Maternal rubella and its effect on the foetus

Congenital Rubella: A Salient Cause of Congenital Heart Defects in Infants

BACKGROUND

Structural congenital heart defects (CHD) take a huge toll of congenital defects in children in India. Limited information is available regarding modifiable risk factors for its causation. This study was planned with an aim to determine the prevalence of congenital rubella infection in Indian infants with structural CHD's.

METHODOLOGY

This cross-sectional, observational study was conducted at a tertiary care hospital in Northern India over 1 year period (1 July 2016 to 30 June 2017). Infants <6 months with structural CHD were enrolled after taking informed consent from their mothers. Blood samples were collected from mother-child binomials and tested for rubella IgM and IgG antibodies.

RESULTS

A total of 80 infants (M : F = 56 : 24), having mean age 69.4 (±56.5) days; were enrolled. In these infants, prevalence of congenital rubella infection (either infant's IgM rubella positive or infant's IgG rubella titers higher than mother's) was 8.75% (7/80). A total of 12.5% of studied mothers were seronegative for rubella IgG antibodies. Statistically significant association was found between the occurrence of congenital rubella and cataract (p = 0.0039), splenomegaly (p = 0.007) and microcephaly (p = 0.0084) in infants having structural CHD.

CONCLUSIONS

Congenital rubella syndrome still remains an important modifiable cause for structural CHD in India. Sincere efforts for rubella elimination via further strengthening current vaccination strategy would help in decreasing burden of structural CHD in India.

Mechanisms and evidence of vertical transmission of infections in pregnancy including SARS-CoV-2s

There remain unanswered questions concerning mother‐to‐child‐transmission of SARS‐CoV‐2. Despite reports of neonatal COVID‐19, SARS‐CoV‐2 has not been consistently isolated in perinatal samples, thus definitive proof of transplacental infection is still lacking. To address these questions, we assessed investigative tools used to confirm maternal‐fetal infection and known protective mechanisms of the placental barrier that prevent transplacental pathogen migration. Forty studies of COVID‐19 pregnancies reviewed suggest a lack of consensus on diagnostic strategy for congenital infection. Although real‐time polymerase chain reaction of neonatal swabs was universally performed, a wide range of clinical samples was screened including vaginal secretions (22.5%), amniotic fluid (35%), breast milk (22.5%) and umbilical cord blood. Neonatal COVID‐19 was reported in eight studies, two of which were based on the detection of SARS‐CoV‐2 IgM in neonatal blood. Histological examination demonstrated sparse viral particles, vascular malperfusion and inflammation in the placenta from pregnant women with COVID‐19. The paucity of placental co‐expression of ACE‐2 and TMPRSS2, two receptors involved in cytoplasmic entry of SARS‐CoV‐2, may explain its relative insensitivity to transplacental infection. Viral interactions may utilise membrane receptors other than ACE‐2 thus, tissue susceptibility may be broader than currently known. Further spatial‐temporal studies are needed to determine the true potential for transplacental migration.

Zika Fetal Neuropathogenesis: Etiology of a Viral Syndrome

The ongoing Zika virus epidemic in the Americas and the observed association with both fetal abnormalities (primary microcephaly) and adult autoimmune pathology (Guillain-Barré syndrome) has brought attention to this neglected pathogen. While initial case studies generated significant interest in the Zika virus outbreak, larger prospective epidemiology and basic virology studies examining the mechanisms of Zika viral infection and associated pathophysiology are only now starting to be published. In this review, we analyze Zika fetal neuropathogenesis from a comparative pathology perspective, using the historic metaphor of "TORCH" viral pathogenesis to provide context. By drawing parallels to other viral infections of the fetus, we identify common themes and mechanisms that may illuminate the observed pathology. The existing data on the susceptibility of various cells to both Zika and other flavivirus infections are summarized. Finally, we highlight relevant aspects of the known molecular mechanisms of flavivirus replication.

Expression of rubella virus cDNA encoding the E1 structural protein

cDNAs synthesized from the 40S RNA genome of rubella virus were cloned into the lambda gt10 bacteriophage. A clone (pRV # 1475) which contains a truncated version of the E1 envelope glycoprotein (amino acid residues 17-481) and the 3' non-coding region was constructed from two overlapping cDNAs. pRV # 1475 was inserted into a eukaryotic expression vector under the control of the cytomegalovirus immediate early promoter. After transfection of 293 cells, a protein with intact antigenic domains could be detected.

Comparison of passive haemagglutination and haemagglutination-inhibition techniques for detection of antibodies to rubella virus

Because of the technical problems and length of time involved in the satisfactory performance of the haemagglutination-inhibition test for detection of rubella-specific antibodies, a commercially available passive haemagglutination (PHA) kit utilising rubella antigen-sensitised human erythrocytes was tested for its suitability for use in diagnostic laboratories. The immune response to acute rubella infections as measured by PHA was considerably delayed compared to the response measured by haemagglutination-inhitition. Titres of rubella-specific antibody only became comparable six months after the infection. The commercially available PHA kits is a useful addition to diagnostic laboratories for the determination of immune status and, in conjunction with the haemagglutination-inhibition test, can be an indicator of recent rubella infection.

