Microbiota-independent antiviral protection conferred by aminoglycoside antibiotics

Smita Gopinath; Myoungjoo V. Kim; Tasfia Rakib; Patrick W. Wong; Michael van Zandt; Natasha A. Barry; Tsuneyasu Kaisho; Andrew L. Goodman; Akiko Iwasaki

These data led us to hypothesize that aminoglycosides may bind to dsRNA and render 334 them more potent for TLR3 activation. To test this, we treated splenocytes with a 335 combination of aminoglycosides and dsRNA Poly I:C. We found that a 1:1000 ratio of Poly 336 I:C to kasugamycin significantly induced ISG expression at greater levels than either 337 compound alone ( Supplementary Fig. 13 ). This enhancement was dependent on both 338 TLR3 and TRIF signaling ( Supplementary Fig. 13 ). Collectively, these data indicate that at 339 high molar ratio, kasugamicin synergizes with dsRNA to stimulate TLR3. DCs. In support of this hypothesis, incubation of these DCs with kasugamycin-treated 385 splenocytes was sufficient to induce ISG expression albeit at lower levels than direct 386 aminoglycoside treatment ( Supplementary Fig. 12 ). As XCR1+DCs are known for their 387 cross-presentation of antigens associated with dead cells 53,54 , it is conceivable that in the 388 vaginal mucosa, phagocytosis of aminoglycoside-containing epithelial cells results in TLR3 389 activation due to the accumulation of aminoglycoside-bound RNA in the endosome. 390