Tissue tropism is the range of cells and tissues of a host that support growth of a particular pathogen, such as a virus, bacterium or parasite.

Some bacteria and viruses have a broad tissue tropism and can infect many types of cells and tissues. Other viruses may infect primarily a single tissue. For example, rabies virus affects primarily neuronal tissue. Similarly, JC virus (JCV) primarily affects and resides in kidneys.

Factors influencing viral tissue tropism include:

The cellular receptors are the proteins found on a cell or viral surface. These receptors are like keys, allowing the viral cell to fuse with or attach itself to a cell. The way that these proteins are acquired is through a similar process to that of an infection cycle.

Tissue tropism develops in the following stages:

Example: HIV has a gp120, which is precisely what the CD4 marker is on the surface of the macrophages and T cells. Thus HIV can enter T cells and macrophages