Some parasites evade host immune responses by altering their surace antigens by DNA rearrangements .
Facts Trypanosomes are tsetse fly-transmitted blood parasites . They are successful parasites because they dodge the host's immune response by changing the antigenic component of their surfaces. The VSG message is the 5' most part of a 55 to 60 knt transcript. The transcript is processed by trans-splicing to yield mRNAs for several surface proteins. There are, in addition, about 20 silent VSG genes near telomeres and about 1000 silent VSG genes at other locations.