Abstract
BackgroundViral and bacterial diseases can cause mass mortalities in commercial shrimp aquaculture. In contrast to studies on the antiviral response, the responses of shrimps to bacterial infections by high throughput techniques have been reported only at the transcriptional level and not at the translational level. In this study, a proteomic analysis of shrimp hemocytes to identify differentially expressed proteins in response to a luminous bacterium Vibrio harveyi was evaluated for its feasibility and is reported for the first time.ResultsThe two-dimensional gel electrophoresis (2-DE) patterns of the hemocyte proteins from the unchallenged and V. harveyi challenged shrimp, Penaeus monodon, at 24 and 48 h post infection were compared. From this, 27 differentially expressed protein spots, and a further 12 weakly to non-differentially regulated control spots, were selected for further analyses by the LC-ESI-MS/MS. The 21 differentially expressed proteins that could be identified by homologous annotation were comprised of proteins that are directly involved in the host defense responses, such as hemocyanin, prophenoloxidase, serine proteinase-like protein, heat shock protein 90 and alpha-2-macroglobulin, and those involved in signal transduction, such as the14-3-3 protein epsilon and calmodulin. Western blot analysis confirmed the up-regulation of hemocyanin expression upon bacterial infection. The expression of the selected proteins which were the representatives of the down-regulated proteins (the 14-3-3 protein epsilon and alpha-2-macroglobulin) and of the up-regulated proteins (hemocyanin) was further assessed at the transcription level using real-time RT-PCR.ConclusionsThis work suggests the usefulness of a proteomic approach to the study of shrimp immunity and revealed hemocyte proteins whose expression were up regulated upon V. harveyi infection such as hemocyanin, arginine kinase and down regulated such as alpha-2-macroglobulin, calmodulin and 14-3-3 protein epsilon. The information is useful for understanding the immune system of shrimp against pathogenic bacteria.
Highlights
Viral and bacterial diseases can cause mass mortalities in commercial shrimp aquaculture
Identification of differentially expressed proteins in hemocytes of Vibrio harveyi infected shrimp A proteomic approach was used in this study to reveal the protein expression in shrimp hemocytes in response to V. harveyi infection
We found that the protein spots identified as proPO-1 and proPO-2 (1 and 3 spots, respectively, out of 39 protein spots) were the most dramatically differentially expressed immune related proteins upon V. harveyi infection
Summary
Viral and bacterial diseases can cause mass mortalities in commercial shrimp aquaculture. Vibriosis is the major bacterial disease caused by bacteria in the genus Vibrio [2]. The outbreaks of these diseases have led to the near or total collapse of the shrimp farming industry throughout the world. In the black tiger shrimp, Penaeus monodon, vibriosis caused by Vibrio harveyi, a luminous bacterium, usually affects the animal at larval stages. It is considered as an opportunistic pathogen for juvenile and adult shrimps under environmental stress [2,3]. The elucidation of the shrimp immune responses to vibriosis is of great interest for the prevention and control of infectious diseases in shrimp aquaculture
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