[Question #139] Dr HHH only, question regarding the 4th generation Antigen & Antibody

96 months ago

Hi Dr HHH I have some questions regarding 4th Gen test and antigen antibody bidding and test detection please.

1. As far as I have read, the p24 antigens are produce first and then the antibodies are formed which binds to the antigens. If someone takes a test early then the antigen part is positive and if someone takes the test later the antibody part becomes positive in other words if the antigen are not bidden then test detets them and vice versa for antibodies. Now, if someone takes a test in the period when the antibodies starts binding to the antigens, can the ANTIBODY part of the test even detect the antibodies that are already BIDDEN or BOUNDED to the antigens. I mean to ask, is there a time period when all the antibodies that are produced are bidden to all the antigens and this test returns a negative for both antigen and antibody?

2. The antibodies that are already bounded to antigen do those antibodies remain in the blood and does the test pick those up.

3. Does the immune system always produce excess antibodies so that though few anitbodies are bounded to antigens enough free antibodies will always be there for the test tp pick up,

4. can you please explain me how does antibodies production happen and how antigen are cleared in blood I mean say the antibody that cleared antigen would that still remain in blood and and binds to other antigen if yes how much time does it takes to clear 1 antigen.

5. Sorry I started getting worried thinking of Q1, is my worry rational or irrational as I took test on 32nd day so I am thinking at that time may be all antibodies produced during that time were may be bounded to antigen so that test didn't pick up any? does this happen or body always produce huge antibodies in response to antigens

Can you please reply asao, am really worried now.

thank you so much for your help Dr

Edward W. Hook M.D.
96 months ago

Sorry, we do not permit clients to choose who answers their questions - I happened to pick up this repetitive question,  For your information, while our verbal styles differ, in over 20 years of working together, the recommendations that Dr. Handsfield and I have given have never disagreed. Your continued questions suggest that you have been unsuccessful in your efforts to stop worrying about the sexual exposure you mentioned in your original e-mail,  I will provide a single answer to your questions but will not address further questions accept for clarification.

4th generation HIV tests detect HIV virus (the antigen) and/or antibodies produced by infected persons in response to infection.  Once a person is infected, the antigen test becomes positive before the antibody test but one or the other (i.e. antigen or antibody) is ALWAYS present in infected persons.  Sometimes both tests are positive but at least one of them will be positive in all infected persons from 28 days following infection onward.  Thus your 32 day test is definitive evidence that you were not infected and you need to stop your needless worries.

1.  In infected persons there is always enough antigen or antibody to assure that tests will be positive.

2.  Once antibodies start to be produced, there will always be enough of one or the other for the test to be positive, even if some of the antibodies are being bound to the virus antigens. 

3.  Yes

4.  The body produces antibodies in response to infection.  Once antibody is bound to the virus, the bound antigen and antibody are removed from the body by a variety of mechanisms and eliminated from the body.  the process is complex and more difficult to explain than space permits.

5.  As I mentioned above, there is no rational reason for you to continue to be concerned about HIV infection from the exposure you described.

I hope these comments are helpful.  EWH

96 months ago

Thank you Dr Hook I really appreciate your help.

If I understood correctly there will ALWAYS ALWAYS be enough antigens or antibodies for the test to pick up at 32 days correct? doesnt matter whether antigen-antibody bounding is ongoing there will ALWAYS be enough free of any for the test to pick up correct?

I also have few more questions if you dont mind me asking please.

1. Would the test accuracy remain same from 28 days onwards, I mean if person 1 takes test at 28 days and person 2 at 35th day will the accuracy of the test will be same for both?

2. I had first test on 13th day of my exposure which was also a 4th gen duo lab test, I read that antigens are detectable after 10 days onwards so was this test also assuring against infection ? My doctor told me that 4th gen abbott's architect assay's are so sensitive that it can pickup even little amount of antigen or antibody.

3. The chance of HIV transmission through insertive vaginal sex is 1 for 1000 exposures does this goes to circumcised men as well or will they have even less chance of contracting ( I am circumcised for more than 20 years and i read 60% less chance than uncircumcised).

4. I am going for counselling already had 3 sessions but not finding it helpful, I really want to move on but going through very hard time. You might have seen patients like me who keep on worrying irrationaly after negative test as well, so can you please suggest me how to overcome this fear and worry. I really want to leave this behind as its effecting my career and also personal life can you please suggest me somethign to forget about this incident.

thank you for your help Dr

96 months ago

Sorry Dr I have one more question,

I found this on http://mobile.aidsmap.com/Accuracy/page/1323356/ website. AIDSMAP

it says under the limitation of 4th gen test as


Levels of p24 start to drop approximately a month after infection, but antibody is usually detectable by this stage. However in some extremely rare cases, p24 may become undetectable before antibodies are detectable, and a fourth-generation test could give a false negative result. Tests for p24 only do exist, and these are more sensitive than the combined tests, so are more likely to show infection at this stage.

So my intention of posting new question was this. Can you please tell me if this really can happen

96 months ago
Sorry Dr also wanted to confirm is my reasoning regarding Q1 of all antigen and antibody bounded that's why test didn't pickup unscientific, can you please tell me whether it has been really proven scientifically that there are always enough antibodies if some antibodies are bounded with antigens for the test to pickup. 
Sorry my mind is playing with me saying at 32 days may be all the antigens were bounded to antibodies and there weren't enough antibodies left for the test to detect. Does this sounds scientific. ? Please clarify this Dr please am in need of this answer badly. Thanks so much Dr Hook
Edward W. Hook M.D.
96 months ago

You are clearly not able to hear the information I am providing.  I will address your redundant and repeated questions and then close this thread.  Further redundant questions will then be deleted, making repeat questions to us a waste of both your time and money.

Persons with HIV do not develop negative tests for infection as they develop antibodies except in extraordinarily rare situations- situations that as so rare that it makes no sense to worry about them at all (there are exceptions to every rule!).  It has been proven through many carefully done scientific studies that once a person develops a positive test with a 4th generation test, they remain positive and that there are sufficient antibodies for the test not to become negative after it was initially positive. 

Your risk for infection is far, far less than 1 in 1000.  It would only be 1 in 1000 IF your partner had HIV and that is statistically unlikely.  Further, with multiple negative tests, you have proven that you were not infected.  Believe the test results.

This thread will now be closed.  EWH