Developmental expression of a 43-kDa secreted glycoprotein from Trichinella spiralis.

Trichinella spiralis is an intracellular parasitic nematode that infects skeletal muscle cells. Infection results in loss of tissue specific characteristics and conversion of the muscle cell to a Nurse cell. The characteristic changes leading to the formation of the Nurse cell appear complete by day 12 after intramuscular infection. Proteins synthesized in the stichocytes (secretory cells) of T. spiralis and secreted in the host cell are believed to be involved in the process of Nurse cell formation. One secreted glycoprotein of 43 kDa has been considered as a candidate factor involved in Nurse cell formation. We determined the timing of synthesis and secretion of the 43-kDa glycoprotein and its temporal correlation to the changes of the infected host cell, to gain an understanding of the role of the 43-kDa glycoprotein in T. spiralis infection. We show that the 43-kDa glycoprotein is first expressed on day 11 following intramuscular infection, several days after the changes in the infected muscle cell have been initiated. Protein(s) immunologically related to the 43-kDa glycoprotein but not the 43-kDa glycoprotein itself are detected in the nuclei of mature Nurse cells. During the intramuscular stage the 43-kDa glycoprotein appears to be stored in the alpha-stichocytes of T. spiralis and appears to be secreted immediately following invasion of the intestinal columnar epithelial cells by the L1 larva. The role of the 43-kDa glycoprotein remains unknown, however, these findings argue against involvement of the 43-kDa glycoprotein in Nurse cell formation.