Heterogeneity of class I and class II MHC sequence

Authors: G H Zhao J Li F C Zou W Liu X H Mo R Q Lin Z G Yuan Y B Weng H Q Song X Q Zhu

Publish Date: 2009/10/15

Volume: 106, Issue: 1, Pages: 201-206

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Abstract

The present study examined sequence variation in class I and class II major histocompatibility complex MHC genes among Schistosoma japonicum isolates from different endemic regions in mainland China and assessed the level of horizontal gene transfer and sequence similarity between parasites and their hosts S japonicum cercariae were used to infect male adult rabbits to obtain adult S japonicum samples A portion of the class I MHC gene pMHC I and class II MHC genes pMHC II were amplified separately from individual adult trematodes by polymerase chain reaction and sequenced Among all the examined isolates of S japonicum sequence differences between male and female parasites were 00–266 for pMHC I and 00–70 for pMHC II Sequence variations between male and female parasites among different geographical locations from the mountainous areas were 11–266 for pMHC I and 15–30 for pMHC II Sequence variations between samples from Yunnan and those from Sichuan were 27–235 for pMHC I and 11–37 for pMHC II In the lake/marshland areas sequence variations between male and female parasites among different geographical locations were 00–250 for pMHC I and 00–70 for pMHC II Sequence variations between S japonicum isolates from mountainous areas and those from lake/marshland areas were 00–261 for pMHC I and 04–61 for pMHC II BLASTN analysis indicated that all the pMHC II sequences showed high homology to a portion of exon 3 in rabbit MHC class II DP beta gene with more than 89 similarity and all the pMHC I sequences except isolates in Yunnan Eryuan revealed high homology to the portion of exon 2 in rabbit MHC I gene with more than 81 similarity Phylogenetic analysis showed no specific clustering comprising parasites from single geographical or endemic regions and the paired parasites were even found in different clusters These results demonstrated that pMHC I and II of S japonicum isolates in mainland China existed heterogeneity but the pMHC I II or combined sequences were not suitable markers for examining genetic relationship among different isolates from endemic regions in mainland ChinaThis work is supported in part by the National Basic Research Program 973 program of China grant number 2007CB513104 and the Program for Changjiang Scholars and Innovative Research Team in University grant number IRT0723 Professor Baozhen Qian of Bioengineering Institute Zhejiang Academy of Medical Sciences China was thanked for providing some S japonicum samples used in the present study The experiments comply with the current laws of the country in which the experiments were performed

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