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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Research Project #442901

Research Project: Leukocyte Immune-type Receptors: Gene Structure and Function (Extension)

Location: Warmwater Aquaculture Research Unit

Project Number: 6066-31000-016-034-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Jul 1, 2022
End Date: Dec 31, 2023

1. Complete the assembly and annotation of the catfish LITR loci. 2. Examine LITR expression in after viral and bacterial challenge. 3. Monitor the cytotoxic immune response to channel catfish virus and E. ictaluri infections using a monoclonal antibody CC41 specific to a LITR subset that are markers for cytotoxic cells.

The overall goal of this project is to better understand the functional roles of Leukocyte Immune-Type Receptors (LITRs) in teleosts. LITRs is a large family of immunoregulatory receptors present in fish. PacBio single molecule long-read sequencing protocols will be used to complete the genomic sequencing of the LITR loci and to sequence the expressed LITR cDNA repertoire after viral and bacterial challenge. For the challenge experiments groups of 50 post-juvenile catfish will be challenged with CCV or Edwardsiella ictaluri. Fish will be harvested on days 3, 4, 5, 6 and 7 after challenge for collection of blood and tissues. Catfish blood will be subjected to flow cytometric analyses using the LITR-specific monoclonal antibody CC41. Total RNA will be isolated from the lymphoid tissues (spleen, head kidney and trunk kidney) and used in transcriptome analyses to determine which LITRs are constitutively expressed in lymphoid tissues and which are expressed in response to CCV and Edwardsiella ictaluri infection. These studies will define the number of LITR genes, their structure and potential for expression. The results will also show whether alternative splicing of exons plays a role in modulating LITR function and/or signaling potential.