Home > HIV Infection in HIV Antibody Negative Individuals > HIV Infection in HIV Antibody Negative Individuals

HIV Infection in HIV Antibody Negative Individuals

  • HIV infection in HIV antibody negative individuals

The possibility that there are individuals who are infected with HIV but who are negative on the test for HIV antibodies has always been theoretically possible. Considerable evidence has accumulated for many years that there are indeed such individuals. Despite the importance of this phenomenon, it receives relatively little comment.

It sometimes seemed to me ever since I first tried to discuss this possibility in the mid 1980s that there was a wilful discouragement of any discussion of this topic.

In 1989 David Imagawa reported that that 31 of 133 HIV antibody negative men showed the presence of HIV.

In 27 of them this persisted for 36 months despite remaining seronegative  [1]. This resulted in a vigorous response culminating in what almost looked like a retraction by the authors. At that time many unsuccessful attempts to replicate these results were reported, and the findings of David Imagawa were generally presented as due to technical errors, such as incorrect specimen labelling. In view of many subsequent findings, the likelihood is that David Imagawa and his colleagues were correct. The furious response to Imagawa’s paper is an indication of how non rational considerations can influence the progress of science. This is of course nothing new.

Curiously in a recent book, Imagawa’s findings are included in a list of what are stated to be errors and controversies in the HIV/AIDS epidemic that impeded scientific progress [2]

What in fact impeded progress was a rigid adherence to what was only a hypothetical, not an empirical model of the course of HIV infection.

David Imagawa died shortly after this controversy, and sadly did not live to see that his initial conclusions were absolutely consistent with what has been learned of the complexity and diversity of individual responses to HIV infection.

I certainly experienced considerable resistance and disbelief when I raised the possibility of silent HIV infections. In the late 1980s I took part in a NPR program, and was quite abruptly dismissed by another scientist (I have forgotten who) when I raised the absolutely reasonable theoretical possibility of persistent latent infections in antibody negative individuals.

Apart from very few exceptions there was an almost complete lack of interest in HIV seronegative, but infected individuals, by science writers; there was no shortage of community commentators who also seemed to be oblivious or uncaring of this phenomenon.

To be sure there were occasional reports of seronegative but infected individuals. Gus Cairns, a UK journalist wrote about this in the UK magazine, Positive nation. I wrote something about this as a result of an interview with him in 2000, which he published. I have scanned the article. I was unable to make a perfect copy, but a legible version can be seen by clicking HERE.

In the US reports confirming the existence of seronegative infected people continued to receive very little comment; what little there was was generally quite hostile..

Today this issue was again brought to my attention by an article I saw reporting the presence of HIV proteins and HIV RNA in cervical biopsies from women who were persistently HIV seronegative , at least for the duration of the study which was one year [3]. They did not have antibodies to HIV despite being infected; of course it is possible that they are in an unusually long “window period” and will eventually seroconvert.  If we use “window period” in this sense then we  can speak of a distribution of window periods of different lengths, including an indefinite one.

I expect that, as is usual this report will provoke little or absolutely no interest.

But it is enormously interesting; (just one of many questions: can these women infect their male partners?)

Seeing this article is the reason why I decided to make this issue the subject of this post.

It was no great surprise when evidence appeared that there were some individuals who were HIV infected but remained negative on the HIV antibody test. It must be said that there were probably more papers in the early years in which silent HIV infections in HIV antibody negative individuals was not observed.

In another approach, reports started to appear that HIV antibody negative individuals had T lymphocyte responses to HIV which means that they were exposed to the virus, not necessarily that they were infected – although that is quite a real possibility. Some early papers, before 2000, including those showing T cell responses can be seen by clicking HERE . There was quite an extensive literature at that time, but most, as mentioned reported that there was no such thing as a silent antibody negative infection, apart from the short window period following infection.

Why has the possibility of prolonged latency always been theoretically possible?

As part of its life cycle HIV is turned into DNA and is then incorporated into the host genome. In infected cells it effectively becomes part of our genetic material. Once inserted into human DNA, it must be activated to start the process of making new virus particles. Cellular signals that start the process of activating HIV DNA include cytokines, which are messenger molecules produced and released by cells, which can then act on other cells to evoke a variety of responses. Amongst these HIV activating cytokines are those that are called proinflammatory cytokines.  These appear during the course of many different infections.  Once HIV DNA is activated, and at least some of its proteins made, these then mediate further activation.

There are some other factors that can activate HIV DNA.

