Rubella: reinfection of vaccinated and naturally immune persons exposed in an epidemic

Vaccine-Associated Enhanced Viral Disease: Implications for Viral Vaccine Development

Vaccine-associated enhanced disease (VAED) is a serious barrier to attaining successful virus vaccines in human and veterinary medicine. VAED occurs as two different immunopathologies, antibody-dependent enhancement (ADE) and vaccine-associated hypersensitivity (VAH). ADE contributes to the pathology of disease caused by four dengue viruses (DENV) through control of the intensity of cellular infection. Products of virus-infected cells are toxic. A partially protective yellow fever chimeric tetravalent DENV vaccine sensitized seronegative children to ADE breakthrough infections. A live-attenuated tetravalent whole virus vaccine in phase III testing appears to avoid ADE by providing durable protection against the four DENV. VAH sensitization by viral vaccines occurred historically. Children given formalin-inactivated measles or respiratory syncytial virus (RSV) vaccines experienced severe disease during breakthrough infections. Tissue responses demonstrated that VAH not ADE caused these vaccine safety problems. Subsequently, measles was successfully and safely contained by a live-attenuated virus vaccine. The difficulty in formulating a safe and effective RSV vaccine is troublesome evidence that avoiding VAH is a major research challenge. VAH-like tissue responses were observed during breakthrough homologous virus infections in monkeys given severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS) vaccines.

COVID-19 Vaccines: Should We Fear ADE?

Might COVID-19 vaccines sensitize humans to antibody-dependent enhanced (ADE) breakthrough infections? This is unlikely because coronavirus diseases in humans lack the clinical, epidemiological, biological, or pathological attributes of ADE disease exemplified by dengue viruses (DENV). In contrast to DENV, SARS and MERS CoVs predominantly infect respiratory epithelium, not macrophages. Severe disease centers on older persons with preexisting conditions and not infants or individuals with previous coronavirus infections. Live virus challenge of animals given SARS or MERS vaccines resulted in vaccine hypersensitivity reactions (VAH), similar to those in humans given inactivated measles or respiratory syncytial virus vaccines. Safe and effective COVID-19 vaccines must avoid VAH.

A novel cell-based high throughput assay to determine neutralizing antibody titers against circulating strains of rubella virus

A large rubella outbreak occurred in Japan 2013, and 14,344 rubella and 45 congenital rubella syndrome (CRS) cases were reported. At that time, the populational immunity was above the protective threshold assessed by hemmaglutination inhibition (HI) titer. The genotype 2B rubella virus (RV) strains were responsible for the outbreak, which are non-indigenous in Japan. In this work, a cell-based high throughput assay was established to measure the neutralizing antibody (NA) titer against circulating RV isolates. RV infection poorly induces cytopathic effects in tissue culture, preventing the casual measurement of NA titer. Our assay system has overcome this hurdle. Using this assay, we re-evaluated the antibody prevalence rate against circulating viral isolates using human sera collected before the outbreak. Individuals with protective IgG titer (≥10 IU/ml) represented 88.1% of the population. Consistently, 85.2% of the population had protective neutralizing antibody titers (≥1:8) against the vaccine strain. In contrast, 50.5% of the population had protective neutralizing antibody titers against circulating genotype 2B RV strains. These data suggest that the herd immunity assessed by HI titer should have been appreciated deliberately.

Does Rubella Cause Autism: A 2015 Reappraisal?

In the 1970s, Stella Chess found a high prevalence of autism in children with congenital rubella syndrome (CRS), 200 times that of the general population at the time. Many researchers quote this fact to add proof to the current theory that maternal infection with immune system activation in pregnancy leads to autism in the offspring. This rubella and autism association is presented with the notion that rubella has been eliminated in today’s world. CRS cases are no longer typically seen; yet, autistic children often share findings of CRS including deafness, congenital heart defects, and to a lesser extent visual changes. Autistic children commonly have hyperactivity and spasticity, as do CRS children. Both autistic and CRS individuals may develop type 1 diabetes as young adults. Neuropathology of CRS infants may reveal cerebral vasculitis with narrowed lumens and cerebral necrosis. Neuroradiological findings of children with CRS show calcifications, periventricular leukomalacia, and dilated perivascular spaces. Neuroradiology of autism has also demonstrated hyperintensities, leukomalacia, and prominent perivascular spaces. PET studies of autistic individuals exhibit decreased perfusion to areas of the brain similarly affected by rubella. In both autism and CRS, certain changes in the brain have implicated the immune system. Several children with autism lack antibodies to rubella, as do children with CRS. These numerous similarities increase the probability of an association between rubella virus and autism. Rubella and autism cross many ethnicities in many countries. Contrary to current belief, rubella has not been eradicated and globally affects up to 5% of pregnant women. Susceptibility continues as vaccines are not given worldwide and are not fully protective. Rubella might still cause autism, even in vaccinated populations.

