Existence of host-related DNA sequences in the schistosome genome

Abstract

DNA sequences homologous to the mouse intracisternal A particle and endogenous type C retrovirus were detected in the DNAs ofSchistosoma japonicumadults andS. mansonieggs. Furthermore, other kinds of repetitive sequences in the host genome such as mouse type 1 Alu sequence (B1), mouse type 2 Alu sequence (B2) and mo-2 sequence, a mouse mini-satellite, were also detected in the DNAs from adults and eggs ofS. japonicumand eggs ofS. mansoni. Almost all of the sequences described above were absent in the DNAs ofS. mansoniadults. The DNA fingerprints of schistosomes, using the mo-2 sequence, were indistinguishable from each other and resembled those of their murine hosts. Moreover, the mo-2 sequence was hypermethylated in the DNAs of schistosomes and its amount was variable in them. These facts indicate that host-related sequences are actually present in schistosomes and that the mo-2 repetitive sequence exists probably in extra-chromosome.