Alloantigens are antigens expressed on foreign cells. When these antigens are in contact with a cell containing integrated HIV DNA, activation occurs; HIV DNA is transcribed and new viral particles made. In earlier days HIV was isolated from infected lymphocytes in this way. Latently infected lymphocytes were induced to produce HIV by culturing them together with lymphocytes from an uninfected donor.

It is the nature of HIV infection that it is frequently acquired in situations which involve exposure to foreign cells (to alloantigens). This may be exposure to semen in sexual transmission, or blood cells in the case of infection by shared needles, or by blood transfusion.

Herpes viruses have the ability to activate HIV if a cell is infected with both viruses. I suppose this must happen but I imagine doubly infected cells may not be found  too frequently. Of course active herpetic infections in non HIV infected cells may be associated with the production of pro inflammatory cytokines, which circulate and can activate HIV DNA in a cell at a distance.

There is absolutely no reason not to expect that in some circumstances incorporation of HIV DNA into human DNA will result in a state of stable integration. This means that HIV DNA remains in the genome, it is not activated, and no virus is produced. Since antibodies are made as a response to viral proteins, and as none are made, the HIV antibody test will be negative.

So it was no surprise when such individuals were again reported in 1999 [4]. These individuals remained in good health and were reported to be antibody negative as long as they were observed [5].

We cannot know if these individuals may seroconvert (or maybe already have), but what is established is that stable integration of HIV DNA without seroconversion can occur. In such individuals limited expression of HIV can occur, at least sufficient to induce, if not antibodies, a cellular immune response.

The presence of such cellular immune responses in HIV antibody negative individuals is further evidence consistent with HIV DNA persistence, but in itself does not indicate this.

Demonstration of cell mediated immunity to HIV:

Apart from the identification of antibodies, specific immunity to HIV can also be detected by a much more elaborate test that measures cellular immunity rather than immunity determined by detecting specific anti HIV antibodies. In this case what is measured is the ability of lymphocytes to recognize HIV. They will do so only if they have been exposed to the virus, which would obviously be the case if they were taken from an infected individual.

The detection of such lymphocyte responses in the mid 1990s was one of the first indications that there may be infected people who don’t make antibodies. Other interpretations are that the infection was overcome, or that that the individual was infected with defective virus.

Gene Shearer was I believe the first to report this phenomenon. HIV antibody negative sexual partners of HIV positive people, as well as individuals who had occupational contact with HIV were among those showing these responses.

It is unknown how widespread this phenomenon of silent HIV infection is. It may be exceedingly rare. It is also unknown if this condition of stable integration is really just a prolonged “window” period that always follows all HIV infections.

But it is entirely possible that there are individuals in whom the ability to control HIV is such that they will remain healthy and HIV negative.

A number of different  outcomes of HIV infection are possible:

Some of the factors that influence this:

Host genetic factors.

Size of the inoculum – the amount of infecting virus.

Route of infection

The particular virus strain.

The presence of associated systemic infections.

these provide signals activating HIV proviral DNA. In the case of some tropical infections there may be cytokines (IL 10) that blunt immune responses.

Sexually transmitted infections with genital ulcers.

Double infection of a cell with HIV and herpes viruses – probably an unusual occurrence.

Exposure to alloantigens; a theoretical possibility.

These are some of the known influences.

Maybe the most common outcome is a productive infection where viral DNA is activated within a few weeks.

But this scenario is also possible:

Infection is followed by insertion of HIV DNA into cellular nuclear DNA. Possibly with small inoculums, and in the absence of strong or sustained activation signals, the proviral DNA remains silent. This has been observed.

Or this one:

There is a limited burst of viral production, not sufficient to elicit an antibody response but enough to induce a cell mediated response with the generation of lymphocytes that recognize HIV antigens and can kill HIV infected cells. HIV seronegative individuals with such specific lymphocyte responses have certainly been observed. In this case if there is an incipient burst of HIV production, the producing cells are promptly killed. Each time this happens the cellular immune response is primed and strengthened. Such a mechanism has been well studied in EBV infections. This common virus is totally unlike HIV, but it does similar things. It remains present in B lymphocytes rather than T lymphocytes for life. The mechanism of persistence is quite different – EBV is not a retrovirus. But the majority of individuals carry this virus – which in rare situations can have lethal effects, in their B lymphocytes for life. We have evolved many mechanisms to keep this virus in check. The ability of some types of lymphocytes to kill EBV infected cells which start to make virus is well understood. Similar mechanisms must exist for HIV – but obviously for most, are insufficiently effective. But in those with very limited HIV production these killer lymphocytes may actually be what allows such rare fortunate individuals to remain HIV seronegative.

With this outcome, one can view the infection as actually having an immunizing effect.

