title: Experimental infection of Aphanomyces invadans and susceptibility in seven species of tropical fish.
abstract: OBJECTIVE
  Epizootic ulcerative syndrome (EUS) causes by aquatic oomycete fungus, Aphanomyces invadans is a dangerous fish disease of a wide range of fresh and brackish water, wild and farmed fish throughout the world. The objective of the present study was to determine the susceptibility of a number of tropical fish species to the EUS and compare the severity of infection between experimental groups.
  
  
  METHODS
  Snakehead, Channa striata (Bloch, 1793); snakeskin gourami, Trichopodus pectoralis (Regan, 1910); koi carp, Cyprinus carpio (Linnaeus, 1758); broadhead catfish, Clarias macrocephalus (Günther, 1864); goldfish, Carassius auratus (Linnaeus, 1758); climbing perch, Anabas testudineus (Bloch, 1792); and Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) were challenged by intramuscular injection using zoospores of Aphanomyces invadans (NJM9701). The infected fish skins and muscles were examined for EUS histopathological characteristics, and the results on the severity of lesions and mortality were analyzed using SPSS program.
  
  
  RESULTS
  All zoospore-injected fish were shown to be susceptible to the EUS infection except Nile tilapia. Although, the general histopathological pattern was similar in the zoospore-injected group, but there were some variation in granulomatous reaction, that is the presence or absence of giant cells, and time of mortality were detected. The result of statistical analysis showed that there was a significant difference between species, (c (2)=145.11 and p<0.01).
  
  
  CONCLUSIONS
  Gourami, koi carp, and catfish were demonstrated to be highly susceptible while goldfish and climbing perch were found to be moderately susceptible to the EUS infection. These findings suggested that the cellular response of fish to mycotic infection and granulomatous reaction varied in different fish species, which could not be an indicator of susceptibility or resistant to the EUS itself, although it was shown that the granulation rate and the level of maturity or solidification (consolidation of granulomas) were higher in resistant fish.
authors.affiliation: Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
authors.forename: Seyedeh F
authors.initials: SF
authors.lastname: Afzali
authors.affiliation: Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400 UPM, Serdang, Selangor, Malaysia.
authors.forename: Hassan Hj
authors.initials: HH
authors.lastname: Mohd Daud
authors.affiliation: Iranian Fisheries Research Organization, Tehran, Iran.
authors.forename: Issa
authors.initials: I
authors.lastname: Sharifpour
authors.affiliation: Iranian Fisheries Research Organization, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Afsharnasab
authors.affiliation: Department of Food Engineering, Mokpo National University, Korea.
authors.forename: Shiv
authors.initials: S
authors.lastname: Shankar
keywords: Aphanomyces invadans; epizootic ulcerative syndrome; freshwater fish; histopathology