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

ATYPICAL CHLAMYDIACEAE IN WILD POPULATIONS OF HAWKS ( BUTEO SPP.) IN CALIFORNIA

Chlamydiaceae bacteria infect many vertebrate hosts, and previous reports based on polymerase chain reaction (PCR) assays and serologic assays that are prone to cross-reaction among chlamydial organisms have been used to describe the prevalence of either DNA fragments or antibodies to Chlamydia spp. in wild raptorial populations. This study reports the PCR-based prevalence of Chlamydiaceae DNA that does not 100% match any avian or mammalian Chlamydiaceae in wild populations of hawks in California Buteo species. In this study, multimucosal swab samples ( n = 291) for quantitative PCR (qPCR) and plasma ( n = 78) for serology were collected from wild hawks. All available plasma samples were negative for antibodies using a C. psittaci-specific elementary body agglutination test (EBA; n = 78). For IgY antibodies all 51 available samples were negative using the indirect immunofluorescent assay. The overall prevalence of Chlamydiaceae DNA detection in wild Buteo species sampled was 1.37% (4/291) via qPCR-based analysis. Two fledgling Swainson's hawks ( Buteo swainsoni) and two juvenile red-tailed hawks ( Buteo jamaicensis) were positive by qPCR-based assay for an atypical chlamydial sequence that did not 100% match any known C. psittaci genotype. Positive swab samples from these four birds were sequenced based on the ompA gene and compared by high-resolution melt analysis with all known avian and mammalian Chlamydiaceae. The amplicon sequence did not 100% match any known avian chlamydial sequence; however, it was most similar (98.6%) to C. psittaci M56, a genotype that is typically found in muskrats and hares. Culture and full genome sequence analysis of Chlamydia spp. isolated from diseased hawks will be necessary to classify this organism and to better understand its epizootiology and potential health impact on wild Buteo populations in California.

Environment, endocrinology, and biochemistry influence expression of stress proteins in bottlenose dolphins

Natural and anthropogenic stressors have been reported to impact the health of marine mammals. Therefore, investigation of quantifiable biomarkers in response to stressors is required. We hypothesized that stress protein expression would be associated with biological and health variables in wild and managed-care bottlenose dolphins (Tursiops truncatus). To test this hypothesis, our study objectives were to (1) determine if stress proteins in skin, white blood cells (WBCs), and plasma could be measured with an antibody-based microarray, (2) measure stress-protein expression relative to biological data (location, sex, age, environment), and (3) determine if stress-protein expression was associated with endocrine, hematological, biochemical and serological variables and gene expression in bottlenose dolphins. Samples were collected from two wild groups (n = 28) and two managed-care groups (n = 17). Proteins involved in the HPA axis, apoptosis, proteotoxicity, and inflammation were identified as stress proteins. The expression of 3 out of 33 proteins was significantly (P < 0.05) greater in skin than plasma and WBCs. Male dolphins had significantly greater expression levels for 10 proteins in skin compared to females. The greatest number of stress-associated proteins varied by the dolphins' environment; nine were greater in managed-care dolphins and 15 were greater in wild dolphins, which may be related to wild dolphin disease status. Protein expression in skin and WBCs showed many positive relationships with measures of plasma endocrinology and biochemistry. This study provides further understanding of the underlying mechanisms of the stress response in bottlenose dolphins and application of a combination of novel methods to measure stress in wildlife.

Comparative Innate and Adaptive Immune Responses in Atlantic Bottlenose Dolphins (Tursiops truncatus) With Viral, Bacterial, and Fungal Infections

Free-ranging Atlantic bottlenose dolphins (n = 360) from two southeastern U.S. estuarine sites were given comprehensive health examinations between 2003 and 2015 as part of a multi-disciplinary research project focused on individual and population health. The study sites (and sample sizes) included the Indian River Lagoon (IRL), Florida, USA (n = 246) and Charleston harbor and associated rivers (CHS), South Carolina, USA (n = 114). Results of a suite of clinicoimmunopathologic tests revealed that both populations have a high prevalence of infectious and neoplastic disease and a variety of abnormalities of their innate and adaptive immune systems. Subclinical infections with cetacean morbillivirus and Chlamydiaceae were detected serologically. Clinical evidence of orogenital papillomatosis was supported by the detection of a new strain of dolphin papillomavirus and herpesvirus by molecular pathology. Dolphins with cutaneous lobomycosis/lacaziasis were subsequently shown to be infected with a novel, uncultivated strain of Paracoccidioides brasiliensis, now established as the etiologic agent of this enigmatic disease in dolphins. In this review, innate and adaptive immunologic responses are compared between healthy dolphins and those with clinical and/or immunopathologic evidence of infection with these specific viral, bacterial, and fungal pathogens. A wide range of immunologic host responses was associated with each pathogen, reflecting the dynamic and complex interplay between the innate, humoral, and cell-mediated immune systems in the dolphin. Collectively, these studies document the comparative innate and adaptive immune responses to various types of infectious diseases in free-ranging Atlantic bottlenose dolphins. Evaluation of the type, pattern, and degree of immunologic response to these pathogens provides novel insight on disease immunopathogenesis in this species and as a comparative model. Importantly, the data suggest that in some cases infection may be associated with subclinical immunopathologic perturbations that could impact overall individual and population health.

