Transcription
Foreign. [Music]
Welcome back, guys. In this video tutorial, we'll be learning a very basic overview of viral pathogenesis. Now, viral pathogenesis, unlike bacterial pathogenesis, is a much simpler process. But how a virus actually infects a host cell and evades immunity is a remarkable feature. We'll be learning all of these steps in detail, but in this video, we'll be talking about the basic overview of viral pathogenesis.
Now, in this viral pathogenesis—again, this is a multi-step process, meaning it's composed of different rounds of processes—let me talk about it. The first process is the attachment of the virus particle to the host cell. Now, let me tell you, the virus particle we are talking about—the virus particle we are talking about—which is responsible for the disease and which is present outside the host cell as a non-living thing, is called a virion. You should know this terminology pretty clearly; it is called a virion. Now, when we are talking about virions, that means they are not living; they're outside the host cell. Now, the virions are always finding the host cell for their entry. So, the very first step is the entry of this virion, or the very first step is the attachment of the virion to the host cell surface. So let me talk about the first step: the attachment, attachment, attachment of the virion to the host cell, to the host cell, via a cell receptor. This process can also be a part of adsorption, that is a simple surface interaction between the virion and the host cell.
Now, the second process is the internalization of that virion inside the host cell, and the virion will convert into a virus, or a mature kind of virus. So, the second part is internalization, internalization, internalization of this inside the host cell. They can be internalized via receptor-mediated endocytosis or via membrane fusion. So there are two processes; we'll be talking about them later. After internalization inside the host cell, it is time for the unpacking of the virus. You can write it as unpacking, unpacking of the virus, unpacking of viral virus, or viral unpacking of the virus. Unpacking of the virus means when the different components of the virus—that means the protein component—is separated from the genomic component.
After the unpacking of the virus inside the host cell, the major part begins, which is DNA replication, DNA replication, and then obviously RNA synthesis, and then obviously protein synthesis. Because ultimately every expression should be conducted by the expression of proteins, protein synthesis is required, and that's how the process is done. So, majorly there are four different steps: one is virus particle attachment; then internalization; third is unpacking; and the fourth is the intracellular processes by the viruses. These are four different simple strategies taken up by viruses to elucidate any kind of pathogenesis in the host cell.