title: Knockdown of Litopenaeus vannamei HtrA2, an up-regulated gene in response to WSSV infection, leading to delayed shrimp mortality.
abstract: HtrA2 is an apoptosis-activating gene that enhances the apoptotic process by preventing the formation of the IAP-caspase complex, thereby freeing caspase to trigger the apoptosis pathway. In this study, we presented the full-length cDNA sequence of HtrA2 from Litopenaeus vannamei (LvHtrA2). The full-length LvHtrA2 was 1335 bp, encoding 444 amino acids. This deduced amino acid sequence contained five conserved domains: a mitochondrial targeting signal (MTS), a transmembrane (TM) domain, an IAP-binding motif (IBM), a trimerization motif, a serine protease domain, and a PDZ domain normally found in the HtrA2 proteins of other organisms. A phylogenetic analysis revealed that LvHtrA2 clustered with the HtrA2 from other invertebrates and was closely related to Penaeus monodon HtrA2 (PmHtrA2). RT-PCR with RNA extracts from L. vannamei revealed that LvHtrA2 expression was found in several tissues, including the lymphoid organs, the haemocytes, the hepatopancreas, the gill, and the stomach, with different expression levels. When determining the role of LvHtrA2 in WSSV infection, it was found that LvHtrA2 transcription was early up-regulated in the WSSV-infected shrimp at 8h post-infection (p.i.) and expression still remained high at 48 h p.i.. It also demonstrated that dsRNA specific to LvHtrA2 reduced the cumulative mortality in the WSSV-infected shrimp compared with the control group. Additionally, depletion of the LvHtrA2 transcripts reduced expression levels for caspase-3 (Cap-3) gene in shrimp. This result could suggest that LvHtrA2 may involved in apoptosis mediated mortality rather than providing immune protection during WSSV infection.
authors.affiliation: Department of Microbiology, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
authors.forename: Termsri
authors.initials: T
authors.lastname: Peepim
authors.affiliation: Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand.
authors.forename: Kornsunee
authors.initials: K
authors.lastname: Phiwsaiya
authors.affiliation: Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand.
authors.forename: Walaiporn
authors.initials: W
authors.lastname: Charoensapsri
authors.affiliation: Department of Microbiology, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand.
authors.forename: Pongsak
authors.initials: P
authors.lastname: Khunrae
authors.affiliation: Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand.
authors.forename: Saengchan
authors.initials: S
authors.lastname: Senapin
authors.affiliation: Department of Microbiology, Faculty of Science, King Mongkut's University of Technology Thonburi, Bangkok 10140, Thailand. Electronic address: triwit.rat@kmutt.ac.th.
authors.forename: Triwit
authors.initials: T
authors.lastname: Rattanarojpong
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D005393:Fish Diseases / Q000235:genetics* / Q000821:virology; D055785:Gene Knockdown Techniques; D033561:Penaeidae / Q000235:genetics*; D010802:Phylogeny; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014018:Tissue Distribution; D015854:Up-Regulation; D046848:White spot syndrome virus 1 / Q000502:physiology
chemical_list: D012697:Serine Endopeptidases; D053148:Caspase 3
keywords: Apoptosis; Caspase; HtrA2; IAP-binding motif; Litopenaeus vannamei; White spot syndrome virus