Yes, the thorns in S4 out of Marcels blood and venom and it was almost used by vincent to sacrifice and kill Klaus so its safe to say that Marcel's bite can kill Klaus too.

Can Klaus bite kill Marcel?

It has already been established that Marcel and Luciens Venom derived from each of the seven original Werewolf packs is lethal even to Klaus and his Vampire-Werewolf Hybrid progeny. Because his blood cannot Cure their Bite it means he is not immune.

Is Marcel stronger than Klaus?

Similarly, Marcel was also stronger than the Originals and Klaus, fighting them with ease. Super Speed: They are also considerably much faster than most supernatural species seen thus far.