Congenital cytomegalovirus infection: a collaborative study on epidemiological, clinical and laboratory findings

Neonatal and short-term outcome after late vertical transmission in congenital CMV-infected fetuses following primary first-trimester maternal seroconversion

OBJECTIVE

To document the course of neonatal and short-term outcomes in pregnancies after first trimester CMV (cytomegalovirus) seroconversion and negative amniotic fluid (AF) CMV PCR.

METHODS

We included 375 patients with a first-trimester CMV seroconversion and amniocentesis at ≥21 weeks. Termination of pregnancy (TOP) was offered in case antenatally severe CMV-related fetopathy was documented either by ultrasound or by MRI. AF CMV PCR-negative fetuses underwent a PCR CMV on neonatal urine (NU). Perinatal and short-term infant outcomes were investigated by a questionnaire, sent to parents.

RESULTS

AF CMV PCR was positive in 118/375 cases (31.4%). TOP was performed in 46/118 (38.9%) and fetal demise occurred twice. Questionnaires were sent to 327 patients with an overall response rate of 77%. Three groups were considered: Group 1: the early infected group (AF CMV PCR positive; N=62), group 2: the late infected group (AF CMV PCR negative, NU CMV PCR positive; N=7) and group 3: the control group (AF+NU CMV PCR negative; N=160). Compared with group 3, group 1 was more frequently symptomatic at birth (6.2% vs 19.4%; p=0.006). In short-term follow-up, hearing impairment (23.5%; p<0.001), mild motor deficit - defined as abnormal early motor development or the need for physiotherapy in later life (21.6%; p=0.005) - and subnormal vision (15.7%; p=0.02) were significantly more frequent. Compared with group 3, group 2 showed more often jaundice (57.1%; p=0.04) and petechiae (28.6%; p=0.04) at birth, but other short-term symptoms were lacking.

CONCLUSION

Although neonates may screen positive on urine for CMV after an AF CMV negative PCR, they show rarely and only mild sequelae in early life.

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.

Review of cytomegalovirus shedding in bodily fluids and relevance to congenital cytomegalovirus infection

Congenital cytomegalovirus (CMV) infections are a leading cause of sensorineural hearing loss (SNHL) and neurological impairment. Congenital transmission of CMV can occur with maternal primary infection, reactivation, or reinfection during pregnancy. We reviewed studies of CMV shedding in bodily fluids (defined as CMV detected by culture or CMV DNA detected by polymerase chain reaction). Following diagnosis at birth, children with congenital CMV infection exhibited the highest prevalences of CMV shedding (median = 80%, number of sample population prevalences [N] = 6) and duration of shedding, with a steep decline by age five. Healthy children attending day care shed more frequently (median = 23%, N = 24) than healthy children not attending day care (median = 12%, N = 11). Peak shedding prevalences in children occurred at 1-2 years of age, confirming that young children are the key transmission risk for pregnant women. CMV shedding among children was more prevalent in urine specimens than in oral secretions (median prevalence difference = 11.5%, N = 12). Adults with risk factors such as STD clinic attendance had higher shedding prevalences (median = 22%, N = 20) than adults without risk factors (median = 7%, N = 44). In adults with risk factors, CMV was shed more frequently in urine; in adults without risk factors genital shedding was most common. The prevalence of CMV shedding in nine sample populations of pregnant women increased with advancing gestation. In seven sample populations of children with congenital CMV infection, higher viral load at birth was consistently associated with an elevated risk of SNHL. Higher CMV viral load at birth also consistently correlated with the presence of symptoms of congenital CMV at birth. Published 2011. This article is a US Government work and is in the public domain in the USA.

