Chromosome studies of human cells infected in utero and in vitro with rubella virus

Viral intruders in the heart: A review of RNA viruses and their role in cardiac disorders

Viral cardiac diseases have a significant impact on global health, and RNA viruses play a crucial role in their pathogenesis. This literature review aims to provide a comprehensive understanding of the complex relationship between RNA viruses and cardiac diseases, focusing on the molecular processes and clinical implications of these interactions. The paper begins by discussing the various RNA viruses that have been linked to cardiac infections. Subsequently, the study explores the mechanisms through which RNA viruses can cause cardiac injury, including direct viral invasion, immune-mediated responses, and molecular mimicry. The review extensively examines the intricate interplay between the host immune system and RNA viruses, shedding light on both protective and harmful immune responses. Additionally, it investigates the role of viral persistence and chronic inflammation in the long-term effects on cardiac health. The thorough analysis presented not only enhances our scientific understanding of how RNA viruses contribute to the development of cardiac diseases but also highlights potential avenues for future research and breakthroughs in this field. Given the significant global health threat posed by viral cardiac disorders, unraveling the molecular foundations of these diseases is essential for advancing diagnostic capabilities and therapeutic interventions.

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 and birth defects: Molecular insights into the viral teratogenesis at the cellular level

BACKGROUND

In utero rubella virus (RV) infection of a fetus can result in birth defects that are often collectively referred to as congenital rubella syndrome (CRS). In extreme cases, fetal death can occur. In spite of the availability of a safe and effective vaccine against rubella, recent worldwide estimates are that more than 100,000 infants are born with CRS annually.

RECENT PROGRESS

Recently, several significant findings in the field of cell biology, as well as in the RV replication and virus-cell interactions, have originated from the authors' laboratory, and other researchers have provided insights into RV teratogenesis. It has been shown that 1) an RV protein induces cell-cycle arrest by generating a subpopulation of tetraploid nuclei (i.e., 4N DNA) cells, perhaps representative of the tetraploid state following S phase in the cell cycle, due to its interaction with citron-K kinase (CK); 2) RV infection induces apoptosis in cell culture, and 3) CK functional perturbations lead to tetraploidy, followed by apoptosis, in specific cell types.

CONCLUSIONS

Based on several similarities between known RV-associated fetal and cellular manifestations and CK deficiency-associated phenotypes, it is reasonable to postulate that P90-CK interaction in RV-infected cells interferes with CK function and induces cell-cycle arrest following S phase in a subpopulation, perhaps representative of tetraploid stage, which could lead to subsequent apoptosis in RV infection. Taking all these observations to the fetal organogenesis level, it is plausible that P90-CK interaction could perhaps be one of the initial steps in RV infection-induced apoptosis-associated fetal birth defects in utero.

Teratogen update: congenital rubella

It is apparent that there are many unanswered questions about the pathogenesis of CRS. For instance, the chance of embryonic infection decreases in the second semester only to increase again in the third trimester. This is presumably due to unspecified changes in the placenta. When the embryo is infected early in the first trimester it does not appear to have any conventional immunological response to prevent spread of the virus. Yet it has been suggested that only 1 in 10(3) to 10(5) of its cells become infected. If this is true, what controls the spread of the virus in the early embryo? Why does the virus not affect major morphogenetic processes? There is considerable evidence that the virus spreads through the vascular system of the infected fetus and the observed cardiovascular, CNS, and hearing defects may be primarily due to focal cytopathic damage to the walls of blood vessels and lining of the heart; subsequent organ infection and/or ischemia may lead to further damage. Damage to blood vessels is probably extensive throughout the fetus and may be the cause of the generalized growth retardation. The effects in the eye appear to be due to a direct cytopathic effect, particularly on the lens. The short susceptible period for cataract formation is consistent with the protective effect of the lens capsule. Deafness, cardiovascular and neurological damage, and retinopathy all occur when infection takes place in the first 16 weeks of gestation and are rare after this time, despite the absence of any obvious morphological or functional changes in the susceptible structures. This termination of susceptibility in the second trimester is consistent with development of the fetal immune response and increased transfer of maternal IgG. The effect on blood vessels in particular may be limited by antibody production, although existing endothelial infection and damage may be progressive. The fetus seems unable to rid itself of established intracellular virus. The causes of the well-established late manifestations remain unknown. If these serious late-appearing effects are due to prenatal damage, then it is possible that other human teratogens may also cause unexpected late symptoms. This should also be a concern in the area of animal reproductive toxicology testing.

Molecular biology of rubella virus

This chapter summarizes the present medical significance of rubella virus. Rubella virus infection is systemic in nature and the accompanying symptoms are generally benign, the most pronounced being a mild rash of short duration. The most common complication of rubella virus infection is transient joint involvement such as polyarthralgia and arthritis. The primary health impact of rubella virus is that it is a teratogenic agent. The vaccination strategy is aimed at elimination of rubella and includes both universal vaccination of infants at 15 months of age with the trivalent measles, mumps, rubella (MMR) vaccine and specific targeting with the rubella vaccine of seronegative women planning pregnancy and seronegative adults who could come in contact with women of childbearing age, although it is recommended that any individual over the age of 12 months without evidence of natural infection or vaccination be vaccinated. Medically, the current challenge posed by rubella virus is to achieve complete vaccination coverage to prevent resurgences.

Acetylsalicylic acid: no chromosome damage in human leukocytes

Acetylsalicylic acid was added to cultures of human leukocytes at several time periods over a wide range of concentrations (0.1 to 300.0 micrograms per milliliter). Leukocytes were also cultured from human volunteers during the ingestion of two 300-milligram tablets four times daily (2400 milligrams per day) over a 1-month period. No significant increase in chromosome aberrations was detected in vitro or in vivo.