Science, Vol 298, Issue 5599, 1727-1728 , 29 November 2002

HISTORICAL ESSAY:
A History of HIV Discovery
Luc Montagnier*

In 1972, Jacques Monod asked me to create a research unit in the new
virology department of the Pasteur Institute. I baptized it the viral
oncology unit because I shared the belief of many biologists that
certain human cancers could be caused by viruses, in particular by
retroviruses. I had some experience with chicken oncogenic viruses,
having confirmed with the late Philippe Vigier the existence of
infectious transforming DNA in chicken cells infected with Rous
Sarcoma virus (first described by Hill and Hillova) (1). Yet, despite
a well-funded effort, the "virus cancer program" failed to reveal a
retrovirus that could cause human cancer.

In 1977, as the viral oncology unit became interested in the action of
interferon, I had an illuminating idea: Perhaps we couldn't isolate
retroviruses from human cancers because their expression was inhibited
by production of endogenous interferon. If we could neutralize this
effect by treating cancer cells with antiserum against interferon, we
might be able to detect a human oncogenic retrovirus. About this time,
Jean Claude Chermann and his young assistant Françoise Sinoussi, both
with expertise in mouse retroviruses, joined the unit. First, we
tested the idea in mouse cells and, indeed, production of exogeneous
and even endogeneous retroviruses could be boosted by treating cells
with low doses of antiserum to mouse interferon (2). Next, we
investigated human cancers, selecting acute and chronic lymphocytic
leukemias and breast cancers for study. We used the new T cell growth
factor (now called interleukin-2) discovered in Robert Gallo's
laboratory to make short-term T lymphocyte cultures from cancer
patients. We hoped that the retrovirus might be hiding not only in
human cancer cells but also in T cell subsets. We examined many
lymphocyte samples from cancer patients, each time culturing the cells
with and without antiserum to human interferon. Françoise Sinoussi
measured reverse transcriptase (RT) activity (a retroviral enzyme) in
the culture supernatants. We had a few (false) positive results due to
RT activity associated with mycoplasma contamination of our T cell
cultures. In 1982, using a DNA probe from the mouse mammary tumor
virus, Michel Crepin detected by molecular hybridization a DNA
sequence in a human breast tumor that resembled a sequence in the
mouse oncogenic retrovirus (3). Strikingly, the same DNA sequence
could be recovered from cultured T lymphocytes taken from the cancer
patient.

It was at this time that I first heard about the "gay disease." There
were only a few patients with this disease in France, but Gallo's idea
that a retrovirus was the cause had already crossed the Atlantic. His
idea was disseminated by a small group of clinicians and immunologists
led by Jacques Leibowitch and Willy Rozenbaum. At the end of 1982,
Françoise Brun-Vezinet, a former student of mine and a member of this
group, proposed that we collaborate to discover if a retrovirus was
the cause of this disease, now called AIDS.

We were ready to start because my laboratory was equipped to hunt for
lymphotropic retroviruses in human T cell cultures. In addition, there
was a risk that human plasma collected from blood in the United States
and used by the Pasteur Institute's industrial subsidiary to prepare a
hepatitis B vaccine might be contaminated by the AIDS agent. On 3
January 1983, Françoise Brun-Vezinet obtained a lymph node biopsy from
one of Rozenbaum's patients, a young gay man (BRU) with a
lymphadenopathy in the neck. I minced the lymph node, dissociated the
fragments into single cells, and cultured the T lymphocytes with
interleukin-2 and antiserum to human interferon. Fifteen days later,
Françoise Sinoussi (by then Barré-Sinoussi) found the first traces of
RT in the supernatant of the lymphocyte culture, indicating the
presence of a retrovirus. The only retroviruses then known were the
human T cell leukemia viruses, HTLV-1 and HTLV-2, identified by
Gallo's group. So, we tested whether the viral proteins in the
supernatant could be recognized by Gallo's antibodies against HTLV.
Surprisingly, our labeled viral supernatant could not be immune
precipitated with the HTLV antibodies, but could be precipitated with
the patient's own serum (4). A protein with a molecular mass of about
25 kD precipitated by the patient's serum seemed to be the counterpart
of the p24 protein of HTLV-1. The virus could not be isolated from
blood lymphocytes, a fact that is now explained by the early stage
(lymphadenopathy) of this patient's disease when the virus is almost
exclusively located in lymphatic tissues. Louis Pasteur's quote that
"luck in science smiles on prepared minds" certainly applied to us. We
received a biopsy from another young gay male patient (MOI), who was
infected with both HTLV and the new lymphadenopathy-associated virus.
If MOI had been our first patient, we would have been very confused.

A few months later, I received a blood sample from a young hemophiliac
(LOI) with full-blown AIDS, and blood and lymph node samples from a
young gay man (LAI) with advanced Kaposi's sarcoma. The LAI virus
could be isolated from the patient's blood cells and grew very quickly
in the patient's cultured T lymphocytes, killing them as well as
killing T lymphocytes from blood donors. In September, we isolated a
similar virus from the blood of a Zairian woman, ELI, who died of AIDS
a week later. All of the isolated viruses showed cross-reactivity
between their gag proteins (p25 and p18) (5). The viruses isolated
from full-blown AIDS patients were more aggressive than the BRU virus,
and so I called them immune deficiency-associated viruses (IDAV). The
viruses like BRU that were isolated from patients who only suffered
from lymphadenopathy were termed lymphadenopathy-associated viruses,
or LAV. This classification corresponded to the later terminology of
syncitium and nonsyncitium-inducing strains.

