Pathogens, including viruses, bacteria, and parasites, often use host cell receptors as a means of attachment and entry. For example, the HIV virus utilizes the CD4 receptor on T-cells to gain entry. Similarly, the SARS-CoV-2 virus, responsible for COVID-19, binds to the ACE2 receptor on respiratory epithelial cells. This interaction between pathogen and receptor is critical for the pathogen's lifecycle and the progression of the disease.
