Rubella epidemic in Vietnam: characteristic of rubella virus genes from pregnant women and their fetuses/newborns with congenital rubella syndrome

Development of a rapid, internally controlled, two target, real-time RT-PCR for detection of rubella virus

Rubella surveillance in elimination setting relies on rapid molecular detection of the virus. In this study a multiplex real-time RT-PCR assay for the detection of rubella virus was validated. The assay includes three independent probes with unique reporter dyes for the simultaneous detection of the rubella viral coding regions for envelope glycoprotein E1 and non-structural p150 protein, and an endogenous control (human RNaseP). Using dilution series of synthetic RNAs, the limits of detection were determined to be at least 50 copies of rubella RNA. The assay is reproducible with low intra-assay and inter-assay coefficients of variation for both the E1 and the p150 targets. After testing 62 confirmed rubella positive and 165 rubella negative archival clinical samples, the sensitivity and specificity of the multiplex assay were 98.4 and 100%, respectively. No cross reactivity was identified with clinical specimens positive for eleven other viruses. This multiplex assay successfully detected nine viral genotypes including the predominant genotypes 1E, 1 G, 1 J, and 2B as well as the 1a vaccine genotype.

Maternal infections

Congenital infections are infections transmitted from mother to child during pregnancy (transplacentally) or delivery (peripartum). They have the potential to adversely affect fetal development and long-term neurodevelopmental outcome through inflammatory, destructive, developmental, or teratogenic lesions of the brain. Because the fetal/neonatal brain has a limited capacity to respond to injury, early inflammatory changes may be difficult to visualize and only manifest as neurocognitive disability later in life. Teratogenic effects, which may include aberrations of neuronal proliferation and migration, are more easily visible on imaging, but may be equally difficult to use to predict long-term neurocognitive outcomes. This chapter reviews the general pathophysiology of congenital infection and describes the epidemiology, the antenatal and postnatal diagnosis, and the treatment of congenital infections as well as the long-term neurodevelopmental outcomes.

No. 368-RUBELLA IN PREGNANCY

OBJECTIVE

To review the epidemiology, natural history, evaluation, and prevention of rubella infection during pregnancy. This will aid obstetric care providers in counseling their patients regarding potentially devastating effects on the developing fetus and the importance of vaccinating susceptible women as appropriate.

OUTCOMES

Outcomes evaluated include fetal rubella infection, maternal seroconversion and response to rubella-containing vaccines.

EVIDENCE

Medline, PubMed, EMBASE, and Cochrane databases were searched for articles in English on subjects related to rubella infection during pregnancy betweenn 1985 and 2017. Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. Other (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUATION METHODS

The quality of the evidence is rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). Recommendations for practice are ranked according to the method described in this Report.

GUIDELINE UPDATE

The guideline will be reviewed 5 years after publication to decide if an update is required. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations SPONSOR: Society of Obstetricians and Gynaecologists of Canada.

RECOMMENDATIONS

Phylogeography of rubella virus in Asia: Vaccination and demography shape synchronous outbreaks

Rubella virus causes mild disease in children but for women in the early stages of pregnancy, it can cause spontaneous abortion, congenital rubella syndrome (CRS) and associated birth defects. Despite the availability of an effective vaccine, rubella virus continues to circulate endemically in several regions of the world. This is particularly true in East and Southeast (E/SE) Asia, where control efforts vary widely among countries that are well connected through travel and immigration. It is therefore important to understand how the regional persistence of rubella is affected both by dynamics occurring across countries and susceptibility within countries. Here, we use genetic and epidemiological data from countries in E/SE Asia to explore the phylogeography of rubella virus in this region. Our results underline that metapopulation dynamics are key for rubella persistence and highlight the source-sink population structure of the region. We identify countries that contribute to the regional metapopulation network and link epidemic dynamics to susceptibility profiles within each country. Our results indicate that human movement plays an important role in driving epidemic dynamics in E/SE Asia.

The BeWo cell line derived from a human placental choriocarcinoma is permissive for respiratory syncytial virus infection

The respiratory syncytial virus (RSV) is the main pathogen associated with upper respiratory tract infections during early childhood. Vertical transmission of this virus has been suggested in humans, based on observations recorded during animal studies that revealed an association of RSV with persistent structural and functional changes in the developing lungs of the offspring. However, human placentas have not yet been evaluated for susceptibility to RSV infection. In this study, we examined the capacity of RSV to infect a human trophoblast model, the BeWo cell line. Our results suggest that BeWo cells are susceptible to RSV infection since they allow RNA viral replication, viral protein translation, leading to the production of infectious RSV particles. In this report, we demonstrate that a human placenta model system, consisting of BeWo cells, is permissive to RSV infection. Thus, the BeWo cell line may represent a useful model for studies that aim to characterize the events of a possible RSV infection at the human maternal-fetal interface.