Review and meta-analysis of the epidemiology of congenital cytomegalovirus (CMV) infection

We reviewed studies that reported results of systematic cytomegalovirus (CMV) screening on fetuses and/or live-born infants. The overall birth prevalence of congenital CMV infection was 0.64%, but varied considerably among different study populations. About 11% of live-born infants with congenital CMV infection were symptomatic, but the inter-study differences in definitions of symptomatic cases limit the interpretation of these data. Non-white race, low socioeconomic status (SES), premature birth, and neonatal intensive care unit admittance were risk factors for congenital CMV infection. Birth prevalence increased with maternal CMV seroprevalence. Maternal seroprevalence accounted for 29% of the variance in birth prevalence between study populations. Maternal seroprevalence and birth prevalence were both higher in study populations that were ascertained at birth rather than in the prenatal period. Thus, timing of ascertainment should be considered when interpreting birth prevalence estimates. Birth prevalence was inversely correlated with mean maternal age, but this relationship was not significant when controlling for maternal seroprevalence. The rate of transmission to infants born to mothers who had a primary infection or a recurrent infection during pregnancy was 32% and 1.4%, respectively. Possible maternal primary infections (i.e. seropositive mother with CMV IgM) resulted in congenital infections about 20% of the time, but are likely to represent a mixture of primary and recurrent infections. In summary, CMV is a common congenital infection worldwide that can lead to permanent disabilities. There is an urgent need for interventions that can reduce the substantial burden of this often overlooked disease.

The incidence of congenital cytomegalovirus infections in The Netherlands

Cytomegalovirus (CMV) is one of the most common causes of congenital infection without an effective treatment or an effective vaccine available to date. The emphasis has to be on preventive strategies, which rely on the epidemiological situation. The incidence of congenital CMV infections, however, is not known for The Netherlands. Therefore, a prospective virological study was carried out in a population of 7,524 pregnant women and 7,793 newborns. CMV-specific IgG antibodies were determined in cord blood by ELISA. When CMV antibodies were present, a CMV specific PCR was performed on the throat swab. A positive PCR was confirmed by urine culture. In addition, the seroepidemiology for CMV was investigated in the metropolitan region (Amsterdam and Rotterdam) which has a different ethnic composition. Congenital CMV infection was found in 7 infants (0.9 per 1,000). None had symptoms at birth or during 24 month follow-up. Carriage or CMV was 41%, with a variation between 35% and 100% depending on ethnicity. The ethnic composition in the south-eastern region was different from that in large cities, but similar to that in the rest of the country. The incidence of congenital CMV infections in The Netherlands is the lowest described to date, which does not justify special preventive policies.

Congenital cytomegalovirus infection after recurrent infection: case reports and review of the literature

Cytomegalovirus (CMV) is one of the most common causes of congenital infections in developed countries with reported incidences varying between 0.15% and 2.0%. The effects of congenital CMV infection may vary from a congenital syndrome to an asymptomatic course. Infants that are asymptomatic at birth may still present handicaps at a later age. It is generally accepted that symptoms of congenitally infected children are more severe after primary infection than after recurrent infection. In this article, we present two case reports which demonstrate that the outcome of recurrent maternal CMV infection may be severe. In the first case, early pregnancy serology showed positive IgG and IgM, but negative IgA, whereas at the time of diagnosed fetal death, 5 weeks later, there was only positive IgG. The second case showed positive IgG and negative IgM and IgA both in early pregnancy and after delivery. Since in both cases CMV was isolated from several organs, these findings are compatible with recurrent rather than primary CMV infection. In the reported patients, fetal death and necrotising enterocolitis occurred after a congenital CMV infection, with mothers having pre-existing immunity to CMV. In conclusion, these case reports and review of the literature emphasise that the outcome of recurrent maternal CMV infection may be severe and that congenital CMV infection should be considered in cases of pregnancy loss and necrotising enterocolitis with recurrent maternal CMV infection.

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.

