Ophidiomycosis in Red Cornsnakes (<i>Pantherophis guttatus</i>): Potential Roles of Brumation and Temperature on Pathogenesis and Transmission

McKenzie, Christina; Oesterle, Paul T.; Stevens, Brian; Shirose, Leonard J.; Mastromonaco, Gabriela F.; Lillie, Brandon N.; Davy, Christina M.; Jardine, Claire M.; Nemeth, Nicole M.

doi:10.1177/0300985820953423

Cited by 23 publications

(35 citation statements)

References 43 publications

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“…Even though we did not include season as a factor in our analyses, generally, our results are consistent with other surveys for Oo that suggest infected snakes are more likely to be encountered during the spring owing to fungal exposure during brumation through the winter months 18,41,49,55 . These observations highlight concerns that climatic factors (i.e., cooler, wetter weather) could act synergistically with Oo and increase the severity of infection 17,43 .…”

Section: Discussionsupporting

confidence: 86%

Comparative host-pathogen dynamics of Snake Fungal Disease in sympatric species of water snakes (Nerodia)

Harding

Becker

Yates

et al. 2022

Preprint

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The ascomycete fungus Ophidiomyces ophiodiicola (Oo) is the causative agent of ophidiomycosis (Snake Fungal Disease), which has been detected globally. However, surveillance efforts in the central U.S., specifically Texas, have been minimal. The threatened and rare Brazos water snake (Nerodia harteri harteri) is one of the most range restricted snakes in the U.S. and is sympatric with two wide-ranging congeners, N. erythrogaster transversa and N. rhombifer, in north central Texas; thus, providing an opportunity to test comparative host-pathogen dynamics in this system. To accomplish this, we surveyed a portion of the Brazos river drainage (~400 river km) over 29 months and tested 150 Nerodia spp. for the presence of Oo via quantitative PCR and recorded any potential signs of Oo infection. We found Oo was distributed across the entire range of N. h. harteri, Oo prevalence was 46 % overall, and there was a significant association between Oo occurrence and signs of infection in our sample. Models indicated adults had a higher probability of Oo infection than juveniles and subadults, and adult N. h. harteri had a higher probability of infection than adult N. rhombifer but not higher than adult N. e. transversa. High Oo prevalence estimates (94.4%) in adult N. h. harteri has implications for their conservation and management owing to their patchy distribution, comparatively low genetic diversity, and threats from anthropogenic habitat modification.

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Section: Discussionsupporting

confidence: 86%

Comparative host-pathogen dynamics of Snake Fungal Disease in sympatric species of water snakes (Nerodia)

Harding

Becker

Yates

et al. 2022

Preprint

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“…The fungus appears to be an opportunistic pathogen with a wide tolerance of environmental conditions (11). Experimental infection of cottonmouths (Agkistrodon piscivorus) and corn snakes (Pantherophis guttatus) with North American strains of O. ophidiicola caused dermal lesions consistent with those observed in wild snakes (22)(23)(24).…”

Section: Introductionmentioning

confidence: 81%

“…Research into ophidiomycosis has been mobilized by concern that O. ophidiicola causes or has the potential to cause widespread morbidity and mortality in free-ranging snakes (7, 11, 14-16, 23, 28). Ophidiomycosis clearly causes or contributes to mortality of snakes under some circumstances (22)(23)(24)(25). However, it is unclear whether the available evidence indicates an impact of ophidiomycosis on the viability of snake populations (i.e., population-level effects).…”

Section: Introductionmentioning

confidence: 99%

Revisiting Ophidiomycosis (Snake Fungal Disease) After a Decade of Targeted Research

