intracellular transport of virus

Definition

Target type: biologicalprocess

The directed movement of a virus, or part of a virus, within the host cell. [GOC:ai, GOC:bf, GOC:jl, PMID:11733033]

Intracellular transport of viruses is a complex and multifaceted process that involves a series of orchestrated steps, enabling the virus to enter the host cell, travel to its target site, replicate, and ultimately spread to infect other cells. This intricate journey is characterized by the virus's interactions with the host cell's machinery, exploiting its mechanisms for its own propagation.

The initial step in the process is **entry**, where the virus encounters the host cell and gains access to its interior. This can occur through various mechanisms, including:

* **Direct penetration:** Some viruses, like the influenza virus, can directly fuse their envelope with the host cell membrane, releasing their genetic material into the cytoplasm.
* **Endocytosis:** Many viruses, including HIV and poliovirus, are engulfed by the host cell through a process called endocytosis, forming a vesicle that encloses the virus.
* **Phagocytosis:** Some viruses can exploit the host cell's phagocytic machinery, typically used to engulf larger particles, to gain entry.

Once inside the cell, the virus embarks on its journey to the **target site**, often the nucleus where it can replicate its genome. This movement can be facilitated by:

* **Passive diffusion:** Some viruses can simply diffuse through the cytoplasm to reach their target.
* **Microtubule-mediated transport:** Viruses can hijack the host cell's microtubule network, a system of protein filaments that act as cellular highways. Motor proteins, like dynein and kinesin, can bind to the virus and propel it along these microtubules to the appropriate location.
* **Actin-mediated transport:** Actin filaments, another type of cellular scaffold, can also be utilized by viruses for movement.

The virus's journey is not always straightforward. It may encounter **cellular barriers** that need to be overcome. For instance:

* **Endosomal escape:** Viruses that enter via endocytosis must escape the acidic environment of the endosome to avoid degradation. Some viruses, like influenza, possess a protein that fuses with the endosomal membrane, releasing the virus into the cytoplasm.
* **Crossing the nuclear membrane:** Viruses that replicate in the nucleus need to traverse the nuclear envelope. This can be achieved by utilizing nuclear import receptors, proteins that facilitate the movement of molecules through the nuclear pores.

Upon reaching its target site, the virus initiates **replication**, using the host cell's machinery to produce new viral proteins and nucleic acids. This can involve:

* **Transcription:** The virus's genetic material is transcribed into messenger RNA (mRNA), which serves as a template for protein synthesis.
* **Translation:** Ribosomes, the protein synthesis machinery of the cell, translate the viral mRNA into viral proteins.
* **Assembly:** The newly synthesized viral components assemble into new viral particles.

Finally, the newly formed viruses **exit** the host cell, ready to infect other cells. This can involve:

* **Budding:** Many enveloped viruses bud from the host cell membrane, acquiring their envelope during the process.
* **Lysis:** Some viruses cause the host cell to burst, releasing a large number of viral particles.

The intracellular transport of viruses is a fascinating example of the intricate interplay between viruses and their hosts. It highlights the adaptability of viruses, their ability to manipulate cellular processes for their own propagation, and the importance of understanding these interactions for developing antiviral therapies.'
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Proteins (4)

Compounds (7)