Rubella specific cell-mediated and humoral immunity following vaccination in college students with low antibody titers

OBJECTIVE

This study measured cell-mediated immunity (CMI) and antibodies to clarify the basis of rubella reinfection after vaccination.

METHODS

In a pool of 65 college students, 39 who exhibited hemagglutination-inhibition (HI) antibody titers against rubella of ≤ 1:16 were vaccinated with a rubella vaccine. The CMI was assessed with interferon-gamma release assay.

RESULTS

There was low correlation (r = 0.24) between the antibody titers and interferon-gamma levels at pre-vaccination status. Preexisting interferon-gamma levels were low in some subjects with low HI antibody titers of 1:8 and 1:16. Fifty-seven percent (4/7) of the subjects who were antibody-negative with past history of rubella vaccination at entry onto the study exhibited CMI. And 57% (4/7) of the subjects remained antibody-negative following a second vaccination, despite exhibiting CMI. HI antibody titers increased significantly after vaccination, whereas post-vaccination interferon-gamma levels did not exhibit significant increases. When subjects were divided (based on their past history of vaccination and antibody values) into natural infection and vaccination groups, HI antibody titers (mean ± SD) increased to 1:2(4.4 ± 1.4) from 1: 2(3.2 ± 0.4) (p = 0.065) in the natural infection group and to 1:2(4.4 ± 1.0) from 1:2(3.0 ± 0.8) (p < 0.00001) in the vaccination group following vaccination. The same classification revealed that interferon-gamma values did not increase significantly in either group following vaccination, but the interferon-gamma values at pre- and post-vaccination in the natural infection group were significantly higher than those at pre- and post-vaccination in the vaccination group (p < 0.05 and p < 0.05, respectively).

CONCLUSION

Pre-vaccination interferon-gamma levels in each HI antibody titer group were similar. And there were some subjects with antibody-positive exhibited CMI-negative. These data may explain why rubella reinfection can occur in vaccinated seropositive individuals.

Epidemiology and Control: Principles, Practice and Programs

Infectious disease epidemiology is concerned with the occurrence of both infection and disease in populations and the factors that determine their frequency, spread, expression and distribution. Viruses show characteristic infectivity, virulence and pathogenicity. The most well established host factors are age, sex and race, but other host biological and behavioral factors affect acquisition of viral infection and/or its course and manifestations. The physical, chemical and biological environment operates on the virus itself and may also alter the host biological or behavioral response. Viral infections have incubation periods lasting days or weeks, while their pathologic sequelae may not manifest for years or decades. Likewise the degree or intensity of host response and clinical expression may range from largely inapparent to highly lethal. The degree of cell, tissue and organ specificity is high. Common syndromes involve the respiratory, gastrointestinal, and central nervous systems, the liver, and mucocutaneous surfaces. Vertical transmission may produce a variety of congenital and perinatal conditions. Viruses spread by multiple modes, using nearly every bodily surface or fluid as a route of exit or entry, either by direct contact or indirectly through an animal vector or other inanimate vehicle. Different viral Infections occur nearly ubiquitously or sporadically; they may be present continuously throughout a population (endemic) or occur in seasonal rhythm or in unexpectedly explosive form (epidemic). Many viruses are refractory to all known therapeutic agents, while for a few, the increasing number of highly effective agents holds great promise. Vaccines have produced many historical successes including the ultimate goal of eradication, but many viral infections continue to elude effective vaccine development. Major government and private sector programs for treatment and prevention have raised expectations of successful control for certain widespread and serious viral diseases; however, in every case a unique set of scientific, socioeconomic, political and behavioral barriers remains to be overcome.

