Intracellular and extracellular mineral crystal formation induced by viral infection of cell cultures.

Intracellular mineral crystals were observed in cell cultures infected with one or more feline viruses. One was a feline syncytium-forming virus, and the other was a new feline virus which produced intranuclear inclusions in cell cultures. Crystals were noted both in autogenous cell cultures from trypsinization of kidneys and urinary bladders of infected cats (three passages) and in subcultures of culture fluids from these, made in a stable feline kidney cell line. Free mineral crystals were also noted in the fluids of the cell cultures. In two bladder and two kidney infected autogenous cultures, structures resembling the urinary calculi observed in obstructed cats were seen. These consisted of mineral crystals in a matrix of cellular debris.