Filling in the gaps of the IMD immune pathway of the kissing bug Rhodnius prolixus
Rhodnius prolixus is a hemathophagous insect that has served for decades as a model to study insect physiology. Rhodnius prolixus is also a major vector of Trypanosoma cruzi, the etiological agent of Chagas disease that kills 45,000 people annually and affects over 8 million people worldwide. The genome of R. prolixus contains ~15,500 predicted protein-coding genes. Many pathways such as the Toll and JAK-STAT pathways were present. Key components of the highly conserved IMD pathway, however, were not detected; this observation is also shared with other hemimetabolous insects: the pea aphid, the bedbug, and the head louse. Despite the fact that many genes of the IMD pathway are not found in the R. prolixus genome, effector immune genes normally regulated by the IMD pathway are still expressed after a bacterial infection.