Respiratory Syncytial Virus (RSV)

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Questions and Answers

Why does Respiratory Syncytial Virus (RSV) primarily affect infants and the elderly, leading to severe respiratory complications?

RSV has a tropism for the unique cellular receptors present only in the lungs of infants and the elderly, facilitating rapid viral entry and replication.
The immune systems of infants and the elderly are less capable of mounting an effective defense against RSV, and infants have narrow airways. (correct)
Infants and the elderly are more likely to be exposed to RSV in specific microenvironments, such as hospitals and nursing homes, where the viral load is higher.
RSV undergoes genetic reassortment more efficiently in infants and the elderly, leading to the emergence of more virulent strains.

How does RSV induce the formation of syncytia, and what is the significance of this process in the pathophysiology of the infection?

RSV triggers the release of cytokines that promote the aggregation of infected cells into syncytia, leading to localized inflammation.
RSV's hemagglutinin mediates the fusion of infected cells, forming syncytia that promote viral shedding and transmission.
The virus's surface spikes which are fusion proteins, induce cell-cell fusion, creating multinucleated giant cells (syncytia), facilitating viral spread while evading antibody neutralization. (correct)
The virus's neuraminidase degrades the extracellular matrix, allowing infected cells to merge and form syncytia, enhancing viral dissemination.

Why does natural immunity not prevent reinfection with RSV, and what implications does this have for vaccine development strategies?

Natural immunity wanes rapidly due to the virus's ability to establish latency in immune cells.
The rapid mutation rate of RSV allows it to evade existing antibody and T cell responses, and vaccination may enhance the severity of subsequent disease. (correct)
Natural immunity redirects the virus, resulting in mild symptoms.
Natural immunity induces robust, lifelong protection against RSV, negating the need for vaccine development.

Given that RSV does not contain hemagglutinin or neuraminidase, how does it attach to and enter host cells, and what implications does this have for therapeutic interventions?

RSV utilizes its fusion proteins to bind directly to host cell receptors, bypassing the need for hemagglutinin or neuraminidase, which informs the development of fusion inhibitors as therapeutic agents. (C) Signup and view all the answers

In the context of RSV infection, what role does immunologically-mediated cell injury play in the overall pathogenesis of the disease, and how does it compare to the direct effects of viral replication?

The pathologic effect of RSV is mainly caused by direct viral invasion of the respiratory epithelium, followed by immunologically-mediated cell injury. (B) Signup and view all the answers

How does the mechanism of action of palivizumab differ from that of a traditional vaccine, and what are the implications of these differences for the prevention of RSV infection in high-risk infants?

Palivizumab is a monoclonal antibody that directly neutralizes RSV, providing passive immunity, and vaccination with the killed vaccine appears to enhance the severity of the subsequent disease. (C) Signup and view all the answers

What are the key differences between subgroup A and subgroup B RSV strains, and how might these differences impact disease severity, diagnostic accuracy, and vaccine development?

The virus has two serotypes: Subgroup A and Subgroup B. These strains differ in their antigenic properties, which may influence the effectiveness of diagnostic assays and vaccine candidates. (C) Signup and view all the answers

What are the advantages and disadvantages of using RT-PCR compared to ELISA for the diagnosis of RSV infection, considering factors such as sensitivity, specificity, turnaround time, and cost?

RT-PCR offers higher sensitivity and specificity compared to ELISA but is more expensive and requires specialized equipment and trained personnel. (D) Signup and view all the answers

How does the effectiveness of ribavirin, when used in combination with hyperimmunoglobulins against RSV, compare to that of supportive treatments (oxygen, intravenous fluids, and antipyretics) alone in severely ill hospitalized infants?

The combination of ribavirin and hyperimmunoglobulins may be more effective for severely ill hospitalized infants. (C) Signup and view all the answers

Given the limitations of current preventive and therapeutic strategies for RSV infection, what are some promising areas of research that could lead to improved outcomes in infants and the elderly?

Future research may include the development of live-attenuated vaccines, subunit vaccines, and mRNA vaccines; and a better understanding of the host immune response to RSV. (B) Signup and view all the answers

Flashcards

Respiratory Syncytial Virus (RSV)

A member of the Paramyxoviridae family with a single-stranded, negative-sense RNA genome. Its fusion proteins cause cells to fuse, forming syncytia.

RSV Transmission

Primarily through respiratory droplets and direct contact with contaminated surfaces.

RSV Pathologic Effect

Direct viral invasion of respiratory epithelium and immunologically-mediated cell injury.

RSV in Infants

Bronchiolitis and pneumonia, along with symptoms like irritability, fever, cough, wheezing, and difficulty breathing.