Detection of Genomic Sequences of Herpes Virus in Tissues of Cetaceans by Polymerase Chain Reaction
Tissues from various captive and stranded cetaceans were analyzed by polymerase chain reaction (PCR) using the totally extracted DNA for genomic sequences of herpes virus. The targeted sequences corresponded to the gene coding for the small subunit of the ribonucleotide reductase enzyme. The primer set utilized was designed to amplify a DNA product of 343-bp. Positive PCR results were obtained more frequently when using DNA extracted from spinal cord, lung, cerebrum, cerebellum, brainstem, various lymph nodes, pancreas and skin lesions. Captive species included one pygmy sperm whale (Kogia breviceps), 11 bottlenose dolphins (Tursiops truncatus), one short-finned pilot whale (Globicephala macrorhynchus), three killer whales (Orcinus orca) and two Pacific white-sided dolphins (Lagenorhynchus obliquidens). Stranded species included four bottlenose dolphins (Tursiops truncatus), two pygmy sperm whales (Kogia breviceps), two dwarf sperm whales (Kogia sima), eight rough toothed dolphins (Steno bredanensis) and one Clymene dolphin (Stenella clymene). The presence of herpes virus DNA was not necessarily associated with histopathological lesions characteristic of herpes virus infection, possibly indicating detection of widespread latency sites. In one case, tissues from a stranded pregnant rough toothed dolphin that later died tested positive by PCR for herpes virus DNA. However, PCR analyses of tissues from its fetus were negative for genomic herpes virus DNA, suggesting no transplacental transmission. Sequence analysis of various DNA amplicons indicate that the herpes virus infecting cetaceans is most likely an alpha herpes virus. Repeated attempts at herpes virus isolation from PCR positive tissues have so far yielded no virus.
Harbor Branch Oceanographic Institution, Inc., Fort Pierce, FL 34946 and a Training Program in the Care of Marine Mammals from the Florida Fish and Wildlife Conservation Commission supported this research.