Comparative genomics and transcriptomics of the Spiroplasma glossinidia strain sGff reveal insights into host interaction and trypanosome resistance in Glossina fuscipes fuscipes.

Tsetse ( spp.) are vectors of African trypanosomes, the causative agents of Human and African Animal trypanosomiases, diseases that remain significant medical and socioeconomic challenges in sub-Saharan Africa. In addition to trypanosomes, tsetse harbor both obligate and facultative symbiotic bacteria that can influence vector competence and reproductive biology. One such facultative symbiont, , infects several tsetse species within the subgroup. In ( ), the strain Gff induces a trypanosome-refractory phenotype and negatively impacts reproductive fitness by reducing female fecundity. However, the mechanisms behind these -derived phenotypes remain poorly understood. Here, we report successful cultivation of Gff and present complete genomes from three sources: cultured Gff and Gff isolated from both laboratory-maintained and wild-caught (Uganda) flies. Comparative genomic analyses revealed a high degree of similarity in gene content and synteny among these Gff samples, confirming that they represent isolates of the same strain. Phylogenomic analyses placed Gff within the clade. The Gff genome is highly dynamic, containing numerous mobile genetic elements. Additionally, annotations indicate that Gff relies on its host for both lipids and carbohydrates and produces several toxins, all of which could be implicated in the observed trypanosome refractory phenotype. Finally, comparative transcriptomic analysis of Gff from host hemolymph versus culture provided insights into potential factors relevant to host-symbiont interactions. Our findings provide a foundation for understanding the nutritional dialogue between Gff and its host and identify symbiotic products that may contribute to trypanosome resistance. Furthermore, the establishment of an culture system for Gff represents a significant resource for future functional studies with potential implications for vector control.