Fish lymphocystis disease virus (FLDV) has been tentatively classified
as a separate genus of the iridovirus family. Iridoviruses were
previously called icosahedral cytoplasmic deoxyriboviruses (ICDV). The
Iridoviridae family contains four genera including lymphocystis disease
virus (proposed name Lymphocystivirus, Willis, 1989 (1. FLDV is a
causative agent of lymphocystis disease (LD) which frequently appears in
Pleuronectidae (flatfish) such as Pleuronectes platessa (plaice),
Platichtys flesus (flounder), Limanda limanda (dab), and Trigla
gurnardus (gurnard). Fish lymphocystis disease is characterized by
papilloma-like lesions, which can be induced experimentally in Lepomis
macrochirus (bluegill) (2) and by subdermal injection of plaice and
flounder (3). The mechanisms of this nonmalignant tumor induction are
unknown. Since the discovery of LD in 1874 by Lowe (4), attempts have
been made to isolate and propagate FLDV in vitro with limited success
(5-7). As a first step towards understanding of the underlying
mechanisms of this infectious disease the structure and properties of
the causal virus must be eluciated. These basical molecular biological
studies provide new facilities for investigation of virus host
interactions which is necessary for understanding the molecular
mechanisms of the viral pathogenesis. MATERIALS AND METHODS A total of
30 fish with LD lesions caught near the Doggerbank areas were analyzed
individually, including 20 flounders, six dabs, and four plaice. Virions
of FLDV from LD lesions of each species of fish were isolated, purified,
and examined by electron microscopy as 205 described previously (8).
Fig.
