Probable NAD(+) hydrolyzing component of antiviral defense system Thoeris, composed of ThsA, TIR1 (thsB1) and TIR2 (thsB2) (PubMed:34853457). Activated by a signal molecule generated by endogenous TIR1, TIR2 or ThsB from B.cereus. After activation it binds and hydrolyzes NAD(+), leading to cell death and inhibition of phage replication (Probable). Expression of Thoeris in B.subtilis (strain BEST7003) confers resistance to phages phi29, phi3T, SPBeta, SBSphi11, SBSphi13, SBSphiJ, SPO1 and SPR but not SBSphiC. The TIR paralogs confer overlapping resistance to different phages (PubMed:34853457). H2O + NAD(+) = ADP-D-ribose + H(+) + nicotinamide Probably activated by a signal molecule generated by endogenous TIR1 and/or TIR2. Can also be activated by the signal generated by ThsB of B.cereus. Activation may alter the oligomerization state of the protein. Truncated N-terminus.