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Phocine herpesvirus 1 (PhHV-1) is a large double stranded DNA virus belonging to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus. It was first isolated and partially characterized during a disease outbreak in young harbor seals (Phoca vitulina) in the North Sea. The disease is frequently seen in seal pups worldwide and is associated with high morbidity and mortality. PhHV-1 isolates from seals of the Atlantic / European waters and isolates from seals ranging in the Pacific Ocean differ genetically and in manifested postmortem findings in diseased animals. Whilst disease in European seals is associated with pneumonia and focal hepatitis, the most striking feature found in seals from Pacific waters is adrenal necrosis. Few studies have addressed seroprevalences of PhHV-1 in different species of free ranging seals, mainly in the Northern hemisphere. Particularly seals in captivity often develop bilateral ocular disease of unknown etiology. These symptoms are also found in free ranging populations but with lower frequency. It is hypothesized that PhHV- 1, similar to feline herpesvirus type 1 (FeHV-1) in terrestrial carnivores, may contribute to the etiology of ocular disease during reactivation events. A PhHV-1-specific quantitative real-time PCR (qPCR) assay was established based on an alignment of known PhHV-1 glycoprotein B sequences. The assay was used to detect viral DNA in ocular, nasal and genital swabs from free ranging harbor seals, harp seals (Phoca groenlandica) and hooded seals (Crystophora crystata) of the Arctic and Antarctic fur seals (Arctocephalus gazella), Weddell seals (Leptonychotes weddellii), and Southern elephant seals (Mirounga leonida) of the Antarctic. The finding of PhHV-1 DNA in genital swabs was unexpected and raises the question whether the virus may, similar to bovine or equine herpesviruses, contribute to reproductive problems. An indirect PhHV-1 ELISA was developed and harbor seals of the Arctic as well as Antarctic fur seals, Weddell seals, crabeater seals (Lobodon carcinophaga), Ross seals (Ommatophoca rossii) and Southern elephant seals of the Antarctic were tested serologically. Harbor seal sera were available from a period spanning 12 years, enabling long-term monitoring of PhHV-1 in this population. Antibodies against PhHV-1 were detected in Ross seals and Southern elephant fur seals for the first time, which demonstrates that these species are susceptible to PhHV-1.