Pathology and Diagnosis of Leporid Herpesvirus-4

Leporid herpesvirus-4 is a novel alphaherpesvirus that has been identified as the cause of mortality in commercial and pet rabbits in North America. Experimental intranasal inoculation of laboratory rabbits has been conducted to determine the clinical course of infection, pathologic findings, virus shedding and development of serum antibodies. Rabbits show peak clinical signs between 3-7 days post infection (dpi) and include respiratory distress, serous nasal and ocular discharge and mild weight loss. Virus can be isolated from nasal secretions during this period and polymerase chain reaction (PCR) can be used to identify the virus. The main histopathologic findings are suppurative, ulcerative rhinitis (3 dpi), multifocalto-coalescing splenic necrosis (5 dpi) and fibrinosuppurative bronchopneumonia (7 dpi). Characteristic herpesviral intranuclear inclusion bodies are present in these tissues at 3 and 5 dpi. Rabbits begin to recover at 8 dpi, and the presence of neutralizing antibodies can be demonstrated at 11 dpi. In the acute phase of the disease, LHV-4 can be diagnosed based on histopathologic findings or virus isolation from nasal secretions. Serology is useful for diagnosis in convalescent animals.