What is the term for the protein coat surrounding a virus?

The term for the protein coat surrounding a virus is "capsid." The capsid serves several important functions, including protecting the viral genetic material and assisting in the delivery of the viral genome into host cells. It is composed of protein subunits called capsomers, which assemble in a specific arrangement to form the protective layer. This structure is crucial for the virus's ability to infect host cells, as it facilitates attachment and entry into the cells it targets.

The other terms do not refer to the viral protein coat. For instance, "capsomere" refers to the individual protein subunits that make up the capsid, while "spore" is a reproductive structure in fungi, plants, and some bacteria, and "cell wall" pertains to the rigid outer layer found in plant cells, bacteria, and fungi, providing structure and protection to those cells. Thus, "capsid" is the appropriate term for describing the protein coat of a virus.