American Society for Microbiology
ASM News, April 2005, Volume 71, Number 4, Page 157
Letter
Origin of AIDS Revisited
The origin of the AIDS pandemic remains a mystery (ASM News, January
2005, p. 15). One theory holds that human immunodeficiency virus type
1 (HIV-1) evolved from a chimpanzee retrovirus, SIVcpz, that crossed
the species barrier in an unknown manner (F. Gao, E. Bailes, D. L.
Robertson, et al., Nature 397:436-441, 1999). This theory is based
primarily on the discovery of a chimp named Marilyn who was found to
be infected with a retrovirus that closely resembled HIV-1 (R. V.
Gilden, L. O. Arthur, W. G. Robey, et al., Lancet i:678-679, 1986).
Extensive testing in other chimps has so far failed to reveal similar
infection in more than a handful of animals, and the origin of SIVcpz
itself remains a mystery.
We have examined new information about chimps such as Marilyn who were
used in animal experiments or followed in the wild in the 1960s (W. D.
Hillis , Am. J. Hyg. 73:316-328, 1961; B. W. Allmond, Jr., J. E.
Froeschle, and N. B. Guilloud, Am. J. Epidemiol. 85:229-239, 1967;
J. Goodall, The Chimpanzees of Gombe: Patterns of Behaviour, Harvard
University Press, Cambridge, 1986; J. van Lawick-Goodall, In the
Shadow of Man, Houghton Mifflin Company, Boston, 1971). Chimps from
African vendors were sometimes inoculated intraperitoneally with
pooled human whole blood in order to "protect them from human
diseases." This practice was thought to be the cause of an infectious
hepatitis outbreak among chimp handlers in 1960 at Holloman Air Force
Base in New Mexico, the same location where Marilyn was housed. Thus
inoculation with human blood in Africa could have been the source of
Marilyn's retroviral infection. Furthermore, chimps in Africa and the
United States suffered from outbreaks of poliomyelitis, and these
animals received an oral polio vaccine derived from human diploid cell
strains on at least one occasion in 1967. Thus, chimps were exposed to
blood products and vaccines that could have transmitted an HIV-1
precursor virus that evolved into SIVcpz (S. Corbet, M. C.
Muller-Trutwin, P. Versmisse, et al., J. Virol. 74:529-534, 2000).
This virus would have been difficult to transmit among chimps, as
HIV-1 is not readily transmitted from infected to uninfected animals
(P. N. Fultz, C. Greene, W. Switzer, B. Swenson, et al., J. Med.
Primatol. 16:341-347, 1987). Hence the small number of SIVcpz cases.
Sporadic exposure of chimps to human blood products and vaccines in
the 1960s suggests that SIVcpz evolved in parallel with HIV-1, rather
than being its evolutionary parent. The common source of the human and
chimp retrovirus that spawned the AIDS pandemic remains to be
elucidated (B. Goldberg and R. B. Stricker, J. Theor. Biol.
204:497-503, 2000).
Billi Goldberg
International DNCB Study Group
San Francisco, Calif.
Raphael B. Stricker
California Pacific Medical Center
San Francisco, Calif.
American Society for Microbiology
ASM News, April 2005, Volume 71, Number 4, Page 157
Letter
Origin of AIDS Revisited
The origin of the AIDS pandemic remains a mystery (ASM News, January
2005, p. 15). One theory holds that human immunodeficiency virus type
1 (HIV-1) evolved from a chimpanzee retrovirus, SIVcpz, that crossed
the species barrier in an unknown manner (F. Gao, E. Bailes, D. L.
Robertson, et al., Nature 397:436-441, 1999). This theory is based
primarily on the discovery of a chimp named Marilyn who was found to
be infected with a retrovirus that closely resembled HIV-1 (R. V.
Gilden, L. O. Arthur, W. G. Robey, et al., Lancet i:678-679, 1986).
Extensive testing in other chimps has so far failed to reveal similar
infection in more than a handful of animals, and the origin of SIVcpz
itself remains a mystery.
We have examined new information about chimps such as Marilyn who were
used in animal experiments or followed in the wild in the 1960s (W. D.
Hillis , Am. J. Hyg. 73:316-328, 1961; B. W. Allmond, Jr., J. E.
Froeschle, and N. B. Guilloud, Am. J. Epidemiol. 85:229-239, 1967;
J. Goodall, The Chimpanzees of Gombe: Patterns of Behaviour, Harvard
University Press, Cambridge, 1986; J. van Lawick-Goodall, In the
Shadow of Man, Houghton Mifflin Company, Boston, 1971). Chimps from
African vendors were sometimes inoculated intraperitoneally with
pooled human whole blood in order to "protect them from human
diseases." This practice was thought to be the cause of an infectious
hepatitis outbreak among chimp handlers in 1960 at Holloman Air Force
Base in New Mexico, the same location where Marilyn was housed. Thus
inoculation with human blood in Africa could have been the source of
Marilyn's retroviral infection. Furthermore, chimps in Africa and the
United States suffered from outbreaks of poliomyelitis, and these
animals received an oral polio vaccine derived from human diploid cell
strains on at least one occasion in 1967. Thus, chimps were exposed to
blood products and vaccines that could have transmitted an HIV-1
precursor virus that evolved into SIVcpz (S. Corbet, M. C.
Muller-Trutwin, P. Versmisse, et al., J. Virol. 74:529-534, 2000).
This virus would have been difficult to transmit among chimps, as
HIV-1 is not readily transmitted from infected to uninfected animals
(P. N. Fultz, C. Greene, W. Switzer, B. Swenson, et al., J. Med.
Primatol. 16:341-347, 1987). Hence the small number of SIVcpz cases.
Sporadic exposure of chimps to human blood products and vaccines in
the 1960s suggests that SIVcpz evolved in parallel with HIV-1, rather
than being its evolutionary parent. The common source of the human and
chimp retrovirus that spawned the AIDS pandemic remains to be
elucidated (B. Goldberg and R. B. Stricker, J. Theor. Biol.
204:497-503, 2000).
Billi Goldberg
International DNCB Study Group
San Francisco, Calif.
Raphael B. Stricker
California Pacific Medical Center
San Francisco, Calif.
