Heterogeneity of class I and class II MHC sequences in Schistosoma japonicum from different endemic regions in mainland China

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 0.0-26.6% for pMHC I and 0.0-7.0% for pMHC II. Sequence variations between male and female parasites among different geographical locations from the mountainous areas were 1.1-26.6% for pMHC I and 1.5-3.0% for pMHC II. Sequence variations between samples from Yunnan and those from Sichuan were 2.7-23.5% for pMHC I and 1.1-3.7% for pMHC II. In the lake/marshland areas, sequence variations between male and female parasites among different geographical locations were 0.0-25.0% for pMHC I and 0.0-7.0% for pMHC II. Sequence variations between S. japonicum isolates from mountainous areas, and those from lake/marshland areas were 0.0-26.1% for pMHC I and 0.4-6.1% 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 China.

Sensitive and rapid detection of Paragonimus westermani infection in humans and animals by loop-mediated isothermal amplification (LAMP)

“…Then the DNA samples were column-purified (Wizard® SV Genomic DNA Purification System, Promega; Zhao et al 2009;Ai et al 2010) and eluted into 60 μl H 2 O, respectively, according to the manufacturer's recommendations. The integrity of all the DNA samples were validated by successful amplification of the mitochondrial cytochrome c oxidase subunit 1 (cox1) using primers and protocols described previously (Bowles et al 1992; data not shown).…”

A cleaved amplified polymorphic sequence (CAPS) method for the identification of geographical isolates ofSchistosoma japonicumin China

“…In previous studies, genetic variation among S. japonicum populations from different endemic provinces in China has been detected using a variety of genetic markers (Bøgh et al, 1999;Sørensen et al, 1999;Zhu et al, 1999;Shrivastava et al, 2005;Zhao et al, 2009a;Zhao et al, 2009b;Zhao et al, 2009c). However, these markers and the detected genetic variability have not been utilized for the practical identification and differentiation of S. japonicum geographical isolates in China.…”

The genetic variation of different developmental stages of Schistosoma japonicum: do the distribution in snails and pairing preference benefit the transmission?

“…Some anthropogenic changes could influence the genetic diversity and population structure of Schistosoma japonicum [ 5 – 8 ]. Geographical differentiation among S. japonicum populations in China has been observed using a variety of markers, including nuclear genes [ 9 , 10 ], mitochondrial genes [ 11 , 12 ], microsatellite loci [ 13 , 14 ], and genome-wide single nucleotide polymorphisms (SNPs) [ 15 , 16 ]. The population differentiation of S. japonicum was thought to result from geographical separation, habitat isolation [ 12 , 17 ], co-evolution with different species of snails [ 18 – 20 ], and different transmission patterns driven by definitive hosts [ 17 , 21 , 22 ].…”