Download Mucosal Profiles of Resistance and Susceptibility to Flavobacterium

MUCOSAL P ROFILES OF RESISTANCE AND SUSCEPTIBILITY TO F LAVOBACTERIUM COLUMNARE
USING RNA-SEQ APPROACHES
Eric J. Peatman*, Chao Li, Ruijia Wang, Fanyue Sun, Zhanjiang Liu, Bradley Farmer,
Benjamin Beck
Department of Fisheries and Allied Aquacultures,
Auburn University, AL 36849
[email protected]
One of the highest priority areas for improvement in aquaculture is the development of effective
strategies for decreasing disease mortality levels in production, including implementation of
better vaccines and robust genetic selection programs. Flavobacterium columnare
(“columnaris”) outbreaks are an annual threat to freshwater aquaculture operations worldwide,
often brought on by routine handling or crowding stress, changes in water quality parameters, or
primary infections by parasites or other bacterial pathogens. Despite its widespread impact, our
understanding of F. columnare infectious processes remains limited. In particular, little is
known regarding the processes mediating early pathogen adhesion and replication on host
mucosal surfaces and how these may differ between resistant and susceptible fish. Here, we first
utilized next-generation sequencing-based RNA-Seq to profile the catfish gill transcriptome
following columnaris infection. We next applied RNA-Seq to individuals from columnaris
resistant and susceptible families to examine transcriptional differences both prior to infection
and at early timepoints following infection. The results revealed a consistent pattern of immune
polarization between resistant and susceptible fish prior to challenge, including key differences
in expression of MHC family members, a rhamnose-binding lectin, mucins and mucin
glycosylation factors, lysozyme-C, and iNOS. We propose that the differing mucosal profiles of
the studied fish are a critical component determining their disease phenotype. Furthermore, the
position of these gene factors on fish surfaces likely make them highly amenable to modulation
through dietary or topical therapeutant approaches.