Final answer:
A virus that specifically infects certain tissues exhibits 'tropism,' which is facilitated by proteins that bind to particular host cell receptors. The term describes the virus's selectiveness in infecting specific cell types within a host.
Step-by-step explanation:
The specificity of viral infection is akin to a key-lock mechanism, where only certain keys (viruses) fit into specific locks (host cell receptors). This interaction is facilitated by attachment proteins in the virus's capsid or glycoproteins in its envelope that bind to specific receptor sites on the host cell membrane, leading to the infection of only particular cells within a host species.
Tissue tropism highlights a particular disease-causing phenotype of viruses, as they often have the ability to infect distinct types of cells within a host. For instance, HIV targets T-helper cells, monocytes, and certain central nervous system cells, while hepatitis viruses attack liver cells due to the presence of specific glycoprotein and glycolipid patterns on the cell surfaces that the viruses can recognize.