Cellular and molecular mechanisms of viral infection in the human placenta

The placenta is a highly specialized organ that is formed during human gestation for conferring protection and generating an optimal microenvironment to maintain the equilibrium between immunological and biochemical factors for fetal development. Diverse pathogens, including viruses, can infect several cellular components of the placenta, such as trophoblasts, syncytiotrophoblasts and other hematopoietic cells. Viral infections during pregnancy have been associated with fetal malformation and pregnancy complications such as preterm labor. In this minireview, we describe the most recent findings regarding virus-host interactions at the placental interface and investigate the mechanisms through which viruses may access trophoblasts and the pathogenic processes involved in viral dissemination at the maternal-fetal interface.

Molecular Epidemiology of Rubella Virus Strains Detected Around the Time of the 2012-2013 Epidemic in Japan

A nationwide rubella epidemic occurred from 2012 to 2013 in Japan, resulting in around 17,000 rubella cases and the birth of 45 infants with congenital rubella syndrome. The aim of this study was to genetically characterize the rubella viruses (RVs) circulating around the time of the epidemic in Japan. In total, 221 RV strains detected from 14 prefectures in Japan between 2010 and 2014 were sequenced in the 739 nucleotide-window region within the E1 gene. The virus strains were chronologically and geographically characterized into groups based on phylogenetic analysis. Among the 221 strains analyzed, 192 (87%), 26 (12%), and 3 (1%) strains were classified into genotypes 2B, 1E, and 1J, respectively. The majority (n = 184) of the genotype 2B strains belonged to lineage 2B-L1 and shared nucleotide homology with the strains detected in Southeast and East Asian countries. Phylogenetic analyses demonstrated that at least six distinct clusters of RV strains (clusters 1-6) induced outbreaks in Japan between 2010 and 2014. Among them, strains from clusters 3, 4, and 6 circulated almost simultaneously during 2012-2013. The cluster 3 strains circulated locally, whereas strains from cluster 4 spread nationwide. The findings suggest that RVs were introduced into Japan many times from neighboring countries. The 2012-2013 epidemic was a complex of outbreaks induced by at least three clusters of RV strains.

Hospital-based surveillance of congenital rubella syndrome in Indonesia

Congenital rubella syndrome (CRS) has serious consequences, such as miscarriage, stillbirth, and severe birth defects in infants, resulting from rubella virus infection during pregnancy. However, rubella vaccine has not yet been implemented in Indonesia. This study aimed (1) to estimate the incidence of CRS in Indonesia, (2) describe the clinical features of CRS at our referral hospital, and (3) pilot a CRS surveillance system to be extended to other hospitals. We conducted a 4-month prospective surveillance study of infants aged <1 year with suspected CRS in 2013 at an Indonesian hospital. Infants with suspected CRS were examined for rubella-specific IgM antibody or rubella IgG antibody levels. Of 47 suspected cases of CRS, 11/47 (23.4%), 9/47 (19.1%), and 27/47 (57.5%) were diagnosed as laboratory-confirmed, clinically compatible, and discarded CRS, respectively. The most common defects among laboratory-confirmed CRS cases were hearing impairment (100%), congenital cataracts (72.7%), microcephaly (72.7%), and congenital heart defects (45.5%).

CONCLUSION

The number of laboratory-confirmed CRS cases among Indonesian infants is high. Furthermore, hearing impairment is the most common clinical feature of CRS in infants. Our findings indicate the importance of implementation of rubella vaccine in Indonesia. Conducting hospital-based surveillance of CRS in other hospitals in Indonesia may be appropriate. What is Known: •Congenital rubella syndrome (CRS) has serious consequences in infants resulting from rubella virus infection during pregnancy. •The incidence of CRS in most developed countries has greatly decreased since implementation of rubella vaccination. •Rubella vaccine has not yet been implemented in many developing countries. What is New: •The number of laboratory-confirmed CRS cases among Indonesian infants was high. •Implementation of rubella vaccine into immunization programs in Indonesia is important because of the high number of CRS cases. •Our study highlights the need for ongoing prospective surveillance of CRS in Indonesia.