Hematological manifestations of congenital cytomegalovirus infection

Nine infants suffering from congenital cytomegalovirus infection were studied for clinical features with special reference to hematological manifestations. The mean age of appearance of first clinical symptom of disease was 14 days and mean age at presentation was 58 days. Significant pallor, thrombocytopenia and evidence of hemolysis were present in 8 (89%), 4 (44%) and 4 (44%) patients respectively out of three bone marrow examination performed, paucity of erythroid and megakaryocytic cells were seen in two. The other clinical features included hepatomegaly in a (100%) splenomegaly in 6 (66%) each, petachial rash in 5 (55%), Hepatitis in 4 (44%) optic atrophy and corneal opacities in one patient each. Two patients died. Remaining patients showed symptomatic improvement without specific therapy.

Prospective study on maternal, intrauterine, and perinatal infections with cytomegalovirus in Japan during 1976-1990

Since 1976, sera obtained serially from 10,218 pregnant women during the first, second, and third trimesters of gestation and cord sera were tested for CMV complement-fixing (CF) and immunofluorescent (IF) antibodies. CMV IgG-IF antibody was positive in 9,735/10,218 (95%) in the first trimester, and a significant rise of CF antibodies during pregnancy was found in 70/9,206 (0.76%) of the seropositive group and in 5/438 (1.14%) of the seronegative group. IgM antibody was found in 6/9,206 (0.06%) of seropositive women during the first trimester and in 7/70 (10.0%) of seropositive mothers with CF antibody rise and in 4/5 of seroconverted mothers of the seronegative group, suggesting that the incidence of primary infection with CMV during pregnancy was approximately 1% of susceptible women. All the mothers with immune response had infants with neither viruria nor IgM antibody in the cord blood, whereas seropositive mothers without an immune response had infants with viruria (7/1,826; 0.4%) or with IgM antibody in the cord blood (6/9,136; 0.06%). None of these 13 babies, shedding CMV or with IgM IF antibody, had physical or mental retardation. CMV IgG-IF antibody was present in almost 80% of infants between 7 and 12 months of age in 1988, suggesting that perinatal or postnatal CMV infection may occur in infants born to seropositive mothers in 70-80% of pregnancies.

Prenatal diagnosis of fetal cytomegalovirus infection

Twelve fetuses were evaluated with a combination of ultrasonography, amniocentesis, and blood sampling for possible cytomegalovirus infection. In seven the mother had a documented primary cytomegalovirus infection. All seven women had normal ultrasonographic findings and one fetus was found to be infected. In the other five cases fetal cytomegalovirus infection was diagnosed in association with abnormal ultrasonographic findings. There was no history of maternal infection in the latter group. All positive and negative diagnoses were confirmed and none of the six infected fetuses survived. In this series, the most reliable parameters of infection were the isolation of the virus from amniotic fluid and elevations of total immunoglobulin M and gamma-glutamyl transpeptidase in fetal blood. In the majority of infected fetuses cytomegalovirus-specific immunoglobulin M was not detected in blood. Prenatal diagnosis of fetal cytomegalovirus infection is possible with a combination of amniocentesis and fetal blood sampling.

Progressive hearing loss in children with congenital cytomegalovirus

Case studies of five children with congenital cytomegalovirus (CMV) who were referred for audiological evaluation are presented. Significant deterioration of hearing was noted in all cases within the first 4 years of life. It is essential that neonates with congenital CMV be referred for hearing assessment and that the child's hearing be monitored on a long-term basis. Early intervention is vital for the speech and language development of the hearing-impaired child.

Infant mortality, microglial nodules and parotid CMV-type inclusions

Nine hundred and fifty-one paediatric autopsies showed 24 cases in which the parotid contained cytomegalovirus-(CMV-) type inclusions. Parotid inclusions were found only during the first two years after birth. Of those with parotid inclusions, 15 showed microglial nodules in the brainstem and/or cerebellum. All the infants with microglial nodules were less than 6 months old. Only four infants without parotid inclusions showed microglial nodules. In just over half of the cases with parotid inclusions and microglial nodules death had been recorded as cases of sudden infant death syndrome. Whether there was any connection between the cause of death and microglial nodules remains uncertain as the microglial nodules were usually sparse and widely distributed. Some theories are proposed in this regard and in connection with those dying with parotid inclusions in the absence of microglial nodules. Until the question is finally resolved it may be prudent to view separately all cases of unexplained sudden death in infancy with evidence of CMV infection.

