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The hiv antigens that are used in the oral rapid tests, are they infectious? The tests do not contain any actual virus but I am curious if the antigens themselves could somehow create the virus on their own if they get into the bloodstream? Like do they contain all of the parts needed for replication inside them? (Not the actual virus but the antigen).

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nope - the test contains antibodies to HIV proteins, but nothing from HIV itself. The 'antigen test' tests for antigens, it doesn't itself contain any antigens.

Antibodies are proteins that animals (like humans) produce to fight of viral and bacterial infections, they don't come from viruses.

Even if the test did contain HIV proteins, it could not infect anyone. You really have to have the HIV RNA, and almost certainly the rest of the virus too, to cause any infection.

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Okay. but the proteins don't contain that RNA do they? Sorry I am not very good at this stuff and get easily confused. – Sarah Dec 23 '12 at 15:46
@Sarah: no, RNA and proteins are two completely different things. Anyway, there is nothing from HIV in the tests. – nico Dec 23 '12 at 18:55
@Nico: Oh okay. Yeah I was just curious because of what I read about the hiv antigen. It kind of scared me because I wasn't sure if those were infectious or not. So just for clarification: proteins and rna are two separate things. The proteins do not have the RNA inside them and without the RNA there can be no infection? – Sarah Dec 23 '12 at 20:24
@Sarah: Exactly. The test contains something (an antibody) that -if present in the sample- binds to HIV proteins. – nico Dec 23 '12 at 20:45
Thanks @Sarah! She's exactly right. – shigeta Dec 23 '12 at 20:49

No, the protein components of viruses may be able to initiate the infectious process, i.e. injection, but if there is no RNA or DNA, there is no virus to inject into the target cell. Hence none of the viral genome's action such as replication or transcription will occur and the cell itself will remain unchanged.

However, some effects of viral infection are actually part of an immune response of some kind, and these are often triggered by viral proteins themselves.

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By taking proteins produced by bacteria and virii and then introducing them with a Carrier the body will mount an immune response and react when the real danger is presented. This is called the Hapten-Carrier effect, and is how we make many vaccines. The Innate Immune response is first, and the Adaptive Immune response creates the "memory" of the encounter so it can effectively fight the actual bacteria/virii/etc. – MCM Dec 26 '12 at 23:29

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