and specificity. This study examined 78 thymomas and 21 thymic carcinomas in Taiwanese patients, to detect the viral genome at both DNA and RNA levels. The tissue blocks were first screened by nested polymerase chain reaction (PCR) targeting on the first tandem internal repeats. The positive cases were further submitted for viral localization by in situ PCR insitu hybridization (ISH) and Epstein-Barr-encoded RNA-1 (EBER-1) ISH. None of the thymomas showed a detectable EBV genome. Eight thymic carcinomas were positive for EBV by nested PCR, of which six displayed nuclear signals within the tumour cells by in situ PCR ISH and/or RNA ISH, one displayed signals within the lymphocytes, and one showed no discernible in situ signals. Most of them exhibited a lymphoepithelioma-like morphology. These results show that nested PCR is a sensitive method for screening the EBV genome in thymic epithelial tumours. In situ PCR ISH is reliable for localization of the virus, in addition to EBER-1 RNA ISH. Thymomas are not related to EBV, even in this endemic area. Thymic carcinomas, especially the lymphoepithelioma-like thymic carcinomas, are more often associated with the virus.

Human cytomegalovirus as a direct pathogen: correlation of multiorgan involvement and cell distribution with clinical and pathological findings in a case of congenital inclusion disease

The human cytomegalovirus (HCMV), a member of the Herpesviridae, is the most frequent cause of congenital virus infections and a major cause of morbidity and mortality in immunocompromised patients. Due to the lack of an appropriate animal model, insight into the pathogenesis of HCMV infections originates primarily from in situ examination of HCMV-infected tissues. Although in immunocompromised adults such tests are complicated frequently by the presence of additional misleading pathogens, the absence of additional pathogens renders congenital inclusion disease the most suitable access for investigation of pathogenetic aspects of HCMV infections. Immunohistochemical examination of tissue sections from a boy with fatal congenital inclusion disease was undertaken to detect the extent of multiorgan and cell involvement. Adrenal gland, bone marrow, diencephalon, heart, kidney, liver, lung, pancreas, placenta, small bowel and spleen were included in this study. Detection of virus antigens from different phases of viral replication revealed that all investigated organs were infected by HCMV. Simultaneous detection of cell type specific marker molecules showed that a variety of cell types stained positive for HCMV antigens including endothelial cells, epithelial cells, smooth muscle cells, mesenchymal cells, hepatocytes, monocytes/macrophages and granulocytes. The lung, the pancreas, the kidneys and the liver were the major target organs with a high number of HCMV infected cells. This correlated with multiorgan failure as the cause of death and strongly indicates direct pathogenetic effects of HCMV.

Congenital cytomegalovirus infection: review of the epidemiology and outcome

Cytomegalovirus (CMV) is one of the most common viral causes of congenital infection. A future decision to lower its incidence by vaccination will depend on epidemiological conditions within a country and on the safety of the vaccine to be used, because a life vaccine may cause latency and subsequent reactivation that still may harm the fetus. The aim was to review the epidemiological studies published so far, with respect to factors that affect the incidence of congenital CMV infection, and factors that may influence its outcome, such as preexisting maternal immunity. The study included the data of 19 studies that were retrieved from a MEDLINE search during the period 1977 to 1997. The incidence of congenital CMV infection varied between 0.15% and 2.0% and seemed to correlate with the level of preexisting immunity in the population. Although preexisting maternal immunity was reported to strongly reduce transmission, the severity of congenital CMV infection (symptoms at birth and or sequelae later in life) was not significantly greater after virus transmission due to a primary infection of the mother as compared with recurrence or reinfection. The data indicate that preexisting immunity of the mother does not significantly mitigate the outcome of congenital infection. Moreover, life vaccines may bear a serious risk when transmittable to the fetus.

TARGET AUDIENCE

Obstetricians and Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the natural course of a CMV infection, to list the potential sequelae of a congenital CMV infection, to outline potential strategies to prevent transmission of CMV, and to summarize the diagnostic work up of a patient with a potential CMV infection.

