PGLYRP1 and infection: Previous analyses of the activity of trypanocidal factors in the tsetse midgut such as attacin [32], peptidoglycan recognition protein (PGRP-LB) [33, 34], reactive oxygen intermediates (ROI) [14, 27] and tsetse EP protein [35, 36] have tended to focus on trypanosome-challenged flies rather than those with an established infection, but there are some results for older flies.