Feline viral rhinotracheitis virus: explant and cocultivation studies on tissues collected from persistently infected cats

Tissues from 16 feline viral rhinotracheitis (FVR) carrier cats and 15 controls were examined by the techniques of homogenisation, cocultivation and explant cultivation. The tissues examined included trigeminal ganglion and maxillary nerve, olfactory lobe and nerve endings, tonsils, submandibular lymph node, spleen and parotid salivary gland. Most of the cats were shedding FVR virus in the oropharynx at the time the tissues were collected. No evidence of a persistent FVR virus infection was found in any of the tissues. Trigeminal ganglion explant cultures from six FVR virus carrier cats were shown to be latently infected with feline syncytia forming virus by treatment with 5-iododeoxyuridine. Five control cats had trigeminal ganglion explant cultures similarly treated but produced no evidence of infection. The possible significance of this is discussed.