The History of Rubella and Rubella Vaccination Leading to Elimination

Congenital rubella syndrome (CRS) was discovered in the 1940s, rubella virus was isolated in the early 1960s, and rubella vaccines became available by the end of the same decade. Systematic vaccination against rubella, usually in combination with measles, has eliminated both the congenital and acquired infection from some developed countries, most recently the United States, as is confirmed by the articles in this supplement. The present article summarizes the clinical syndrome of CRS, the process by which the vaccine was developed, and the history leading up to elimination, as well as the possible extension of elimination on a wider scale.

A synthetic peptide ELISA for the screening of rubella virus neutralizing antibodies in order to ascertain immunity

One hundred and fifty-one human sera from patients exposed to rubella virus (RV) and shown to be negative for IgM antibodies were tested for total RV-IgG, hemagglutination inhibition (HAI) and for virus neutralizing (VN) antibodies using a peptide enzyme-linked immunosorbent assay (ELISA) based on BCH-178, a peptide representing one of several known neutralizing epitopes on RV hemagglutinin (E1). The data showed that, among 39 and 51 sera with HAI and RV-IgG titres of 1/128 and >150 IU/ml, respectively, neutralizing antibody readings using the BCH-178 ELISA were above cut-off values. However, 13% of HAI positive sera (titre > or =1/16) and 16% of RV-IgG ELISA positive sera (> or =20 IU/ml) were below the cut-off value of the BCH-178 ELISA. This may explain why several cases of congenital rubella syndrome (CRS) have been observed in spite of positive titres. We suggest that a diagnosis of sufficient immunity against RV infection or reinfection may be safer if an additional test detecting antibodies against VN RV epitopes is positive as well.

Maturation of IgG avidity to individual rubella virus structural proteins

BACKGROUND

the structural proteins of rubella virus, the capsid protein C and the envelope glycoproteins E1 and E2 were produced in lepidopteran insect cells using baculovirus expression vectors. The C-terminal ends of the corresponding proteins were fused to a polyhistidine tag for easy and gentle purification by metal ion affinity chromatography.

OBJECTIVES

to investigate the maturation of natural and vaccinal IgG avidity against individual authentic and recombinant rubella virus (RV) structural proteins.

STUDY DESIGN

the analysis was carried out using a modified immunoblotting technique where the purified baculovirus-expressed proteins were compared with authentic rubella virus proteins. Altogether, 47 well-characterised serum samples from both naturally infected patients and vaccines were studied.

RESULTS

after natural RV infection, IgG antibodies specific for the E1 protein were predominant not only in terms of levels, but also in terms of rate and magnitude of avidity maturation. The avidity development of the IgG antibodies was much slower in vaccines than in patients after a natural RV infection.

CONCLUSIONS

together, our results indicate that IgG avidity determination in conjunction with immunoblot analysis is useful in the diagnosis of a RV infection. The recombinant proteins showed similar reactivity patterns in the immunoblot analyses as compared with the authentic viral structural proteins, suggesting suitability for serodiagnostics.

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.

Neutralizing monoclonal antibody to the E1 glycoprotein epitope of rubella virus mediates virus arrest in VERO cells

The best-known mechanism of action of antibody-mediated virus neutralization is to impede the entrance of viruses to host cells, as determined by neutralization assays. Antibodies may also inhibit the exit of rubella virus (RV) from infected host cells; in this case, the interaction of the antibodies with their domains must occur on the plasma membrane, because antibodies cannot enter the cells. In the present study, we were able to block temporally the exit of virions from RV-infected cells by the binding of monoclonal antibody (mAb) H3 to their surface. The objective was accomplished in three steps: first, we determined the duration of the viral replication cycle; then we established the kinetics of the presence of the domains defined by our mAbs in the cytoplasm of RV-infected VERO cells; and, finally, we assessed the release of viral particles to the supernatant of infected VERO cells in the presence or absence of mAbs or positive and negative mice sera. RV-specific mice sera and mAb H3, which binds to the amino acid sequence 208-239 of the RV-E1 glycoprotein, were able to delay for 24 hours the release of virions from infected cultures, suggesting that the reaction of mAb H3 with its epitope may arrest any change necessary for the assembly and/or release of virions. In conclusion, the neutralizing domain recognized by mAb induces antibodies that can block the viral replication by several mechanisms of action, such as the obstruction of virus entry into cells and the delay of viral release. All of these mechanisms are intimately involved in the critical virus-host cell interactions that allow self-limitation of the infection.

