Papillomaviruses (PVs), small DNA-tumorviruses, represent the most frequently sexually transmitted viruses of the world and may thus have an impact on population dynamics. PV-caused lesions such as warts, condyloma, and papilloma frequently disappear due to a cell-mediated immune response. However, there are high risk PV-types, which bear a stronger oncogenic potential and contribute to malignant progression of epithelial tumors. The significance of these infections in humans and in some animals has long been proven. In human beings 10-30% of PV-induced severe neoplasia lead to an invasive cervical carcinoma, the second most frequent cancer of women worldwide. During health assessment studies with free-ranging bottlenose dolphin populations off the coasts of FL and SC conducted by HBOI (Harbor Branch Oceanographic Institution) and NOAA (National Oceanic and Atmospheric Administration) in 2003, 2004, and 2005 the authors recognized a significant rise of genital lesions in these dolphin populations over this period of time. Out of one of these lesions we could recently isolate the first North-American bottlenose dolphin papillomavirus (TtPV2--Tursiops truncatus Papillomavirus type 2) and clone, sequence, and characterize the complete viral genome. To gain first data on the prevalence of these pathogens in dolphin populations, virus-like particles (VLPs) consisting of the major component of the viral capsid of TtPV2 and TtPV1 (a PV isolated from a genital tumor of a captive bottlenose dolphin maintained in a Portuguese aquarium) were developed to induce antibody-production in rabbits. These VLPs and the corresponding antibodies served in ELISAs (Enzyme-linked immunosorbent assays) to screen four different Tursiops populations, two free-ranging and two captive, for PV-infections. The results suggested prevalences of 83% and 100% of investigated free-ranging and 38% and 75% of investigated captive populations. Future research such as health assessments, screening tests, and possible vaccinations with the developed VLPs will provide further insights in transmission, prevalence, and significance of these infections in dolphin species.
We thank Dr. Marc van Ranst and Dr. Annabel Rector from the Laboratory of Clinical and Epidemiological Virology in the Rega Institute for Medical Research, University of Leuven, Belgium for sharing the TtPV1 DNA with us. Samples were collected under National Marine Fisheries Permit No. 998-1978-00, issued to Dr. Gregory Bossart.