Clinicoimmunopathologic findings in Atlantic bottlenose dolphins Tursiops truncatus with positive cetacean morbillivirus antibody titers

Abstract

Sera from free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL), Florida were tested for antibodies to cetacean morbilliviruses from 2003 to 2007 as part of a multidisciplinary study of individual and population health. A suite of clinicoimmunopathologic variables were evaluated in morbillivirus-seropositive dolphins (n = 14) and seronegative healthy dolphins (n = 49). Several important differences were found. Serum alkaline phosphatase, creatine phosphokinase, chloride, albumin and albumin/globulin ratios were significantly lower in seropositive dolphins. Innate immunity appeared to be upregulated with significant increases in lysozyme concentration and marginally significant increases in monocytic phagocytosis. Adaptive immunity was also impacted in dolphins with positive morbillivirus antibody titers. Mitogen-induced T lymphocyte proliferation responses were significantly reduced in dolphins with positive morbillivirus antibody titers, and marginally significant decreases were found for absolute numbers of CD4+ lymphocytes. The findings suggest impairment of cell-mediated adaptive immunity, similar to the immunologic pattern reported with acute morbillivirus infection in other species. In contrast, dolphins with positive morbillivirus antibody titers appeared to have at least a partially upregulated humoral immune response with significantly higher levels of gamma globulins than healthy dolphins, which may represent an antibody response to morbillivirus infection or other pathogens. These data suggest that subclinical dolphin morbillivirus infection in IRL dolphins may produce clinicoimmunopathologic perturbations that impact overall health. KEY WORDS: Bottlenose dolphin · Viral disease · Cetacean morbillivirus · Seroepidemiology · Clinical pathology · ImmunologyResale or republication not permitted without written consent of the publisher Dis Aquat Org 97: 103-112, 2011 104 (PDV) and cetacean morbilliviruses (dolphin morbillivirus [DMV] and porpoise morbillivirus [PMV]) have emerged and dramatically impacted the health and population status of various marine mammal species worldwide (Kennedy 1998, Di Guardo et al. 2005, Di Guardo 2008, Van Bressem et al. 2009). The DMV and PMV viruses appear to be closely related strains of a cetacean morbillivirus (CMV) from a genomic and antigenic standpoint (BlixenkroneMøller et al. 1994, Kennedy 1998, Di Guardo et al. 2005, distinct from PDV and CDV and more closely related to the ruminant morbilliviruses and measles virus (Barrett et al. 1993, Visser et al. 1993.In domestic animals and primates, morbilliviruses produce a seemingly paradoxical interaction with the immune system. Morbilliviruses are lymphotrophic and induce multisystemic infections in their highly susceptible natural hosts, causing disease with high morbidity and mortality. In these cases, the pathogenesis of morbillivirus infections shares common features, including transient profound immune suppression which may lead to secondary viral and b...

Novel Cetacean Morbillivirus in Guiana Dolphin, Brazil

“…A high number of morbillivirus-related deaths have not yet been reported among aquatic mammals in the waters off Brazil, but our findings shows that Guiana dolphin calves are susceptible to infection. Subclinical morbillivirus infection with immune suppression has been reported in bottlenose dolphins in Florida ( 10 ). It is unknown whether subclinical infection occurs in this host population or whether the virus has undergone species-adaptive changes, as proposed for PWMV ( 4 ).…”

Protein Electrophoresis of Serum from Healthy Atlantic Bottlenose Dolphins (Tursiops truncatus)

“…More specifically, increased total globulins were reported in dolphins with orogenital papillomas (Bossart et al, 2008). Lower albumin and increased globulins were also observed in dolphins which were seropositive for cetacean morbillivirus (Bossart et al, 2011). Alternatively, although the animals appeared clinically healthy, mild underlying inflammatory or infectious processes may have been present which were not evident in the routine test results.…”

Phenotyping and comparing the immune cell populations of free-ranging Atlantic bottlenose dolphins (Tursiops truncatus) and dolphins under human care

“…Dolphins with antibody titers positive to bacterial infection, Chlamydiaceae , showed changes in their innate and adaptive immunological parameters [20]. Dolphins with positive morbilliviral antibody titers had decreased T cell proliferation and absolute number, suggestive of adverse changes in their immune system [21]. Also, the deceased dolphins affected by UMEs on the Atlantic coast of the U.S. and the Gulf of Mexico had high prevalence of morbilliviral antigens, lesions indicative of a morbillivirus infection, and secondary infections [22].…”

“…Overall, these studies [6–16, 19–21, 24] shed light on the immunosuppressive effects of contaminants or microorganisms on dolphins’ immune system. In order to better investigate a cause and effect relationship between contaminants, immunosuppression, diseases susceptibility and mortality leading to UMEs, it is essential to characterize, monitor, and evaluate specific changes in their immune cells.…”