Molecular aspects of the teratogenesis of rubella virus

Trends in the cytogenetic and immunologic status of healthy persons; Kazakhstan, 2007-2022

Environmental pollution can affect immune health and genome stability. We have studied the immunological and cytogenetic status of healthy urban (Almaty City, which has high levels of air pollution) and rural residents of southern Kazakhstan, over the past 15 years. Differences between the groups in plasma immunoglobulin levels and chromosomal aberration frequencies were noted. Over the 15-year study period, decreases of immunoglobulin levels and increases of chromosomal aberration frequencies were observed and correlated with place of residence and ecological status of the region of residence; both ecological deterioration and the coronavirus pandemic are likely to have had negative effects.

Fundus imaging features of congenital rubella retinopathy

PURPOSE

To evaluate the clinical characteristics of congenital rubella retinopathy (CRR) with modern fundus imaging.

METHODS

Single-center case series. Eleven patients (2005-2020) at the Emory Eye Center with known or presumed CRR. Trained image readers reviewed fundus imaging (color fundus photography, widefield pseudocolor imaging, near-infrared reflectance imaging, autofluorescence imaging, and spectral-domain optical coherence tomography) for pre-specified features suggestive of CRR.

RESULTS

Eleven patients with confirmed (63.6%) or presumed (36.3%) CRR were identified. All were female with median (range) age of 53 (35-67) years. Six (54.5%) were born during the 1964-1965 United States rubella epidemic. All had congenital hearing loss. Two (18.2%) had a congenital heart defect. Eleven (50.0%) eyes had salt-and-pepper retinal pigmentary changes. Twenty-two eyes (100.0%) had irregularly distributed regions of speckled hypoautofluorescence. One eye (4.5%) had a presumed macular neovascularization.

CONCLUSION

Modern fundus imaging demonstrates characteristic features of CRR, even when pigmentary changes are not readily apparent on examination. Widefield autofluorescence findings of irregularly distributed speckled hypoautofluorescence are particularly revealing. This series of newly diagnosed adults with CRR may represent the milder end of the phenotypic spectrum of this condition, highlighting imaging findings that may aid in diagnostically challenging cases of CRR.

Rubella Vaccine Uptake among Women of Childbearing Age in Healthcare Settings

BACKGROUND

Rubella is a contagious viral infection that occurs most often in children and young adults. Rubella is the leading vaccine-preventable cause of birth defects. Rubella infection in pregnant women may cause fetal death or congenital defects known as congenital rubella syndrome. There is no specific treatment for rubella, but the disease is preventable by vaccination with an efficacy of over 95%. Vaccination coverage is still below the recommended levels and many cases have occurred worldwide. The COVID-19 pandemic has had a negative impact on the immunization programs and the quality of disease surveillance worldwide. Operators of the healthcare setting are at increased risk of infection due to their work duties and should receive preventive vaccination or serologic protection to work in a healthcare setting.

AIMS

To evaluate the serological evidence of rubella IgG antibodies in female healthcare operators of childbearing age, to assess the risk of a breakthrough infection and the need for an additional dose of vaccine.

METHODS

We collected age and antibody titers from 449 young female operators aged <50 years who underwent the periodic surveillance at the Occupational Medicine Unit of the Policlinico Tor Vergata, Rome, from January to July 2022. Subjects were considered immune if the anti-rubella IgG titer was >11.00 IU/mL.

RESULTS

The rate of serologically unprotected subjects was 9.13% (41/449). The mean age of protected subjects was 26.93 years, while the mean age of unprotected subjects was 28.24 years. Age did not correlate with mean titer on statistical analysis (p = 0.10). The acceptance rate among unprotected operators was 31.7%. A positive attitude towards vaccination was found in 11/28 (39.3%) of the unvaccinated subjects, while a negative tendency was found in 2/28 (7.1%) of these subjects; most of the unvaccinated operators 15/28 (53.6%) prefer to postpone the administration of the vaccine. When compared with a similar population from the pre-pandemic period, the actual proportion of immune female subjects was not significantly different from that found in 2019 (90.87% vs. 90.3%).

