Cloning and expression analysis of MHCⅡα cDNA in Pelodiscus sinensis

Abstract:

To study the structure and function of MHC (major histocompatibility complex) in Pelodiscus sinensis, we obtained the full-length cDNA of MHCⅡα using RACE-PCR (rapid amplification of cDNA ends PCR) technology. The resulting sequence was 1296 bp in length, including an ORF (open reading frame) region of 807 bp. The peptide-encoded MHCⅡα gene could be divided into four parts, including the signal peptide, MHCⅡ alpha domain, IGc1 domain, and transmembrane region. A neighbor-joining tree showed that the MHCⅡα gene from P. sinensis and Chrysemys picta bellii cluster into one cluster. The P. sinensis gene had a close genetic-relationship with C. picta bellii and a farther genetic-relationship with mammals, aves, and fish. Using qRT-PCR in all 8 tissues, the highest expression of the MHCⅡα gene was observed in the spleen, heart, liver, and intestine, while the lowest level was found in muscle. Meanwhile, MHCⅡα mRNA expression levels were significantly up-regulated in the liver and intestine (after 12 h), the spleen (on the 1st day), and the kidney (on 1st and 5th day) after being infected with Aeromonas hydrophila. The liver, spleen, intestine, and kidney are closely related to immunity, which indicates that this gene has important effects on the immune response.