Final answer:
The spike proteins of SARS-CoV-2 are crucial for virus attachment and cell entry, with variations in these proteins leading to different virus variants. Vaccines target these spike proteins to elicit an immune response. Antigenic variation in viruses can lead to changes in how the virus spreads and the severity of the disease, influencing the development of vaccines and treatments.
Step-by-step explanation:
The spike proteins on the SARS-CoV-2 virus play a critical role in its ability to infect host cells. These proteins extend outward from the viral envelope and act as the virus's method of attaching to and entering cells. Variants of SARS-CoV-2, such as those responsible for COVID-19, have arisen over time with changes in these spike proteins.
One of the ways that the immune system can target viruses is by recognizing and attacking the spike proteins. Vaccines, like the Pfizer and Moderna COVID-19 vaccines, use mRNA technology to instruct our cells to produce the spike protein of the virus, without the virus itself, to train the immune system to recognize and fight off the actual virus. As the virus mutates, resulting in different variants with potentially altered spike proteins, vaccines and treatments continue to be monitored and updated to ensure efficacy against these new strains.
Antigenic variation, such as the processes of antigenic drift and antigenic shift observed in influenza viruses, also occurs in coronaviruses, resulting in minor or major changes in the spike proteins. This can affect how fast the virus spreads or the severity of the illness it causes. Strategies to combat viral infections include the development of sub-unit vaccines focused on the immunogenic epitopes present in the viral proteins.