STK16 and infection: Interestingly, when we tested the role of Tsf1 in Spiroplasma-mediated protection against S. aureus, we observed that the protective effect in the Tsf1 mutant was still present (Fig. 3F) since the Spiroplasma-harboring Tsf1 mutant survived longer after infection compared to the Spiro− Tsf1 mutant, although the degree of protection was not as strong as in wild-type flies.