Escherichia coli infection in mice and impaired fetal development

Investigations were undertaken, using the mouse as an animal model, to study the effect of Escherichia coli on fetal development. The i.v. injection of 7.5 X 10(6) bacteria, originally obtained from a suspected case of human pyelonephritis, caused only a mild and transient disturbance of maternal health but caused severe fetal wastage. Groups of mice were examined 4, 7 and 11 days after infection and the numbers of organisms were determined in the spleen, liver, kidneys, placentas and resorptions. From the findings obtained, it was concluded that the Esch. coli grew preferentially in the placentas. By the 7th day the placentas showed marked degenerative and necrotic changes and the bacteria could be recovered from the majority of fetuses at this time. Histologically, no significant changes were seen in the spleen, liver and kidneys. As a result of these findings in an animal model, and taking into consideration the observations of other workers, it is suggested that coliform bacteraemia in human pregnancies may also cause infections of the placenta and bring about abortion or premature delivery.

Role of rubella in congenital malformations in India

In the present study rubella HI antibodies were determined in cases of congenital malformation and bad obstetric history to determine the role of rubella in such cases in India, as it has been reported to be rare in Japan in contrast to Western countries. The incidence of antibodies was statistically significant in cases of congenital eye, C.N.S., visceral and miscellaneous malformations and cases of spontaneous abortion and still-birth compared with controls of matching age groups. This is further supported by the demonstration of IgM antibodies in seven cases of congenital malformations and ten cases of spontaneous abortion. Our findings show that congenital rubella is not rare in India.

Chronic progressive panencephalitis due to rubella virus simulating subacute sclerosing panencephalitis

Late-onset chronic progressive panencephalitis developed in a 12-year-old boy with congenital rubella syndrome from whose brain rubella virus was isolated. Progressive dementia began at eight, and ataxia, choreiform movements, myoclonic seizures, and fine perimacular pigmentation appeared at 11 years of age. The cerebrospinal fluid was minimally pleocytotic and had a total protein of 156 mg per deciliter, of which 52 per cent was gamma globulin. Electroencephalography demonstrated generalized medium and occasional high-voltage slowing without burst suppression. The antibody titer to rubella virus (hemagglutination inhibition) was 1:8192 in serum and 1:256 in cerebrospinal fluid. Antibody titer to measles virus (complement fixation) was less than 1:8 in serum. Microscopical study of biopsied brain tissue at the age of 11 disclosed panencephalitis similar to subacute sclerosing panencephalitis, but with perivascular deposits and without inclusion bodies. Rubella virus was isolated from the brain by cocultivation with CV-1 cells.

Disease accompanying in utero viral infection. The role of maternal antibody in tissue injury after transplacental infection with lymphocytic choriomeningitis virus

Early, after in utero infection with LCM virus, SWR/J and HA/ICR mice developed manifestations of immune complex disease. Observations based on nursing such mice with virus-infected, immune, or noninfected mouse mothers indicated that maternal antiviral antibody was responsible for the early immune complex glomerulonephritis. Despite comparable viral persistance, in utero-infected offspring failed to develop glomerulonephritis when nursed by noninfected mouse mothers, but did when suckled by virus-infected mouse mothers. Nursing by mouse mothers carrying high titers of anti-LCM viral antibody markedly enhanced the Ig glomerular deposits and the resultant nephritis.

Congenital perceptive deafness: role of intrauterine rubella

Rubella antibody was detected in 85 (61%) of 139 children aged from 6 months to 7 years with congenital perceptive deafness. Of the 112 children who were aged under 4 years 61 (54%) had rubella antibody (seropositive) compared with 7.1% in randomly selected children of the same age. A close correlation was found between the presence of antibody in children with perceptive deafness and (1) a maternal history of rash or contact in early pregnancy, and (2) with the presence of other rubella-type defects. Intrauterine rubella was thought to be the cause of the deafness in 82 (59%) of the 139 children, in 60 of whom deafness was the only rubella defect detected. Thus intrauterine rubella should be considered a likely cause of congenital perceptive deafness in a child under 4 years in whom rubella antibody is present.

Retrospective survey of congenital rubella syndrome in the state of Washington, 1963-68

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Congenital rubella in schoolchildren and adolescents

Forty-one cases of congenital rubella in schoolchildren and adolecents are reported. Most children had multiple defects, the nature and severity of which could not be correlated with the reported time during pregnancy of the maternal rubella infection.

Clinical and laboratory studies with rubella vaccines in adults

Three live attenuated rubella vaccines were tested in adult volunteers. Clinical reactions were mild, but were more noticeable in vaccinated non-immune subjects than in control subjects. With the exception of two individuals, all of the remaining 54 subjects developed an immune response; the level of antibodies found was somewhat lower than that resulting from natural infection. Though virus could be isolated from some of the seronegative volunteers after vaccination, no evidence was found of transmission of infection.

Cellular viraemia in babies infected with rubella virus before birth

Chronic viraemia has been detected in 10 out of 12 rubella syndrome babies at periods ranging from 1 to 196 days. The virus was found to be associated with leucocytes, and it is assumed that removal of neutralizing antibody is the most likely explanation for the high success rate in detecting viraemia. The findings are discussed in relation to diagnosis by virus isolation, to pathogenesis, and to the possible significance in explaining the failure of the foetus to develop a tolerance to rubella virus. Several published reports of viraemia in the acute exanthematous disease are contrasted with the less frequent reports of viraemia in the chronic disease of early postnatal life.