CONCLUSIONS

Protection against rubella was suboptimal among female healthcare workers of childbearing age. Acceptance of the rubella vaccine among these operators was low. Most of those who were hesitant intended to postpone the vaccination, while a minority had negative attitudes toward vaccination. A policy of mandatory vaccination policy should overcome the reluctance of operators.

Sphingomyelin synthase 1 supports two steps of rubella virus life cycle

Our knowledge of the regulatory mechanisms that govern the replication of the rubella virus (RV) in human cells is limited. To gain insight into the host-pathogen interaction, we conducted a loss-of-function screening using the CRISPR-Cas9 system in the human placenta-derived JAR cells. We identified sphingomyelin synthase 1 (SGMS1 or SMS1) as a susceptibility factor for RV infection. Genetic knockout of SGMS1 rendered JAR cells resistant to infection by RV. The re-introduction of SGMS1 restored cellular susceptibility to RV infection. The restricted step of RV infection was post-endocytosis processes associated with the endosomal acidification. In the late phase of the RV replication cycle, the maintenance of viral persistence was disrupted, partly due to the attenuated viral gene expression. Our results shed light on the unique regulation of RV replication by a host factor during the early and late phases of viral life cycle.

Maternal Toxoplasma gondii infection affects proliferation, differentiation and cell cycle regulation of retinal neural progenitor cells in mouse embryo

Background

Toxoplasmosis affects one third of the world population and has the protozoan Toxoplasma gondii as etiological agent. Congenital toxoplasmosis (CT) can cause severe damage to the fetus, including miscarriages, intracranial calcification, hydrocephalus and retinochoroiditis. Severity of CT depends on the gestational period in which infection occurs, and alterations at the cellular level during retinal development have been reported. In this study, we proposed a mouse CT model to investigate the impact of infection on retinal development.

Methods

Pregnant females of pigmented C57BL/6 strain mice were infected intragastrically with two T. gondii cysts (ME49 strain) at embryonic day 10 (E10), and the offspring were analyzed at E18.

Results

Infected embryos had significantly smaller body sizes and weights than the PBS-treated controls, indicating that embryonic development was affected. In the retina, a significant increase in the number of Ki-67-positive cells (marker of proliferating cells) was found in the apical region of the NBL of infected mice compared to the control. Supporting this, cell cycle proteins Cyclin D3, Cdk6 and pChK2 were significantly altered in infected retinas. Interestingly, the immunohistochemical analysis showed a significant increase in the population of β-III-tubulin-positive cells, one of the earliest markers of neuronal differentiation.

Conclusions

Our data suggests that CT affects cell cycle progression in retinal progenitor cells, possibly inducing the arrest of these cells at G2/M phase. Such alterations could influence the differentiation, anticipating/increasing neuronal maturation, and therefore leading to abnormal retinal formation. Our model mimics important events observed in ocular CT.

Rubella Virus Infections: A Bibliometric Analysis of the Scientific Literature from 2000 to 2021

Rubella virus (RuV) generally causes a mild infection, but it can sometimes lead to systemic abnormalities. This study aimed to conduct a bibliometric analysis of over two decades of RuV research. Medical studies published from 2000 to 2021 were analyzed to gain insights into and identify research trends and outputs in RuV. R and VOSviewer were used to conduct a bibliometric investigation to determine the globally indexed RuV research output. The Dimensions database was searched with RuV selected as the subject, and 2500 published documents from the preceding two decades were reviewed. The number of publications on RuV has increased since 2003, reaching its peak in 2020. There were 12,072 authors and 16,769 author appearances; 88 publications were single-authored and 11,984 were multi-authored. The United States was the most influential contributor to RuV research, in terms of publications and author numbers. The number of RuV-related articles has continued to increase over the past few years due to the significant rubella burden in low-income nations. This study will aid in formulating plans and policies to control and prevent RuV infections.

