title: Differences in uptake and killing of pathogenic and non-pathogenic bacteria by haemocyte subpopulations of penaeid shrimp, Litopenaeus vannamei, (Boone).
abstract: Phagocytosis is an important function of both invertebrate and vertebrate blood cells. In this study, the phagocytic activity of haemocyte subpopulations of penaeid shrimp, Litopenaeus vannamei, (Boone), against pathogenic and non-pathogenic particles was investigated in vitro. The haemocytes of penaeid shrimp were firstly separated by centrifugation on a continuous density gradient of iodixanol into four fractions with five subpopulations (sub), of which sub 1 (hyalinocytes) and sub 4 (semi-granulocytes) have the main function in phagocytosis of both pathogenic and non-pathogenic bacteria as well as fluorescent polystyrene beads. It was found that these haemocyte subpopulations engulfed virulent Vibrio campbellii and Vibrio harveyi at a higher rate than non-virulent Escherichia coli and polystyrene beads. When these bacteria were mixed with shrimp haemocyte subpopulations and incubated for 180 min, the percentage of viable intracellular V. campbellii (25.5 ± 6.0%) recovered was significantly higher than the percentage recovered from V. harveyi (13.5 ± 1.1%). No viable intracellular E. coli was observed in this study. In contrast to V. harveyi and E. coli, V. campbellii containing endosomes did not acidify in time. Incubation of haemocyte subpopulations with the most virulent V. campbellii strain resulted in a significant drop in haemocyte viability (41.4 ± 6.3% in sub 1 and 30.2 ± 15.1% in sub 4) after 180 min post-inoculation in comparison with the less virulent V. harveyi (84.1 ± 5.6% in sub 1 and 83.4 ± 4.1% in sub 4) and non-virulent E. coli (92.7 ± 2.8% in sub 1 and 92.3 ± 5.6% in sub 4) and polystyrene beads (91.9 ± 1.6% in sub 1 and 84.4 ± 3.4% in sub 4). These findings may be a valuable tool for monitoring shrimp health and immunological studies.
authors: Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium.
authors: V V
authors: VV
authors: Tuan
authors: Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium.
authors: J J
authors: JJ
authors: Dantas-Lima
authors: Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium.
authors: K V
authors: KV
authors: Thuong
authors: Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium.
authors: W
authors: W
authors: Li
authors: Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium.
authors: K
authors: K
authors: Grauwet
authors: Laboratory of Aquaculture & Artemia Reference Center, Faculty of Bioscience Engineering, Department of Animal Production, Ghent University, Ghent, Belgium.
authors: P
authors: P
authors: Bossier
authors: Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium.
authors: H J
authors: HJ
authors: Nauwynck
mesh_terms: D000818:Animals; D002470:Cell Survival; D004926:Escherichia coli / Q000502:physiology*; D006434:Hemocytes / Q000276:immunology / Q000502:physiology / Q000821:virology; D006863:Hydrogen-Ion Concentration; D033561:Penaeidae / Q000276:immunology* / Q000821:virology*; D010587:Phagocytosis; D011137:Polystyrenes / Q000378:metabolism; D013047:Specific Pathogen-Free Organisms; D014733:Vibrio / Q000502:physiology*
chemical_list: D011137:Polystyrenes
keywords: Litopenaeus vannamei; bacteria; haemocyte subpopulations; phagocytosis