Monitoring green sea turtles in Brazilian feeding areas: relating body condition index to fibropapillomatosis prevalence

Rossi, Silmara; Sánchez-Sarmiento, Angélica María; Santos, Robson G.; Zamana, Roberta Ramblas; Prioste, Fabíola Eloisa Setim; Gattamorta, Marco Aurélio; Ochoa, Pablo Felipe Cruz; Grisi-Filho, José Henrique Hildebrand; Matushima, Eliana Reiko

doi:10.1017/s0025315419000730

Cited by 23 publications

(24 citation statements)

References 56 publications

(66 reference statements)

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“…Body condition index of green turtles did not differ by tumor score category, and all animals sampled for this study were given subjective body condition scores of “good” or “robust.” In green turtles from Hawaii, Brazil, and Taiwan, no differences in BCI were observed between FP tumor score categories [ 24 , 49 , 91 , 92 , 93 ]. Interestingly, BCI in Brazilian green turtles was significantly higher in those with FP (all tumor scores combined) compared to FP-free turtles.…”

Section: Discussionmentioning

confidence: 99%

Insights on Immune Function in Free-Ranging Green Sea Turtles (Chelonia mydas) with and without Fibropapillomatosis

Perrault¹,

Levin

Mott³

et al. 2021

Animals

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Chelonid alphaherpesviruses 5 and 6 (ChHV5 and ChHV6) are viruses that affect wild sea turtle populations. ChHV5 is associated with the neoplastic disease fibropapillomatosis (FP), which affects green turtles (Chelonia mydas) in panzootic proportions. ChHV6 infection is associated with lung-eye-trachea disease (LETD), which has only been observed in maricultured sea turtles, although antibodies to ChHV6 have been detected in free-ranging turtles. To better understand herpesvirus prevalence and host immunity in various green turtle foraging aggregations in Florida, USA, our objectives were to compare measures of innate and adaptive immune function in relation to (1) FP tumor presence and severity, and (2) ChHV5 and ChHV6 infection status. Free-ranging, juvenile green turtles (N = 45) were captured and examined for external FP tumors in Florida’s Big Bend, Indian River Lagoon, and Lake Worth Lagoon. Blood samples were collected upon capture and analyzed for ChHV5 and ChHV6 DNA, antibodies to ChHV5 and ChHV6, in vitro lymphocyte proliferation using a T-cell mitogen (concanavalin A), and natural killer cell activity. Despite an overall high FP prevalence (56%), ChHV5 DNA was only observed in one individual, whereas 20% of turtles tested positive for antibodies to ChHV5. ChHV6 DNA was not observed in any animals and only one turtle tested positive for ChHV6 antibodies. T-cell proliferation was not significantly related to FP presence, tumor burden, or ChHV5 seroprevalence; however, lymphocyte proliferation in response to concanavalin A was decreased in turtles with severe FP (N = 3). Lastly, green turtles with FP (N = 9) had significantly lower natural killer cell activity compared to FP-free turtles (N = 5). These results increase our understanding of immune system effects related to FP and provide evidence that immunosuppression occurs after the onset of FP disease.

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Section: Discussionmentioning

confidence: 99%

Insights on Immune Function in Free-Ranging Green Sea Turtles (Chelonia mydas) with and without Fibropapillomatosis

Perrault¹,

Levin

Mott³

et al. 2021

Animals

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“…Both destructive (body composition) and nondestructive (body mass and linear measures of body size) are used to estimate or determine condition indices (CI) of an individual. Body condition is assumed to influence an animal's health and fitness and may affect many aspects in an organism's life such as social status (darkbellied brent geese Branta bernicla bernicla, [23]), reproductive success (crimson finch Neochmia phaeton, [19]), foraging strategy (white-tailed deer Odocoileus virginianus, [38]; meerkat Suricata suricatta, [39]), survival through stressed periods (golden-mantled ground squirrel Callospermophilus lateralis, [42]), disease status (green sea turtle Chelonia mydas, [26]) and dispersal (viviparous lizard Zootoca vivipara, [18]). It is highly desirable to understand body condition, both temporally and ontogenetically, in order to provide supporting evidence and mechanistic linkages for population studies [37].…”

Section: Introductionmentioning

confidence: 99%

Measuring body condition of lizards: a comparison between non-invasive dual-energy X-ray absorptiometry, chemical fat extraction and calculated indices