Biological properties of domestic strain vRub-Ant of rubella virus

Introduction. Rubella is a mild infectious disease affecting mainly children and is caused by the rubella virus, part of the Matonoviridae family, genus Rubivirus. Rubella causes congenital rubella syndrome (CRS) and is the main cause of developmental abnormalities, especially blindness and deafness. There is no specific treatment for rubella and CRS. In order to avoid possible complications from rubella infection, a live attenuated rubella vaccine based on the foreign strain of Wistar RA 27/3 rubella virus is used. However, the actual, more effective and preferred vaccine strain the rubella virus for the Russian Federation is considered to be a viral strain of rubella circulating on its territory. The aim of the study was to study the biological properties of the developed domestic cold-adapted strain vRub-Ant circulating in the territory of the Russian Federation. Materials and methods. Following cell cultures were used in the study human embryo lung diploid cell strain LECH-3, transferable cell line from embryonic kidney cells of green monkeys Vero CCL-81 and Vero ECC, human mesenchymal stem cells, human peripheral blood mononuclear cells (PBMC). Cell cultures were grown on a DMEM/F12 nutrient medium with the addition of 5% fetal bovine serum. Swabs from the pharynx and nasal passages from a child with rubella were used as clinical virus-containing material. Monoclonal anti-idiotypic antibodies m(anti-ID)Ab were used to assess the expression level of alpha/beta and gamma interferon receptors (/ and IFN-R)Ab, imitating the biological effects of alpha/beta and gamma interferons (/ and IFN) of humans. The cultural, virological, immunochemical and serological research methods were applied in the study. Results. Attenuation of the vRub-Ant clinical isolate of rubella virus was carried out for 20 consecutive passages on LECH-3 diploid cells at a reduced temperature of 30C. The main biological markers of attenuation were determined to be ts and ca phenotypes. The avirulence of the attenuated viral strain (att-phenotype) was assessed by the level of expression of / and IFN-R. A lower level of / and IFN-R expression was found on the membranes of human PBMC induced by the vaccine strain vRub-Ant in comparison with the parent wild variant of the rubella virus. This trait,the att phenotype, is characteristic of attenuated viral strains. It has been shown that the vaccine strain vRub-Ant has lost neurotropism and was unable to bind to the membrane receptors of the brain (MRB) of guinea pig embryos, unlike its parent rubella virus strain. The high immunogenicity of the domestic cold-adapted strain vRub-Ant was confirmed by high titers of neutralizing rubella antibodies observed in guinea pigs immunized subcutaneously with one vaccination dose of the virus. Conclusion. A domestic attenuated vaccine strain vRub-Ant of the rubella virus that has the main biological markers of attenuation (ts-ca and att phenotypes) has been developed. The vaccine strain vRub-Ant induces a high levels of neutralizing antibodies in guinea pigs following the immunization with a single vaccination dose of the vaccine. The viral strain vRub-Ant has lost its tropism to the MRB of guinea pig embryos, unlike its parent variant.

Rubella Virus Triggers Type I Interferon Antiviral Response in Cultured Human Neural Cells: Involvement in the Control of Viral Gene Expression and Infectious Progeny Production

The type I interferon (IFN) response is one of the primary defense systems against various pathogens. Although rubella virus (RuV) infection is known to cause dysfunction of various organs and systems, including the central nervous system, little is known about how human neural cells evoke protective immunity against RuV infection, leading to controlling RuV replication. Using cultured human neural cells experimentally infected with RuV RA27/3 strain, we characterized the type I IFN immune response against the virus. RuV infected cultured human neural cell lines and induced IFN-β production, leading to the activation of signal transducer and activator of transcription 1 (STAT1) and the increased expression of IFN-stimulated genes (ISGs). Melanoma-differentiation-associated gene 5 (MDA5), one of the cytoplasmic retinoic acid-inducible gene I (RIG-I)-like receptors, is required for the RuV-triggered IFN-β mRNA induction in U373MG cells. We also showed that upregulation of RuV-triggered ISGs was attenuated by blocking IFN-α/β receptor subunit 2 (IFNAR2) using an IFNAR2-specific neutralizing antibody or by repressing mitochondrial antiviral signaling protein (MAVS) expression using MAVS-targeting short hairpin RNA (shRNA). Furthermore, treating RuV-infected cells with BX-795, a TANK-binding kinase 1 (TBK1)/I kappa B kinase ε (IKKε) inhibitor, robustly reduced STAT1 phosphorylation and expression of ISGs, enhancing viral gene expression and infectious virion production. Overall, our findings suggest that the RuV-triggered type I IFN-mediated antiviral response is essential in controlling RuV gene expression and viral replication in human neural cells.

