Ranavirus infection dynamics and shedding in American bullfrogs: consequences for spread and detection in trade

Pooled samples and eDNA-based detection can facilitate the “clean trade” of aquatic animals

“…The concentration of target DNA in an eDNA sample co-varies with the type and intensity of infection and details of the sampling method (here volume sampled, pore size, storage conditions 78 ), as with individual samples 26 , but also depends on the conditions in which animals are held (e.g., temperature, volume, time in the water; Fig. 3).…”

“…All of which means that fairly little target DNA may end up in any given eDNA sample. Thus, one would expect the diagnostic sensitivity of eDNA samples to be quite low relative to individual-based samples 26,73 (Fig. 3).…”

“…The eDNA approach seems especially relevant to aquatic and semi-aquatic taxa, which make up a large portion of the wildlife trade 6 , as eDNA can be simply filtered from water housing animals; they need not even be handled. (Semi-aquatic species or life stages are often shipped in moist sphagnum moss or paper, but can then be placed in water to collect eDNA during a quarantine period 26 .) Environmental DNA sampling is being used to detect pathogens in a growing number of settings, from natural environments [27][28][29][30] to ballast water 31 and even in trade [32][33][34] .…”

Evaluating the Within-Host Dynamics of Ranavirus Infection with Mechanistic Disease Models and Experimental Data

“…A full qualitative and statistical analysis of the experimental data can be found in [17]. For our purposes, it is important to note the clear rise and fall of viral titers over time in the medium and high dosage treatments, which suggested a possible immune response that was leading towards viral clearance, and which motivated our modeling-fitting and model comparison routine.…”

“…Details of the experiment can be found in Brunner et al [17], but the essential details are that tadpoles (Gosner [18] stages 25–28) were exposed in 400 mL water baths for 24 h to one of three doses of the ranavirus FV3: a high dose (10 5 plaque-forming units [pfu] mL −1 ; n = 150), medium-dose (10 3 pfu mL −1 ; n = 150), or a low, but unknown dose ( n = 90 in “mock” exposure to inadvertently contaminated cell culture media). The tadpoles were assigned to be euthanized and sampled on days 2, 4, 6, 8, 14, 21, 28, 35, 42, and 49 post exposure ( n = 15 high-dose, n = 15 low-dose, and n = 9 “mock” tadpoles per time point), although some died and were sampled before their assigned date.…”