Tetrahymena: an alternative model host for evaluating virulence of Aeromonas strains

• Published in: PloS one 2012-11, Vol.7 (11), p.e48922
• Main Authors: Pang, Mao-Da, Lin, Xiao-Qin, Hu, Meng, Li, Jing, Lu, Cheng-Ping, Liu, Yong-Jie
• Format: Article
• Language: English
• Subjects: Aeromonas; Aeromonas hydrophila; Aeromonas hydrophila - isolation & purification; Aeromonas hydrophila - pathogenicity; Analysis; Animals; Bacteria; Biology; Coculture Techniques; Culture; Danio rerio; E coli; Escherichia coli; Fish; Gene expression; Genomes; Gram-Negative Bacterial Infections - microbiology; Health aspects; High-throughput screening; Lethal dose; Lethal Dose 50; Medical research; Medicine; Protozoa; Strains (organisms); Survival; Tetrahymena; Tetrahymena - microbiology; Tetrahymena pyriformis; Tetrahymena thermophila; Veterinary colleges; Veterinary medicine; Veterinary Science; Virulence; Virulence (Microbiology); Zebrafish; Zebrafish - microbiology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0048922

An easier assessment model would be helpful for high-throughput screening of Aeromonas virulence. The previous study indicated the potential of Tetrahymena as a permissive model to examine virulence of Aeromonas hydrophila. Here our aim was to assess virulence of Aeromonas spp. using two model hosts, a zebrafish assay and Tetrahymena-Aeromonas co-culture, and to examine whether data from the Tetrahymena thermophila model reflects infections in the well-established animal model. First, virulence of 39 Aeromonas strains was assessed by determining the 50% lethal dose (LD(50)) in zebrafish. LD(50) values ranging from 1.3×10(2) to 3.0×10(7) indicated that these strains represent a high to moderate degree of virulence and could be useful to assess virulence in the Tetrahymena model. In Tetrahymena-Aeromonas co-culture, we evaluated the virulence of Aeromonas by detecting relative survival of Aeromonas and Tetrahymena. An Aeromonas isolate was considered virulent when its relative survival was greater than 60%, while the Aeromonas isolate was considered avirulent if its relative survival was below 40%. When relative survival of T. thermophila was lower than 40% after co-culture with an Aeromonas isolate, the bacterial strain was regarded as virulent. In contrast, the strain was classified as avirulent if relative survival of T. thermophila was greater than 50%. Encouragingly, data from the 39 Aeromonas strains showed good correlation in zebrafish and Tetrahymena-Aeromonas co-culture models. The results provide sufficient data to demonstrate that Tetrahymena can be a comparable alternative to zebrafish for determining the virulence of Aeromonas isolates.