Appearance of multinucleated giant cells in association with an adenovirus infection in two guinea pigs

In two guinea pigs (five years old, neutered male, and two and a half months old male, respectively) suffering from interstitial pneumonia, multinucleated giant cells were observed histologically in lungs, spleen and liver. The giant cells showed intranuclear, pale basophilic inclusions. Adenovirus could be demonstrated by electron microscopy.The multinucleated cells are supposed to be of histiocytic origin, since they contained variable amounts of haemosiderin in their cytoplasm. Formation of histiocyte-derived syncytia as a result of virus-induced cell fusion is discussed.