Rubella Immunity in Pregnant Native Taiwanese and Immigrants from Asian Countries

Vaccination is considered the most effective method to prevent rubella spread and congenital rubella syndrome (CRS). The aim of the present study was to investigate the rubella immunity among native and immigrant pregnant women in Taiwan. From 2000 to 2014, a total of 16,879 pregnant women who received routine prenatal examinations were recruited in this study. The rubella IgG antibodies were assayed using a microparticle enzyme immunoassay or chemiluminescent microparticle immunoassay. Subjects were categorized by nationality and subcategorized by specific periods of time for comparison. The rubella susceptibility was 12.7% in total, 11.1% in Taiwanese and 20.3% in immigrant population from 2000 to 2014. Among the immigrant women, those from Vietnam had the highest susceptibility (22.3%) and those from Thailand had the lowest susceptibility (3.8%). The immigrant women from Vietnam and China showed a significantly higher susceptibility compared with the native Taiwanese women in which the odds ratio was 2.30 (95% confidence interval [CI]: 2.04-2.60), 1.96 (95% CI: 1.59-2.41), respectively (P < 0.001). It meant that immigrants from Vietnam and China had a higher likelihood of rubella susceptibility and related CRS sequela than native women. From 2000-2004 to 2010-2014 cohort, there was no obvious change in rubella susceptibility in native women, which varied between 10.0% and 11.9%. However, there was a decreasing trend of rubella susceptibility in the immigrant women overall, from 24.5% to 11.5% (P < 0.001). To eliminate congenital rubella in Taiwan, additional catch-up immunization strategies are needed.

Rubella

Rubella remains an important pathogen worldwide, with roughly 100,000 cases of congenital rubella syndrome estimated to occur every year. Rubella-containing vaccine is highly effective and safe and, as a result, endemic rubella transmission has been interrupted in the Americas since 2009. Incomplete rubella vaccination programmes result in continued disease transmission, as evidenced by recent large outbreaks in Japan and elsewhere. In this Seminar, we provide present results regarding rubella control, elimination, and eradication policies, and a brief review of new laboratory diagnostics. Additionally, we provide novel information about rubella-containing vaccine immunogenetics and review the emerging evidence of interindividual variability in humoral and cell-mediated innate and adaptive immune responses to rubella-containing vaccine and their association with haplotypes and single-nucleotide polymorphisms across the human genome.

Digital microfluidic platform for the detection of rubella infection and immunity: a proof of concept

BACKGROUND

Whereas disease surveillance for infectious diseases such as rubella is important, it is critical to identify pregnant women at risk of passing rubella to their offspring, which can be fatal and can result in congenital rubella syndrome (CRS). The traditional centralized model for diagnosing rubella is cost-prohibitive in resource-limited settings, representing a major obstacle to the prevention of CRS. As a step toward decentralized diagnostic systems, we developed a proof-of-concept digital microfluidic (DMF) diagnostic platform that possesses the flexibility and performance of automated immunoassay platforms used in central facilities, but with a form factor the size of a shoebox.

METHODS

DMF immunoassays were developed with integrated sample preparation for the detection of rubella virus (RV) IgG and IgM. The performance (sensitivity and specificity) of the assays was evaluated with serum and plasma samples from a commercial antirubella mixed-titer performance panel.

RESULTS

The new platform performed the essential processing steps, including sample aliquoting for 4 parallel assays, sample dilution, and IgG blocking. Testing of performance panel samples yielded diagnostic sensitivity and specificity of 100% and 100% for both RV IgG and RV IgM. With 1.8 μL sample per assay, 4 parallel assays were performed in approximately 30 min with <10% mean CV.

CONCLUSIONS

This proof of concept establishes DMF-powered immunoassays as being potentially useful for the diagnosis of infectious disease.

Pathogenesis of Congenital Rubella Virus Infection in Human Fetuses: Viral Infection in the Ciliary Body Could Play an Important Role in Cataractogenesis

Background

Development of congenital rubella syndrome associated with rubella virus infection during pregnancy is clinically important, but the pathogenicity of the virus remains unclear.

Methods

Pathological examination was conducted on 3 aborted fetuses with congenital rubella infection.

Findings

At autopsy, all 3 aborted fetuses showed congenital cataract confirmed by gross observation. Rubella virus infection occurred via systemic organs including circulating hematopoietic stem cells confirmed by immunohistochemical and molecular investigations, and major histopathogical changes were found in the liver. It is noteworthy that the virus infected the ciliary body of the eye, suggesting a possible cause of cataracts.

Interpretation

Our study based on the pathological examination demonstrated that the rubella virus infection occurred via systemic organs of human fetuses. This fact was confirmed by immunohistochemistry and direct detection of viral RNA in multiple organs. To the best of our knowledge, this study is the first report demonstrating that the rubella virus infection occurred via systemic organs of the human body. Importantly, virus infection of the ciliary body could play an important role in cataractogenesis.

