Early divergent responses to virulent and attenuated vaccine isolates of Flavobacterium covae sp. nov. In channel catfish, Ictalurus punctatus
Issued Date
2024-01-01
Resource Type
ISSN
10504648
eISSN
10959947
Scopus ID
2-s2.0-85179062408
Pubmed ID
38030028
Journal Title
Fish and Shellfish Immunology
Volume
144
Rights Holder(s)
SCOPUS
Bibliographic Citation
Fish and Shellfish Immunology Vol.144 (2024)
Suggested Citation
Zhang D., Zhou G., Thongda W., Li C., Ye Z., Zhao H., Beck B.H., Mohammed H., Peatman E. Early divergent responses to virulent and attenuated vaccine isolates of Flavobacterium covae sp. nov. In channel catfish, Ictalurus punctatus. Fish and Shellfish Immunology Vol.144 (2024). doi:10.1016/j.fsi.2023.109248 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/91505
Title
Early divergent responses to virulent and attenuated vaccine isolates of Flavobacterium covae sp. nov. In channel catfish, Ictalurus punctatus
Author(s)
Other Contributor(s)
Abstract
Columnaris disease continues to inflict substantial losses among freshwater cultured species since its first description one hundred years ago. The experimental and anecdotal evidence suggests an expanded range and rising virulence of columnaris worldwide due to the warming global climate. The channel catfish (Ictalurus punctatus) are particularly vulnerable to columnaris. A recently developed live attenuated vaccine (17–23) for Flavobacterium columnare (now Flavobacterium covae sp. nov.) demonstrated superior protection for vaccinated catfish against genetically diverse columnaris isolates. In this study, we aimed to elucidate the molecular mechanisms and patterns of immune evasion and host manipulation linked to virulence by comparing gene expression changes in the host after the challenge with a virulent (BGSF-27) or live attenuated F. covae sp. nov. vaccine (17–23). Thirty-day-old fry were accordingly challenged with either virulent or vaccine isolates. Gill tissues were collected at 0 h (control), 1 h, and 2 h post-infection, which are two critical time points in early host-pathogen interactions. Transcriptome profiling of the gill tissues revealed a larger number (518) of differentially expressed genes (DEGs) in vaccine-exposed fish than those exposed to the virulent pathogen (321). Pathway analyses suggested potent suppression of early host immune responses by the virulent isolate through a higher expression of nuclear receptor corepressors (NCoR) responsible for antagonizing macrophage and T-cell signaling. Conversely, in vaccinated fry, we observed induction of Ca2+/calmodulin-dependent protein kinase II (CAMKII), responsible for clearing NCoR, and commensurate up-regulation of transcription factor AP-1 subunits, c-Fos, and c-Jun. As in mammalian systems, AP-1 expression was connected with a broad immune activation in vaccinated fry, including induction of CC chemokines, proteinases, iNOS, and IL-12b. Relatedly, divergent expression patterns of Src tyrosine kinase Lck, CD44, and CD28 indicated a delay or suppression of T-cell adhesion and activation in fry exposed to the virulent isolate. Broader implications of these findings will be discussed. The transcriptomic differences between virulent and attenuated bacteria may offer insights into how the host responds to the vaccination or infection and provide valuable knowledge to understand the early immune mechanisms of columnaris disease in aquaculture.