If there were not yet enough reason to study the phenomenon of persistently seronegative HIV infection, this is an important one. What are the circumstances that produce this outcome?

So, for many reasons individuals who are seronegative but have lymphocyte responses to HIV are of great interest.

Yet another scenario is one of stable integration, but where some HIV proteins, but not complete virus, are produced. Maybe the women referred to whose cervical biopsies contained HIV antigens might be in this category. This is a strange situation as antigens were detected but these women apparently did not develop antibodies.

Another very early observation that can be explained by the prior presence of integrated HIV  DNA that is only activated by a subsequent non HIV  infection is the finding that  episodes  of EBV reactivation may precede HIV seroconversion. [6].  This raises the possibility that at least some illnesses associated with primary HIV infection are nothing of the sort. They instead may represent rather non specific viral infections that activate already present integrated HIV DNA, and thus  followed by HIV seroconversion. This is a completely plausible scenario. Of course self reported sexual histories may sometimes  not be too reliable, but nontheless, I well recall an older gay male patient of mine who told me that he had had no sexual contact for years, he had several negative HIV tests over a period of a few years, and then tested positive.  I wondered  then if he may possibly have been infected years before, that he carried latent HIV DNA and this was subsequently activated by some febrile illness. I know this is only an anecdote, and that individuals can be guarded about their sexual histories.  I wonder if others have had similar experiences?

I think around 1996  a description of the course of infection was produced. Everyone interested in this disease will have seen this picture: Here it is again:


This may represent a typical course of infection.  But HIV disease is probably so variable in the course it can take that there may well not be such a thing as a typical infection.

This depiction does however give the impression that there is,  and discourages an appreciation of the probably  immense variations in the course of  HIV disease.  The notion of a “standard” course of HIV disease has  had implications for treatment.  Recommendations are made that take no account of  individual  rates of disease progression;  a one size fits all approach has been adopted.

The  rapid acceptance that there is a typical – or an  average  course of HIV infection is particularly odd as not only is the disease new – we have no precedents of human retroviral diseases (apart from HTLV-1 associated disease);  the techniques used to study the disease are themselves new. The ability to identify T lymphocyte subsets with monoclonal antibodies is about as old as the HIV epidemic. So we had no idea then of the variation in T subset numbers in health and disease. Other immunological and virological techniques were, and continue to be introduced as the epidemic is proceeding.

A model was constructed before sufficient evidence was available to justify it.  It really had no empirical basis; moreover it seemed to utterly ignore what we knew of other chronic viral diseases.  For example, hepatitis B and Hepatitis C can both have very variable courses.  These can range from clearing the infection, running a fulminant course ending fatally  to the establishment of a chronic active state which may progress at varying rates.  If we were to construct a model of the course of HIV disease only about  12 to 15 years after the disease was first seen, why on earth did we not consider the precedents of other chronic viral diseases?   Thus we might have  included the real possibility that some exposures may result in infections that may be cleared , as well as the now demonstrated situation where silent antibody negative infections occur.    The picture shown above – and presented in every text on HIV disease may indeed represent the most common course of HIV infection. But even this is not  known.

HIV infection, like other chronic viral infections  can progress in different ways. If we were more open to this there may have been greater interest and funding into research that investigates the various factors that influence how the disease progresses. This has obvious therapeutic implications  –  for example as proinflammatory cytokines promote HIV replication, the control of endemic infections in some areas where they are highly prevalent is absolutely relevant to the control of HIV infection.  Steps as simple as the provision of sanitation and clean water may well have an impact on the control of HIV infection in some geographical areas.  Had we not been so tied to the notion of  a fixed course of HIV infection, we might have placed importance on the individualization of therapy, not only considering a fixed CD4 count as a signal to start therapy, but also considering each individuals rate of disease progression.

HIV disease is in this sense like  every other infectious disease, the course of which  to a greater or lesser extent can be influenced by many different factors , including host factors, factors related to the pathogen, the particular variant , the size of the infecting dose, the route of infection amongst many others.

I have often wondered why there has been such resistance to not only the reasonable idea, but also to actual evidence that HIV disease  does not necessarily  take the course  shown above.

In conclusion, the study of prolonged HIV seronegativity in infected people is important. Some reasons are:

1. There are obvious implications for vaccine development.

2. Seroprevalence may significantly underestimate the prevalence of HIV infection.

3. Understanding the phenomenon will advance our understanding of the pathogenesis of this disease, which in turn will open new therapeutic approaches.

4. There are instances of infected people remaining seronegative and in good health.


Imagawa, D.T., M.H. Lee. S.M Wolinsky. et al..