et al. 2021

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Emerging infectious diseases (EIDs) are typically characterized by novelty (recent detection) and by increasing incidence, distribution, and/or pathogenicity. Ophidiomycosis, also called snake fungal disease, is caused by the fungus Ophidiomyces ophidiicola (formerly “ophiodiicola”). Ophidiomycosis has been characterized as an EID and as a potential threat to populations of Nearctic snakes, sparking over a decade of targeted research. However, the severity of this threat is unclear. We reviewed the available literature to quantify incidence and effects of ophidiomycosis in Nearctic snakes, and to evaluate whether the evidence supports the ongoing characterization of ophidiomycosis as an EID. Data from Canada remain scarce, so we supplemented the literature review with surveys for O. ophidiicola in the Canadian Great Lakes region. Peer-reviewed reports of clinical signs consistent with ophidiomycosis in free-ranging, Nearctic snakes date back to at least 1998, and retrospective molecular testing of samples extend the earliest confirmed record to 1986. Diagnostic criteria varied among publications (n = 33), confounding quantitative comparisons. Ophidiomycosis was diagnosed or suspected in 36/121 captive snakes and was fatal in over half of cases (66.7%). This result may implicate captivity-related stress as a risk factor for mortality from ophidiomycosis, but could also reflect reporting bias (i.e., infections are more likely to be detected in captive snakes, and severe cases are more likely to be reported). In contrast, ophidiomycosis was diagnosed or suspected in 441/2,384 free-ranging snakes, with mortality observed in 43 (9.8 %). Ophidiomycosis was only speculatively linked to population declines, and we found no evidence that the prevalence of the pathogen or disease increased over the past decade of targeted research. Supplemental surveys and molecular (qPCR) testing in Ontario, Canada detected O. ophidiicola on 76 of 657 free-ranging snakes sampled across ~136,000 km2. The pathogen was detected at most sites despite limited and haphazard sampling. No large-scale mortality was observed. Current evidence supports previous suggestions that the pathogen is a widespread, previously unrecognized endemic, rather than a novel pathogen. Ophidiomycosis may not pose an imminent threat to Nearctic snakes, but further research should investigate potential sublethal effects of ophidiomycosis such as altered reproductive success that could impact population growth, and explore whether shifting environmental conditions may alter host susceptibility.

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“…S2) and identified the expression of genes involved in hyphal growth. Necrosis on skin cell due to penetration of fungal hyphal into the epidermis have been confirmed in many SFD studies (29, 30, 80) and is the mode of P. destructans pathogenesis in white nose syndrome (9). Identifying functional genes within O. ophidiicola genome and quantifying their expression on snakeskin would help researchers identify pathogenesis mechanisms and potential deterrents against the pathogen.…”

Section: Discussionmentioning

confidence: 82%

Section: Insights Into Sfd Host Pathology From Gene Expression Datamentioning

confidence: 75%

Genetic mechanisms and biological processes underlying host response to ophidiomycosis (Snake Fungal Disease) inferred from tissue-specific transcriptome analyses

Mathur

Haynes

Allender

et al. 2022

Preprint

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There is growing concern about infectious diseases in wildlife species caused by pathogenic fungi. Detailed knowledge exists about host pathology and the molecular mechanisms underlying host physiological response to some fungal diseases affecting amphibians and bats but is lacking for others with potentially significant impacts on large groups of animals. One such disease is ophidiomycosis (Snake Fungal Disease; SFD) which is caused by the fungus Ophidiomyces ophidiicola and impacts diverse species of snakes. Despite this potential, the biological mechanisms and molecular changes occurring during infection are unknown for any snake species. To gain this information, we performed a controlled experimental infection of captive Prairie rattlesnakes ( Crotalus viridis ) with O. ophidiicola at different temperatures. We then generated liver, kidney, and skin transcriptomes from control and infected snakes to assess tissue specific genetic responses to infection. Given previous SFD histopathological studies and the fact that snakes are ectotherms, we expected highest fungal activity on skin and a significant impact of temperature on host response. In contrast, we found that most of the differential gene expression was restricted to internal tissues and fungal-infected snakes showed transcriptome profiles indicative of long-term inflammation of specific tissues. Infected snakes at the lower temperature had the most pronounced overall host functional response whereas, infected snakes at the higher temperature had overall expression profiles similar to control snakes possibly indicating recovery from the disease. Overall, our results suggest SFD is a systemic disease with a chronic host response, unlike acute response shown by amphibians to Batrachochytrium dendrobatidis infections. Our analysis also generated a list of candidate protein coding genes that potentially mediate SFD response in snakes, providing tools for future comparative and evolutionary studies into variable species susceptibility to ophidiomycosis.

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Ophidiomycosis in Red Cornsnakes (Pantherophis guttatus): Potential Roles of Brumation and Temperature on Pathogenesis and Transmission

Cited by 23 publications

References 43 publications

Comparative host-pathogen dynamics of Snake Fungal Disease in sympatric species of water snakes (Nerodia)

Comparative host-pathogen dynamics of Snake Fungal Disease in sympatric species of water snakes (Nerodia)

Revisiting Ophidiomycosis (Snake Fungal Disease) After a Decade of Targeted Research

Genetic mechanisms and biological processes underlying host response to ophidiomycosis (Snake Fungal Disease) inferred from tissue-specific transcriptome analyses

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