However, Peter Walsh et al. proposed that the term J-proteins should be used more strictly to describe only J proteins with well-conserved Jdomain in the HPD motif, while structurally less-conserved proteins should be referred to as J-like proteins. Although heat shock proteins are traditionally regarded as being induced by heat and stresses, recent studies suggested HSPs may actually play important roles in immune responses. For example, HSPs are considered to mediate humoral and cellular innate immune responses ; HSPs in extracellular environment serve as a danger signal to activate innate immune cells such as dendritic cells and macrophages. Several cytokines can be induced by HSPs, including TNFa, IL-1b, IL-12, nitric oxide and some chemokines ; HSPs can also stimulate adaptive immune responses as potent antigen carriers. Hsp60, Hsp70, Hsp90 have been reported to interact with immune cells as a ligand for a variety of cell-surface receptors such as Toll-like receptors and a number of CDs such as CD14 and CD91. Due to Hsp40 and Hsp70 worked together as a co-chaperone, the immune function especially the expression fold change trend of this two proteins should be taken into consideration at the same time. In teleost, hsp70 genes have been found to be involved in bacterial kidney disease in coho salmon and vibriosis in rainbow trout. In olive flounder, Hsp40 proteins were found to be upregulated in flounder embryonic cells after viral infection and a flounder hsp70 gene was also expressed in heat-shocked and virus treated FEC cells, indicating hsp40 and hsp70 functioned as co-chaperone in antiviral immune responses. In the kidney of olive flounder, dnaja4, dnajb6 and dnajb11 were found to be expressed after being infected by Streptococcus parauberis. However only limited studies have been done on the roles of Hsp40s in disease resistance. RNA-Seq-based expression analysis has become a robust method to assess transcriptional profile to different challenge experiments. In our recent RNASeq studies, we have successfully obtained comprehensive transcriptome assemblies from catfish intestine and liver after E. ictaluri infection and from catfish gill after F. Columnare infection. The expression patterns of differentially expressed genes from these three studies were validated by quantitative real-time 8-(3-Chlorostyryl)caffeine RT-PCR with average correlation coefficient around 0.9. Channel catfish is the leading aquaculture species in the United States. Its genomic resources have been well developed in recent years, particularly ESTs, transcriptome sequences generated by RNA-Seq and draft whole genome sequence. These resources make it feasible to conduct systematic analysis of hsp40 genes in channel catfish genome. The objective of this study was to 7-Chlorokynurenic acid determine the involvement of hsp40 genes in disease responses after bacterial infection in catfish. Here we report the genomewide identification of a full set of 57 hsp40 genes, their phylogenetic and syntenic analyses, and their involvement in disease responses after bacterial infection with ESC and columnaris using RNA-Seq datasets.