Revisiting Regulated Cell Death Responses in Viral Infections

The fate of a viral infection in the host begins with various types of cellular responses, such as abortive, productive, latent, and destructive infections. Apoptosis, necroptosis, and pyroptosis are the three major types of regulated cell death mechanisms that play critical roles in viral infection response. Cell shrinkage, nuclear condensation, bleb formation, and retained membrane integrity are all signs of osmotic imbalance-driven cytoplasmic swelling and early membrane damage in necroptosis and pyroptosis. Caspase-driven apoptotic cell demise is considered in many circumstances as an anti-inflammatory, and some pathogens hijack the cell death signaling routes to initiate a targeted attack against the host. In this review, the selected mechanisms by which viruses interfere with cell death were discussed in-depth and were illustrated by compiling the general principles and cellular signaling mechanisms of virus–host-specific molecule interactions.

Pregnancy and viral infections: Mechanisms of fetal damage, diagnosis and prevention of neonatal adverse outcomes from cytomegalovirus to SARS-CoV-2 and Zika virus

Some maternal infections, contracted before or during pregnancy, can be transmitted to the fetus, during gestation (congenital infection), during labor and childbirth (perinatal infection) and through breastfeeding (postnatal infection). The agents responsible for these infections can be viruses, bacteria, protozoa, fungi. Among the viruses most frequently responsible for congenital infections are Cytomegalovirus (CMV), Herpes simplex 1–2, Herpes virus 6, Varicella zoster. Moreover Hepatitis B and C virus, HIV, Parvovirus B19 and non-polio Enteroviruses when contracted during pregnancy may involve the fetus or newborn at birth. Recently, new viruses have emerged, SARS-Cov-2 and Zika virus, of which we do not yet fully know the characteristics and pathogenic power when contracted during pregnancy.

Viral infections in pregnancy can damage the fetus (spontaneous abortion, fetal death, intrauterine growth retardation) or the newborn (congenital anomalies, organ diseases with sequelae of different severity). Some risk factors specifically influence the incidence of transmission to the fetus: the timing of the infection in pregnancy, the order of the infection, primary or reinfection or chronic, the duration of membrane rupture, type of delivery, socio-economic conditions and breastfeeding. Frequently infected neonates, symptomatic at birth, have worse outcomes than asymptomatic. Many asymptomatic babies develop long term neurosensory outcomes.

The way in which the virus interacts with the maternal immune system, the maternal-fetal interface and the placenta explain these results and also the differences that are observed from time to time in the fetal‑neonatal outcomes of maternal infections. The maternal immune system undergoes functional adaptation during pregnancy, once thought as physiological immunosuppression. This adaptation, crucial for generating a balance between maternal immunity and fetus, is necessary to promote and support the pregnancy itself and the growth of the fetus. When this adaptation is upset by the viral infection, the balance is broken, and the infection can spread and lead to the adverse outcomes previously described. In this review we will describe the main viral harmful infections in pregnancy and the potential mechanisms of the damages on the fetus and newborn.

The Epithelial-to-Mesenchymal Transition-Like Process Induced by TGF-β1 Enhances Rubella Virus Binding and Infection in A549 Cells via the Smad Pathway

Virus–host cell interactions in rubella virus (RuV) are of great interest in current research in the field, as their mechanism is not yet well understood. By hypothesizing that the epithelial-to-mesenchymal transition (EMT) may play a role in RuV infection, this study aimed to investigate the influence of TGF-β1-induced EMT of human lung epithelial A549 cells on the infectivity of RuV. A549 cells were cultured and treated with TGF-β1 for 1 to 2 days prior to virus infection (with a clinical strain). Viral infectivity was determined by flow cytometry analysis of cells harvested at 24 and 48 h post-infection (hpi) and by titration of supernatants collected at 48 hpi. The results showed that the percentages of the TGF-β1-treated A549 cells that were positive for RuV were at least twofold higher than those of the control, and the viral progeny titers in the supernatants collected at 48 hpi were significantly higher in the treatment group than in the control group. In addition, the virus binding assay showed a strong increase (more than threefold) in the percentages of RuV-positive cells, as determined by flow cytometry analysis and further confirmed by real-time PCR. Such an enhancement effect on RuV infectivity was abolished using LY364947 or SB431542, inhibitors of the TGF-β/Smad signaling pathway. The findings suggest that the TGF-β1-induced EMT-like process enhances RuV binding and infection in A549 cells via the Smad pathway. Further studies are necessary to identify possible proteins that facilitate viral binding and entry into treated cells.

