In this video, we're going to talk about the second step in bacterial pathogenesis, which is adhesion to the host. After pathogen exposure and entry of the pathogen at the portal of entry, the pathogen must then properly adhere to the host. Adhesion is the ability of the pathogen to bind to host cells by using adhesion factors or adhesins. These adhesins are simply molecules on the surface of pathogens that bind to very specific receptors on the host cells. These adhesins can be found on bacterial pili, fimbriae or flagella. It is important to note that the Adhesin Receptor Binding is actually very very specific, and it ultimately controls the cell type that the Pathogen will adhere to and the tissue that the pathogen will cause disease in. This means that a pathogen will only be able to cause disease if it has the appropriate adhesins to bind to very specific host cell receptors. Without these very specific adhesins, they will not be able to adhere, and then they will not be able to cause disease.
If we take a look at our image down below, we can see an image focused on adhering or adhesion to the host cell. Notice once again we have our portal of entry; we have our microbe entering via our portal of entry, and there are two different microbes entering here. We have the green microbe entering right here and then we have the blue microbe entering right here. On the nasal mucus membranes, we have the green pathogen and the blue microbe. If we zoom in further into this particular region, the green pathogen has the appropriate adhesins to bind to this very specific host receptor. These host receptors are down below here, and the adhesins are these little molecules sticking off right around here. Because this green microbe has the appropriate adhesins to bind to the host cell receptors, it is going to be able to attach and adhere. However, notice that the blue microbe has a different set of adhesins. Because adhesion receptor binding is very specific, this blue microbe is not going to be able to bind. The turn away arrow here means that it will not be able to bind to the host cell receptors, and this means that this microbe will not be able to adhere and will not be able to cause an infection. Perhaps this microbe would need to make its way to a different set of cells, whose receptors are going to be compatible with these particular adhesins. Adhesion to the host is a critical step in bacterial pathogenesis.
This here concludes our brief lesson on this topic and we will be able to talk about the other steps of bacterial pathogenesis as we move forward. See you all in our next video.