A novel herpesvirus in blue penguins putatively associated with myocardial degeneration and necrosis

We identified a novel herpesvirus in 2 deceased captive blue penguins (Eudyptula minor). Moderate-to-severe myocardiocyte atrophy and necrosis, and eosinophilic intranuclear inclusion bodies (INIBs), were seen in myocardiocytes in one bird; reticuloendothelial (RE) cell INIBs and multifocal RE cell necrosis were seen in both birds. The histologic findings were suggestive of viral infection. A herpesvirus PCR assay was positive in myocardial tissue from the bird with myocardial degeneration and in splenic tissue from both birds. Sequencing and phylogenetic analysis showed that the virus, accessioned as spheniscid alphaherpesvirus 2 (SpAHV2), groups within the Alphaherpesvirinae subfamily and forms a unique branch point in a subclade containing members of the Mardivirus, Simplexvirus, and Varicellovirus genera. Herpesvirus screening of tissues from 8 additional blue penguin postmortem examination cases (7 spleen, 1 liver) and combined conjunctival-choanal-cloacal swab samples from 13 live penguins revealed 5 additional dead and 7 live penguins that were positive for SpAHV2. The presence of SpAHV2 in healthy live animals and lack of significant herpesvirus-associated lesions as the cause of death in 6 of 7 SpAHV2-positive dead penguins suggests that this virus may be an endemic in blue penguins, and that recrudescence may cause disease and death.