Molecular aspects of the teratogenesis of rubella virus.

Rubella or German measles is an infection caused by rubella virus (RV). Infection of children and adults is usually characterized by a mild exanthematous febrile illness. However, RV is a major cause of birth defects and fetal death following infection in pregnant women. RV is a teratogen and is a major cause of public health concern as there are more than 100,000 cases of congenital rubella syndrome (CRS) estimated to occur every year. Several lines of evidence in the field of molecular biology of RV have provided deeper insights into the teratogenesis process. The damage to the growing fetus in infected mothers is multifactorial, arising from a combination of cellular damage, as well as its effect on the dividing cells. This review focuses on the findings in the molecular biology of RV, with special emphasis on the mitochondrial, cytoskeleton and the gene expression changes. Further, the review addresses in detail, the role of apoptosis in the teratogenesis process.

Molecular aspects of the teratogenesis of rubella virus

Rubella or German measles is an infection caused by rubella virus (RV). Infection of children and adults is usually characterized by a mild exanthematous febrile illness. However, RV is a major cause of birth defects and fetal death following infection in pregnant women. RV is a teratogen and is a major cause of public health concern as there are more than 100,000 cases of congenital rubella syndrome (CRS) estimated to occur every year. Several lines of evidence in the field of molecular biology of RV have provided deeper insights into the teratogenesis process. The damage to the growing fetus in infected mothers is multifactorial, arising from a combination of cellular damage, as well as its effect on the dividing cells. This review focuses on the findings in the molecular biology of RV, with special emphasis on the mitochondrial, cytoskeleton and the gene expression changes. Further, the review addresses in detail, the role of apoptosis in the teratogenesis process.

Rubella virus does not induce apoptosis in primary human embryo fibroblast cultures: a possible way of viral persistence in congenital infection.

Congenital rubella is a persistent infection that contrasts with acute postnatal infection. Basis of the Rubella virus (RV) persistence still remain unknown, though several hypotheses have been postulated. RV induces apoptosis in cell lines, maybe as a way of cell-autonomous defense mechanism against virus. Considering the pattern of c-oncogenes expression during embryogenesis, which promotes proliferation while it inhibits apoptosis in specific cells, at certain times, it can be proposed that when RV infection establishes early in gestation, embryo cells that are proliferating have their apoptotic pathways shut down; then infected proliferating embryo cells cannot execute their apoptotic death program. We here report that RV induces apoptosis in human normal-term placenta chorionic villi explants (CVE) and in monolayers of cytotrophoblasts (CTB), but does not induce apoptosis in primary human embryo fibroblasts (HEF) cultures. These results suggest distinct responses to RV infection when comparing differentiated cells, as CTB, to cells with high proliferating potential, as HEF. RV shoots apoptosis in the former, whereas in fibroblastic dividing cells derived from embryo, RV appears not to be enough stimulus to activate the genetic program of cell death.

Detection of rubella-virus-induced apoptosis in Vero cell cultures with hematoxylin and eosin staining.

In order to facilitate the detection of apoptotic cells (Apo C) in Rubella virus (RV) infected cultures in settings of low resources, we compared hematoxylin and eosin staining (H&E) with the conventional TUNEL technique, and confirmed our findings with DNA electrophoresis and transmission electron microscopy. H&E allowed to distinguish Apo C from non-apoptotic cells. The proportion of Apo C in infected cultures was proportional to the multiplicity of infection (MOI). At a MOI of 10, the percent of Apo C at 3, 4 and 5 days post infection (pi) were 26, 45 and 47%, respectively, which were significantly reduced when the caspase inhibitor z-VAD-fmk was present in the supernatant. By the TUNEL assay, the percent of Apo C in RV-infected cultures were lower (0.8, 1.2 and 1.2% at 3, 4 and 5 days pi, respectively). Our results have shown that H&E staining is an easy, rapid, economic and reproducible method to detect Apo C in RV infected Vero cells cultures. It is possible that H&E makes evident early stages of apoptosis, when an apoptotic cell shows chromatin condensation, nuclear and cytoplasmic contraction (but is still attached to the monolayer), while TUNEL detects later stages of apoptosis because it needs an extensive DNA fragmentation, when apoptotic cells are about to or have already detached from the substratum.

RC-IAL cell line: sensitivy of rubella virus grow

Objetivo: Descreve-se o crescimento do vírus-padräo da rubéola RA-27/3 na linhagem celular RC-IAL, com desenvolvimento de efeito citopático em resposta à infecçäo viral. Para este propósito, o vírus-padräo foi titulado simultaneamente nas linhagens celulares Vero, SIRC e RK13. Métodos: O vírus-padräo da rubéola RA-27/3 foi inoculado na linhagem celular RC-IAL (rim de coelho, Instituto Adolfo Lutz). Placas contendo 1,5c105 células/ml foram inoculadas com 0,1ml do contendo 1x104 DICT50/0,1 ml. O efeito citopático correspondente a 25 por cento foi observado após 48h e 100 por cento após 96h. Os resultados obtidos foram comparados com o crescimento do vírus nas linhagens celulares SIRC, Vero e RK13. O vírus da rubéola na linhagem celular RC-IAL foi detectado por imuno-histoquímica. Resultados: As células inoculadas com o vírus da rubéola apresentaram efeito citopático nas primeiras 48h. As células apresentaram aspecto arredondado, com formaçäo de alguns prolongamentos citoplasmáticos e sincícios, produzindo células multinucleadas. A curva do crescimento da infectividade do vírus foi praticamente a mesma que a observada nas outras linhagens celulares. Conclusäo: Os resultados obtidos mostram que a linhagem celular RC-IAL é um ótimo substrato para crescimento do vírus da rubéola, pois poucas linhagens celulares descritas na literatura apresentam efeito citopático considerável e podem ser utilizadas para preparaçäo de antígenos e nos testes de diagnóstico sorológico para o vírus da rubéola

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.

The maternal awareness of the effect of the rubella infection and the sero-epidemiology of the virus among women in urban Trinidad - abstract

The objectives of this study were to assess the effectiveness of health education on immunization and to determine the immune status of a cohort of pregnant females. A questionnaire survey was conducted on 200 consecutive pregnant women attending antenatal clinic at the General Hospital, Port-of-Spain from May 22 to May 31, 1989 to determine their awareness of the symptoms and teratogenicity of rubella. Overall, 179 (89.5 percent) subjects were aware of the disease but one-third of this group were uncertain of its symptoms. The older more parous women and those with a superior level of education were better informed about rubella. Only 43 percent of women knew about the specific teratogenetic effects of the virus. The target groups identified for a rubella education programme were pregnant teenagers, those of low parity and women with a primary level of education. There was a rise in seropositivity by about 20 percent to 58.5 percent over the preceding 20 years and this may be due to the occurrence of 2 epidemics during this period and an increasing population density. The immunization campaign started in 1984 was not considered a major contributory factor. It is suggested that a more comprehensive health education programme be implemented as well as extension of vaccination to prepubertal boys and those in high-risk groups (e.g., health workers) (AU)