Clinical trial results on the use of a recombinant feline interferon-ω to protect Japanese pearl oysters Pinctada fucata martensii from akoya-virus infection

Abstract

Japanese pearl oysters (akoya oyster: Pinctada fucata martensii) are currently suffering mass mortalities from akoya-virus infection. In the present study, akoya oysters were injected with an anti-viral, recombinant feline interferon-ω (rFeIFN-ω) in an attempt to confer resistance to this virus. In infectivity experiments, oysters were twice injected with rFeIFN-ω at 1 mega unit kg -1 of the meat weight. They were challenged with a single inoculation of cultured akoya-virus and held for 20 to 30 d at 25°C. Control oysters received only the viral challenge without rFeIFN-ω administration. In prophylactic experiments, oysters that were given the akoya-virus on Days 1 to 5 after rFeIFN-ω administration showed lower mortalities. Furthermore, the survivors had fewer muscular lesions resulting from the virus infection than the controls. In treatment experiments, the virus was inoculated on Days 1 to 3 before rFeIFN-ω administration. None of the treated oysters died within a 30 d experimental period. Survivors displayed repaired lesions with fibrous tissues that were produced by enhanced agranulocytes in the body musculature. Moreover, rFeIFN-ω was not toxic to akoya oysters. Thus, rFeIFN-ω administration is efficacious in preventing mortality of akoya oysters with akoya-virus infection.KEY WORDS: Japanese pearl oyster · Akoya-virus infection · Recombinant feline interferon-ω · Efficacy in enhancement · Agranulocyte · Collagen fiber production Resale or republication not permitted without written consent of the publisher

Two Vibrio splendidus related strains collaborate to kill Crassostrea gigas: taxonomy and host alterations

“…Furthermore, other pathogens were described as inducing muscular lesions in marine animals. For instance, the akoya-virus infection in the Japanese pearl oyster Pinctada fucata martensii induced necrosis, atrophy, swelling and vacuolisation of the muscle fibres of the adductor, foot, and pallial muscles (Miyazaki et al 1999, Miyazaki et al 2000. Co-infection of the giant freshwater prawn Macrobrachium rosenbergii by the yeast Metschnikowia bicuspidata and the bacteria Enterococcus faecium led to important edema and liquefactive necrosis in abdominal, pereipod and pleopod muscles (Chen et al 2003).…”

Receptors for recombinant feline interferon-w in hemocytes of the Japanese pearl oyster Pinctada fucata martensii

“…We chose to observe agranulocytes because they are involved in the repair of necrotic lesions associated with akoya-virus in the musculature (Miyazaki et al 2000). The granulocytes contained granules that autofluoresced orange.…”

“…In the akoya oysters we examined, almost 56% of the agranulocytes bore rFeIFN-ω receptors. We have previously shown that rFeIFN-ω administration is markedly effective in treating akoya-virus infection in akoya oysters (Miyazaki et al 2000). The activity of r+agranulocytes appears to be enhanced when rFeIFN-ω reacted with their rFeIFN-ω receptors.…”

“…Treated r+agranulocytes performed active phagocytosis of necrotized cells and produced collagen fibers to repair necrotic lesions caused by akoya-virus infection. Thus, rFeIFN-ω administration is effective in repairing necrotic lesions and preventing mortality in akoyavirus infected oysters (Miyazaki et al 2000). In previous studies, the process of natural wound-healing has been examined in akoya oysters (Suzuki et al 1991, Suzuki & Awaji 1995, The Pacific oyster Crassostrea gigas (DesVoigne & Sparks 1968, Ruddell 1971) and the freshwater mussel Andonta oregonensis (Pauley & Heaton 1969).…”

“…In a previous study, we found that administration of recombinant feline interferon-ω (rFeIFN-ω) was effective in preventing mortality in Japanese pearl oysters (akoya oyster) Pinctada fucata martensii due to infection by the akoya-virus which has caused mass mortalities in recent years in western Japan (Miyazaki et al 1999(Miyazaki et al , 2000. Akoya oysters injected with akoya-virus and subsequently treated by injections with rFeIFN-ω survived and displayed the regenerating characteristics of necrotic lesions associated with akoya-virus infection: many agranulocytes phagocytized necrotic cells and synthesized collagen fibrils which produced fibrous tissues to replace the necrotic lesions in the adductor, pallial and peduncle musculature as well as in the myocardium.…”