Gastrointestinal helminths increase Bordetella bronchiseptica shedding and host variation in supershedding

  1. Nhat TD Nguyen
  2. Ashutosh K Pathak
  3. Isabella M Cattadori  Is a corresponding author
  1. Center for Infectious Disease Dynamics, The Pennsylvania State University, United States
  2. Department of Biology, The Pennsylvania State University, United States
  3. Department of Infectious Diseases, University of Georgia, United States
21 figures, 4 tables and 1 additional file

Figures

Observed levels of B. bronchiseptica shedding by contact of infected rabbits with a Bordet-Gengou agar petri dish.

Rabbits (infected shedders and non-shedders) from the four types of infection are reported, B. bronchiseptica (B), B. bronchiseptica-G. strigosum (BG), B. bronchiseptica-T. retortaeformis (BT) and B.…

Observed level of B.bronchiseptica shedding by days post infection (Dpi) and type of infection.

Shedding events (points), host individual trajectories (thin lines) and median population trend (smoothed thick lines) with 95% CI (blue shadows) are reported. The trajectories of few individuals …

Frequency of observed B.bronchiseptica shedding events for the four types of infection.

Events have been grouped by shedding level using 0.5 CFU/s unit intervals, the first interval represents events with zero shedding. Red lines indicate the 95th and 99th percentile thresholds, …

B. bronchiseptica shedding on BG-blood agar petri dishes.

Examples of A: supershedding event and B: average shedding event.

Estimated immune responses in the blood by time and type of infection.

Empirical longitudinal data (points) with estimated trajectories (black lines) for every individual rabbit, and group means (blue lines) with 95% CIs (blue shadows) are reported. The abrupt …

Estimated rates of infection in the whole respiratory tract and immune response in the blood by time and type of infection.

Means (continuous lines) and 95% CIs (shaded areas) are reported for neutrophils (black), IgA (blue), IgG (red), and B. bronchiseptica infection (green). Individual trends (dotted lines) have been …

Estimated dynamics of B. bronchiseptica shedding by time and type of infection.

The empirical shedding events (gray points), the estimated individual trajectories (smoothed thin black lines) and the estimated median group trends (blue lines), with the related 95%CIs (blue …

Appendix 1—figure 1
Parameter estimates from posterior distribution for BG.

Individual average (black points) with 95% CIs (black segments), and group average (named ’Pop’, red points) with 95% CIs (red segments), are reported. X-axis lists the rabbit’s ID every 5 animals …

Appendix 1—figure 2
Parameter estimates from posterior distribution for BT.

Full details in Appendix 1—figure 1.

Appendix 1—figure 3
Parameter estimates from posterior distribution for BTG.

Full details in Appendix 1—figure 1.

Appendix 2—figure 1
Relationship between B.bronchiseptica peak of shedding and percentile changes in neutrophils, IgA, and IgG.

The growth a, and neutralizing c, rates of neutrophils (subscript 1), IgA (subscript 2) and IgG (subscript 3), including bacterial growth rate r, are reported by group. Mean estimates with 95% CIs …

Appendix 2—figure 2
Relationship between B.bronchiseptica time to peak of shedding and percentile changes in neutrophils, IgA, and IgG.

Full details in Appendix 2—figure 1.

Appendix 3—figure 1
MCMC trace plot for B.

Different colors represent the four chains.

Appendix 3—figure 2
MCMC trace plot for BG.

Different colors represent the four chains.

Appendix 3—figure 3
MCMC trace plot for BT.

Different colors represent the four chains.

Appendix 3—figure 4
MCMC trace plot for BTG.

Different colors represent the four chains.

Appendix 3—figure 5
MCMC posteriors from B.

Histograms (diagonal), pair-wise scatterplots (upper right) and related correlations (lower left) from the parameter posteriors.

Appendix 3—figure 6
MCMC posteriors from BG.

Histograms (diagonal), pair-wise scatterplots (upper right) and related correlations (lower left) from the parameter posteriors.

Appendix 3—figure 7
MCMC posteriors from BT.

Histograms (diagonal), pair-wise scatterplots (upper right) and related correlations (lower left) from the parameter posteriors.

Appendix 3—figure 8
MCMC posteriors from BTG.

Histograms (diagonal), pair-wise scatterplots (upper right) and related correlations (lower left) from the parameter posteriors.

Appendix 4—figure 1
Model validation using group-level parameters.

The vertical lines represent the true parameters that were used to simulate the datasets.

