Since 1986 high mortality of hatchery-reared sea bass, Lates Calcarifer, larvae appeared in Ifremer's Pacifie Oceanological Center (Tahiti). Light and electron microscopy show vacuolation and cells with cytoplasmic inclusion bodies in the brain, the cord and the eye relina of affected larvae. Numerous non-enveloped particles identified as viral units, icosahedral in morphology and measuring about 25 nm in diameter were found in the cytoplasm of the degenerating cells. In affected larvae, these particles were isolated by density grandient centrifugations. In vitro tests on cell lines and in vivo test on fish are performed with samples of diseased larvae. And immunisation of mice are made with purified immunoglobulins of Lates calcarifer. |