The disease and the virus
Viral Encephalopathy and Retinopathy is a viral disease affecting more than 50 fish species, both wild and farmed (sea bass, grouper, sea bream, striped jack, flat fish etc.)(OIE, 2016). The disease causes neurological symptoms and increased mortalities. The disease occurrence has a seasonal pattern, with most outbreaks during the summertime, because of the higher temperatures of the water, which favors virus replication. Fish fry and larvae seem to be most susceptible, and in this age-group the disease can cause up to 100% mortality. Transmission of the disease can occur both horizontal (from fish to fish or equipment/feed to fish) and vertically associated (from brood stock to progeny), and the virus is very persistent in the environment, making spread with vectors (such as boats, feed and equipment) possible. As the name suggest, the disease manifest in the central nervous system causing histopathological necrosis in the brain and retina. Affected fish will either show clinical symptoms such as loss of buoyance control, spiral swimming pattern and darkening of the skin, or die before symptoms appear.Continue reading
Viral encephalopathy and retinopathy (VER), also known as viral nervous necrosis (VNN), is a severe neuropathological disease caused by RNA viruses belonging to the Nodaviridae family, genus Betanodavirus. This infectious agent, detected in the early nineties, has rapidly spread worldwide becoming endemic and representing one of the most important limiting factors to the development of mariculture in several countries. Given the expanding host range and geographic diffusion, the disease has recently been included among the most significant viral pathogens of finfish.
Sparycotyle chrysophrii is a monogenean gill parasite specific for the sea bream (Sparus aurata), causing mortalities when contacted at high prevalence (61.5%) in fish cages (Sanz, 1992; Alvarez-Pellitero, 2004; Vigianou et al. 2006). A parasite has been isolated from the wild (Rajduković and Euzet, 1989; Faisal and Imam, 1990) and the cultured sea bream, and cultured sharpsnout bream (Diplodus puntazzo) (Mladineo and Maršić-Lučić, 2007).Continue reading
The term “Epigenetics” was first introduced by Conrad H. Waddington (1905–1975) in 1942  to describe events that were found not to be congruent with the genetic principles. Today, epigenetic changes concern changes in the structure of DNA resulting from DNA modifications. Contrary to DNA mutations, epigenetic changes are reversible and occur fast.
Apart from the programmed epigenetic regulation that ensures cell differentiation, epigenetic regulation can be influenced by the environment, emphasizing the importance to investigate in depth epigenetic mechanisms (Fig.1). Especially in terms of climate change, which results in changes of temperature, acidity, and salinity in the marine milieu, epigenetics may shed light on the mechanism of phenotypic response triggered by environmental signals.Continue reading