Encephalomyelitis associated with microsporidian infection in farmed greater amberjack, Seriola dumerili (Risso)

The pathogenesis of cyprinid herpesvirus-3 (CyHV-3) was studied using different lineages of carp/koi. After exposure to the virus, infected cells were first found in the skin by histopathology and by in situ hybridization. The epidermis of the skin was most severely damaged and often sloughed off in the fish sampled on days 5 through 8, and the fish that were highly sensitive to the virus died within 8 or 10 days after infection. Serum osmolality of the infected fish, particularly just before death, was significantly lower, suggesting that the osmotic shock consequent on the damage to the skin was the direct cause of the acute deaths. On the other hand, clinical and histopathological observations indicate that the carp of a less sensitive lineage most probably died of viral encephalitis around 3 weeks after infection. For these fish, the largest number of infected cells was found in the central nervous system (CNS) sampled on day 12. A substantial amount of viral genome was found in the CNS of carp surviving more than 1 year after the infection. Thus, the CNS is probably a major target for CyHV-3, and the virus can persistently infect the CNS, presumably establishing latency.

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“…; Miwa et al . ). Although abnormal swimming of CyHV‐3‐infected carp/koi was observed previously (Hedrick et al .…”

Section: Discussionmentioning

confidence: 97%

Pathogenesis of acute and chronic diseases caused by cyprinid herpesvirus‐3

Miwa

Kiryu

Yuasa

et al. 2014

Journal of Fish Diseases

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“…), an unknown species in amberjack (Miwa et al. ), and Loma salmonae in rainbow trout (Sanchez and Speare ). Sanchez and Speare () used this technique to track the initial stages of the parasite, finding proliferative stages of the parasite in the cells underlying the endocardium, which was present prior to the appearance of xenomas containing mature spores in the gills of infected fish.…”

mentioning

confidence: 99%

Early Development and Tissue Distribution of Pseudoloma neurophilia in the Zebrafish, Danio rerio

Sanders

Peterson

Kent

2014

J Eukaryotic Microbiology

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The early proliferative stages of the microsporidian parasite, Pseudoloma neurophilia were visualized in larval zebrafish, Danio rerio, using histological sections with a combination of an in situ hybridization probe specific to the P. neurophilia small-subunit ribosomal RNA gene, standard hematoxylin-eosin stain, and the Luna stain to visualize spores. Beginning at 5 days post fertilization, fish were exposed to P. neurophilia and examined at 12, 24, 36, 48, 72, 96, and 120 h post exposure (hpe). At 12 hpe, intact spores in the intestinal lumen and proliferative stages developing in the epithelial cells of the anterior intestine and the pharynx and within hepatocytes were observed. Proliferative stages were visualized in the pancreas and kidney at 36 – 48 hpe and in the spinal cord, eye, and skeletal muscle beginning at 72 hpe. The first spore stages of P. neurophilia were observed at 96 hpe in the pharyngeal epithelium, liver, spinal cord, and skeletal muscle. The parasite was only observed in the brain of larval fish at 120 hpe. The distribution of the early stages of P. neurophilia and the lack of mature spores until 96 hpe indicates that the parasite gains access to organs distant from the initial site of entry, likely by penetrating the intestinal wall with the polar tube.

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“…These species, and another one also belonging to the same family Tetramicridae, Tetramicra brevifilum (AF364303), formed a clade supported by 67% (MP), 72% (ML), 88% (NJ) bootstrap. Recently an rRNA gene sequence (AB623034) belonging to a microsporidian classified as Spraguea sp., a parasite of the greater amberjack, Seriola dumerili , from Japan was deposited, with the report that it is clustered with those species (Miwa et al 2011). This event is unexpected because it is known that Spraguea species formed a monophyletic clade and all of them have lophiid fishes as hosts (Freeman et al .…”

Section: Discussionmentioning

confidence: 99%

Ultrastructural and molecular studies of Microgemma carolinus n. sp. (Microsporidia), a parasite of the fish Trachinotus carolinus (Carangidae) in Southern Brazil

et al. 2012

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A new species of Microsporidia Microgemma carolinus n. sp. found in the marine teleost Trachinotus carolinus collected in Florianópolis, Brazil was described based on light, ultrastructural and phylogenetic studies. This parasite developed in the liver forming whitish xenomas that contained different developmental stages with monokaryotic nuclei. The periphery of the xenoma presented some vacuolization and possessed several small projections in the membrane. The mature spores, measuring 3·8 ± 0·4 μm in length and 2·4 ± 0·4 μm in width, were slightly pyriform to ellipsoidal and had rounded ends. The polaroplast was bipartite and the isofilar polar filament was coiled with 8 - 9 turns in a single or double row at the posterior end of the spore. The nucleus was voluminous and in a central position, measuring ~0·9 μm in diameter. A large posterior vacuole appeared as a pale area, occupying about a third of the spore length. The SSU rRNA gene was sequenced and analysed using maximum parsimony, maximum likelihood and neighbour-joining methods. This study allowed us to conclude that this was a new species of the genus Microgemma, being the first description of this genus from among South America fauna.

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Encephalomyelitis associated with microsporidian infection in farmed greater amberjack, Seriola dumerili (Risso)

Cited by 16 publications

References 22 publications

Pathogenesis of acute and chronic diseases caused by cyprinid herpesvirus‐3

Pathogenesis of acute and chronic diseases caused by cyprinid herpesvirus‐3

Early Development and Tissue Distribution of Pseudoloma neurophilia in the Zebrafish, Danio rerio

Ultrastructural and molecular studies of Microgemma carolinus n. sp. (Microsporidia), a parasite of the fish Trachinotus carolinus (Carangidae) in Southern Brazil

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