Cytomegalovirus infection: perinatal implications

Cytomegalovirus (CMV), a member of the herpes virus family, is the most common cause of congenital infection in humans, affecting 0.5-3% of all newborns worldwide. Congenital cytomegalovirus infection is the leading infectious cause of deafness, learning disabilities, and mental retardation in children. The high prevalence of cytomegalovirus in the general population, unpredictability of transmission, and asymptomatic nature of the disease in otherwise healthy women challenge prevention and treatment efforts.

[Viral infections and pregnancy: contribution of amniotic fluid and blood samples]

The main viral infections prenatally detected in fetuses are: cytomegalovirus, parvovirus B19, rubella virus and varicellazoster virus infections. Prenatal diagnosis is based on the direct detection of the virus by culture (CMV), of its antigens or of its genome, essentially by PCR. This direct detection can be done either on fetal blood or on amniotic fluid. Prenatal diagnosis can also be performed by detection of specific IgM in fetal blood (rubella). Non specific markers of viral infection can also help in diagnosis. At the present time, prenatal diagnosis is essentially based on the detection of the viral genome in amniotic fluid. In order to better appreciate the severity of fetal infections, some groups have tried to identify prognostic markers of these infections. The viral load as well as the level of specific IgM could play a role in certain infections (CMV).

Prenatal diagnosis of congenital cytomegalovirus infection in 189 pregnancies with known outcome

Prenatal diagnosis (PD) of fetal cytomegalovirus (CMV) infection was performed in 242 pregnancies, with known outcome in 189 cases. In 141/189 pregnancies, PD was carried out on account of suspicious maternal CMV serology up to gestational week (WG) 23, and in 48 cases on account of abnormal ultrasonic findings detected between WG 18 and 39. Chorionic villus samples (n = 6), amniotic fluid (AF, n = 176) and/or fetal blood specimens (n = 80) were investigated for detection of virus by cell culture, shell vial assay, PCR and/or CMV-specific IgM antibodies. Of 189 fetuses correctly evaluated by CMV detection either in fetal tissue following therapeutic abortion/stillbirth (n = 24) or in urine of neonates within the first 2 weeks of life (n = 33), 57 were congenitally infected. In women with proven or suspected primary infection, the intrauterine transmission rates were 20.6% (7/34) and 24.4% (10/41), respectively. Of the congenitally infected live-born infants, 57.6% (19/33) had symptoms of varying degree. The overall sensitivity of PD in the serologic and ultrasound risk groups was 89.5% (51/57). A sensitivity of 100% was achieved by combining detection of CMV-DNA and CMV-specific IgM in fetal blood or by combined testing of AF and fetal blood for CMV-DNA or IgM antibodies. There was no instance of intrauterine death following the invasive procedure. The predictive value of PD for fetal infection was 95.7% (132/138) for negative results and 100% (51/51) for positive results. Correct results for congenital CMV infection by testing AF samples can be expected with samples obtained after WG 21 and after a time interval of at least 6 weeks between first diagnosis of maternal infection and PD. In case of negative findings in AF or fetal blood and the absence of ultrasound abnormalities at WG 22-23, fetal infection and neonatal disease could be excluded with high confidence. Positive findings for CMV infection in AF and/or fetal blood in combination with CMV suspicious ultrasound abnormalities predicted a high risk of cytomegalic inclusion disease (CID). Furthermore, detection of specific IgM antibodies in fetal blood was significantly correlated with severe outcome for the fetus or the newborn (p = 0.0224). However, normal ultrasound of infected fetuses at WG 22-23 can neither completely exclude an abnormal ultrasound at a later WG and the birth of a severely damaged child nor the birth of neonates which are afflicted by single manifestations at birth or later and of the kind which are not detectable by currently available ultrasonographic techniques.