Placental transfer of maternal rubella antibodies to full-term and preterm infants

Premature infants are vulnerable to infections, partly because of the low transplacental transfer of maternal antibodies. The present study investigated the placental transfer of maternal rubella-specific antibodies to full-term and preterm infants. The study group consisted of 133 healthy, native Israeli mothers and their 159 newborns. Of these, 69 were full-term infants (gestational age > 37 weeks) of 69 mothers, and 90 were preterm infants (gestational age < 35 weeks) of 64 mothers. Antibody titers against rubella were measured in maternal and umbilical cord blood samples by hemagglutination inhibition and microneutralization techniques. There was no significant difference in the level of protection and in geometrical mean titers by hemagglutination between the full-term and preterm groups. Conversely, significant differences in geometric mean titers of neutralizing antibodies were found between full-term and preterm infants, e.g., 65.9 and 39.8, respectively (P < 0.001). Very low birth weight preterm infants are at greater risk of rubella infection during the first year of life, due to the diminished transfer of neutralizing maternal antibodies. Therefore, earlier vaccination of this group may be beneficial.

Subclinical rubella reinfection during pregnancy followed by transmission of virus to the fetus

We report a documented case of rubella reinfection during pregnancy in a previously vaccinated woman with residual antibody titre to rubella of 15 IU/ml. The reinfection occurred following an exposure to rubella virus (contact with 6-year-old daughter with clinical rubella) between the 7th and 10th week of pregnancy which resulted in transmission of the virus to the fetus. Umbilical cord blood drawn by cordocentesis was found to be strongly positive for rubella IgM antibody. After termination of the pregnancy rubella virus was isolated in cell culture from fetal tissues.

[Mumps vaccines: vaccination failures from an immunological viewpoint]

The significance of mucosal and systemic immunity is illustrated with the example of the different immune response of Poliovaccine live oral (Sabin) and Poliovaccine inactivated parenteral (Salk). On the occasion of rubella- and measles-outbreaks it will be demonstrated that in vaccinated people subclinical reinfections may much more frequently occur than clinically manifest diseases. On the basis of these findings one may consider the large number of parotitis cases without complications in mumps vaccinated Swiss pupils as secondary mucosal vaccine failures at a time, when systemic immunity still was protective. Significance for vaccination policy and consequences for handling of vaccines shall be briefly discussed.

Comparison of a whole-virus enzyme immunoassay (EIA) with a peptide-based EIA for detecting rubella virus immunoglobulin G antibodies following rubella vaccination

A total of 250 human serum samples were tested for rubella virus immunoglobulin G antibodies by two enzyme immunoassays (EIAs), one using whole rubella virus antigen and the other based on the use of synthetic peptide antigen. The samples were taken from 125 volunteers before and after their immunization with the RA 27/3 rubella vaccine. This study indicates that a synthetic peptide-based EIA can favorably replace current viral lysate-based EIAs to detect rubella virus antibodies following immunization. Because the synthetic peptide used in this newly developed EIA represents a putative neutralization epitope of the rubella virus, it could also be instrumental in determining rubella immune status and in assessing vaccine program efficiency.

Congenital rubella syndrome after maternal reinfection

This report concerns a case of congenital rubella syndrome (CRS) with atypical immune response affecting an infant whose mother had repeated evidence of immunity before pregnancy. Laboratory diagnosis of CRS could only clearly be achieved by virus isolation after the second month of life despite typical clinical features of CRS and multiple organ involvement. After the first month of age, low concentrations of specific IgM antibodies were revealed by ELISA and confirmed by a reference test system (IgM-specific haemagglutination inhibition assay). Persistent and increasing high levels of IgM antibodies were detected only after the 6th month of life. Later on IgG antibody levels decreased. Immunological investigations showed an IgG1-hypoglobulinaemia. The unusual feature of the present case report is not only the failure of the maternal rubella immunity to prevent CRS, but the defect of the child's immune system, probably attributable to congenital infection. As a consequence, laboratory diagnosis of CRS could not be achieved initially by the proved serological methods.

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.

