, spp., and Intestinal Lesions in Experimentally Infected Zebrafish .

Intestinal neoplasms and preneoplastic lesions are common in zebrafish research facilities. Previous studies have demonstrated that these neoplasms are caused by a transmissible agent, and two candidate agents have been implicated: a sp. related to and the intestinal parasitic nematode, , and both agents are common in zebrafish facilities. To elucidate the role of these two agents in the occurrence and severity of neoplasia and other intestinal lesions, we conducted two experimental inoculation studies. Exposed fish were examined at various time points over an 8-month period for intestinal histopathologic changes and the burden of and nematodes. Fish exposed to sp. isolated from zebrafish were associated with preneoplastic lesions. Fish exposed to the nematode alone or with the isolate developed severe lesions and neoplasms. Both inflammation and neoplasm scores were associated with an increase in burden. These results support the conclusions that is a strong promoter of intestinal neoplasms in zebrafish and that alone can also cause intestinal lesions and accelerate cancer development in the context of nematode infection.