Genotyping and pathogenicity of Streptococcus iniae strains recovered from cultured Oreochromis niloticus at Kafr El-Shiekh Governorate, Egypt. | ||||
| Egyptian Journal of Aquatic Biology and Fisheries | ||||
| Article 35, Volume 23, Issue 3, July 2019, Page 467-474 PDF (730.61 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejabf.2019.51630 | ||||
 View on SCiNiTO | ||||
| Authors | ||||
| Abdelgayed M. Younes; Alkhateib Y. Gaafar; Alaa El-Din Z. Abu-Bryka; Laila A. Mohamed; El-Sayed M. Bayoumy | ||||
| Abstract | ||||
| Streptococcus iniae causes high mortalities in aquaculture farms all over the world. This study aimed to isolate, identify pathogenicity and genetic relatedness of S. iniae obtained from cultured Nile tilapia (O. niloticus) at Kafr El-Shiekh Governorate. Fourteen isolates of pure S. iniae cultures were biochemically identified, and confirmed through amplification and sequencing of the 16S rRNA gene. Experimental challenge with six selected isolates resulted in marked clinical signs similar to those recorded in natural infections. The LD50 values were ranged between 3.7×107 to 4.3×108 cfu/fish. All strains were sensitive to oxytetracycline and florfenicol. In repetitive sequence-based PCR (rep-PCR) analysis using the BoxA primer, isolates presented genetic heterogeneity and were divided into six genotypes banding patterns. Understanding the epizootiology and genetic variability between S. iniae isolates, could help for better control and vaccine development. | ||||
| Keywords | ||||
| Streptococcus iniae; cultured fish; Oreochromis niloticus; rep-PCR; Epizootiology | ||||
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