Cellular and humoral immune responses to rubella virus structural proteins E1, E2, and C

Better understanding of cell-mediated immune responses to rubella virus would provide the basis for the development of safe and effective vaccines against rubella and would aid in analysis of the pathophysiology of congenital rubella syndrome. We have expressed individual rubella virus structural proteins, E1, E2 and C, via vaccinia virus recombinants. Using the expressed recombinant proteins as antigens, we were able to demonstrate antigen-specific lymphocyte proliferative responses in control individuals and individuals with congenital rubella syndrome. Among the two human groups studied, E1 glycoprotein proved to be a better immunogen than E2 or C. For the control individuals, significant differences in proliferative responses to the structural proteins E1, E2, and C were observed. These differences were not significant in individuals with congenital rubella syndrome. In parallel to the lymphoproliferative responses, immunoglobulin G responses were also found directed mainly to the E1 glycoprotein. These results suggest that E1 may be the most important rubella virus antigen to study in determining the domains required for constructing subunit vaccines against rubella.

Congenital rubella infection from reinfection of previously immunised mothers

Two children developed congenital rubella infection when their mothers had been proven to be satisfactorily immunised against rubella before the affected pregnancy. One child was severely affected with heart lesions, brain damage, severe deafness, physical retardation, cataracts and rubella retinopathy. The other child had moderately severe sensorineural deafness and a mild reduction in visual acuity due to rubella retinopathy.

Clinical rubella reinfection--a case of arthropathy

We describe a case of arthropathy due to rubella reinfection. Clinical rubella reinfection with rash and lymphadenopathy has been reported but as far as we are aware this is the first report of a case with arthropathy as the sole presentation. Rubella IgG subclass and avidity tests confirmed the reinfection.

Rubella and mumps vaccines

As a fetal infection occurring during early pregnancy, rubella's potential for teratogenicity is unparalleled. In the postnatal period it is a relatively benign disease. Mumps, on the other hand, causes moderate morbidity and occasional mortality. Both infections cause considerable morbidity and disruption in the lives of young people gathered for group activities. Widespread use of safe and effective live attenuated vaccines has dramatically reduced the incidence of rubella, congenital rubella, and mumps in the United States. Nevertheless, significant numbers of young children, especially in areas of urban and rural immigration and poverty, fail to be immunized in a timely fashion; and some adolescents and young adults remain susceptible either because they escaped immunization in childhood or are primary vaccine failures. These individuals remain the source of individual cases and small outbreaks of rubella and mumps. For total eradication of these infections, we need to intensify vaccine efforts and to maintain surveillance efforts for mumps, rubella, and congenital rubella syndrome.

Development of automated immunoassays for immune status screening and serodiagnosis of rubella virus infection

The fully automated IMx immunoassay analyzer was used to develop a system for the detection of IgG and IgM antibodies to rubella virus for immune status screening and diagnosis of primary infections. Reagents and assay protocol software were developed using rubella virus sensitized microparticles as the solid phase to capture specific antibodies from serum samples. Anti-human IgG or IgM antibody coupled to alkaline phosphatase enzyme followed by methylumbelliferyl phosphate substrate was used to detect the presence or absence of antibodies specific to the antigens on the solid phase. To evaluate the efficacy of the IMx rubella IgG assay, immune status screening was performed with a clinical patient population of 501 sera. When compared to an IgG specific enzyme immunoassay and passive hemagglutination assay the agreement was greater than 99%. The IMx rubella IgM assay was utilized to determine the presence of rubella specific IgM antibodies in 462 sera. These results were compared to IgM specific enzyme immunoassay results and also demonstrated greater than 99% agreement. Seroconversion following rubella vaccination of susceptible individuals was demonstrated by IgG and IgM antibody responses as early as two weeks postvaccination. In addition to automation, the IMx system offers rapid assay times and calibration curve storage without sacrificing clinical efficacy.

A bio-engineered rubella E1 antigen

The major rubella envelope protein, E1, and a segment of it, comprising amino acids 207-353, have been separately expressed as fusion proteins with the IgG binding region of Staphylococcus aureus protein A in Escherichia coli. The proteins carry E1-specific antigenicity recognized by monoclonal antibodies raised against whole virus confirming that correct glycosylation is not required for antigenicity. The use of these bioengineered antigens in immunoassays for diagnosis of rubella infection and for immunization in experimental animals is described.