Role of Inflammation in Virus Pathogenesis during Pregnancy

Viral infections during pregnancy lead to a spectrum of maternal and fetal outcomes, ranging from asymptomatic disease to more critical conditions presenting with severe maternal morbidity, stillbirth, preterm birth, intrauterine growth restriction, and fetal congenital anomalies, either apparent at birth or later in life. In this article, we review the pathogenesis of several viral infections that are particularly relevant in the context of pregnancy and intrauterine inflammation. Understanding the diverse mechanisms employed by viral pathogens as well as the repertoire of immune responses induced in the mother may help to establish novel therapeutic options to attenuate changes in the maternal-fetal interface and prevent adverse pregnancy outcomes.

Rubella Immunity among Italian Female Healthcare Workers: A Serological Study

Rubella, also known as German measles or three-day measles, is an infectious disease caused by virus of the genus Rubivirus, which may be prevented by vaccination. The infection is potentially dangerous for non immune subjects, although 20-50% of infected subjects are asymptomatic. Healthcare workers (HCWs) have an increased potential exposure to rubella in comparison to the general population, putting them and their patients at risk of infection and its complications. In 2019, 20 cases of rubella have been reported in Italy. According to the Italian National Immunization and Prevention Plan, HCWs should provide a written certification of vaccination for rubella or serological evidence of protective antibodies. The aim of the study was to evaluate the rubella immunization status in female HCWs of the teaching hospital Policlinic Rome Tor Vergata (PTV) of childbearing age. For this purpose, we retrospectively checked the serologic values of rubella-specific IgG antibodies analyzing the clinical records of the HCWs of undergoing the occupational health surveillance program from January 1st to June1st 2020. Five hundred fourteen HCWs with a mean age of 23.19 (range 19-37, DS: 2.80) were included: 90.3% (464) showed a protective antibody titre. The mean value of the anti-rubella IgG was 49.59 IU/mL. Our study shows a non-protective anti rubella IgG titre in a substantial percentage of HCWs (9.7%). As vaccine protection decreases over the years and the risk of congenital rubella syndrome (CRS) in vaccinated subjects should not be underestimated, we suggest routine screening of the immunological status followed by the administration of a third dose of vaccine if the antibody titre becomes non-protective.

Implications of TORCH Diseases in Retinal Development-Special Focus on Congenital Toxoplasmosis

There are certain critical periods during pregnancy when the fetus is at high risk for exposure to teratogens. Some microorganisms, including Toxoplasma gondii, are known to exhibit teratogenic effects, interfering with fetal development and causing irreversible disturbances. T. gondii is an obligate intracellular parasite and the etiological agent of Toxoplasmosis, a zoonosis that affects one third of the world's population. Although congenital infection can cause severe fetal damage, the injury extension depends on the gestational period of infection, among other factors, like parasite genotype and host immunity. This parasite invades the Central Nervous System (CNS), forming tissue cysts, and can interfere with neurodevelopment, leading to frequent neurological abnormalities associated with T. gondii infection. Therefore, T. gondii is included in the TORCH complex of infectious diseases that may lead to neurological malformations (Toxoplasmosis, Others, Rubella, Cytomegalovirus, and Herpes). The retina is part of CNS, as it is derived from the diencephalon. Except for astrocytes and microglia, retinal cells originate from multipotent neural progenitors. After cell cycle exit, cells migrate to specific layers, undergo morphological and neurochemical differentiation, form synapses and establish their circuits. The retina is organized in nuclear layers intercalated by plexus, responsible for translating and preprocessing light stimuli and for sending this information to the brain visual nuclei for image perception. Ocular toxoplasmosis (OT) is a very debilitating condition and may present high severity in areas in which virulent strains are found. However, little is known about the effect of congenital infection on the biology of retinal progenitors/ immature cells and how this infection may affect the development of this tissue. In this context, this study reviews the effects that congenital infections may cause to the developing retina and the cellular and molecular aspects of these diseases, with special focus on congenital OT.