The major tegumental antigen of Fasciola hepatica contains repeated elements

In order to provide a butter understanding of the interaction between the l iver fluke (Fasciola hepatica) and the immune system of its mammalian host immunoreactive lambda bacteriophage clones containing F. hepatica cDNA hale been isolated. Plasmids from these clones were sequenced and found to enco de a family of proteins containing certain common elements dagger. All the clones contained a coding repeating sequence (RRRXCA) which is conserved at the nucleic acid level followed by a non-repeating clement coding for the C terminal used by the proteins which shows conservation of amino acids at certain positions. Antisera raised against a beta-galactosidase fusion prot ein with one of these sequences as a terminal extension was used to localiz e the immunoreactive antigens. Binding was predominantly in the tegument of the juvenile fluke but was reduced in the adult tegument. The wall of the uterus showed strong reactivity in the adult. Rats immunized with the beta- galactosidase fusion protein showed enhanced resistance to challenge infect ions. The role of these antigens in the host response to infection by F. he patica is discussed.