Prenatal diagnosis of intrauterine rubella

Prenatal diagnosis of congenital rubella infection in São Paulo

Objective: rubella during the early stages of pregnancy can lead to severe birth defects known as congenital rubella syndrome (CRS). Samples collected from pregnant women with symptoms and suspected of congenital rubella infection between 1996 and 2008 were analyzed. Methods: a total of 23 amniotic fluid samples, 16 fetal blood samples, 1 product of conception and 1 placenta were analyzed by serology and RT-PCR. Results: all patients presented positive serology for IgG / IgM antibodies to rubella virus. Among neonates, 16 were IgG-positive, 9 were IgM-positive and 4 were negative for both antibodies. Of the 25 samples analyzed in this study, 24 were positive by RT-PCR. Changes in ultrasound were found in 15 (60%) of 25 fetuses infected with rubella virus. Fetal death and miscarriage were reported in 10 (40%) of the 25 cases analyzed. The rubella virus was amplified by PCR in all fetuses with abnormal ultrasound compatible with rubella. Fetal death and abortion were reported in 10 of 25 cases analyzed. Conclusion: this study, based on primary maternal rubella infection definitely confirms the good sensitivity and specificity of RT-PCR using amniotic fluid and ultrasound. The results showed that molecular assays are important tools in the early diagnosis of rubella and congenital rubella syndrome.

Diagnostic value of reverse transcription-PCR of amniotic fluid for prenatal diagnosis of congenital rubella infection in pregnant women with confirmed primary rubella infection

The diagnostic value of RT-PCR of amniotic fluid (AF) for prenatal diagnosis of congenital rubella virus infection in 45 pregnant women with confirmed primary infection was assessed. Specificity of RT-PCR was 100% and sensitivity ranged between 83 and 95%.

L'infection rubéolique maternofœtale : apport de la biologie moléculaire

AIM OF THE STUDY

To assess the diagnostic value of RT-PCR on amniotic fluid (AF) for prenatal diagnosis of congenital rubella infection.

MATERIAL AND METHODS

RT-PCR on AF was compared to specific IgM antibody detection in foetuses and/or newborns in 45 pregnant women with confirmed primary infection.

RESULTS

specificity of RT-PCR was 100% and sensitivity ranged between 83 and 95%.

CONCLUSION

RT PCR may be considered as a valuable tool for prenatal diagnosis of foetal rubella infection.

Rubella

Maternal rubella is now rare in many developed countries that have rubella vaccination programmes. However, in many developing countries congenital rubella syndrome (CRS) remains a major cause of developmental anomalies, particularly blindness and deafness. WHO have provided recommendations for prevention of CRS, and, encouragingly, the number of countries introducing rubella vaccination programmes has risen. However, declining uptake rates due to concerns about the measles-mumps-rubella vaccine in the UK, and increasing numbers of cases in some European countries coupled with poor uptake rates might jeopardise this progress. Surveillance of postnatally and congenitally acquired infection is an essential component of CRS prevention since rubella is difficult to diagnose on clinical grounds alone. Laboratory differentiation of rubella from other rash-causing infections, such as measles, parvovirus B19, human herpesvirus 6, and enteroviruses in developed countries, and various endemic arboviruses is essential. Reverse transcriptase PCR and sequencing for diagnosis and molecular epidemiological investigation and detection of rubella-specific IgG and IgM salivary antibody responses in oral fluid are now available.

Prenatal diagnosis of congenital rubella infection in the second trimester of pregnancy

OBJECTIVES

This case report describes the clinical presentation, diagnosis and management of a case of acute rubella infection in the second trimester. The complex issues of prenatal diagnosis of a congenital rubella infection are discussed.

METHODS

A 30-year-old woman presented with a fine macular rash at 15 weeks' gestation. Laboratory testing included maternal rubella-specific IgG and IgM detection (booking blood and acute-phase sample) together with measurement of IgG avidity. Prenatal diagnosis at 19 weeks (amniocentesis) and 23 weeks (amniocentesis and fetal blood) was done using a reverse-transcriptase polymerase chain reaction to detect rubella-specific RNA. The fetal blood sample was also tested for rubella-specific IgM.

RESULTS

Maternal serological results confirmed an acute rubella infection at 15 weeks' gestation. Rubella-specific RNA and IgM were detected in the fetal blood taken at 23 weeks' gestation. However, no rubella RNA was detected in either of the amniotic fluid samples collected at 19 and 23 weeks.

CONCLUSION

In second-trimester rubella where risk of fetal damage is low, prenatal diagnosis can identify the rubella-infected fetus, allowing the parents to make a more informed decision about their options. The optimal sample for prenatal diagnosis is fetal blood as no rubella-specific RNA was detected in the amniotic fluid.