Molecular detection of Chlamydia abortus in a stranded Mediterranean striped dolphin Stenella coeruleoalba

This study reports gross, histopathological, and molecular features of a Chlamydia abortus infection in a stranded female striped dolphin Stenella coeruleoalba from the Tyrrhenian coast of southern Italy. Post-mortem examination revealed liver congestion, splenic lymphoid depletion with capsular petechiae, and pneumonia. Histology revealed disseminated intravascular coagulation with vasculitis and congestion. Hepatocellular and acute myocardial degeneration were also observed. Basophilic, coccobacillary inclusions consistent with Chlamydia spp. were observed histologically in the type II pneumocytes, myocardial fibers, and hepatocytes, and in macrophages and plasma cells of liver, spleen, and prescapular lymph nodes. Chlamydial antigen was detected by immunofluorescence assay using genus-specific anti-Chlamydia antibodies. PCR assay revealed C. abortus in spleen, liver, heart, and lungs. C. abortus was the only pathogen detected. The main pathological changes suggest that Chlamydia infection may have been the cause of stranding and death of the striped dolphin. This case represents the first molecular detection of a member of the Chlamydiaceae in a marine mammal.

Health and Environmental Risk Assessment Project for bottlenose dolphins Tursiops truncatus from the southeastern USA. I. Infectious diseases

From 2003 to 2015, 360 free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL, n = 246), Florida, and coastal waters of Charleston (CHS, n = 114), South Carolina, USA, were captured, given comprehensive health examinations, and released as part of a multidisciplinary and multi-institutional study of individual and population health. The aim of this review is to summarize the substantial health data generated by this study and to examine morbidity between capture sites and over time. The IRL and CHS dolphin populations are affected by complex infectious and neoplastic diseases often associated with immunologic disturbances. We found evidence of infection with cetacean morbillivirus, dolphin papilloma and herpes viruses, Chlamydiaceae, a novel uncultivated strain of Paracoccidioides brasiliensis (recently identified as the causal agent of dolphin lobomycosis/lacaziasis), and other pathogens. This is the first long-term study documenting the various types, progression, seroprevalence, and pathologic interrelationships of infectious diseases in dolphins from the southeastern USA. Additionally, the study has demonstrated that the bottlenose dolphin is a valuable sentinel animal that may reflect environmental health concerns and parallel emerging public health issues.

The environment as a driver of immune and endocrine responses in dolphins (Tursiops truncatus)

Immune and endocrine responses play a critical role in allowing animals to adjust to environmental perturbations. We measured immune and endocrine related markers in multiple samples from individuals from two managed-care care dolphin groups (n = 82 samples from 17 dolphins and single samples collected from two wild dolphin populations: Indian River Lagoon, (IRL) FL (n = 26); and Charleston, (CHS) SC (n = 19). The immune systems of wild dolphins were more upregulated than those of managed-care-dolphins as shown by higher concentrations of IgG and increases in lysozyme, NK cell function, pathogen antibody titers and leukocyte cytokine transcript levels. Collectively, managed-care care dolphins had significantly lower levels of transcripts encoding pro-inflammatory cytokine TNF, anti-viral MX1 and INFα and regulatory IL-10. IL-2Rα and CD69, markers of lymphocyte activation, were both lower in managed-care care dolphins. IL-4, a cytokine associated with TH2 activity, was lower in managed-care care dolphins compared to the free-ranging dolphins. Differences in immune parameters appear to reflect the environmental conditions under which these four dolphin populations live which vary widely in temperature, nutrition, veterinary care, pathogen/contaminant exposures, etc. Many of the differences found were consistent with reduced pathogenic antigenic stimulation in managed-care care dolphins compared to wild dolphins. Managed-care care dolphins had relatively low TH2 lymphocyte activity and fewer circulating eosinophils compared to wild dolphins. Both of these immunologic parameters are associated with exposure to helminth parasites which is uncommon in managed-care care dolphins. Less consistent trends were observed in a suite of hormones but significant differences were found for cortisol, ACTH, total T4, free T3, and epinephrine. While the underlying mechanisms are likely multiple and complex, the marked differences observed in the immune and endocrine systems of wild and managed-care care dolphins appear to be shaped by their environment.

