title: Tetrahymena: an alternative model host for evaluating virulence of Aeromonas strains.
abstract: 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.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
authors.forename: Mao-Da
authors.initials: MD
authors.lastname: Pang
authors.forename: Xiao-Qin
authors.initials: XQ
authors.lastname: Lin
authors.forename: Meng
authors.initials: M
authors.lastname: Hu
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Cheng-Ping
authors.initials: CP
authors.lastname: Lu
authors.forename: Yong-Jie
authors.initials: YJ
authors.lastname: Liu
mesh_terms: D016980:Aeromonas hydrophila / Q000302:isolation & purification* / Q000472:pathogenicity*; D000818:Animals; D018920:Coculture Techniques; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology*; D007928:Lethal Dose 50; D013768:Tetrahymena / Q000382:microbiology*; D014774:Virulence; D015027:Zebrafish / Q000382:microbiology