Clinical rubella reinfection during pregnancy in a previously vaccinated woman

We report a documented case of clinically apparent rubella reinfection during pregnancy with rubelliform rash and fever followed by lymphodenopathy at the 18th week of gestation, in a previously vaccinated woman with haemagglutination inhibition (HI) antibody titre of 1:32. The serological tests results (including neutralizing antibodies) demonstrated a significant rise in her rubella specific IgG level with strongly positive IgM reactivity. In addition, rubella-specific IgG antibody avidity testing displayed high avidity index (53-88%) typical of rubella reinfection. Umbilical cord blood, drawn by sonographic-guided cordocentesis at 24 weeks' gestation, was found to be negative for rubella-specific IgM antibody. The pregnancy was continued to term, and a healthy infant was born.

Bilateral deafness due to congenital CMV and not rubella reinfection

We report on an infant with bilateral deafness discovered at the age of 5 months caused by a retrospectively diagnosed primary maternal CMV infection after definitive exclusion of maternal rubella reinfection as a cause of fetal infection.

Diagnosis of fetal rubella infection with reverse transcription and nested polymerase chain reaction: a study of 34 cases diagnosed in fetuses

OBJECTIVE

Our purpose was to develop a reliable method for prenatal diagnosis of fetal rubella infection through the detection of viral ribonucleic acid extracted from the chorionic villi, amniotic fluid, or fetal blood in pregnant women.

STUDY DESIGN

Double amplification of rubella viral ribonucleic acid by nested polymerase chain reaction after reverse transcription was applied to samples from 34 women suspected of having rubella. The results were compared with those of serum antibody and levels of rubella virus-specific immunoglobulin M antibodies in fetal blood.

RESULTS

Viral ribonucleic acid was revealed in 8 of 34 cases (23.5%). In the remaining 26 cases, healthy babies were born in 24, 1 was electively aborted, and 1 died in the thirty-sixth week of pregnancy of unknown causes.

CONCLUSIONS

This method allowed very early detection of fetal rubella infection by sampling of chorionic villi and amniotic fluid compared with evaluation of the maternal symptoms and serum antibody levels. Fetal blood was also more useful for making a diagnosis up to the twentieth week of pregnancy than was measuring rubella virus-specific immunoglobulin M antibodies.

Use of PCR for prenatal and postnatal diagnosis of congenital rubella

A reverse transcription-nested PCR assay (RT-PCR) was evaluated for diagnosis of congenitally acquired rubella in utero and during infancy. RT-PCR was compared with virus isolation for retrospective detection of rubella virus in placental and fetal tissues obtained after termination of pregnancy following primary rubella or rubella virus reinfection. Concordant results were obtained for 85% of samples; rubella virus RNA was detected by RT-PCR alone in four samples, and rubella virus was detected by isolation alone in two samples. Samples were also obtained for prenatal diagnosis of congenital infection; rubella virus RNA was detected in three of seven chorionic villus samples and one of three amniotic fluid samples by RT-PCR, while rubella virus was isolated in only one chorionic villus sample. To demonstrate that the RNA extracted from chorionic villus samples contained amplifiable RNA, a nested RT-PCR was used to detect keratin mRNA. Rubella virus was detected in placenta in two cases in which the fetus was uninfected, and there was no evidence of rubella virus in the placenta from one case in which the fetus was infected. Thus, detection of rubella virus in chorionic villus samples by RT-PCR may not always correctly predict fetal rubella virus infection. RT-PCR was successfully used for the diagnosis of congenitally acquired rubella in infancy. Rubella virus RNA was detected in cyropreserved or formalin-fixed lens aspirates obtained from infants in India with serologically confirmed congenital rubella but not in samples from controls with inherited cataract.

PCR for detection of rubella virus RNA in clinical samples

A reverse transcription nested PCR (RT-PCR) assay for the detection of rubella virus RNA using primers from the E1 open reading frame was established. This assay was found to be sensitive (detecting approximately two synthetic RNA copies and RNA extracted from 0.1 50% tissue culture infective dose of rubella virus) and specific; five wild-type rubella strains and four vaccine strains were detected, and no nonspecific amplification of 16 other RNA viruses or RNAs from seven cell types occurred. Rubella virus RNA was detected in 12 pharyngeal swabs from patients with serologically confirmed rubella; these RT-PCR results were in complete agreement with virus isolation. Analysis of products of conception obtained after confirmed primary maternal rubella infection by RT-PCR gave 92% agreement (12 of 13 samples) with virus isolation. No false-positive results were obtained. The potential use of this assay for prenatal diagnosis of congenital rubella infection and for investigating aspects of the pathogenesis of chronic disease is discussed.