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This study demonstrates that congenital rubella virus infection occurred via systemic organs of human fetuses.

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Virus infection of the ciliary body could play an important role in cataractogenesis.

Measles Epidemics Among Children in Vietnam: Genomic Characterization of Virus Responsible for Measles Outbreak in Ho Chi Minh City, 2014

Background

Measles remains poorly controlled in Southeast Asia, including Vietnam.

Objectives

The aim of this study was to characterize genes of virus responsible for a measles outbreak among children in Vietnam in 2014.

Study design

Throat swab samples were collected from 122 pediatric patients with suspected measles. Furthermore, peripheral blood mononuclear cells (PBMCs) from 31 of these cases were also collected. Measles virus (MV) RNA was obtained directly from the clinical specimens, amplified by PCR, and then the N and H genes were sequenced.

Results

MV RNA was detectable in throat swabs from all 122 patients tested. Positive-strand viral RNA, which indicates the intermediate replicative form of MV, was also detected in PBMCs from all 31 cases from whom these cells were collected. One hundred and eighteen strains with the N gene were obtained by RT-PCR and sequenced. Using phylogenetic analysis with measles reference sequences, all of the Vietnamese strains were found to be genotype D8. However, all strains formed a distinct cluster within the genotype D8 group (D8-VNM) suggesting their own lineage. This distinct cluster was supported by a branch with a 99% bootstrap value and 3.3% nucleotide divergence in the N-450 region of the N gene from the D8 reference strain. Notably, all of the D8-VNM variant strains represented unique amino acid sequences consisting of R442, S451 and G452 in the N-450 region of the N gene.

Conclusions

Measles viruses responsible for outbreaks in Southern Vietnam belonged to a genotype D8 variant group which had unique amino acid sequences in the N gene. Our report provides important genomic information about the virus for measles elimination in Southeast Asia.

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Measles viruses responsible for outbreaks among children in Southern Vietnam in 2014, belonged to genotype D8 variant group which had unique amino acid sequences in the N-450 region of the N gene.

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Our report provides important genomic information of the virus for measles elimination in Southeast Asia.

Surveillance for congenital rubella in Australia since 1993: cases reported between 2004 and 2013

OBJECTIVE

To describe the epidemiology of congenital rubella infections notified to the Australian Paediatric Surveillance Unit (APSU) from 2004 to 2013 and compare that with previously published APSU data for 1993-2003.

METHODS

Active national surveillance for congenital rubella infection has been conducted through the APSU since 1993. Monthly reporting by child health clinicians according to pre-defined case criteria triggers requests for clinicians to provide de-identified clinical, epidemiological, and laboratory information. Data were extracted for cases reported between January 2004 and December 2013 and compared with previous years.

RESULTS

Five cases of confirmed congenital rubella infection were identified during the reporting period. All five infants had defects consistent with congenital rubella syndrome (CRS). Four of the infants were born in Australia during the study period, and all were born to mothers born overseas. Three of the five mothers had not had rubella vaccination, and in two vaccination status was unknown, although both were from countries without routine rubella immunization programmes. Since 1993, there have been 57 notifications of congenital rubella infection to the APSU; 40 of these infants were born between January 1993 and December 2013, of whom 34 had confirmed CRS.

CONCLUSIONS

Congenital rubella infection in Australia is predominantly among children born to unimmunized immigrant mothers. Migrant women born in rubella endemic countries without routine immunization remain an important group to target for vaccination. Rubella-susceptible women, especially those in the early stages of pregnancy, should also carefully consider the risks of travelling to rubella endemic countries.

Characterization of rubella virus genotypes among pregnant women in northern Vietnam, 2011-2013

Rubella virus (RV) infection is an unresolved clinical complication that affects children in developing countries including Vietnam. RV infection during the first trimester of pregnancy causes severe birth defects known as congenital rubella syndrome. This study reports on the genomic characterization of RV strains circulating in northern Vietnam during 2011-2013. RV-IgM positive amniotic fluid specimens were collected from 38 women from northern Vietnam who presented with clinical rubella at the National Hospital of Obstetrics and Gynecology in Hanoi, Vietnam. The RV genes were determined by nested PCR with primers amplifying the 739-nucleotide coding region of the E1 gene. The sequences from the amplified DNA fragments were phylogenetically analyzed and compared to reference RV strains. Seventeen out of 38 samples are positive for RV detecting. All new RV isolates are clustered to genotype 2B. Eighteen amino acid mutations were found in the T and B cell epitopes. These results suggest that genotype 2B RV strains frequently circulate in northern Vietnam. These data describe the RV genotype in Vietnam with the aim of improving maternal and child health in this country.