Genetic diversity of geographically distinct Streptococcus dysgalactiae isolates from fish.
Streptococcus dysgalactiae is an emerging pathogen of fish. Clinically, infection is characterized by the development of necrotic lesions at the caudal peduncle of infected fishes. The pathogen has been recently isolated from different fish species in many countries. Twenty S. dysgalactiae isolates collected from Japan, Taiwan, Malaysia and Indonesia were molecularly characterized by biased sinusoidal field gel electrophoresis (BSFGE) using SmaI enzyme, and tuf gene sequencing analysis. DNA sequencing of ten S. dysgalactiae revealed no genetic variation in the tuf amplicons, except for three strains. The restriction patterns of chromosomal DNA measured by BSFGE were differentiated into six distinct types and one subtype among collected strains. To our knowledge, this report gives the first snapshot of S. dysgalactiae isolates collected from different countries that are localized geographically and differed on a multinational level. This genetic unrelatedness among different isolates might suggest a high recombination rate and low genetic stability.
Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt.
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Abdelsalam
Department of Fish Diseases and Management, Faculty of Veterinary Medicine, Cairo University, Giza, Egypt ; Departments of Poultry and Fish Diseases, Faculty of Veterinary Medicine, Tripoli University, Tripoli, Libya.
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Eissa
Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Pingtung, Taiwan ; Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan.
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Chen
BSFGE; Epidemiology; Streptococcus dysgalactiae; tuf gene sequencing