ARS | Publication request: Identification of in vitro upregulated genes in a modified live vaccine strain of Edwardsiella ictaluri compared to a virulent parent strain

Submitted to: Comparative Immunology Microbiology and Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2009
Publication Date: November 19, 2010
Repository URL: http://hdl.handle.net/10113/55440
Citation: Wei Pridgeon, Y., Russo, R., Shoemaker, C.A., Klesius, P.H. 2010. Identification of in vitro upregulated genes in a modified live vaccine strain of Edwardsiella ictaluri compared to a virulent parent strain. Comparative Immunology Microbiology and Infectious Diseases. 33(6):e31-e40.

Interpretive Summary: In order to understand why a modified live vaccine strain of bacterium Edwardsiella ictaluri was able to protect fish, while the wild type caused fish to die from the bacterial infection, we compared the two strains at transcriptional level. Using Polymerase Chain Reaction (PCR)-select subtractive cDNA hybridization technique, 41 expressed sequence tags (ESTs) were isolated from the modified live vaccine strain vs the virulent parent strain. Transcriptional levels of the 41 ESTs were then evaluated by quantitative PCR (qPCR). The qPCR results revealed that 33 ESTs were consistently upregulated at least 3 fold in the modified live vaccine strain compared to the virulent parent strain. Of the 33 upregulated ESTs, 11 were upregulated greater than 5 fold. The 41 ESTs were found to be homologues of genes involved in protective immunity (22%), adhesion (7%), cell growth and survival (20%), signaling (7%), metabolism (5%), and transcriptional regulation (5%). However, putative functions of 20% of the genes identified are currently unknown. The functions of some of the upregulated genes identified in protective immunity induced by the vaccine strain are discussed in this paper.

Technical Abstract: Using PCR-select subtractive cDNA hybridization technique, 41 expressed sequence tags (ESTs) were isolated from a modified live vaccine strain (AQUAVAC-ESC©, formerly RE-33) vs a virulent parent strain (EILO) of Edwardsiella ictaluri. Transcriptional levels of the 41 ESTs in the vaccine strain and the virulent strain were then evaluated by quantitative PCR (qPCR). The qPCR results revealed that 33 ESTs were consistently upregulated at least 3 fold in the modified live vaccine strain compared to the virulent parent strain. Of the 33 upregulated ESTs, 11 were upregulated greater than 5 fold. The 41 ESTs were found to be homologues of genes involved in protective immunity (22%), adhesion (7%), cell growth and survival (20%), signaling (7%), metabolism (5%), and transcriptional regulation (5%). However, putative functions of 20% of the genes identified are currently unknown. Putative roles of some upregulated genes in protective immunity induced by the vaccine strain are discussed.