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

Background

Studies suggest that free-ranging bottlenose dolphins exhibit a suppressed immune system because of exposure to contaminants or microorganisms. However, due to a lack of commercially available antibodies specific to marine mammal immune cell surface markers, the research has been indecisive. The purpose of this study was to identify cross-reactive terrestrial-specific antibodies in order to assess the changes in the immune cell populations of dolphins under human care and free-ranging dolphins. The blood and PBMC fraction of blood samples from human care and free-ranging dolphins were characterized by H&E staining of cytospin slides and flow cytometry using a panel of terrestrial-specific antibodies.

Results

In this study, we show that out of 65 terrestrial-specific antibodies tested, 11 were cross-reactive and identified dolphin immune cell populations within their peripheral blood. Using these antibodies, we found significant differences in the absolute number of cells expressing specific markers within their lymphocyte and monocyte fractions. Interestingly, the peripheral blood mononuclear cell profile of free-ranging dolphins retained an additional population of cells that divided them into two groups showing a low (<27%) or high (>56%) percentage of smaller cells resembling granulocytes.

Conclusions

We found that the cross-reactive antibodies not only identified specific changes in the immune cells of free-ranging dolphins, but also opened the possibility to investigate the causal relationship between immunosuppression and mortality seen in free-ranging dolphins.

Chlamydial infections in wildlife-conservation threats and/or reservoirs of 'spill-over' infections?

Members of the order Chlamydiales are biphasic intracellular pathogens known to cause disease in both humans and animals. As we learn more about the genetic diversity of this group of pathogens, evidence is growing that these bacteria infect a broader range of animal hosts than previously thought. Over 400 host species are now documented globally with the majority of these being wild animals. Given the impact of chlamydial infections on humans and domesticated animals, the identification of members of the order Chlamydiales in wildlife raises significant questions over a) their impact on animal health and b) the relationships to those strains also found in humans and domestic animals. In some species such as the iconic marsupial, the koala, the conservation impact is known with chlamydial infections associated with debilitating disease, however, in general, little is known about the pathogenic potential of Chlamydiae infecting most wildlife hosts. Accumulating evidence suggests contact with wild animals is a risk factor for infections in domestic animals and/or humans. Beyond the well-recognised zoonotic pathogen, Chlamydia psittaci, a range of studies have now reported traditional pathogens in the family Chlamydiaceae such as Chlamydia pecorum, Chlamydia suis, Chlamydia pneumoniae and Chlamydia abortus in wild animals. The spectre of cross-host transmission 'spill-over' and 'spill-back' in the epidemiology of infections is of potential concern, however, comprehensive epidemiological studies are lacking for most of these. Accurate evaluation of the significance of chlamydial infections in wildlife is otherwise hampered by i) the cross-sectional nature of most impact studies, ii) a lack of standardised diagnostic approaches, iii) limited study sizes, and iv) biases associated with opportunistic sampling.

Mucocutaneous lesions in free-ranging Atlantic bottlenose dolphins Tursiops truncatus from the southeastern USA

Mucocutaneous lesions were biopsied from free-ranging Atlantic bottlenose dolphins Tursiops truncatus inhabiting the Indian River Lagoon (IRL), Florida, and estuarine waters of Charleston (CHS), South Carolina, USA, between 2003 and 2013. A total of 78 incisional biopsies from 58 dolphins (n=43 IRL, n=15 CHS) were examined. Thirteen dolphins had 2 lesions biopsied at the same examination, and 6 dolphins were re-examined and re-biopsied at time intervals varying from 1 to 8 yr. Biopsy sites included the skin (n=47), tongue (n=2), and genital mucosa (n=29). Pathologic diagnoses were: orogenital sessile papilloma (39.7%), cutaneous lobomycosis (16.7%), tattoo skin disease (TSD; 15.4%), nonspecific chronic to chronic-active dermatitis (15.4%), and epidermal hyperplasia (12.8%). Pathologic diagnoses from dolphins with 2 lesions were predominately orogenital sessile papillomas (n=9) with nonspecific chronic to chronic-active dermatitis (n=4), TSD (n=3), lobomycosis (n=1), and epidermal hyperplasia (n=1). Persistent pathologic diagnoses from the same dolphins re-examined and re-biopsied at different times included genital sessile papillomas (n=3), lobomycosis (n=2), and nonspecific dermatitis (n=2). This is the first study documenting the various types, combined prevalence, and progression of mucocutaneous lesions in dolphins from the southeastern USA. The data support other published findings describing the health patterns in dolphins from these geographic regions. Potential health impacts related to the observed suite of lesions are important for the IRL and CHS dolphin populations, since previous studies have indicated that both populations are affected by complex infectious diseases often associated with immunologic disturbances and anthropogenic contaminants.