Prof. ZHAO Yaofeng from China Agricultural University Visited Institute of Hydrobiology, Chinese Academy of Sciences (IHB) on Oct. 13th, 2016. During his visit, he gave a presentation with the title of “The IgH gene loci of cattle and mechanism of Ig diversity” for IHB researchers and students.
The basic structure of an Immunoglobulin (IG) consists of four polypeptide chains linked by disulphide bridges, two larger structures called heavy chains and two smaller called light chains. Cattle express all of the five classes of IgH genes: IGHM, IGHG, IGHE, IGHA, IGHD. It has been suspected for many years that cattle possess two functional IgH gene loci, located on Bos taurus autosome (BTA) 21 and BTA11, respectively. In his presentation, Prof. Zhao showed us new findings from his research team that all functional bovine IgH genes were located on BTA21, and only a truncated mCH2 exon was present on BTA11.
By sequencing of seven bacterial artificial chromosome clones screened from a Hostein cow bacterial artificial chromosome library, Prof. Zhao’s team generated a 678-kb continuous genomic sequence covering the bovine IGHV, IGHD, IGHJ, and IGHC genes, which are organized as Vn-Dn-Jn-μ1-(ψδ-ψV-Dn)3-Jn-μ2-δ-γ3-γ1-γ2-ε-α. Although both of two functional IGHM genes, IGHM1 and IGHM2, can be expressed via independent VDJ recombinations, the IGHM2 can also be expressed through class switch recombination.
Prof. Zhao and his research team also confirmed cattle rely on long germline IGHD segments to generate remarkable CDRH3 length variability forming the antibody recombinatorial repertoire. After the presentation, IHB researchers and students communicated with Prof. Zhao regarding issues related to immunity.