Calculation of the frequency of congenital rubella syndrome in Poland

The annual number and incidence of congenital rubella syndrome (CRS) in Poland was evaluated by means of a methematical model and on the basis of serological studies. In its principles this model describes the infectious kinetics of rubella by the formula y = 1--e-at, where "y" is the rate of immune persons, "a" is a parameter representing the transfer of susceptibles to immunes and "t" is age. The calculated incidence of congenital rubella syndrome resulted in average values of 0.15 to 0.38%, i.e. 15 to 38 CRS cases among 100,000 children born to mothers primarily infected by rubella virus during the first trimester of pregnancy.     

Immunoglobulin G avidity in the serodiagnosis of congenital rubella syndrome

The avidity of specific IgG was investigated in three infants with serologically verified congenital rubella infection. Two sera were taken from each infant: the first soon after birth and the second at the age of 23 to 31 months. Avidity of specific IgG was measured by a protein-denaturing enzyme immunoassay using urea as the elution factor, and avidity then determined by the end-point ratio (derived from antibody titration) and the avidity index methods. Rubella-specific IgM was present in the first sera of all patients, but not in the second sera. However, low avidity of specific IgG persisted in two children until age 23 to 31 months, as determined by the end-point ratio method. These data are in agreement with the findings of previous studies of avidity in congenital rubella, and show the usefulness of the protein-denaturing IgG-avidity assays employing the end-point ratio method for serological diagnosis of congenital rubella even after disappearance of specific IgM.     

Antibody response to the rubella virus structural proteins in infants with the congenital rubella syndrome

Forty-five serum samples from 31 newborns and infants with the congenital rubella syndrome (CRS) were tested by immunoprecipitation to determine their antibody spectra to each of the structural proteins of rubella virus. Most sera (37/45) contained little or no E2 protein-specific antibody, but some (6/45) precipitated a greater amount of the E2 glycoprotein than the E1 glycoprotein. The relative E1/E2 ratio was found to decrease with time when serial serum samples from the same patient were tested. No correlation between the IgG class hemagglutination inhibition antibody titers and the E1/E2 ratio could be demonstrated. However, in some serum specimens relatively high neutralizing antibody titers were correlated with immunoprecipitation of the E2 glycopolypeptide. None of the CRS sera reacted well with the C protein. The immunoprecipitation patterns found in CRS sera were qualitatively different from those observed in a series of 25 sera from young adults with conventional serologic evidence of rubella immunity following natural infection. All of the natural immune sera recognized each of the three structural polypeptides of rubella virus.     

Use of the direct haemolysis-in-gel test for rubella antibodies in the Icelandic prevention programme for congenital rubella.

Untreated earlobe capillary blood samples from 5958 girls were screened for rubella antibodies by placing them directly onto haemolysis-in-gel (HIG) test plates. The method is in our experience quick, reliable and also acceptable to young girls. The method is convenient for testing for natural immunity before vaccination and in most but not all cases satisfactory as a test for seroconversion after vaccination. A comparison was made between naturally infected girls and a group of vaccinated girls. Vaccinated girls had lower values and most of the low or doubtful positives were in this group. Serum samples from 51 low positive girls were tested by the haemagglutination inhibition (HI) test and the serum HIG test and their results compared with their respective direct HIG values.     

Rubella reimmunization: comparative analysis of the immunoglobulin G response to rubella virus vaccine in previously seronegative and seropositive individuals.

