The Innate Immune Response of Frog Embryos to Antisense Morpholino Oligomers Depends on Developmental Stage, GC Content and Dose

In this issue of Developmental Cell, Paraiso and colleagues report that antisense morpholino oligomers (MOs), frequently used by developmental biologists to inhibit gene function, do not cause immunogenic side effects at gastrula stages in the clawed frog Xenopus. This valuable observation is consistent with our previous work showing that MOs can activate components of the innate immune system, where, although we did not explore the exact stage of onset of the response, we commented that “this cell-intrinsic reaction was first detected during neurulation and intensified during axial elongation” ( Gentsch et al., 2018 ).