The smORF-containing gene mille-pattes is required for moulting and Trypanosoma cruzi metacyclogenesis in the Chagas disease vector Rhodnius prolixus

Summary Chagas disease is estimated to affect 8 million people worldwide and is responsible for circa 10,000 deaths in Latin America every year. Vector control has been developed as the main strategy to control disease spreading. The identification of new targets is essential, and genes containing small open reading frames (smORFs - < 100 amino acids) are present as hundreds of putative new candidate targets in insect genomes. Here, we show that the prototypic smORF containing gene mille-pattes/polished-rice/tarsalless ( mlpt/pri/tal ) is essential for post-embryonic development of the kissing bug Rhodnius prolixus and for the metacyclogenesis of the Trypanosoma cruzi parasite during nymphal stages. Injection of double-stranded RNA against mlpt (Rp-ds mlpt ) during nymphal stages leads to a plethora of phenotypes which impairs post-embryonic development. First, nymphs of fourth or fifth stage injected with Rp-ds mlpt do not moult. Second, vector digestive physiology is largely modified, and haemozoin is significantly increased in the posterior midgut of Rp-ds mlpt nymphs. Third, Rp- mlpt knockdown inhibits the metacyclogenesis of Trypanosoma cruzi , the etiologic agent of Chagas disease. Thus, our study provides the first evidence of a smORF-containing gene regulating vector physiology, parasitic cycle and disease transmission.