Rubella virus (RV)-specific immunoglobulin G (IgG) antibodies were studied in military recruits undergoing unselected immunization with live attenuated measles, mumps, and rubella virus (MMR) vaccine. Three different whole-RV enzyme immunoassays (EIAs) and an epitope-specific EIA with a synthetic peptide (BCH-178c) representing a heutralization domain on the RV E1 envelope protein were used. Before vaccination, 84.2, 87.7, and 84.5% of the subjects tested (n = 399) were found to be seropositive (> 10 IU/ml or assay equivalent) by the three whole-RV EIAs, respectively, while only 82.5% were seropositive by the BCH-178c EIA. Although prevaccination seropositivity rates were similar for the whole-RV EIAs (sensitivity, 94 to 100%), many sera considered seropositive by the whole-RV EIAs had E1 peptide EIA antibody levels of < 10 IU/ml (sensitivity, 77.4 to 80.7%). One month after vaccination, 97.8, 97.2, and 93.5% of the subjects who were followed (n = 356) were seropositive by the three whole-RV EIAs, respectively, while 89% had BCH-178c peptide-specific IgG titers of > 10 IU/ml. After vaccination, depending on the assay used, up to 20.6% of initially seropositive individuals exhibited a greater than fourfold increase in RV-specific IgG, while up to 47.3% showed a greater than twofold increase. Increased antibody titers after vaccination (seroboosting) were most frequently associated with low levels of BCH-178c peptide-specific IgG before vaccination. RV protein-specific IgG was also studied by immunoblot assays in a subset (n = 56) of individuals receiving the MMR vaccine. Of these, 89.4 and 91.1% exhibited RV protein (E1, E2, and C protein)-specific IgG before and after vaccination, respectively. Seroboosting (two- to fourfold increase in EIA titers of individuals seropositive by the whole-RV EIA before vaccination) was usually accompanied by a shift in the IgG immunoblot pattern from a single (E1) to multiple (E1-E1, E1-C, or E1-E2-C) specificities, suggesting exposure of new epitopes as a result of viral replication.     

Humoral beta-cell autoimmunity is rare in patients with the congenital rubella syndrome

The congenital rubella syndrome (CRS) is associated with increased risk for diabetes and thyroid disease. However, the mechanisms by which the rubella virus may cause these diseases are poorly characterized. Previous studies were carried out before modern immunological methods were available. The present study aimed at evaluating whether autoimmune mechanisms are involved in the pathogenesis by analysing antibodies to biochemically characterized autoantigens. The incidence of clinical diabetes, thyroid disease, coeliac disease and related antibodies (islet cell antibodies, ICA; insulin autoantibodies, IAA; antibodies to the tyrosine phosphatase related IA-2 molecule, IA-2 A and glutamic acid decarboxylase, GADA; thyroid peroxidase, TPO; tissue transglutaminase, TTGA; and gliadin, AGA) and HLA risk genotypes were analysed in 37 subjects affected by or exposed to rubella during fetal life (mean age 22.5 years). One patient had diabetes and four patients had clinical hypothyroidism at the time of the examination. ICA, IAA, GADA or IA-2 A were not detected in any of the patients, while five patients tested positive for TPO antibodies. Coeliac disease or TTGA were not observed. Eight patients carried the HLA-DR3-associated HLA-DQB1*02-DQA1*05 haplotype. These results provide no evidence of an increased frequency of markers for humoral beta-cell autoimmunity in patients with CRS suggesting that diabetes in CRS may be caused by other than autoimmune mechanisms.     

Laboratory confirmation of congenital rubella syndrome in infants: an eye hospital based investigation

A total of 190 specimens from South Indian children aged 0-59 months with ocular anomalies consistent with suspected congenital rubella syndrome (CRS) were investigated. Twenty-six of the 65 infants (40%) were confirmed as CRS by detection of rubella specific IgM. Rubella RNA was detected in 41 samples from 26 infants by both real-time and block based PCR. The PCR results correlated well with the presence of anti-rubella IgM/IgG (23/27 cases with rubella IgM were PCR positive). Whereas, only 17 of 26 infants met the WHO CRS case definition. Amongst the various specimens tested from the sero-confirmed cases (n = 27), a high percentage of positives were detected in lens (92%) and oral fluid (60%) specimens, when compared to other samples. The quantification of viral load by real-time PCR demonstrated higher copy number of virus in lens samples of 0-11 months infants. The rubella viruses were characterized and revealed the circulation of genotype 2B in three South Indian states. The integrated analysis of clinical manifestations, serological and molecular data in the study has generated baseline information of rubella infection and CRS in infants with ocular anomalies.     