Reactivity of a recombinant rubella E1 antigen expressed in E. coli

The E1 nucleic acid sequence of rubella virus strain Judith (RJ) has been cloned into an E. coli expression vector LB03. The reactivity of the expressed unglycosylated antigen (E1J) was compared with its glycosylated counterpart in native virus (RJ) using rabbit and human sera. Rabbit antisera raised against RJ and E1J reacted differently with wild type, RJ (laboratory strain) and RA27/3 (vaccine virus) strains in a kinetic neutralisation test. Reciprocally, human post RA27/3 vaccination sera were also found to differ from post infection or post re-infection sera in their reactivity with RJ and E1J antigens. Our observations suggest that E1, in the conformation adopted in the RA27/3 virion may have unique antigenic properties.

Laboratory diagnosis of rubella: past, present and future

Fifty years ago in New South Wales the late Sir Norman Gregg [1] described congenital cataracts in 78 babies, 67 of whose mothers had had clinical rubella in early pregnancy; he concluded that the disease in the mother caused the abnormality in the baby. Gregg [1–3] and Swan [4, 5] and their colleagues reported that deafness, heart disease and microcephaly were also major components of the congenital rubella syndrome. The need to prevent this tragic outcome stimulated intensive work on laboratory diagnosis and vaccine development, leading to the isolation of rubella virus in 1962 and then to methods for antibody detection. These complementary advances established the two traditional pillars of virological diagnosis and opened the way to immunization, with the result that some countries are now on the verge of eliminating a disease which for over 100 years was regarded as no more than a mild and harmless exanthem of childhood.

Prenatal diagnosis of rubella infection by fetal blood sampling

Prenatal diagnosis of rubella infection was attempted at 21 to 23 weeks of gestation by measuring rubella-specific IgM by ELISA in blood obtained from 16 fetuses whose mothers had been confirmed rubella infection during pregnancy. Specific IgM was detected in 9 fetuses. In 1 case, the time of the appearance of the rash was 20 weeks of gestation and this pregnancy went to term resulting in a healthy baby without clinical evidence of congenital rubella. The remaining 8 patients had their pregnancies terminated, and fetal infection was confirmed by blood tests after the abortion. No specific IgM was detected in the 7 other fetuses. However, in 2 IgM fetal blood negative cases whose mothers had had the rash at 17 and 20 weeks of gestation, the neonates showed positive IgM findings, but were apparently healthy. The reasons for the false-negative findings are discussed.

Detection of rubella virus antigen by one-step time-resolved fluoroimmunoassay and by enzyme immunoassay

A one-step time-resolved fluoroimmunoassay (TR-FIA) and a conventional two-step enzyme immunoassay (EIA) for the detection of rubella virus antigen were developed. Two noncompetitive mouse monoclonal antibodies reactive with epitopes on the E1 polypeptide of rubella virus served as immunoreagents. One of the monoclones (7A6) was used for coating the solid phase, and the other (2C3) was labeled with either Europium chelate or with horseradish peroxidase. For TR-FIA, the specimen was incubated simultaneously with the label at 4 degrees C overnight. EIA required an overnight incubation with the specimen and after washing another 1 hr of incubation at 37 degrees C with the conjugate. The sensitivity of TR-FIA was 10 pg in an assay volume of 100 microliters, and the sensitivity of EIA was between 50 and 100 pg. Antigens could be detected by TR-FIA in supernatant of cultures of Vero cells 48 hr after inoculation with approximately 1 TCID50, while cytopathogenic effect (CPE) at that time was detected only in cultures inoculated with 10(5) TCID50 or more. Virus mixed with human amniotic fluid containing antirubella-specific IgG was detectable after an incubation at 37 degrees C for 5 days. The assays may find applications in prenatal diagnosis of intrauterine rubella infection, in early identification of viral antigens in cell culture and in monitoring production, concentration, and purification of rubella antigen for antibody assays.

Fetal infection after maternal reinfection with rubella: criteria for defining reinfection

Five cases of asymptomatic maternal reinfection with rubella are described that occurred in England and Wales during 1985-8 and resulted in intrauterine infection. The criteria for diagnosing reinfection are described. In four cases the rubella contact was with the woman's own children. Two women had therapeutic abortions, rubella virus being recovered from the products of conception, and three were delivered of infants with congenitally acquired disease. Though the risks associated with maternal reinfection with rubella are very small and being measured in a prospective study, it is hoped that the recently introduced augmented programme of rubella vaccination will reduce rubella in the community and therefore this small risk still further.

Congenital rubella infection after previous immunity of the mother

A newborn boy was admitted with a congenital rubella infection. Seven years previously his mother had been vaccinated against rubella; 3 years previously rubella immunity had been confirmed. Therefore, intrauterine transmission must have occurred after maternal reinfection during pregnancy. Prenatal diagnosis of rubella embryopathy with serological methods after subclinical maternal reinfection is nearly impossible.