Pathogenesis of gut virus infection.

In summary, the pathogenesis of many gut virus infections remains uncertain. However, human and animal studies indicate that the majority of gut viruses infect villous enterocytes. Viruses appear to have different affinities for enterocytes at different sites on the villus. Infection of enterocytes leads to cell death, extrusion into the lumen, and villous atrophy when the rate of cell production in the crypts cannot keep pace with the rate of enterocyte loss. This results in a reduced surface area as well as impairment of digestive and absorptive functions. This may also result in a net secretory state. All these changes, along with others such as reduced enzymatic activity and reduced epithelial integrity, may contribute to the induction of an acute but transient malabsorptive diarrhoea which may persist until the digestive/absorptive functions of the enterocyte are restored. However, if colonic compensation is sufficient to handle the increased fluid load, diarrhoea may not be evident. The roles of villous ischaemia, altered countercurrent exchanger of altered immune responses still remain uncertain and require further investigation.