The retrovirus was new, as was the disease. My collaborator, the
electron microscopist Charles Dauguet, showed me pictures of the viral
particles whose dark, cone-shaped centers suggested that this virus
was not the same as HTLV. Fellow virologist Edwald Edlinger suggested
that I compare the new virus with animal lentiviruses, and, indeed,
the pictures of viral particles we obtained in June 1983 looked
identical! As I told Robert Gallo, I was convinced that we were
dealing with a virus quite different from the HTLV family.

To better characterize the new virus, we tried (unsuccessfully) to
grow the BRU isolate in different T cell lines. If we had tried the
LAI isolate instead, we would have been able to grow the virus without
any trouble. In October 1983, we were finally able to grow the BRU
isolate in Epstein-Barr virus-transformed B cell lines, although we
discovered later that the LAI virus had contaminated our BRU culture
(6). At least six laboratories received the LAI sample (under the name
BRU) from our group and experienced the same contamination. We think
that the LAI virus readily contaminated the BRU culture because it
associates with a mycoplasma species, Mycoplasma pirum, usually
present in T cell lines. This physical association makes a fraction of
the LAI virus highly infectious, and, in fact, this fraction can be
neutralized with antibodies against M. pirum. As mycoplasmas are
common contaminants of cultured cells, an infectious pseudotype virus
(LAI associated with M. pirum) may have caused several contaminations
between 1983 and 1984 in different laboratories.

New evidence that this strange retrovirus was the cause of AIDS came
from our team in the fall of 1983 and the winter of 1984 (7). We
observed a high frequency of antibodies against the virus in
lymphadenopathy patients, and noted the favored tropism of this virus
for CD4+ T lymphocytes. Our results were still controversial, however,
and we had difficulty in obtaining the funding needed to better
characterize the virus and to develop a blood test. The tide only
turned in France when Robert Gallo and his group in the United States
made a similar discovery. In the spring of 1984, Gallo published more
convincing evidence that HIV causes AIDS (8) (see the Viewpoint by
Gallo on page 1728), a finding that was confirmed by Jay Levy's group
(9). In 1985 came the cloning and sequencing of the HIV genome with
identification of new open reading frames specific for lentiviruses
(10). This was followed by identification of the HIV large surface
glycoprotein (11) and of T cell CD4 as the receptor for HIV (12, 13).
In 1986, HIV-2 was isolated from West African patients (14).

Over the past 20 years, the scientific and legal controversies between
our team and Gallo's group have faded. We are left with the salient
fact that HIV was identified and shown to be the cause of AIDS less
than 2 1/2 years after this disease was first identified. It took only
another 2 years for blood tests to become commercially available,
reducing almost to zero the transmission of AIDS through blood
transfusion in developed countries. In 1987, the first anti-HIV drug,
AZT, which blocks HIV RT activity, was introduced. With the arrival of
the HIV protease inhibitors and triple drug therapy in 1995, many
patients are alive today who would otherwise have died.

But we must not be complacent--the task ahead is immense. We still do
not understand the origin of the AIDS epidemic; the slow destruction
of the immune system by factors in addition to HIV infection of CD4+ T
cells; the importance of cofactors in AIDS progression and virus
transmission; and the nature of the HIV reservoir that resists triple
drug therapy. The next wave of advances in the fight against this
worldwide scourge will require the contribution and energy of us all.

References and Notes

  1. P. Vigier, L. Montagnier Int. J. Cancer 15, 67 (1975). [Medline]
  2. F. Barré-Sinoussi et al., Ann. Microbiol. (Inst. Pasteur) 130 B,
349 (1979). [Medline]
  3. M. Crepin, Biochem. Biophys. Res. Commun. 118, 324 (1984).
[Medline]
  4. F. Barré-Sinoussi et al., Science 220, 868 (1983). [Medline]
  5. L. Montagnier et al., in Human T Cell Leukemia and Lymphoma
Viruses, R. C. Gallo, M. E. Essex, L. Gross, Eds. (Cold Spring Harbor
Laboratory, New York, 1984), pp. 363-379.
  6. S. Wain-Hobson et al., Science 252, 961 (1991). [Medline]
  7. Between 1983 and 1985 the team included the superb
retrovirologists Jean-Claude Chermann and Françoise Barré-Sinoussi and
the following talented individuals to whom I am indebted: M. Alizon,
C. Axler-Blin, F. Brun-Vezinet, J. B. Brunet, S. Chamaret, F. Clavel,
S. Cole, O. Danos, C. Dauguet, J. C. Gluckman, J. Gruest, D. Guetard,
D. Klatzmann, B. Krust, N. T. Nugeyre, F. Rey, C. Rouzioux, W.
Rozenbaum, P. Sonigo, E. Vilmer, and S. Wain-Hobson.
  8. R. Kulstad, Ed., AIDS: Papers from Science, 1982-1985 (AAAS,
Washington DC, 1986).
  9. J. A. Levy et al., Science 225, 840 (1984). [Medline]
 10. S. Wain-Hobson et al., Cell 40, 9 (1985). [Medline]
 11. J. S. Allan et al., Science 228, 1091 (1985). [Medline]
 12. A. G. Dalgleish et al., Nature 312, 763 (1984). [Medline]
 13. D. Klatzmann et al., Nature 312, 767 (1984). [Medline]
 14. F. Clavel et al., Science 233, 343 (1986). [Medline]