Application of molecular and serological assays to case based investigations of rubella and congenital rubella syndrome

Rubella and congenital rubella syndrome continue to be important health problems worldwide. The detection of rubella RNA directly in clinical specimens is a critical factor in early laboratory diagnosis of recent or congenital infection, in addition to detection of rubella-specific IgM. In order to comply with recent WHO recommendations for establishing uniform genetic analysis protocols for rubella virus we have developed a new block based PCR assay (PCR-E317), which extends the sequence generated by the block based PCR-E592 currently in use, to cover the minimum acceptable 739 nucleotides (nt) window at the E1 gene. In addition, a real-time PCR assay has been developed to allow rapid detection of the virus in the laboratory. The assays were applied to a number of clinical specimens collected from patients including recent rubella incidences in the UK, Ethiopia and Turkey, two prenatal and two congenital rubella syndrome cases. Rubella RNA was detected in specimens from two patients that were collected too early for IgM detection, in two amniotic fluids for prenatal diagnosis and in the follow up specimens from the two infant with congenital rubella syndrome tested for viral secretion. At least four genotypes were identified among these patients. The results showed that molecular assays are important tools in the early diagnosis of rubella and congenital rubella syndrome, in the provision of molecular epidemiological information for tracking transmission pathways and in adding to the knowledge of rubella strain distribution worldwide.     

Primary investigation of 31 infants with suspected congenital rubella syndrome in Sudan

Between 2005 and 2006, clinical specimens were collected from 31 infants with suspected congenital rubella syndrome (CRS) who presented at six hospitals in Khartoum, Sudan. Eleven (35.5%) were laboratory confirmed as CRS cases by testing for anti-rubella IgM, IgG and viral genome. For the first time in Sudan, the rubella virus genome was directly detected in clinical specimens of six CRS cases and two viruses were isolated in cell culture. Phylogenetic analysis suggested that three genotypes of rubella virus (RV; 1E, 2B and 1G) were co-circulating in Sudan. The study introduced the methodology for CRS confirmation and surveillance in Sudan and provides preliminary data.     

The association of rubella virus in congenital cataract - a hospital-based study in India.

BACKGROUND: The association of rubella virus (RV) with congenital cataract has been well established. Since the data on association of RV with congenital cataract in India are scanty, a study was done based on virus isolation from lens aspirates in patients undergoing therapeutic lensectomy and serology. OBJECTIVE: To determine the incidence of the association of rubella virus with congenital cataract. STUDY DESIGN: The lens aspirates collected during the 9-year period (from 1990 to 1998), from 70 children up to 12 years of age with congenital cataract were processed for the isolation of rubella virus by conventional viral isolation culture method using BHK-21 and Vero cell lines. Identification of the virus was confirmed by immunofluorescence using human anti-rubella virus specific hyperimmune serum. Serum samples were collected from 55 out of these 70 children and the presence of antibodies to RV was detected by ELISA test. RESULTS: RV was isolated from lens aspirates in seven (10%) out of the 70 children with congenital cataract. Of the 55 sera tested, 22 had both anti-rubella IgM and IgG antibodies, in 13 only anti-RV IgG antibodies, in seven only IgM antibodies and the rest of the 13 samples did not have detectable levels of rubella antibodies. Among the children who had IgM antibodies, 12 (24.5%) were below the age of 6 months. CONCLUSION: It can be concluded based on virus isolation that 10% of patients with congenital cataract were due to rubella infection and the detection of 24.5% anti-RV IgM antibodies in children below 6 months old shows the possible association of rubella virus with congenital cataract.     

Humoral immunity in congenital rubella

1. Rubella complement-fixing (CF) and neutralizing antibodies are reported for eighty-one patients with congenital rubella, six adults with acute rubella, and a control series of fifty-four children. In some of the congenital rubella patients virus isolation and serum immunoglobulin levels are recorded, together with maternal antibody and immunoglobulin levels.

2. In children infected with rubella in utero (with neutralizing antibody), the incidence and titres of CF antibody are significantly higher in those with defects than those without defects.

3. Whereas neutralizing antibody persists in congenital rubella and is probably a combination of IgG produced by both mother and child, and IgM produced by the child alone, CF antibody presents a more complex picture. It is nearly always detectable at some time in patients with congenital rubella, but may show a rising, falling or constant titre. The titre correlates significantly with the IgG concentration, and this and other data suggest that it may be predominantly IgG produced by both mother and child.

4. There is no obvious relationship between virus elimination and either CF or neutralizing antibodies or levels of IgG or IgM.