Epidemiologic patterns in childhood hearing loss: a review

In an attempt to clarify international epidemiologic trends, a review of the published literature pertaining to childhood hearing loss is presented. Inconsistencies of methodology and classification, which complicate the interpretation of data and make difficult the quantification of the influence of genuine population differences, are discussed. Selective review of the literature allows certain crude statements to be made regarding childhood hearing loss. In developed countries, serous otitis media is the most common cause of hearing loss in children, affecting up to two thirds of preschool children. In addition, 1.0-2.0/1000 children have bilateral SNHL of at least 50 dB. In underdeveloped countries, suppurative middle ear disease is common and is still frequently associated with either an intratemporal or intracranial complication. SNHL appears to occur almost twice as often as in developed countries, with a greater proportion being of infectious etiology. In specific populations, the Inuits, Amerindians and Aboriginals, acute and chronic suppurative otitis media are almost endemic, yet both cholesteatoma and serous otitis media are uncommon.

Congenital cytomegalovirus infection: a cause of sensorineural hearing loss

Prospective studies have suggested that about 108 children with congenital cytomegalovirus (CMV) infection and bilateral sensorineural hearing loss are born each year in England and Wales; this represents about 12% of all children with congenital sensorineural hearing loss. Over a nine year period 1644 children aged between 6 months and 4 years who were attending the Nuffield Hearing and Speech Centre were screened for CMV infection. The prevalence of CMV in the urine of children with sensorineural hearing loss but no immediate family history of deafness was nearly twice that (13%) found in other children with impaired hearing and those with normal hearing (7%). These findings indicate the importance of CMV as a cause of hearing loss.

Early acquisition of cytomegalovirus infection

Two hundred and fifty three infants were screened for cytomegalovirus (CMV) in the urine at birth and were followed up at regular intervals for one year. Twelve per cent (of 249) were excreting virus at 3 months, and 20% (of 234) at 12 months. In all cases infection was subclinical. The major factors determining risk of acquiring infection were the mother's serological state and whether the infant was breast fed. There was no association with social class, mother's age, or whether the child had been in a special care baby unit or a postnatal ward. By one year 33% (of 123) of infants of seropositive mothers had acquired CMV infection compared with 4% (of 123) born to seronegative mothers. Twenty per cent (17) of seropositive women who breast fed had virus isolated from their breast milk on at least one occasion, and 76% (13) of their infants became infected. In four mother-infant pairs comparison of CMV isolates from the mother's milk and the child's urine was made by restriction endonuclease digestion; in each pair infection had apparently occurred with the same strain of virus. All 13 infected infants followed up for three years were still shedding virus. Infection with CMV is common in infancy, and virus shedding persists for years. Congenital infection cannot be distinguished from acquired infection unless the presence of CMV in the urine is identified within three or four weeks after birth, even when clinical problems suggestive of congenital infection are present.

Cytomegalovirus infections: occupational risk for health professionals

Health care personnel are becoming increasingly aware of potential hazards associated with caring for patients with contagious diseases. The cytomegalovirus is of special concern, because infection with this virus in a pregnant female employee could be associated with significant neurologic injury in her fetus. Nosocomial transmission from patient to health care worker has not been documented. A review of cytomegalovirus excretion in hospitalized patients and prospective evaluations of primary infection in hospital personnel do not support frequent occurrence of cytomegalovirus infection despite ample opportunity for exposure. Adherence to proper isolation techniques should be adequate to prevent nosocomial transmission of the cytomegalovirus.

