Viruses Can Cause Disease in the Absence of Morphological Evidence of Cell Injury: Implication for Uncovering New Diseases in the Future

A viruscan replicatein differentiated cells, therebyaltering their ability to make specialized products such as endocrine hormones, neurotransmitters, and lymphokines. Systemically, the outcome can be an imbalance in homeostasis, resulting in diseases of the endocrine, nervous, immune,or other systems, frequentlyin the absenceof detectablecelldestruction. Virology and, indeed, all microbiology developed from pathology. From characteristic profiles of cel-lular necrosis that appear in particular tissues or or-gans in association with a specific clinical picture came recognition by pathologists of virally caused lesions. This association of specific viruses with spe-cific diseases, although limited and incomplete, forms the basis of modern clinical virology; for ex-ample, infection of anterior horn cells with poliovi-rus results in their injury and the associated disease, poliomyelitis