In this video, we're going to continue to talk about animal viruses and animal virus infections by specifically focusing on the 4th step of an animal virus infection, which is the assembly of the virus inside of the host cell. And so it turns out that the mechanism of virus assembly inside of a host cell is actually really, really similar in all types of viruses. And so the assembly of the virus is specifically referring to the packaging of all of the viral components, including the viral genome and the viral proteins, all packaging and assembling together to form new viruses. Now the assembly of a virus actually occurs spontaneously when there is an abundance of viral genome and capsid proteins inside of the cell. Now it turns out that the location of viral assembly inside the host cell depends on whether the virus is an enveloped virus or a non-enveloped virus.
And so recall from our previous lesson videos that enveloped viruses have an outer lipid envelope that surrounds the nucleocapsid. And so the enveloped virus assembly is not completed until during the release of the virus from the host cell. And the reason for that is because the outer lipid envelope that the enveloped viruses have is acquired as the virus is leaving the cell, And so the complete assembly is not done until the virus is released. And so if we take a look at our image down below, notice we're showing you an image of animal virus assembly. And on the left-hand side, we're specifically focusing on the animal virus assembly of an enveloped virus. And so what you'll notice is that here we have viral proteins and viral genome that have just been synthesized and replicated. And so after the synthesis and replication of the viral components, they need to assemble together. And so here what we can see is the assembly of the nucleocapsid, the nucleic acid, and the protein shell here, And this occurs in the cytoplasm. However, for enveloped viruses, the complete assembly of the fully mature virus is not done until the release of the virus. And that's because as the envelope virus is being released, that is when it acquires its outer lipid envelope. And so it acquires the outer lipid envelope from the cytoplasmic membrane of the host cell as the virus is being released.
Now, on the other hand, for non-enveloped viruses, recall that they do not have an outer lipid envelope. And so for non-enveloped viruses, the assembly is actually completed within the host cell's cytoplasm before the virus is actually released. And so if we take a look at our image down below over here on the right-hand side, notice that we're showing you the animal virus assembly of a non-enveloped virus, which again does not have that outer lipid envelope. And so notice that here we have the viral proteins and the viral genome that were just synthesized and replicated, and they need to assemble into the virus. And the complete assembly of a non-enveloped virus occurs in the cytoplasm before the virus is actually released from the cell.
And so this is the 4th step of an animal virus infection, and after animal virus assembly is going to be the release of the animal virus. And so we'll get to talk more about the release of the animal virus later in our course. But for now, this here concludes our lesson on the 4th step of an animal virus infection, assembly of the virus inside the host cell, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.
