The passage discusses the Drosophila Toll pathway which has additional components compared to the mammalian TLR pathway. It mentions GNPB1, PGRP-SA, proteases, Spatzle, and Toll as components of the Drosophila pathway. The passage asks which protein is most likely evolving under positive selection and provides two ways a pathogen could counter-evolve to prevent a host immune response.

1. Q3 The Drosophila Toll pathway has additional components relative to mammalian TLR
pathway, summarized in the Janeway textbook figure below. GNPB1, PGRP-SA, proteases,
Spatzle, and Toll are A) Which protein of the Drosophila pathway is most likely to be evolving
under positive selection? Provide a brief rationale. B) Provide 2 distinct ways the pathogen could
counter-evolve to prevent successful host immune responses.