2013 International Symposium on Ranaviruses by Debra Miller

1. Ranaviral Disease
Pathology and Physiology
Debra L. Miller, DVM, PhD
Center for Wildlife Health and Department
Biomedical and Diagnostic Sciences, University of
Tennessee, Knoxville, TN
http://scienceblogs.com/tetrapodzoology/wp-
content/blogs.dir/471/files/2012/05/i-
ef0fe026ef8adf268fbce8dda99e3d45-
Uroplatus_fimbriatus_Piotr-Naskrecki_April-2010.jpg
Photo: Blind Pony Hatchery
Photo: N Haislip
Photo: N Haislip

2. What information do we get when
we identify lesions (pathology)?
 Presence of disease (response of the
individual to a pathogen/agent)
 NOT exact etiology (generally not) but often
a ‘list of differentials (possible causes)’
 Insight into what might be happening to
function (organ, system) within the
individual (physiology)

3. Ranavirus
 Amphibians: Anurans and Caudates
 Reptiles: Turtles, Lizards, Snakes
 Fish: Boney fish
3 Classes

4. Gross changes
 Lesions can look similar across classes (amphibian, reptile, fish)
– Hemorrhage, swelling and necrosis (tissue death) are common gross
changes
W. Sutton N. Haislip
T. Waltzak

5. Amphibians: larvae
Photo: J. Chaney
Boreal Toad
Photo: Nathan Haislip
Bullfrog
affected
unaffected
Photo: N. Haislip
Bullfrog
Photo: N. Haislip
Wood frog

6. Amphibians: metamorphs
Photo: Jordan Chaney
Boreal Toad

7. Amphibian: adults
Common frog (Rana temporaria)
Photos: Amanda Duffus
ulceration
Midwife toad (Alytes obstetricans)
Photos: Amanda Duffus
ulceration
Eastern spotted newt (Notophthalmus viridescens)
Photo: Betsie B. Rothermel
Hemorrhage
Friable spleen
Hemorrhage
Gopher frog
Photos: B Sutton and R Hardman

8. Is this ranaviral disease?
Cryptobranchus alleganiensis alleganiensis
Photo: Dale McGinnity and Sherri Reinsch

9. Photo: B Sutton and R Hardman
And what role do
ectoparasites (leeches) play?

10. Bullfrog (~10%; 0% FV3)
Cope’s Gray tree frog (~70% RI; ~40% FV3)
Wood frog (~ 100% for both)
Varies by host (species)-susceptibility & isolate
(mortality: RI [ranaculture isolate] vs FV3 = Amphibian isolates)

11. Necrotic (white )
areas inside the
mouth (circles and
arrows). Upper
photo with mouth
opened. Lower photo
with mandible
removed
Photo: Mark Ruder
Photo: Mark Ruder
Photo: Mark Ruder
Reptiles
Similar reports in snakes and
lizards
(including being off feed, weight
loss, dermatitis)
Eastern Box Turtle (West Virginia)
(Terrapene carolina carolina) Eastern Box Turtle (Kentucky)
(Terrapene carolina carolina)

12. Blue arrows = left lung
Yellow arrows = necrosis
Liver
Intestine
Stomach
Ocular
discharge
Ranavirus-Negative
Herpesevirus-Negative
Mycoplasma-POSITIVE (M. agassizzi)
Ranavirus-POSITIVE
Herpesvirus-Negative
Mycoplasma-Negative
Determining etiology
Oral mucosal necrosis
Photo: Mark Ruder
Lung necrosis
Photo: Mark Ruder
Eastern Box Turtle (Virginia)
(Terrapene carolina carolina)
Eastern Box Turtle (Kentucky)
(Terrapene carolina carolina)

13. Fish
Photo: Emilie Travis
Photos: Tom Waltzek
Photo: Ted Henry

14. Histology

15. Histology
 Lesions can look similar across classes (amphibian, reptile, fish)
– Cellular necrosis of the hematopoietic tissue, vascular endothelium and
epithelial cells and intracytoplasmic inclusion bodies are common
microscopic lesions
Endothelium
Endothelial necrosis
Spleen Necrosis

16. Amphibians

19. FV3 Box turtle isolate
Pallid sturgeon isolate Ranaculture isolate
Wood Frog Spleen

20. Reptiles

21. Pallid isolate; bath exposure

22. Pallid isolate; bath exposure

25. vasculitis
Myofibers disrupted
Ulcerated crust on oral mucosa
Disrupted muscle fibers
Photos: Mark Ruder

26. Fish

27. Photo: Emilie Travis

28. Hematopoietic necrosis; tubular epithelial necrosis
Endothelium
Endothelial necrosis
Photo: Tom Waltzek

29. Visualizing the virus

30. Concurrent
Infections

31. Concurrent infections
Photo: Betsie B. Rothermel

32. Ranavirus-positive animals
plus: Parasites increased
In Tennessee: Die-off in
L. clamitans, L. catesbeianus, N.
viridescens
Concurrent infections

33. Concurrent
infections
URTI
Gopher Tortoise (Gopherus polyphemus)
Photo: Jess Gonynor McGuire
Eastern Box Turtle
(Terrapene carolina carolina)

34. Concurrent infections
 Parasitism
– Soft shells (adults)
 Spirorchid eggs (often systemic)
 Entomeoba spp trophozoites
(intestines only)
 Bacterial Enteritis
– Sliders (adults, not pictured)

35. Conclusions

36. Eastern spotted newt
Notophthalmus viridescens
American bullfrog
Lithobates catesbeiana
Creek chub
Semotilus
atromaculatus
affected
unaffected
Eastern box turtle
(Terrapene carolina carolina)
Photo: Mark Ruder
Red-eared slider
(Trachemys scripta elegans)
Pallid sturgeon
Scaphirhynchus
albus
Photo: Tom WaltzekPhoto: Emilie Travis
Photo: Betsie B. Rothermel
CONCLUSIONS
1. Lesions can look similar
across classes
2. Multiple age groups are
affected
3. Interclass transmission is
possible

37. Conclusions
 Isolates from culture facilities appear to have considerably
high virulence
 Host susceptibility varies (and thus community composition
may matter in epizootics)
Pallid sturgeon isolate Ranaculture isolate
Bullfrog (~10%; 0% FV3)Cope’s Gray tree frog (~70% RI; ~40% FV3)
Wood frog (~ 100% for both)

38. Ranaviral Disease Pathology and Physiology
 Current research directives:
– characterizing the pathogenesis of ranaviral disease among virus
isolates and among hosts (including lizards and snakes)
– Elucidating the effects of concurrent pathogens on disease
progression (chytrid and ranavirus; other viruses; mycoplasma)
 In situ hybridization and immunohistochemistry are being
used to visualize the virus within the tissues. Optimization
for detecting multiple ranaviruses is being explored.

39. Acknowledgements
 Matt Gray
 Tom Waltzek
 Bill Sutton
 Jordan Chaney
 Rachel Marschang
 Becky Hardman
 Rachel Goodman
 Julia Lankton
 Sharon Schlosshan and
UT histology laboratory
Histology Funding:
 UT CVM Faculty
Education and Research
(FEAR) Fund
 UT CVM Center of
Excellence

40. Questions?