Experimental Transmission of Discrete Epidermal Hyperplasia in Walleyes

Abstract

Two related retroviruses, designated walleye epidermal hyperplasia virus type 1 (WEHV1) and type 2 (WEHV2), have been identified in discrete epidermal hyperplasia skin lesions from adult walleyes Stizostedion vitreum. A transmission experiment was conducted in an effort to provide evidence for a viral etiology and to develop a model for pathogenesis studies. Cell-free filtrates derived from discrete epidermal hyperplasia lesions and known to harbor WEHV1 and WEHV2 were injected into young-of-the-year (age-0) walleyes. Discrete epidermal hyperplasia developed in 97% of walleyes inoculated with lesion filtrates; whereas those injected with a cell-free filtrate of normal walleye skin did not develop lesions. The presence of WEHV1 or WEHV2 was detected by polymerase chain reaction (PCR) assay. Amplified DNA products from the PCR assays indicated the presence of viral sequences in 100% and 69% of the skin lesions for WEHV2 and WEHV1, respectively.