Adult onset Still's disease and viral infections

Several micro-organisms, especially viruses, have been associated with juvenile and adult onset Still's disease. In the present study a search for probable triggering viral infections in five consecutive patients with early, active adult onset Still's disease has been made. In one patient echovirus 7 was identified as a probable triggering agent. Evidence of infection with this virus was acquired by virus cultures and serological tests. In two patients the illness was probably initiated by a rubella reinfection. Both had initially high stable monospecific IgG antibody titres but no IgM antibodies to this virus. In the remaining two cases no particular triggering viral infection could be designated. Evidence of a viral infection was thus found in three of these five patients. Adult onset Still's disease may represent a reaction pattern to certain infections.

Rubella vaccination

Rubella vaccination programmes aim to prevent congenital rubella infections. Previously differing programmes have now converged according to the following principle: First vaccination should be given at the age of 15 months (together with measles and mumps vaccine) to both boys and girls, in order to diminish the circulation of the wild virus. Teenage girls require (re-)vaccination to ensure their immunity. Also non-immune women have to be identified and vaccinated before they become pregnant. A low acceptance rate increases the risk of infection of pregnant women, independent of the vaccination omitted. As a rule natural and vaccine-induced immunity prevents congenital rubella infections. These infections are exceedingly rare in children born to immune mothers, and are always caused by the wild virus. This minimal risk will disappear only with the eradication of rubella virus, still a distant goal in countries offering vaccination only on a voluntary basis.

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.

Evaluation of a rapid passive hemagglutination assay for anti-rubella antibody: comparison to hemagglutination inhibition and a vaccine challenge study

A rapid passive hemagglutination assay (Rubaquick) was developed that detects antibody to rubella virus in serum specimens. The test result is read visually after an incubation period of 15-30 minutes. When compared with a hemagglutination inhibition assay, the Rubaquick assay results obtained from 1,470 sera were greater than 99% specific, sensitive, and accurate. Studies of 179 paired serum specimens obtained before and 27 days after rubella vaccination showed that if antibody was detectable by the Rubaquick assay in the prevaccination specimens, the vaccine induced a secondary response consisting of increasing IgG antibody reactivity in the absence of a positive IgM response. In contrast to the positive prevaccination specimens, a negative prevaccination result was associated with IgM antibody in 98 of the 133 postvaccination specimens. Seroconversion was noted in all cases in which the prevaccination specimen was negative by the Rubaquick assay.

Rubella: immunity and vaccination in schoolgirls

Of 191 schoolgirls, 128 volunteered to take part in a feasibility study of serotesting before and after rubella vaccination, and all responded to RA 27/3 vaccine. Had the serum samples been taken by a fingerprick method the number of volunteers would probably have increased considerably. A change in policy for rubella vaccination to testing both before and after vaccination would cost no more than the existing policy, would ensure primary response, and would differentiate those women who were protected by the vaccine from those with antibody to wild virus.

Detection of rubella-specific IgM in subclinical rubella reinfection in pregnancy

Seven cases of asymptomatic rubella reinfection in early pregnancy are described. In each, there was a history of exposure to a rubelliform illness and low levels of rubella-specific IgM subsequently appeared in the serum. Four of the women had been immunised, after having been shown to be susceptible to rubella, one had been immunised at school without previous antibody screening, and two were uncertain about immunisation. One pregnancy was terminated and rubella virus was not isolated from the products of conception. Six pregnancies went to term and the infants showed no evidence of intrauterine infection. In a further case it was impossible to discriminate between reinfection and primary infection, and termination of pregnancy was offered.

Clinically apparent rubella reinfection

We report two cases of rubella reinfection in apparently immunocompetent young women. In both cases rubella-specific IgG had been detected on two occasions prior to an illness clinically diagnosed as rubella. Rubella-specific IgM was detected by various techniques in samples of serum collected at the time of the illness.

Rubella control--1984

The incidence of rubella and the congenital rubella syndrome has decreased dramatically in the United States since rubella vaccine became available in 1969. A marked shift in susceptibility rate has occurred so that 70% of current rubella cases involve teenagers and young adults. The history of rubella control is reviewed. Future research as well as altered public health strategies are suggested to optimize rubella control.

