The Toll signaling pathway in Drosophila melanogaster regulates several 
immune-related functions, including the expression of antimicrobial peptide 
(AMP) genes. The canonical Toll receptor (Toll-1) is activated by the cytokine 
Spätzle (Spz-1), but Drosophila encodes eight other Toll genes and five other 
Spz genes whose interactions with one another and associated functions are less 
well-understood. Here, we conducted in vitro assays in the Drosophila S2 cell 
line with the Toll/interleukin-1 receptor (TIR) homology domains of each Toll 
family member to determine whether they can activate a known target of Toll-1, 
the promoter of the antifungal peptide gene drosomycin. All TIR family members 
activated the drosomycin promoter, with Toll-1 and Toll-7 TIRs producing the 
highest activation. We found that the Toll-1 and Toll-7 ectodomains bind Spz-1, 
-2, and -5, and also vesicular stomatitis virus (VSV) virions, and that Spz-1, 
-2, -5, and VSV all activated the promoters of drosomycin and several other AMP 
genes in S2 cells expressing full-length Toll-1 or Toll-7. In vivo experiments 
indicated that Toll-1 and Toll-7 mutants could be systemically infected with two 
bacterial species (Enterococcus faecalis and Pseudomonas aeruginosa), the 
opportunistic fungal pathogen Candida albicans, and VSV with different survival 
times in adult females and males compared with WT fly survival. Our results 
suggest that all Toll family members can activate several AMP genes. Our results 
further indicate that Toll-1 and Toll-7 bind multiple Spz proteins and also VSV, 
but they differentially affect adult survival after systemic infection, 
potentially because of sex-specific differences in Toll-1 and Toll-7 expression.