2013 International Symposium on Ranaviruses by David Lesbarreres

1. Pierre Echaubard,
and David Lesbarrères
Ranavirus II, Knoxville, TN
Environmental dependency of Ranavirus/Amphibian genotypic
interactions: a coevolutionary Rubik’s Cube

2. (Lambrechts et al 2005)
(Salvaudon et al 2005)
(Carius et al 2001)
(Lambrechts et al 2006)
(P1)
(P2)
GH x GP
indicate the potential for non
trivial coevolution based on
Frequency dependent selection
(Wolinska and King 2009)
GH x GP x E
Reaction norm and Phenotypic
plasticity
On the importance of H-P genotypic interactions in
understanding coevolution

3. ***
L > H
• Density is detrimental
Pollution
Competition for resources
• Virulence is context dependent
Visible effects in low density only
a
a
b
b
a
a
b
b
a
a a a
a
a a
a
Context-dependent effects
Echaubard et al. 2010 PLoS One

4. Investigation of GHxGPxE
Hosts
Parasites
Environments
Wt FV3 Azac Ssme
Objectives

5. WtFV3 AzacFV3 SsMV Control
14 °C
Life history traits:
-Size
-Time to metamorphose
-Growth rate
-Mortality rate
22 °C
2
1
1
WtFV3 AzacFV3 SsMV Control
Infection:
1.0x104 pfu/ml)

6. Temperature (F1,369 =5.422;
p=1.07x 10-7)
0
0.05
0.1
0.15
0.2
0.25
0.3
COLD WARM
Weight(g),±SE
COLD
WARM
***
TEMP effects are
SPECIES specific
TEMP affects
Weight at
metamorphosis
Temp*Species*Strain
(F23,3369=7.584; p=2.2x 10-16)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Azac Control SsMeV WtWeight(g),±SE
COLD LF
COLD WF1
COLD WF2
***
a
a
a
a
aa
a
a
a
b
b
b
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Azac Control SsMeV Wt
Weight(g),±SE
WARM LF
WARM
WF1
WARM
WF2
a
b
a
a
a
aa
aa
a
a
b
***
***
***
0
0.1
0.2
0.3
0.4
0.5
LF WF1 WF2
Weight(g),±SE
COLD
WARM
b
a
a
a
aa
***
Temp*Species
(F5,387 =21.98; p=2.2x 10-16)
STRAIN effects are conditional of both TEMP and SPECIES
-No difference between virus Strains in cold temperature but strong
effect of Wt in Warm
-No difference for Wood frogs but strong effect of Wt in Leopard
frogs
Weight at metamorphosis

7. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7 8 9 10
Cumulativemortalityrate(%)
Time period
WARM
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7 8 9 10
Cumulativemortalityrate(%)
Time period
COLD
Mortality

8. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7 8 9 10
Cumulativemortalityrate(%)
Time period
WARM
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1 2 3 4 5 6 7 8 9 10
Cumulativemortalityrate(%)
Time period
COLD
Significant Effects
1. Temperature (Warm)(t =-2.33 ; p=0.021)
2. Time(t =-3.553 ; p<0.0001)
3. TempWarm:WF1(t =-3.553 ; p<0.02)
4. TempWarm:WF2(t =2.165; p<0.03)
5. WF2:Control (t =-4.188; p= 4.29x 10-5)
6. Warm:Time (t =-2.513; p= 0.013)
7. Warm:WF1:Control (t =-2.011; p= 0.045)
8. Warm:WF2:SsMeV (t =2.034; p= 0.043)
9. Warm:WF1:Wt (t =2.253; p= 0.025)
10. Warm:Wt:Time (t =2.798; p= 0.005)
11. Warm:WF2:Wt:Time (t =-1.808; p= 0.001)
-Mortality is influenced by both TEMP (1) and
TIME (2)
- TEMP effect is different among SPECIES (3, 4)
- Mortality is dependant of STRAIN (7, 8, 9)
- TIME effect is dependent of TEMP (6), SPECIES
and STRAIN (10,11)
Repeated measure ANOVA, Bonferroni correction applied
Conclusion/Interpretation

9. 2 – Infection stimulates resource allocation to growth
End point Growth Rate
COLD WF Azac WF ControlLF Azac LF Control
Trade-off immuno/development
1 - Interaction Species*Strain
Growth Rate
3 - Below a certain threshold of virulence, allocation of more resources to growth than
when confronted with a more virulent strain (Wt).

10. Susceptibility
Azac SsMeVWt
Virulence
Weight Growth RateMortality rate
LF
FLIGHT or FIGHT?
Conclusions

11. The analysis revealed considerable variation in life history trait in response to:
Temperature Host Species Virus Strain
GHxGPxE
Amphibian / Ranavirus associated die-offs variability
Integrative approaches for H-P epidemiology and coevolution.
Take Home

12. Work in progress
-Pathogens co-occurrence and environmental variability
-TCID50 at different temperatures
-Strain variability and distribution
deletion of 757bp of
coding region