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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI: https://doi.org/10.3354/dao03634

    Electron microscopy reveals viral-like particles and mitochondrial degradation in scombrid puffy snout syndrome

    Emily A. Miller*, Savanah Leidholt, Tatiana Galvin, Alexander Norton, Kyle Van Houtan, Rebecca Vega Thurber, Andre Boustany

    *Corresponding author:

    ABSTRACT: Aquaculture is an increasingly important food resource, but its sustainability is often limited by disease. In Scombridae fishes, puffy snout syndrome (PSS) is a debilitating condition where tumor-like collagenous growths form around the eyes, nares, and mandibles which impair vision and feeding, and frequently lead to mortality. While PSS is considered an infectious or metabolic disease, no disease agents or promoters have been identified. Here we use the first attempt of electron microscopy (EM) to describe the cellular pathology and search for etiological agents of PSS in Pacific mackerel (Scomber japonicus), the first use of this approach for PSS. We examined aquaculture specimens across a range of apparent PSS severity, comparing the results to both wild and aquaculture asymptomatic mackerel. EM imagery consistently revealed viral-like particles in PSS samples, as well as the uniform absence of bacteria, protists, fungi, and other multicellular parasites. In addition to viral-like particles, symptomatic fish had a higher mean percentage of swollen and disintegrating mitochondria than both asymptomatic aquaculture and wild mackerel. This suggests that degraded mitochondria may be related to PSS and could be important to further understanding the origin, promoters, and prevention of PSS. This study serves as a first step in identifying PSS etiological agents.