Membrane fusion

Definition

Membrane fusion is the process by which two lipid bilayers merge to form a single continuous membrane, allowing for the entry of viruses into host cells. This mechanism is crucial for viral infection, as it facilitates the delivery of viral genetic material into the host cell's cytoplasm, enabling replication. Understanding membrane fusion helps explain how viruses achieve host range and tissue tropism, as different viruses may use specific pathways to interact with various cell types.

5 Must Know Facts For Your Next Test

1. Membrane fusion is a critical step in the lifecycle of enveloped viruses, such as HIV and influenza, which rely on this process to infect host cells.
2. The mechanism of membrane fusion can occur at the cell surface or after endocytosis, depending on the type of virus and its entry strategy.
3. Fusion proteins often undergo conformational changes triggered by binding to host cell receptors, promoting the merging of viral and cellular membranes.
4. The efficiency of membrane fusion can influence a virus's host range and tissue tropism, as some viruses may only fuse with specific cell types.
5. Membrane fusion can be inhibited by certain antiviral drugs that target viral fusion proteins, providing a therapeutic strategy to combat viral infections.

Review Questions

• How does membrane fusion contribute to the process of viral entry into host cells?
  • Membrane fusion allows enveloped viruses to merge their lipid bilayer with the host cell membrane, effectively releasing their genetic material into the cytoplasm. This step is vital for initiating infection since it enables the virus to bypass physical barriers and gain access to the cellular machinery necessary for replication. Without successful membrane fusion, a virus would be unable to enter and establish an infection within a host.
• Discuss the relationship between membrane fusion and viral host range and tissue tropism.
  • Membrane fusion plays a significant role in determining a virus's host range and tissue tropism because different viruses have evolved unique mechanisms and receptors for fusion. This specificity allows some viruses to infect only certain cell types or species. For example, a virus that requires a specific receptor on a cell's surface for membrane fusion will only be able to infect cells expressing that receptor, thereby limiting its potential host range and defining its tissue preferences.
• Evaluate the implications of targeting membrane fusion in antiviral therapies and how this approach could alter treatment strategies for viral infections.
  • Targeting membrane fusion presents a promising strategy for antiviral therapies by inhibiting the fusion proteins necessary for viral entry. By disrupting this process, drugs can prevent viruses from successfully infecting host cells. This approach could lead to the development of more effective treatments that are less prone to resistance than traditional antiviral medications. Additionally, understanding the mechanisms of membrane fusion can aid in vaccine design by identifying key targets that elicit immune responses, providing a dual avenue for combating viral infections.

Related terms

Viral envelope: A lipid bilayer derived from the host cell membrane that surrounds some viruses, playing a key role in the fusion process.

Receptor-mediated endocytosis: A cellular process where cells internalize substances by engulfing them in membrane-bound vesicles, often involving receptor proteins.

Fusion proteins: Specific viral proteins that facilitate the membrane fusion process, enabling the virus to enter the host cell.