2021

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Background Condition indices (CIs) are used in ecological studies as a way of measuring an individual animal’s health and fitness. Noninvasive CIs are estimations of a relative score of fat content or rely on a ratio of body mass compared to some measure of size, usually a linear dimension such as tarsus or snout-vent length. CIs are generally validated invasively by lethal fat extraction as in a seasonal sample of individuals in a population. Many alternatives to lethal fat extraction are costly or time consuming. As an alternative, dual-energy X-ray absorptiometry (DXA) allows for non-destructive analysis of body composition and enables multiple measurements during an animal’s life time. DXA has never been used for ecological studies in a small, free-ranging lizard before, therefore we calibrated this method against a chemical extraction of fat from a sample of 6 geckos (Israeli fan toed gecko Ptyodactylus guttatus) ranging in body mass between 4.2–11.5 g. We then used this calibrated DXA measurements to determine the best linear measurement calculated CI for this species. Results We found that fat mass measured with DXA was significantly correlated with the mass of chemically extracted fat for specimens more than 4.8 g (N = 5, R2 = 0.995, P < 0.001). Fat percentage regressed with body mass significantly predicted the DXA fat percentage (N = 29, R2adj. = 0.862, p < 0.001). Live wet mass was significantly correlated with predicted fat mass (N = 30, R2 = 0.984, P < 0.001) for specimens more than 4.8 g. Among the five calculated non-invasive CIs that we tested, the best was mass/SVL. Conclusions We recommend that in situations where DXA cannot be used, that the most accurate of the body condition estimators for this species is mass/SVL (snout-vent length) for both sexes.

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“…While advances in our understanding of the fibropapillomatosis tumor disease epizootic in sea turtles continue to be made 7,26,27,30,[46][47][48][49][50][51][52][53] , many questions remain unanswered in relation to this enigmatic disease. There is virtually no molecular information about the relationship (e.g.…”

Section: Introductionmentioning

confidence: 99%

Mutational, transcriptional and viral shedding dynamics of the marine turtle fibropapillomatosis tumor epizootic

Yetsko

Farrell

Stammnitz

et al. 2020

Preprint

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Sea turtle populations are directly and indirectly under threat from a range of anthropogenic processes. Perhaps the most visibly apparent of these is the disfiguring tumor disease epizootic (animal epidemic) known as fibropapillomatosis. Fibropapillomatosis continues to spread geographically, with prevalence of the disease also growing at a number of affected sites globally. Environmental exposures seem key to inducing tumor development, possibly through weakening host immune systems to the point of enabling pathogen-induced tumor formation. However, we do not yet understand the precise molecular and mutational events driving fibropapillomatosis tumor formation and progression. Similarly, many open questions remain about the role of the herpesvirus (chelonid herpesvirus 5, ChHV5) associated with the disease as a potential co-trigger, and whether its occurrence within tumors is causative or opportunistic. Without improved understanding of the basic biology of this disease epizootic, treatment, containment and mitigation options are severely hampered.To address fundamental questions relating to the oncogenic signaling, mutational spectrum, viral load, viral transcriptional status (lytic or latent) and spread, we employed transcriptomic profiling, whole genome sequencing, immunohistochemistry and environmental (e)DNAbased monitoring of viral shedding. In particular we focused on the mutational landscape of tumors and assessing the transcriptional similarity of external (skin) and internal (visceral organs) tumors, and the oncogenic signaling events driving early stage tumor growth and post-surgical tumor regrowth. These analyses revealed that internal fibropapillomatosis tumors are molecularly distinct from the more common external tumors. However, our molecular analyses also revealed that there are a small number of conserved potentially therapeutically targetable molecular vulnerabilities in common between internal and external tumors, such as the MAPK, Wnt, TGFβ and TNF oncogenic signaling pathways. We also determined that the tumor genomes can harbor copy number gains, indicating potentially viral-independent oncogenic processes. Genes within such mutated genomic regions have known roles in human skin cancer, including MAPK-associated genes. Turtles attempt to mount an immune response, but in some animals this appears to be insufficient to prevent tumor development and growth. ChHV5 was transcriptionally latent in all tumor stages sequenced, including early stage and recurrent tumors. We also revealed that the tumors themselves are the primary source of viral shedding into the marine environment and, if they are surgically removed, the level of ChHV5 in the water column drops.Together, these results offer an improved understanding of fibropapillomatosis tumorigenesis and provide insights into the origins, therapeutic treatment, and appropriate quarantine responses for this wildlife epizootic. Furthermore, they provide insights into human pathogen-induced cancers, particularly mechanisms which are difficult to s...

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Monitoring green sea turtles in Brazilian feeding areas: relating body condition index to fibropapillomatosis prevalence

Cited by 23 publications

References 56 publications

Insights on Immune Function in Free-Ranging Green Sea Turtles (Chelonia mydas) with and without Fibropapillomatosis

Insights on Immune Function in Free-Ranging Green Sea Turtles (Chelonia mydas) with and without Fibropapillomatosis

Measuring body condition of lizards: a comparison between non-invasive dual-energy X-ray absorptiometry, chemical fat extraction and calculated indices

Mutational, transcriptional and viral shedding dynamics of the marine turtle fibropapillomatosis tumor epizootic

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