Interaction of the fish pathogen Aeromonas hydrophila with tilapia, Oreochromis aureus (Steindachner), phagocytes

K. Y. LEUNG, K. W. LOW, T. J. LAM, Y. M. SIN*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Abstract. Interaction of Aeromonas hydrophila and tilapia, Oreochromis aureus (Steindachner), phagocytes was studied in vitro. All virulent and avirulent strains of A. hydrophila tested could multiply in non‐activated and Freund's complete adjuvant activated phagocytes. Activated phagocytes increased the uptake of bacteria into cells, and the rates of intracellular replication for these bacteria were faster than in non‐activated phagocytes. Among the A. hydrophila strains examined, virulent strain PPD134/91 replicated at the fastest rate inside phagocytic cells and produced cytopathic effect in the phagocytes in the shortest incubation time. Opsonized avirulent A. hydrophila were sensitive to phagocyte‐mediated killing or unable to grow in phagocytes. Serum components and phagocytes may together prevent the growth of avirulent A. hydrophila in fish. The release of extracellular oxygen radicals during phagocytosis was examined using chemiluminescence assay (CL). Virulent strains induced CL responses but avirulent strains did not. This suggests that the virulent strains interacted with the phagocytes somewhat differently from the avirulent strains.

Original languageEnglish
Pages (from-to)435-447
Number of pages13
JournalJournal of Fish Diseases
Issue number5
StatePublished - Sep 1995
Externally publishedYes


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