Human immunod­eficiency virus type 1 infection in homosexual men who remain seronegative for prolonged periods.

New England Journal of Medicine 1989 320:1458-1462.


Scientific Errors and Controversies in the U.S. HIV/AIDS Epidemic: How They Slowed Advances and Were Resolved

By Scott D. Holmberg

Published by Greenwood Publishing Group, 2008


Human Immunodeficiency Virus (HIV) Antigens and RNA in HIV-Seronegative Women with Cervical Intraepithelial Neoplasia
Jayasri Basu, Seymour L. Romney, Ruth H. Angeletti, Sten H. Vermund, Edward Nieves, Anna S. Kadish, Magdy S. Mikhail, and George A. Orr

The publisher of this journal kindly sends me the contents of each issue as I started this journal around 1983 and was its first editor, seeing it through its first two volumes. It was then simply called AIDS Research.


Zhu T, Corey L, Akridge R, Change Y, Feng F, Kim J, Alef C, Mcelroy J, Mullins J, Mcelrath J.

Evidence for HIV-1 latent infection in exposed seronegative individuals.

Abstract No.8, 6th Conference on Retroviruses and Opportunistic Infections. Chicago. 1999.


Persistence of extraordinarily low levels of genetically homogeneous human immunodeficiency virus type 1 in exposed seronegative individuals.

Journal of virology, {J-Virol}, Jun 2003, vol. 77, no. 11, p. 6108-16,

Zhu-Tuofu, Corey-Lawrence, Hwangbo-Yon, Lee-Jean-M, Learn-Gerald-H, Mullins-James-I, McElrath-M-Juliana.


Some individuals remain inexplicably seronegative and lack evidence for human immunodeficiency virus type 1 (HIV-1) infection by conventional serologic or virologic testing despite repeated high-risk virus exposures. Here, we examined 10 exposed seronegative (ES) individuals exhibiting HIV-1-specific cytotoxicity for the presence of HIV-1. We discovered HIV-1 DNA in resting CD4(+) T cells (mean, 0.05 + /- 0.01 copies per million cells) at multiple visits spanning 69 to 130 weeks in two ES individuals at levels that were on average 10(4)-to 10(6)-fold lower than those of other HIV-1-infected populations reported. Sequences of HIV-1 envelope and gag genes remained markedly homogeneous, indicating little to undetectable virus replication. These results provide the evidence for HIV-1 infection in ES individuals below the detection limit of standard assays, suggesting that extraordinary control of infection can occur. The two HIV- infected ES individuals remained healthy and were not superinfected with other HIV-1 strains despite continued high-risk sexual exposures to multiple HIV-infected partners. Understanding the mechanisms that confer diminished replicative capacity of HIV-1 in these hosts is paramount to developing strategies for protection against and control of HIV-1 infection.

Schattner, A, Hanuka N, Sarov B, Sarov I, Handzel Z, Bentwich Z.

Sequential serological studies of homosexual men with and without HIV infection. Epstein-Barr virus activation preceding and following HIV seroconversion.

Clin Exp Immunol 1991; 85: 209-13.

  1. April 14, 2009 at 4:48 am

    I take Valtrex for suppressive therapy. My daily life is so much more manageable emotionally and physically since taking Valtrex as a suppressive treatment. For those who suffer with this virus, you will understand how our lows are very low when experiencing regular outbreaks. Valtrex allows my condition to be a minor inconvenience and no longer a dark lonely place. I now experience an outbreak twice yearly.

  2. David
    July 4, 2009 at 7:52 am

    A very interesting article.I was exposed to HIV over a year ago and developed Guillain Barre Syndrome, many mouth ulcers, bleeding tongue, fatigue, lymph node pain, metallic tongue, mosquito allergy, brain fog, depression, 3 fungal infections including toe nail, folliculitus and balanitis. Over one year on and I still get neuropathic pain and lymph node pain under arms, in groin and in neck areas.I have persistently tested HIV negative and have received correspondence with people whio have experienced similar symptoms to me following high risk exposures in Thailand.Here is one example of someone from Holland who has a CD4 count of less than 500 a year after a high risk exposure in Thailandhttp://www.thebody.com/Forums/AIDS/SafeSex/Arch…Here is an example of someone who seroconverted after 30 monthshttp://www.thebody.com/Forums/AIDS/Labs/Archive…And this guy believes he took 18 years to seroconverthttp://pozguys.tribe.net/thread/9e3db7d8-7578-4…I am happy to believe I could have another infection but can't find one with the symptoms I have.There certainly seems to be something going on but most doctor's will shoo patients away and so we are left in a void with no suppoprt whilst still feeling ill following an exposure to HIV.

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