After having the same zombie nightmare for the past month or so, I wanted to know how Akatsuki might handle such a crisis. Oh, and I thought it would make a nice 100th-post special, as well as a major thank-you to followers for reaching fifty again! :) I'm going by each individual character's hypothesized reaction/zombie transformation, rather than contemplating the general reaction of the group. Let's begin, shall we?
Deidara: Considering his goal to become "eternal art", I highly doubt Deidara would live to see the apocalypse. However, if he did, I theorize he would lure a shitload of zombies into one general area, attracting them with noise (in a manner similar to that of Wichita at the amusement park [Zombieland, 2009]). Deidara would then use himself as a bomb, detonating thousands of zombies in the midst (10 km radius, remember?). That would be cool, if it wouldn't attract even more zombies from 10+ km away to the detonation site, forming a humongous hoarde/pack.
I honestly think Deidara would be the coolest zombie ever. Think about it, he has mouths on his hands! You are running from a couple other zombies, when Deidara reaches out and chomps your jugular without pulling you towards him. He could infect multiple people at once - four, including his chest-mouth.
Sasori: I am honestly unsure of how to contemplate Sasori were in his human state, I highly doubt he would be any different from the run-of-the-mill zombie. However, in his puppet form... The only way one could hypothetically infect Sasori is if the virus came in contact with his blood, which is stored in his "heart" capsule. Alas, the only way to access the blood in the capsule is if it was penetrated, killing Sasori in the process. Even if Sasori would manage to patch up his wound, would the virus even spread through his body? As a human puppet, I always assumed he kept chakra coursing through his body through his blood, suggesting that the blood still runs through his body. However, what would the virus infect? Wood? Still, the bigger question lingering is, how would Sasori pass the infection on to others? The only way I could think of would be contact with his infected blood after killing him. Hm.
Hidan: At first, I thought Hidan might last okay in an apocalypse such as this. However, his Jashin-forsaken rituals would be his pitfall. Hidan's signature technique, "Curse Technique: Shiji Hyouketsu" can only be done with the blood of a victim. Since the zombie virus is transmitted the same way, Hidan would succumb to it quickly. Well, we in the fandom could at least hope that he'd get in a few hundred mele-style kills beforehand.
The one major question I have about Hidan is, would his immortality last post-infection? If not, he'd be a run-of-the-mill like Danna. If it did, though, he'd be like fucking Zeus for the zombies. Usually, destroying/dislocating the brain stops a zombie, effectively "killing" it. However, Hidan could still possibly infect others as a severed head rolling around on the battlefield. (That's a really amusing thought...)
Kakuzu: Sadly, Kakuzu's five hearts would make his impending death quicker than most others'. With five hearts beating simultaneously, I assume that blood flows much quicker throughout his body. With the positions of the hearts according to his back-faces, I presumed that his four other hearts carry blood to and from one limb, as well as joining with the original heart. (I will create a diagram and link it here) So, no matter where Kakuzu would be butten, it would be impossible for him to ditch a heart and save himself...unless the hearts were disconnected from his body and fighting off zombies.
Itachi: I suppose, like Sasori and (maybe?) Hidan, Itachi would end up as a run-of-the-mill zombie. Alas, the question is, if he died with his Sharingan activated, would that give him any sort of advantage? This leads to an even bigger question that I may bring up on NarutoBase as well as here, could shinobi zombies manipulate chakra? Although this is an opinionated question, I doubt it would be possible. Because of their extensive physical training, I theorize that shinobi zombies would have an advantage without any chakra needed. So, in Itachi's case, his Sharingan would be void, leaving with no major advantages.
Kisame: Setting his strength and immense height to the side, Kisame would have two distinct abilities - presumably, of course - that would set him apart from all other zombies. First, his sharpened teeth would allow for a much easier bite. Normal teeth lack the pointedness of shark teeth, so a bite from a typical zombie would require immense force applied by the zombie. (Which is why they aim for the right side of the neck - the main vessels to and from the brain lie there, with only skin to protect them. Additionally, the virus could be directed straight to the brain, effectively killing the host.) Kisame's teeth require less force to tear with, allowing for quicker kills.
Secondly, Kisame has gills. Now, I have seen movies where zombies walk through rain and puddles and shit. But I have never seen a zombie cross an ocean on foot. I think Kisame could be the one zombie to accomplish that, with his gills and such.
Zetsu: In truth, I think examining Zetsu's possibilities as a zombie would require me to know the possible virus in-depth, which is impossible, considering that just about any virus could mutate to a point where it causes behaviours/symptoms associated with zombies. Since Shiro Zetsu is an artificial being created using Hashirama's DNA, the Demonic Statue of the Outer Path, the Yin-Yang Release, and possibly some sort of plant, I have no way of knowing how the virus would react with him. The same goes for Kuro Zetsu.
Pein: The Six Paths of Pain are corpses controlled by chakra sensors throughout their bodies. Seeing as they are already dead, it would be impossible for them to be infected. If anything, they could become zombies themselves! ... JK, I suspect this sort of apocalypse would be caused by some sort of air-born or water-born virus, preventing already-deceased corpses from resurrecting themselves. I highly doubt chakra sensors could infect Nagato without physical contact with a zombie, considering that colds cannot be spread wirelessly through texts or emails. The only way for the Six Paths to stop "functioning" would be if Nagato became infected. And, considering his health state by the time Naruto found him in Amegakure, I think Nagato would be quite seceptible to infections.