Viral Antigens

RSV is characterized by its negative-sense, single-stranded RNA genome, which is approximately 15.2 kb in length and encodes 11 proteins . The virus primarily infects the epithelial cells of the respiratory tract, leading to inflammation and cell damage . RSV has two major antigenic subgroups, A and B, which differ in the hypervariable region of the G protein gene . The virus is known for its ability to form syncytia, large multinucleated cells, by fusing infected cells .

RSV plays a crucial role in immune responses and pathogen recognition. It is a leading cause of lower respiratory tract infections, such as bronchiolitis and pneumonia, particularly in infants and the elderly . The virus triggers an immune response that includes the activation of various immune cells and the production of cytokines and chemokines . Despite the immune response, reinfection with RSV is common due to the virus’s ability to evade the immune system .

RSV infects host cells through the attachment of its F and G glycoproteins to the host cell receptors, such as TLR4 and nucleolin . The F protein facilitates the fusion of the viral envelope with the host cell membrane, allowing the virus to enter the cell . Once inside, the virus replicates its RNA genome and produces viral proteins, leading to the assembly of new virions . The infection process results in the formation of syncytia and the release of pro-inflammatory mediators, contributing to the symptoms of RSV infection .

The expression and activity of RSV are regulated at multiple levels. Transcriptional regulation involves the control of viral RNA synthesis by the viral RNA-dependent RNA polymerase . Post-translational modifications, such as glycosylation of the G protein, play a role in the virus’s ability to evade the host immune system . Additionally, RSV employs various strategies to interfere with the host’s innate immune response, including the inhibition of interferon signaling pathways .

RSV has significant applications in biomedical research, diagnostics, and therapeutics. In research, RSV serves as a model for studying viral pathogenesis and host immune responses . Diagnostic tools for RSV include antigen testing, molecular testing, and viral culture . Therapeutic strategies for RSV infection primarily involve supportive care, such as oxygen therapy and mechanical ventilation, with antiviral medications like ribavirin used in severe cases . Recently, vaccines for RSV have been developed and approved for use in older adults and pregnant women to protect infants .

RSV plays a role throughout the human life cycle, from infancy to old age. In infants, RSV is a leading cause of hospitalization due to severe respiratory infections . As individuals age, the immune response to RSV wanes, leading to increased susceptibility to reinfection and more severe disease outcomes . In the elderly and immunocompromised individuals, RSV can cause significant morbidity and mortality . The development of vaccines and other preventive measures aims to reduce the burden of RSV across all age groups .