Congenital cytomegalovirus infection: predisposing maternal factors

In a prospective study of cytomegalovirus (CMV) infection in pregnancy 69 congenitally infected infants were identified. The age, race, marital status, social class, and parity of the mothers of congenital CMV infants were compared with those of the screened population of women with non-infected infants. These factors were all individually strongly associated with the prevalence of congenital CMV. However, once age, marital status, and race were accounted for, neither social class nor parity had any additional effect. The overall congenital CMV rate was 3 per 1000 livebirths, ranging from 25/1000 for single black women under 20 to 1.6/1000 in married or cohabitating white women over 25.

Sudden infant death and cytomegalovirus inclusion disease

Four infants, apparently thriving and without clinical evidence of disease, died suddenly at ages ranging from 2 to 6 months. Inclusions bearing cells pathognomonic of cytomegalovirus infection were shown microscopically in a small number of extraneural organs. In view of the lack of associated tissue destruction on microscopy and the apparent well being of the infants before death whether the function of these organs had been impaired to any important degree was questionable: such limited disease, consequently, could not have contributed substantially to the cause of death. The brainstem, on the other hand, consistently showed small numbers of glial nodules. Damage to strategically located neurones associated potentially with the organisation of vital function was a possible basis of sudden death. Alternatively, the small number of glial nodules may have represented a residue of previous more severe brainstem disease, which had possibly started while the baby was in the uterus.

Detection of cytomegalovirus antigen and antibodies in the urine of small infants and children

The diagnostic efficacy of an enzyme immune assay to detect cytomegalovirus (CMV) antigen in the urine of infected infants and children was determined, and the effect that CMV-specific antibodies present in the urine have on the sensitivity of the test was ascertained. The antigen was detected in 84.4% of the CMV-culture-positive samples, while CMV-specific IgA was detected in 24% of CMV-culture-positive specimens. The absence of CMV-specific IgA correlated with detection of CMV antigen in the CMV-culture-positive urine specimens (p less than 0.05).

Inhibition of human cytomegalovirus by combined acyclovir and vidarabine

The inhibition of human cytomegalovirus (HCMV) isolates by acyclovir (ACV) and vidarabine (ara-A) was assessed by using an infectious-center plaque-reduction assay. When fixed concentrations of 4.5 micrograms of ACV and 250 ng of ara-A per ml were compared singly and in combination, the viral inhibition resulting from the ACV-ara-A combination was synergistic for three of four HCMV clinical isolates studied and additive for one HCMV isolate. An additional four HCMV strains obtained at postmortem examination from the lungs of bone marrow transplant patients were assessed for sensitivity to ACV-ara-A by using the dose required for 50% viral inhibition (ID50) as the endpoint. The mean ID50 of ACV for the four HCMV isolates was 12.3 micrograms/ml, whereas the mean ID50 of ara-A was 3.4 micrograms/ml. When 1 microgram of ara-A per ml (which yielded a mean plaque reduction of 23.6%) was combined with ACV, a mean of 5.2 micrograms of ACV per ml was required for 50% viral inhibition. The sum of the fractional inhibitory concentrations for each of the four HCMV isolates was less than 1, indicating synergy by the ACV-ara-A combination. Although DNA synthesis in growing human embryonic lung fibroblast (HEL) cells, as determined by [3H]thymidine incorporation, was diminished to 61% of that in untreated control cells when 22.5 micrograms of ACV and 1 microgram of ara-A per ml were used, there was no additive inhibition of DNA synthesis when the two-drug combination was used. HEL cell growth remained at 97% of control cell growth at 72 h when concentrations as high as 45 micrograms of ACV combined with 1 microgram of ara-A per ml were used.

