With infected what abilitys would be lost besides powers if they had fuel natured defender used that ability and entered an area three eats magic?

The important part is would they loose the initiative dice that the get with the infection? Would they lose the attribute points? would the vulnerabilities go away? What parts are magic and what would be "racial"?

I would say that they just lose Powers, not Weaknesses. And alterations to attributes are constant (not given or altered by powers) so those would stay too.

Dual-Natured Defender just says that the critter cannot use critter powers, it doesn't say anything about losing access to Magic-based abilities vs racial ones. It's an understandable logical assumption, but you seem to be reading more into it than is there.

I am trying to determine what parts of infected are magic and what pats are changes.

I brought up duel natured defender whay says you can not use powers, because that is the only way I could think of for a duel natured being to survive in an area with no mana. That then leads to what more drastic changes might happen to the being or if the changed where biological and no longer magic.

Unless you're using ornate pistols at fifty paces, it won't be "duel" natured or "jewel" natured. It'll just be the normal "dual" natured since it is naturally on two planes at once.
Normally one just takes a cyberzombie backpack along for the ride or an Astral Hazer if you can find one.

Simple answer is that a dual-nature critter wouldn't survive in an area with no magic. Assuming you mean an Astral Void, which is an extreme negative background, it would eventually kill the dual-natured critter. Even Dual-Natured Defender would only protect for minutes.

What sort of area that "eats magic" are you talking about?

That is the type of situation I was talking about. Yes, they could only live mins with defender.

I guess my root question is what parts of infected are magic and what isn't, what changes are physical/ biological and what ones are supported with magic?

Infected are inherently magical beings, that's why they are dual-natured. There really isn't a way to separate what is and isn't magical.

As for your question, how about you give a bit more background into the why you're asking the question? It sounds like you might be a bit confused with the way magic works in the Shadowrun setting. Unlike in a setting like D&D (which has the anti-magic field), SR doesn't have any way for magic to just be "cut off" entirely. Areas with such extreme negative backgrounds (Mana Voids) that Magic just can't survive will deal damage to magical creatures and eventually kill them.

Dual-Natured Defender would let a dual-natured critter (like any Infected) survive in that area by suppressing their magic enough so that it doesn't get ripped out of them forcefully. It would be sort of like wearing a space-suit in the vacuum of space, a temporary one at least.

I think I have the answer I was looking for.

Does the BYO portable background count no longer help in SR5 the way it did for SR3 and SR4?

I skimmed Chrome Flesh, and there's only talk about cyberzombies. No game rules.

Astral Hazing's in Run Faster, and considering the hit that BGC took to nerfing awakened the quality took a real hit in the transition to SR5. Effectively the rules are a C&P from SR4's Runner's Companion, with the noted change that the Astral Hazer is in a Rating 3 positive background count, one point weaker than it used to be. Used to be something more serious, but now it's nothing more than any "Significant, but brief emotional or magical impact or small but continuous spiritual or magical influence." You'll be more hampered at a Maria Mercurial concert than in the presence of an Astral Hazer.

ROFL