Effects of oral treatment with TNP-470 on rainbow trout (Oncorhynchus mykiss) infected with Tetracapsuloides bryosalmonae (Malacosporea), the causative agent of proliferative kidney disease

Citation

Morris D, Adams A, Smith P & Richards R (2003) Effects of oral treatment with TNP-470 on rainbow trout (Oncorhynchus mykiss) infected with Tetracapsuloides bryosalmonae (Malacosporea), the causative agent of proliferative kidney disease. Aquaculture, 221 (1-4), pp. 51-64. https://doi.org/10.1016/S0044-8486%2803%2900024-3

Abstract
At present, there are no licensed chemical treatments for proliferative kidney disease (PKD) in rainbow trout Oncorhynchus mykiss. An analogue of fumagillin, TNP-470, has been suggested as a treatment for the disease in sockeye salmon, Oncorhynchus nerka. We report on a series of trials to examine the use of TNP-470 for the treatment of PKD in rainbow trout. Through these trials, we found that, unlike sockeye salmon, this compound can be deleterious to rainbow trout. Histopathological studies on fish treated continuously for 14 days demonstrated a substantial reduction in the haematopoeitic tissues of the kidney along with destruction of tubules. Cell counts also revealed reductions in the number of circulating lymphocytes suggesting that the fish are immunocompromised by the drug. Experimental trials were conducted to develop a treatment regime that was successful in eliminating Tetracapsuloides bryosalmonae, the parasite that causes PKD, from the kidney of rainbow trout. Field trials indicated that the drug compromised the ability of treated fish to mount an effective response against opportunistic bacterial infections, thus limiting its usefulness in the treatment of farmed rainbow trout with T. bryosalmonae. These results suggest that the toxicity of TNP-470 in rainbow trout is similar to that of fumagillin.

Keywords
Tetracapsuloides bryosalmonae; PKD; PKX; TNP-470; Fumagillin

Journal
Aquaculture: Volume 221, Issue 1-4