title: Shrimp pathogenicity, hemolysis, and the presence of hemolysin and TTSS genes in Vibrio harveyi isolated from Thailand.
abstract: The virulence factors of Vibrio harveyi, the causative agent of luminous vibriosis, are not completely understood. We investigated the correlations between shrimp mortality, hemolysis, the presence of a hemolysin gene (vhh), and a gene involved in the type III secretion system (the Vibrio calcium response gene vcrD). V harveyi HY01 was isolated from a shrimp that died from vibriosis, and 36 other V. harveyi isolates were obtained from fish and shellfish in Hat Yai city, Thailand. An ocean isolate of V. harveyi BAA-1116 was also included. Thirteen isolates including V harveyi HYO1 caused shrimp death 12 h after injection. Most V harveyi isolates in this group (designated as Group A) caused hemolysis on prawn blood agar. None of the shrimp died after injection with V harveyi BAA-1116. Molecular analysis of all V harveyi isolates revealed the presence of vcrD in both pathogenic and non-pathogenic strains. Although vhh was detected in all V harveyi isolates, some isolates did not cause hemolysis, indicating that vhh gene expression might be regulated. Analysis of the V harveyi HYO1 genome revealed a V cholerae like-hemolysin gene, hlyA (designated as hhl). Specific primers designed for hhl detected this gene in 3 additional V harveyi isolates but the presence of this gene was not correlated with pathogenicity. Random amplified polymorphic DNA (RAPD) analysis revealed a high degree of genetic diversity in all V harveyi isolates, and there were no correlations among the hhl-positive isolates or the pathogenic strains.
authors.affiliation: Department of Microbiology, Faculty of Science, Prince of Songkla University, Hat Yai, 90112 Songkhla, Thailand.
authors.forename: Pimonsri
authors.initials: P
authors.lastname: Rattanama
authors.forename: Kanchana
authors.initials: K
authors.lastname: Srinitiwarawong
authors.forename: Janelle R
authors.initials: JR
authors.lastname: Thompson
authors.forename: Rattanaruji
authors.initials: R
authors.lastname: Pomwised
authors.forename: Kidchakarn
authors.initials: K
authors.lastname: Supamattaya
authors.forename: Varaporn
authors.initials: V
authors.lastname: Vuddhakul
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D005393:Fish Diseases / Q000382:microbiology; D005399:Fishes / Q000382:microbiology; D006461:Hemolysis; D007928:Lethal Dose 50; D033561:Penaeidae / Q000382:microbiology*; D010802:Phylogeny; D019105:Random Amplified Polymorphic DNA Technique; D016019:Survival Analysis; D013785:Thailand; D014733:Vibrio / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C434936:VhhA protein, Vibrio harveyi