Functional genes and proteins of Trichinella spp.

Research of Trichinella proteins has been conducted with emphasis on excretory-secretory (E-S) products of muscle larvae because of two reasons. The first is that it has prominent and narrow specific antigenicity, and the second is that it may play some role in nurse cell formation after being secreted into host muscle cells. Proteomic analysis of E-S proteins was further advanced by the aid of new analytical methods such as gene cloning, matrix-assisted laser desorption-ionization time-of-flight mass spectrometry, and expressed sequence tags database analysis. As the research progressed, the interest of researchers moved to identification of function of E-S products, which has shed further light on the intriguing relationships between parasites and hosts. Major constituents of the E-S products include 43-, 53-, and 45-kDa glycoprotein derived from the stichosome. Many proteins were discovered in E-S products after the 43-, 53-, and 45-kDa proteins although the relationships among them remain unclear. Some of the new proteins were partially defined in terms of their function including nuclear antigens, MyoD-like protein, TsJ5 protein, etc. There are better-characterized proteins based on the gene molecular method, which allow easier identification of the function of proteins of interest. Such examples were demonstrated by proteinases, proteinase inhibitors, heat shock proteins, glycosidases, etc.