Intranasal administration of RA 27/3 rubella virus vaccine. A clinical trial in young adults

Of the vaccines and inoculation routes studied for the prevention of rubella, only the RA27/3 vaccine, administered intranasally, has the ability to stimulate a humoral antibody pattern very similar to that evoked by wild rubella infection. Because information about intranasal (IN) vaccination has only been obtained using the RA 27/3 vaccine manufactured in Europe, we conducted a trial of IN vaccination among young adults using Meruvax II which is manufactured in the USA. Of 597 family planning clinic patients screened in 1980-1981, 71 (11.9%) were susceptible to rubella; forty-one subjects were randomly assigned to receive IN or subcutaneous (SC) vaccine. All 20 SC vaccinees, but only 8/21 (38%) IN vaccinees, were successfully immunized. We conclude that standard doses of commercially available RA 27/3 vaccine are insufficient for IN immunization against rubella. Additional study of the dose-response relationship is needed if IN vaccination is to be recommended.

Rubella embryopathy after previous maternal rubella vaccination

This report concerns a boy with congenital rubella infection and features of the classical and expanded rubella syndrome who was born to a mother who had been successfully vaccinated with Cendehill vaccine seven years previously. The diagnosis of rubella embryopathy was confirmed by demonstrating rubella-specific serum IgM antibodies using four different methods, by the persistence of rubella HAI and IgG antibodies in serum taken between three and eight months of age and by the isolation of rubella virus from throat secretion, urine and blood mononuclear cells. The child died at eight-and-a-half months of age. This case is discussed in relation to the persistence of vaccine-induced immunity with particular respect to the protective quality of low levels of antibodies against intrauterine infection in the event of re-infection during pregnancy.

Determination of rubella immunity by latex agglutination: its place in clinical routines

The sensitivity and specificity of Rubascan (r) (RSC), a new latex agglutination test for rubella antibodies, was compared with those of the single radial hemolysis (SRH) and hemagglutination inhibition (HI) tests. We found RSC to have a sensitivity versus SRH and HI of 90-95% and 70-72%, respectively. RSC had a specificity versus SRH and HI of 97-100% and 96-100%, respectively. However, only 4/7 titer rises from cases of acute rubella or rubella vaccinations were clearly discernible in RSC. Moreover, only 2/10 anti-rubella IgG and IgM containing sera were RSC positive after protein A absorption although 10/10 were still HI positive. Additionally, the HI-positive IgM fractions from a sucrose density gradient centrifugation of an anti-rubella IgM containing serum were negative. We conclude that IgM reacts differently from IgG in RSC. We consider RSC a potentially useful reagent for determination of immunity in non-acute situations, and in non-pregnant persons like in pre-employment testing. This could be performed by relatively untrained personnel. On the other hand a rubella immunity test in pregnant women or in acute rubella should preferably be truly quantitative, in order to allow precise titer comparisons. In these cases, the interpretation of tests may require experience, and they should be performed at more specialized laboratories.

Enzyme-linked immunosorbent assay for rubella immunoglobulin G: new method for attachment of antigens to microtiter plates

Many of the enzyme-linked immunosorbent assay (ELISA) techniques previously described for detection of rubella-specific antibodies employ complex technology not available in routine diagnostic laboratories. The method described allows the use of commercially available rubella hemagglutination inhibition (HI) antigen. Passive adsorption of these antigens to plastic is variable, but with the use of albumin as a bridge, it is possible to attach the antigen reliably to the plastic wells. Over 1,500 sera were tested by both HI and ELISA techniques to detect the presence of rubella antibodies. These sera were selected with a bias towards those with low levels of rubella-specific antibody, since it has been demonstrated that it is in this range that discrepancies are more likely to occur between HI and ELISA techniques. In 99% of the sera tested, the results of both techniques were in agreement. On the basis of these results, the technique offers a useful alternative to the routine rubella HI test and other ELISA techniques which need sophisticated antigen preparations.

Comparison of the latex agglutination test with the hemagglutination inhibition test, enzyme-linked immunosorbent assay, and neutralization test for detection of antibodies to rubella virus

