Virus Entry

In the last entry, I mentioned and explained about virus attachment onto the host cell. Now I will go onto the second part of the 1st stage of the virus life cycle - Routes of host entry (Penetration).



Even if the virus particle attaches itself onto the cell surface, it does not gain entry into the host cell. There are several routes for the virus to take in order to penetrate into the host cell. Without further ado, I shall explain the routes of entry to the best of my abilities.



I. Attachment and Entry

After the virus attaches itself onto the host cell, there are 2 main routes a virus particle would take to enter an animal host cell and only 1 route in the case of a plant and bacteria host cell. In an animal cell, a virus particle can use....



1. Envelope Membrane Fusion

In envelope membrane fusion, the virus's envelope blends with the cell membrane, releasing its genome into the host cell and starts its replication.

2. Endocytosis


2a. Receptor-Mediated Endocytosis (Envelope)

In receptor-mediated endocytosis, the enveloped virus particle tricks the cell into thinking that it is nothing more than nutrients or harmless proteins. The host cell will then take in the virus particle along with its membrane. Once inside, the virus particle will then release its genome and starts its replication.


2b. Clathrin endocytosis (Naked)

In clathrin endocytosis, the naked virus binds with the host cell membrane to gain entry into the host along with the newly binded membrane from the host.

In a plant and bacteria cell particle, virus particle can only gain entry when there is a breach in their respective cell walls. From there, the virus particle will start to uncoat and starts to infect the host.

Below is a link to an animation which summarizes what the whole stage of attachment and entry is all about.

http://www.blackwellpublishing.com/wagner/animations/attach/attach.html