Tables

Table 1
Description and unit of parameters and variables used in the dynamical and observed models.
Parameters/DescriptionsUnitValue
Variables
Rabbit ith specific parameters
a1,i,b1,i,c1,iGrowth, decay and B. bronchiseptica neutralization rates of neutrophilsday-1Estimated
a2,i,b2,c2,iGrowth, decay and B. bronchiseptica neutralization rates of IgAday-1Estimated
a3,i,b3,c3,iGrowth, decay and B. bronchiseptica neutralization rates of IgGday-1Estimated
riPer capita B. bronchiseptica replication rateday-1Estimated
x1,i(t)Time-dependent neutrophil responsecells/mlCalculated
x2,i(t)Time-dependent IgA responseO.D. indexCalculated
x3,i(t)Time-dependent IgG responseO.D. indexCalculated
yi(t)Time-dependent B. bronchiseptica infection intensityCFU/g countCalculated
Group parameters
μa1,μb1,μc1Mean of neutrophil growth, decay and neutralization ratesday-1Estimated
σa1,σb1,σc1Standard deviation (S.D.) of neutrophil growth, decay and neutralization ratesday-1Estimated
μa2,μc2Mean of IgA growth, and neutralization ratesday-1Estimated
σa2,σc2Standard deviation (S.D.) of IgA growth, and neutralization ratesday-1Estimated
μa3,μc3Mean of IgG growth, and neutralization ratesday-1Estimated
σa3,σc3Standard deviation (S.D.) of IgG growth, and neutralization ratesday-1Estimated
μr,σrMean and S.D. of B. bronchiseptica replication ratesday-1Estimated
x1*Neutrophils level at equilibriumcells/mlObserved
μy0B. bronchiseptica infection intensity at time t=0CFU/g countEstimated
Table 2
Model prior and posterior parameters for the immune response and B. bronchiseptica infection.

We report: mean and S.D. of priors, and mean, 95% CI and S.D. from posterior distributions for each group. The complete description of the parameters is provided in Table 1.

ParametersPriorsPosteriors BPosteriors BGPosteriors BTPosteriors BTG
μa1*10-40.10 (0.05)2.89 (1.17–4.61)1.08 (0.31–1.85)3.32 (1.73–4.90)0.93 (0.35–1.50)
μa21051.10 (0.20)2.00 (1.65–2.35)0.81 (0.51–1.11)0.99 (0.61–1.36)1.36 (0.91–1.81)
μa3*10-50.30 (0.10)1.51 (1.27–1.75)0.66 (0.43–0.89)0.78 (0.49–1.36)0.86 (0.59–1.81)
μb1 0.50 (0.10)1.20 (0.83–1.57)0.54 (0.37–0.71)0.86 (0.61–1.11)0.58 (0.40–0.77)
b2*10-30.30 (0.10)7.07 (5.55–8.59)3.10 (2.4–3.80)5.57 (4.97–6.16)7.43 (6.50–8.36)
b3*10-40.10 (0.07)0.93 (0.03–1.83)0.66 (0.02–1.30)0.39 (0.01–0.77)0.49 (0.01–0.97)
μc10.20 (0.05)0.11 (0.06–0.16)0.13 (0.06–0.20)0.05 (0.03–0.07)0.30 (0.19–0.42)
μc20.12 (0.02)0.044 (0.003–0.085)0.13 (0.03–0.22)0.22 (0.16–0.27)0.01 (.0004–0.02)
μc30.10 (0.07)0.042 (0.002–0.083)0.29 (0.18–0.40)0.33 (0.25–0.42)0.32 (0.23–0.42)
r1.70 (0.30)0.06 (0.01–0.12)1.18 (0.83–1.54)1.01 (0.83–1.18)1.47 (1.10–1.83)
μy0*1030.68 (0.68–0.68)0.71 (0.35–1.07)0.68 (0.36–1.01)0.82 (0.46–1.18)
x*0.051.891.932.75
σx10.450.380.530.70
σx20.220.400.330.22
σx30.080.100.150.15
σy1.006.024.504.01
Appendix 3—table 1
Scale reduction factors for each parameter of the four types of infection.
ParametersBBGBTBTG
μa11.0002341.0001031.0002521.000047
μb11.0001661.0002051.0001221.000073
μc11.0000531.0000470.9999771.000423
μa21.0001201.0001741.0002850.999986
μb21.0000431.0000491.0000511.000128
μc21.0000600.9999731.0002401.000316
μa31.0000681.0001661.0000271.000059
μb31.0000130.9999270.9999191.000089
μc30.9999671.0000161.0002241.000204
μr0.9999720.9999611.0001391.000517
log(LLH)1.0006501.0004061.0005211.000401
Appendix 5—table 1
Bayesian Information Criterion (BIC) and level of model complexity (N), including pair-wise Δ BIC with the best fitted model.
ModelsBIC-ΔBICBBGBTBTGN
Neutrophils+IgA+IgGBIC-652.9-351.2594.8-610.512
Neutrophils+IgABIC-251.3-302.2-570.9-507.79
Neutrophils+IgAΔBIC401.548.923.9102.8
Neutrophils+IgGBIC-314.8-105.6-442.0-423.99
Neutrophils+IgGΔBIC338.1245.6152.7186.5

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