Abstract

Morbilliviruses are highly contagious pathogens causing repeated mass mortalities in marine mammals. In 1988 and 2002 an outbreak of PDV killed more than 21,000 harbour seals in the North Sea. The virus spread over macrophages, lymphocytes or unattached in the blood through the body causing catarrhalic inflammation of mucosal membranes of the respiratory and digestive tract and a lymphopenia. Virus infects cells over specific receptors. Tatsuo et al. described CD150 or SLAM as MV and CDV receptor at lymphocytes. We investigated phocine lymphocytes for the expression of CD150 as possible receptor for PDV. Blood samples from juvenile and adult wild harbour seals were taken during routinely monitoring seal catches at different places in the North Sea. Phocine lymphocytes were isolated with density gradient centrifugation (Vacutainer cell preparation tubes; BD, Germany) and RNA was isolated using a RNeasyMini Kit (Quiagen, Europe) according to the manufacturers protocol. After Dnase treatment (Ambion, Europe) rewriting in cDNA followed using the RT-PCR Core Kit (Applied Biosystems, Germany). Primer pairs were selected from canine SLAM-sequence (NCBI-Nr. AF325357) and a PCR accomplished using the Brilliant SYBRGreen QPCR Master mix (Stratagene, Europe). PCR products were sequenced (SEQLAB, Göttingen, Germany) and compared with canine, human and murine sequences using sequence analyzing software (NCBI-BLAST, DNAstar). The comparison showed a compliance of about 93% to the canine sequence. There were no notable age-related differences in SLAM-expression. This is the first report on the morbillivirus receptor SLAM on phocine lymphocytes.