Phocine herpesvirus 1 (PhHV-1) in harbor seals from Svalbard, Norway

Phocine herpesvirus 1 (PhHV-1) infections in seals are associated with disease and sometimes high mortality, primarily in young animals. PhHV-1 has been detected in seals from European waters as well as in waters on both coasts of North America. Serological surveys of various pinniped species have indicated a wide geographical distribution of PhHV-1. A quantitative and sensitive real-time PCR assay targeting the gene encoding glycoprotein B of PhHV-1 was developed for detection of PhHV-1 in ocular and nasal swab samples from wild harbor seals (Phoca vitulina) from Svalbard (Norway). PhHV-1 DNA was detected in samples from 6 (8%) seals collected in 2009 and 2 (3%) in 2010; all had herpesvirus DNA in the ocular swab sample, whereas only one of these animals also had herpesvirus DNA in the nasal swab sample. Four PCR positive animals were approximately 1 year of age and four were pups of the year. Serum samples obtained in 1998 (n=59), 1999 (n=74), 2000 (n=81), 2009 (n=69) and 2010 (n=83) were tested for anti-PhHV-1 antibodies in an indirect ELISA. The PhHV-1 seroprevalence in the population remained high throughout this period, varying from 77 to 100% between years. No eye disease was observed in this harbor seal population, but the ELISA and PCR findings reported here suggest that PhHV-1 is endemic in this globally northernmost harbor seal colony, and that the virus is shed on the mucosa of the eye and nose.