This episode explores the paramyxoviruses, enveloped negative-sense single-stranded RNA viruses known for their ability to induce cell fusion. Drawing from Murray’s Chapter 48, it examines how viral surface proteins drive respiratory infection and characteristic cytopathic changes.
The family includes:
Respiratory syncytial virus (RSV)
Parainfluenza viruses
Measles virus
Mumps virus
The defining mechanistic feature is the fusion (F) protein, which allows viral envelopes to merge with host cell membranes and, importantly, promotes the formation of syncytia - multinucleated giant cells created by fusion of infected cells.
Clinically:
RSV is a major cause of bronchiolitis in infants
Parainfluenza viruses cause croup
Measles produces systemic infection with rash and immunosuppression
Mumps can affect salivary glands, testes, and central nervous system
Conceptually, paramyxoviruses illustrate how membrane fusion facilitates direct cell-to-cell spread, bypassing extracellular immune defences. Vaccination plays a critical preventive role in measles and mumps.
Key Takeaways
Paramyxoviruses are enveloped negative-sense RNA viruses
Fusion protein enables syncytium formation
Primarily infect respiratory epithelium
Some cause systemic disease with rash or glandular involvement
Vaccination significantly reduces disease burden
