Analysis of the protein repertoire revealed in the medium during prolonged incubation of Trichinella pseudospiralis muscle larvae in vitro

Proteins accumulated in the medium during prolonged incubation of Trichinella pseudospiralis ISS7626 (domestic pig Sus scrofa (Kamchatka)) muscle larvae were analysed by LC-MS/MS. A wide repertoire of excretory-secretory and somatic proteins ranging from 72 to 238 was revealed in samples, correlating with a decrease in the reproduction potential of the larvae, which remained invasive. A gene ontology annotation shows that most of revealed proteins are nucleases, proteases or their regulators; enrichment in extracellular compartment-related proteins and proteins involved in cell attachment predominated. Sixty-nine of the revealed proteins were permanently present in all analysed samples, which indirectly confirm that most of the larvae were alive during the incubation period. Orthologous clustering demonstrates that most of the permanently present proteins are T. pseudospiralis strain-specific. High level of sequence identity within clusters and frequent presence of paralogous genes within cluster point to the recent emergence of these orthologous groups and rapid evolving of proteins during adaptation to wide range of hosts.