Congenital cytomegalovirus infection

Clinical details of 50 infants with congenital cytomegalovirus infection identified in a prospective study are reported. The mean birthweight, gestational age, and head circumference of children with congenital cytomegalovirus infection were not significantly different from those of controls. Three (6%) had symptoms at birth--two neurological and one pneumonitis. In the first four months of life transient hepatosplenomegaly occurred in two infected children and six suffered interstitial pneumonitis. Three congenitally infected children have major neurological handicaps including spastic quadriplegia, microcephaly, and psychomotor delay, and five (10%), including the one with quadriplegia, have sensorineural deafness which is bilateral in three (6%). Estimates based on these findings suggest that the impact of congenital cytomegalovirus infection is comparable to that of congenital rubella in the era before vaccination. Of the 42 children where the nature of maternal infection was classifiable, congenital infection followed primary maternal infection in 32 (76%) and recurrent infection in 10 (24%). Neurological defects followed exposure to primary maternal infection in all three trimesters of pregnancy and also recurrent maternal infection.

The consequences of primary cytomegalovirus infection in pregnancy

Altogether 54 children exposed prenatally to maternal cytomegalovirus (CMV) infection were followed up in a prospective study. Nine had congenital infection with CMV and 37 escaped congenital infection; in 8 congenital CMV could not be confirmed. The birthweight of children with congenital CMV was significantly lower than that of both controls and those who escaped congenital infection. Intrauterine infection was not clinically suspected in any of the children with congenital CMV, although two had head circumferences less than the third centile. Subsequently one child with congenital CMV developed marked psychomotor retardation, and one, in whom congenital CMV was not confirmed, showed mild developmental delay. Speech and language ability was significantly impaired in children with congenital CMV compared with controls and those who escaped congenital infection, suggesting that subtle damage may have occurred. The incidence of intrauterine transmission of CMV after exposure to infection in the first trimester was 20% and in the third trimester 40%, but no congenital infections resulted from exposure in the second trimester. The severity of congenital infection was not related to the time of exposure in utero. Our findings suggest that the risk to an individual fetus from maternal infection in early gestation is so low that termination of pregnancy cannot be recommended; screening of women for primary CMV infection in pregnancy seems therefore to have limited value.

Cytomegalovirus infection in pregnancy: preliminary findings from a prospective study

8278 (56%) of 14 789 pregnant women who were screened for cytomegalovirus (CMV) antibodies at their first antenatal visit were seropositive. 42 (3 per 1000) infants screened were congenitally infected. 3 (7%) have serious handicaps, 14 (33%) have minor or transient problems, and 25 (60%) have so far had no problems. In 26 of the 42 mothers with infected infants CMV antibodies were present in the first antenatal blood sample. 28 (67%) of the infected infants were born to mothers who had experienced a primary infection in pregnancy and 7 (17%) to mothers who had experienced recurrent infection. In the remaining 7 (17%) it was not possible to determine the type of maternal infection. One handicapped infant was born after a probable recurrent CMV infection during pregnancy. These preliminary findings suggest that routine screening of pregnant women to detect evidence of primary CMV infection is not helpful.

The prevention of hearing loss

Hearing loss can affect up to 20% of the adult population and prevalence increases with age. However, hearing loss in childhood may have the most profound effects because of the block to the development of communication skills. Prevention of hearing loss is of major importance as treatment is often unsatisfactory. Causes are numerous, and may be multifactorial in an individual. Important causes include trauma, including noise and air pressure changes; genetic hearing loss; infection, including rubella; drug damage, metabolic and neoplasia.

Avian reovirus polypeptides: analysis of intracellular virus-specified products, virions, top component, and cores

