Figure 1.

Tissue barriers to arbovirus infection. A midgut infection barrier (bottom left) occurs when viruses are unable to enter or unable to replicate in midgut epithelial cells. In contrast, a midgut escape barrier (bottom right) occurs when viruses are able to infect and replicate in midgut cells but do not disseminate from this tissue. A salivary gland infection barrier (upper left) occurs when the virus fails to infect the cells of the salivary gland, while a salivary gland escape barrier (upper right) occurs when the virus is unable to pass into the saliva. Figure created with Biorender.com.