Identification of genes preferentially expressed by highly virulent piscine Streptococcus agalactiae upon interaction with macrophages.
Streptococcus agalactiae, long recognized as a mammalian pathogen, is an emerging concern with regard to fish. In this study, we used a mouse model and in vitro cell infection to evaluate the pathogenetic characteristics of S. agalactiae GD201008-001, isolated from tilapia in China. This bacterium was found to be highly virulent and capable of inducing brain damage by migrating into the brain by crossing the blood-brain barrier (BBB). The phagocytosis assays indicated that this bacterium could be internalized by murine macrophages and survive intracellularly for more than 24 h, inducing injury to macrophages. Further, selective capture of transcribed sequences (SCOTS) was used to investigate microbial gene expression associated with intracellular survival. This positive cDNA selection technique identified 60 distinct genes that could be characterized into 6 functional categories. More than 50% of the differentially expressed genes were involved in metabolic adaptation. Some genes have previously been described as associated with virulence in other bacteria, and four showed no significant similarities to any other previously described genes. This study constitutes the first step in further gene expression analyses that will lead to a better understanding of the molecular mechanisms used by S. agalactiae to survive in macrophages and to cross the BBB.
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Chang-Ming
CM
Guo
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Rong-Rong
RR
Chen
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Dildar Hussain
DH
Kalhoro
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Zhao-Fei
ZF
Wang
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Guang-Jin
GJ
Liu
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Cheng-Ping
CP
Lu
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Yong-Jie
YJ
Liu
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000382:microbiology / Q000473:pathology; D004269:DNA, Bacterial / Q000378:metabolism; D020869:Gene Expression Profiling; D005798:Genes, Bacterial / Q000235:genetics*; D007124:Immunoenzyme Techniques; D008264:Macrophages / Q000382:microbiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D020411:Oligonucleotide Array Sequence Analysis; D010587:Phagocytosis; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013290:Streptococcal Infections / Q000235:genetics / Q000382:microbiology*; D013292:Streptococcus agalactiae / Q000235:genetics*; D014774:Virulence / Q000235:genetics*
D015415:Biomarkers; D004269:DNA, Bacterial; D012333:RNA, Messenger