Avian reovirus-specified polypeptides can be separated into three size classes: large (lambda), medium (mu), and small (sigma), similar to those of the mammalian reoviruses. A nomenclature has been proposed to indicate the individual polypeptides within each size class by progressive alphabetical subscripts. Three lambda polypeptides (lambda(A), lambda(B), and lambda(C)) are found in infectious viral particles and have molecular weights of 145,000, 130,000, and 115,000, respectively. All are present in core preparations, and two (lambda(A) and lambda(B)) appear to be exposed at the surface of the virion. Two mu polypeptides can be distinguished in purified virus (mu(A), 72,000 daltons; mu(B), 70,000 daltons), and another is occasionally evident by immunoprecipitation from infected-cell extracts (mu(NS)). mu(B) represents the major outer capsid protein and is structurally homologous to mu(1C) of the mammalian reoviruses. No additional mu proteins can be detected, and there is no evidence for a product-precursor relationship among these proteins. Three major sigma proteins are evident in viral particles. sigma(C) has the lowest molecular weight, is part of the outer capsid of the virion, and appears homologous to the mammalian sigma(1) protein. Interestingly, it demonstrates the greatest polymorphism of all the polypeptides among the different avian reoviruses examined. sigma(B) (36,000 daltons) is a major constituent of the outer capsid and, like sigma(C), is exposed to the surface of the virion. sigma(A) (39,000 daltons) appears to be an internal protein. An additional polypeptide band in the sigma class having an apparent molecular weight of 34,000 to 35,000 can be seen under three different conditions: (i) in some S1133 reovirus preparations, particularly after prolonged storage, a new band (sigma(B')) appears with a reduction in intensity of sigma(B), suggesting that sigma(B') is a degradation product of sigma(B); (ii) in polypeptides immunoprecipitated from infected-cell extracts, a major band (sigma(NS)) is apparent migrating just ahead of sigma(B); (iii) in top component preparations from all avian reoviruses examined, a band (sigma(TC)) with mobility identical to that of sigma(NS) represents a major constitutent and appears to be incorporated within the particle itself. The relationship among these three bands is not currently known. Avian reovirus polypeptides are thus in general similar to those found in mammalian reoviruses, but differences do exist which may be important for understanding viral structure and assembly.

Neurological and electroencephalographic abnormalities after febrile seizures. Possible association with cytomegalovirus

In order to assess the possible association of cytomegalovirus (CMV) with cerebral damage, 65 children aged between 2 and 10 years were tested for CMV isolation and antibody status. All of them had previously presented one or more episodes of febrile convulsions. At the time of our study, they were grouped according to their clinical features and electroencephalogram (EEG). 21 had typical and/or atypical absence attacks with 3 c/s spike-wave EEG (primary generalized epilepsy), 21 presented febrile seizures and spontaneous fits with focal EEG abnormalities, 23 had no seizures and a normal EEG. We performed the same investigation in 41 healthy children. The study showed a similar isolation rate of CMV in healthy subjects and in patients without neurological and EEG alterations, while a significantly higher isolation rate was observed in the groups with neurological and EEG abnormalities. As for serology, no significant difference was observed between the four groups, although the positivity rate of the healthy children was lower than in the other three groups. The study suggests a possible association of CMV with neurological and EEG abnormalities after febrile seizures.

A prospective study of primary cytomegalovirus infection in pregnant women

During a four year study, sera were obtained from 5575 women attending for antenatal care and 3188 (57.2 per cent) were shown to possess complement fixing antibodies to cytomegalovirus (CMV). A total of 1608 seronegative women were followed to term and 14 (0.87 per cent) primary CMV infections occurred in either the second or third trimester. Transplacental spread of CMV occurred in 3 out of 12 (25 per cent) of the 14 babies born to infected mothers. All 14 babies were apparently normal at birth but short term clinical follow-up has already revealed that one child has impaired hearing whilst another is microcephalic. The women were also monitored serologically throughout pregnancy for evidence of rubella infections. Only 12 infections were detected and 7 of these occurred during the large rubella epidemic of 1978. Of the 10 pregnancies which were allowed to proceed to term, transplacental spread of rubella virus occurred in 1 out of 7 (14 per cent). During this study period, CMV infections occurred as frequently as did rubella infections. We therefore conclude that, apart from those years when extensive epidemics occur, many more pregnant women are infected with CMV than with rubella virus.

Herpesviruses

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