The ability of a rapid, latex agglutination test to diagnose rubella infection and to measure immune status was evaluated by comparison with the hemagglutination-inhibition (HAI) test, enzyme-linked immunosorbent assay (ELISA), and the neutralization (NT) test. The latex agglutination test accurately detected serological conversions in 74 pairs of sera representing 21 natural infections and 53 immunizations. The antibody levels of 276 sera from the general population were determined by latex agglutination, HAI, and ELISA. The correlation coefficients between the titers obtained by HAI and latex agglutination and by ELISA and latex agglutination were statistically significant. Results on 12 sera did not agree when measured by the three tests. These sera were included among the 196 specimens tested by NT. The correlation coefficient between NT and latex agglutination titers was statistically significant. There was one serum positive by latex agglutination but negative by NT, and five sera were negative by latex agglutination but had titers of 4 to 8 in the NT. The relative sensitivity of detecting antibody was greater by latex agglutination than by HAI. An additional 49 sera containing residual nonspecific hemagglutinin inhibitors were evaluated by latex agglutination and NT. The untreated sera showed no false positive reactions, and 36 of 39 NT positive sera were positive in the latex agglutination test.

Congenital rubella after successful vaccination

We report a case of a patient who had a subclinical rubella infection in the first trimester of pregnancy which resulted in the delivery of a baby suffering from congenital rubella. Rubella virus vaccine, liver attenuated (Cendevax) vaccine had been administered to the mother nearly three years before, with proven seroconversion from a rubella haemagglutination-inhibition titre of 1:10 to 1:80.

Rubella screening and vaccination programme at a Melbourne maternity hospital. A five-year review

Antibody to rubella virus titres were measured in 7133 serum samples collected from pregnant women and nurses between 1976 and 1980. A significant decline in susceptibility to rubella was found in women under 25 years of age, but not in those over 25 years of age. Most of the former would have been vaccinated at school. One hundred and sixty of 325 women vaccinated with Cendehill vaccine (Cendevax) were subsequently retested. Two failed to develop antibodies and 19 initially "seronegative" women responded poorly. Ten of 38 women with low prevaccination titres had a significant boost in titre, and the remaining 28 showed little or no change. All 13 women who were revaccinated with RA 27/3 vaccine (Almevax) after responding poorly to Cendevax vaccination had a boost in titre; in 10, the rise was four-fold or greater. it is disappointing that Almevax is no longer available in Australia.

Public health implications of rubella antibody levels in California

Rubella hemaggluttination inhibition (HI) antibody determinations were performed in 1977 on a sample of California school children and in 1977-1979 on young women who were about to be married or who were pregnant. Among the pupils, 66 per cent reported prior rubella immunization; immunization history was more common in younger pupils. Seventy-seven per cent had detectable antibody, with little trend of greater seropositivity at older ages. Over 86 per cent of those with a written record of immunization had detectable antibody. There was no consistent indication of loss of seropositivity with increasing time since immunization. Children immunized at 12-14 months of age tended to have a lower seropositivity rate than those immunized at older ages. Among young women, the prevalence of detectable antibody was 80-83 per cent. Comparison with data obtained in 1968-1969 indicates that rubella immunization has had a marked impact on antibody levels in children but less impact on levels in teenagers and adults. The pool of rubella-susceptibles entering secondary schools will probably not decrease soon, so that rubella outbreaks may continue in high school and college-age populations. Ultimately, school entry immunization requirements should drastically curtail disease activity. In the interim, programs to immunize teenagers and young adult females must be strengthened. (Am J Public Health 1982; 72:167-172.)

Outcome of asymptomatic infection with rubella virus during pregnancy

We have tried to detect prenatal infection in 34 infants whose mothers were re-infected with rubella virus during pregnancy and in six infants whose mothers had primary subclinical rubella during pregnancy. Two methods of assessment were used: first, serum obtained soon after birth was tested for IgM antibody; secondly, serum obtained after the age of 8 months was tested for specific IgG. The 34 women with re-infections had increases in IgG antibody titre but no IgM response. No evidence of prenatal infection was found in 33 of their 34 infants. One infant was found to have IgG antibody at the age of 11 months. This infant was IgM-negative at birth and had a rubelliform rash at the age of 5 1/2 months; it therefore probably contracted post- rather than pre-natal infection. Fetal infection from maternal re-infection during pregnancy is probably rare. The six women with primary subclinical rubella produced both IgG and IgM classes of antibody. Three of their six infants showed serological evidence of intrauterine infection. One, infected when its mother was 8 weeks pregnant, had clinical evidence of congenital rubella. Primary subclinical rubella during pregnancy therefore carries a significant risk of fetal infection. Because of the difference in outcome, great care should be taken to distinguish between primary infection and re-infection when investigating symptomless increases in antibody titre after contact with rubella during pregnancy.