Question about aids vaccine.

[Willoughbyva]

The other day I posted a question in off topic about a new vaccine that was tested in brazil.
http://www.nature.com/nm/journal/v10/n12/full/nm1147.html

I was wondering if someone could break down the lingo and tell me what it really means. I think the pdf is different and has more stuff in it. I don't have hiv or aids, but this seems like it is going in the right direction. I was just wondering how the vaccine works.

Thanks

Perry

 

[TraumaRN]

Well.....what exactly do you want to know?? Do you want to know how the vaccine itself did in terms of supressing the virus? or would you like to know how the vaccine works??



EDIT: I just noticed you wanted to know how the vaccine works. Well I'll just try and put this in simple language so my explanation might be lacking a little but, essentially a vaccine works by introducing a sample of a virus that is either 'dead' or weakened, or is genetically similar to another virus(example the first smallpox vaccine was really a cowpox virus and because of the way the body's immune response is designed it wouldnt be able to tell the difference between a smallpox or cowpox virus...it would just kill both.) However with this vaccine they introduced a dendritic cell (which is an antigen-presenting immune cell that will initiate an immune response), this cell was loaded with a 'dead' version of HIV-1 cells, this in turn fired up an immune response and suddenly the body had an idea of what it was fighting and used an appropiate response to supress the virus in the body, sadly they seem to imply that this isnt a true cure but essentially controls the virus and stops long-term progression, but you are right it's promising.

I know I'm missing some info so you want to know more let me know, or possibly someone else will help me explain this. I tried to keep it simple

 

[Gibsons]

The big deal here, imo, is using dendritic cells. Dendritic cells are "antigen presenting cells." Other antigen presenting cells include more ordinary T-cells and B-cells. "Antigen presenting cell" means that the cell collects foreign stuff from a pathogen (usually proteins), breaks it down into small pieces, then it takes one of of these pieces and displays it on its cell surface (typically a peptide of about 5-8 amino acids is displayed). Other immune cells will recognize this very specific structure of how the antigen is presented and this cell-cell interaction is what gets the immune system mobilized against the pathogen. For reasons not completely understood, dendritic cells are very very good at presenting antigens, apparently better than B-cells. It's probably more complex than the simple observation that they have more surface area with which to present. Dendritic cells are few in number and hard to get at though, so they haven't been as well studied as other 'arms' of the immune system.

Some of the jargon:

HIV-1-specific CD4+ TH1 cell responses --- This is a T-cell of the "helper 1" subtype, that specifically recognizes HIV-1. CD4+ means the T-cell is of the CD4 (vs CD8) subtype. Most (all? my memory is fuzzy) CD4+ cells are helpers, CD8+ cells are cytotoxic, meaning they kill other cells. Helper cells tend to help other cells (like B-cells) do their work.

The suppression of viral load was positively correlated with HIV-1-specifc interleukin-2 or interferon-bold gamma-expressing CD4+ T cells and with HIV-1 gag-specific perforin-expressing CD8+ effector cells,

When they saw a reduction in the number of viruses in the blood, they also saw a reduction in a very particular subtype of T-cells. One type is a kind that produces interleukin-2 and/or interferon gamma when it encounter HIV proteins. Both of these are small proteins that have (mostly) stimulatory effects on other immune cells.

"HIV-1 gag-specific perforin expressing CD8+ effector cells" These are cytotoxic T-cells (CD8 sort of marks them, perforin is what perforates the target cell). When this kind of cell finds another cell, it will "look it over." A cell harboring HIV will usually display some of the HIV proteins on its surface, similar to how an antigen presenting cell does. This particular type of T-cell recognizes the HIV protein called "gag" and kills any cell that displays it (this is a seperate but similar system from the antigen presenting cells above).

tired of typing right now, maybe more later....

 

[RaiderJ]

My take is that they've managed to control the "viral load", or total virus count in the bloodstream. My medical knowledge is very minimal, but I think that just by increasing the white blood cell count you can accomplish the same thing. Not that this isn't great, but maybe it's just a white cell booster? Bump for someone who knows more than I do!

 

[Gibsons]

Originally posted by: RaiderJ
My take is that they've managed to control the "viral load", or total virus count in the bloodstream. My medical knowledge is very minimal, but I think that just by increasing the white blood cell count you can accomplish the same thing. Not that this isn't great, but maybe it's just a white cell booster? Bump for someone who knows more than I do!

In a normal vaccine, you take say, dead viral particles and inject them into the blood or maybe into the spleen. Immune system gradually absorbs/recognizes/fights whatever they were immunized against.

it seems what they did here, was first collect normal immune cells from the patients. they cultivated and grew these cells up, then "activated" them, basically by feeding them dead hiv or parts of it (I haven't read the whol paper yet). They then take these primed up cells (dendritic cells) and inject them into lymph nodes where they'll have good exposure to the immune system.

 

[TraumaRN]

They then take these primed up cells (dendritic cells) and inject them into lymph nodes where they'll have good exposure to the immune system.

Remember in the initial stages of HIV the virus will usually cluster in the lymph nodes with the CD4 cells??(i think)