Kudoa Iwatai (Myxosporea: Multivalvulida) in Wild and Cultured Fish in the Red Sea: Redescription and Molecular Phylogeny

Abstract

Gilt-head sea bream, Sparus aurata L., the Mediterranean's most important mariculture species, has been cultured for the last 30 yr in Eilat (Israeli Red Sea). Kudoa sp. was the first myxosporean parasite reported from this species. In recent years, an increase in prevalence in both land-based and sea-cage facilities in Eilat has been observed. Infections with the same Kudoa species appeared in cultured European sea bass Dicentrarchus labrax (L.) and grey mullet Mugil cephalus in the same farms, as well as in 10 species of wild Red Sea reef fish, indicating that Kudoa sp. is not fastidious with regard to its host. All affected species displayed 1- to 2-mm (up to 5 mm) whitish, spherical, or oval polysporous plasmodia. The parasite established multiple site infections, most commonly in the muscles and intracranial adipose tissue of the brain and eye periphery. Other sites were subcutaneous adipose tissue, nerve axons, mouth, eye, mesenteries, peritoneum, swim bladder, intestinal musculature, heart, pericardium, kidney, and ovary. On the basis of spore morphology, the parasite was identified as Kudoa iwatai Egusa and Shiomitsu, 1983. Ultrastructural features were comparable to those of previously studied Kudoa species. The 18S rDNA from 7 Red Sea isolates was sequenced and compared with the sequence of the same gene from K. iwatai isolated from cultured red sea bream, Pagrus major, in Japan. The phylogenetic position of K. iwatai within the genus was determined using sequence analysis of all related taxa available in GenBank. The 3 isolates of K. iwatai clustered together on a newly formed, highly supported clade. The Red Sea strain of K. iwatai is apparently native to the region. In the absence of records of this Kudoa sp. from the extensive Mediterranean sea bream and sea bass production industries, introduction with its Mediterranean hosts seems unlikely. Therefore, we conclude that K. iwatai is an Indo-Pacific species that, in the Red Sea, has extended its host range to include the allochthonous gilt-head sea bream, European sea bass, and grey mullet.

Experimental transmission of Enteromyxum leei to freshwater fish

“…The spore dimensions produced in freshwater hosts in this study are comparable with those previously reported from sea bream, red drum and various other aquarium-held host species (Diamant et al 1994, Diamant 1998, Padrós et al 2001. Some morphometric variability has been reported for Enteromyxum leei, assumed to be a result not only of spore fixation method but also of differences in host, a phenomenon addressed by several authors (Kovaleva et al 1979, Diamant 1998, Padrós et al 2001, Diamant et al 2005. Thus, for standardization purposes, measurement of fresh spores should be the preferred method.…”

Kudoa alliaria in flesh of Argentinian hoki Macruronus magellanicus (Gadiformes; Merlucciidae)

“…Thus, some of the differences in dimensions observed here for K. alliaria from M. magellanicus could also be accounted for by variation between hosts. Similar morphological variation between hosts and locations has been shown for Kudoa iwatai (Diamant et al 2005). However, as other studies indicate, it is equally likely that morphologically distinct spores from different hosts can represent separate Kudoa species (Whipps et al 2003.…”

“…This sequence was compared to those of other related Kudoa species as determined from previous analyses (Blaylock et al 2004, Abollo et al 2005, Diamant et al 2005) and using the basic local alignment search tool (BLAST) on GenBank (Altschul et al 1990). Sequences were aligned with Clustal X (Thompson et al 1997) and pairwise sequence similarities were generated with BioEdit version 7.0.5 (Hall 1999).…”

Myxozoans on the Move: Dispersal Modes, Exotic Species and Emerging Diseases

“…Infections can result in post-mortem myoliquifaction and render fillets unmarketable (Moran et al 1999). In the Red Sea, native K. iwatai produced heavy infections in gilt head sea bream (Sparus aurata) when this fish species was introduced from the Mediterranean for cage culture (Diamant et al 2005). In Japan, heavy outbreaks of native K. amamiensis occurred in exotic yellowtail (Seriola quinqueradiata) and amberjack (S. dumerilii) (Sugiyama et al 1999).…”