[Final Program, International Conference on AIDS (4th: 1988: Stockholm, Sweden), Book 2]

2585 SIMIAN IMMUNODEFICIENCY VIRUS FROM A
MOLECULAR CLONE PRODUCTIVELY INFECTS
RHESUS MACAQUE MACROPHAGES IN VITRO
Babak Banapour*, Marta Marthas*, Niels Pedersen** and Paul Luciw*
Departments of Medical Pathology* and Veterinary Medicine**,
University of California, Davis CA 95616
Objective: Simian immunodeficiency virus (SIV) is a lymphocytopathic
lentivirus which causes severe immunodeficiency leading to death in
rhesus macaques (Mucaca mulatta). DNA sequence analysis has
indicated that SIV shows about 50% and 75% homology to human
immunodeficiency virus (HIV) type 1 and type 2, respectively. Thus, SIV
is a critically important model for HIV infection and disease. Our aim is
to determine whether a molecular clone of SIVmac can productively infect
peripheral blood mononuclear cells (PMBCs) as well as primary
macrophage cultures established from adherent subpopulations of PMBCs
from rhesus macaques. One of our goals is to establish the pathological
consequences of this molecularly cloned virus in susceptible monkeys.
Methods: Recently, we molecularly cloned an SIV isolate which was
originally recovered from a rhesus macaque. This molecular clone of
SIVmac produces infectious virus when transfected into the human
lymphoid T-cell line, HUT-78.
Results: SIVmac recovered from the molecular clone was observed to
infect rhesus PMBCs resulting in high levels of particle associated
reverse transcriptase activity as well as characteristic cytopathic effect.
Furthermore, it was noted that SIVmac can infect primary macrophage
cultures established from adherent subpopulations of PMBCs.

2586 THE HOST RANGE OF HIV AND ITS RELATIONSHIP TO
TISSUE TROPISM AND PATHOGENESIS. Jay A. Levy,
University of California, San Francisco, CA.
HIV replicates to high titer in human T cells and
infects macrophages, B cells and other hematopoietic
cells which express the CD4 protein. HIV can also infect glial cells including some astrocyte lines that do
not express CD4. Moreover, human monolayer cells lacking CD4 expression can be infected with some HIV isolates and HIV has been recovered from bowel epithelial
cells. These observations underscore the wide tropism
of HIV and suggest other receptors or mechanisms for its
infection of human cells.
HIV isolated from the brain and blood can be distinguished by their relative ability to infect human T
and macrophage cell lines, primary macrophages, and
induce plaques in MT-4 cells. Moreover, individuals who
progress to severe disease have HIV that emerge with
properties suggesting increased virulence. These
isolates replicate rapidly in a wide variety of human
cells, are cytopathic and plaque in MT-4 cells. Restriction enzyme studies suggest that these longitudinally
isolated HIV are related. Furthermore, only highly
cytopahtic HIV grow in human fibroblast cells. Anlayses
of these HIV and those recovered from other tissues may
reveal further biologic features that reflect pathogenesis in the host.

Conclusion: These results show that virus from the molecular clone of
SIVmac, demonstrating both T-cell and macrophage tropism, will enable
us to establish the viral determinants of pathogenesis responsible for the
fatal immunodeficiency induced by primate lentiviruses.
Notes:

2587 THE SUSCEPTIBILITY OF NON-HEMATOPOIETIC CELL
LINES TO HIV INFECTION. Masatoshi Tateno and Jay
A. Levy, Cancer Research Institute, University of
California, School of Medicine, San Francisco, CA.
Objective. Infect non-hematopoietic cell lines with HIV.
Methods. HOS, Huf (human fibroblasts), RD and mink lung cell
lines were inoculated with various strains of HIV. Residual virus
was removed by trypsin and washings. After two weeks,
uninfected peripheral mononuclear cells (PMC) or MT-4 cells
were added to the monolayers.
Results. After infection with ten different HIV, the HOS, Huf
and RD human cells did not show virus by cytopathic effects
(CPE), indirect immunofluorescence (IFA), reverse
transcriptase (RT) or antigen (Ag) assays. However, when
normal PMC or MT-4 cells were added, these cells were
infected by 4/10 HIV as reflected by CPE, IFA, RT and Ag
assays. The four isolates formed plaques in MT-4 cells. Nonplaquing HIV did not replicate in the human monolayer cells.
None of the ten HIV infected mink lung cells. The HOS, Huf and
RD lines did not express CD4 antigen.
Conclusion. Some HIV can productively infect nonhematopoietic cell lines which do not express detectable CD4
protein. These viruses are cytopathic and replicate rapidly in
PMC. These findings on the ability of certain HIV to infect
human monolayer cells may relate to pathogenesis in the host.

2588 CELL-TYPE SPECIFIC TROPISM OF HIV-1 ISOLATES:
MOLECULAR AND BIOLOGICAL CHARACTERIZATION
Mikulas Popovic, S. Gartner, E. Read-Connole, B. Beaver,
R.C. Gallo, M. Reitz, Jr.
Lab. of Tumor Cell Biology, NCI/NIH Bethesda, MD, USA
Our previous studies have shown that HTLV-IIIB, in
contrast to fresh isolates (e.g. HTLV-IIIBa.L; Gartner,
S. et al Science 233:215, 1986) manifests a significantly
lower (1000-fold) ability to infect monocyte/ macrophages
(M/M) than T lymphocytes.
Objective: To determine the molecular basis for this loss
of ability to productively infect M/M.
Methods: A 4.2Kb HIND III fragment of HTLV-III was
cloned and sequenced from DNA recovered from M/M infected
with this isolate. Biologically active recombinant
clones containing various.portions of this 4.2Kb fragment
were generated by substitution of analogous regions into
HTLV-IIIB-derived clones. Viruses recovered from COS-1
cells transfected with the molecular clones were assessed
for infectivity using normal M/M and T cells as targets
in endpoint titration experiments.
Results: Nucleic acid sequence analysis revealed that
this fragment contains a portion of sor and 3'orf and the
entire tat, trs and env genes. Comparative sequence
analyses revealed no unusual differences between the
HTLV-IIIBa-L genome and those of the other HIV-1 cloned
isolates. The extent of differences between other
isolates and that part of the HTLV-IIIa L genome
examined is 8-10% which is comparable to the extent of
differences between any two independent isolates.
Preliminary assessment of the recombinant viruses have
failed to identify a specific portion of the HIND-III
fragment able to fully restore the macrophage tropism of
HTLV-III.
Conclusion: These data suggest that small, discreet
changes, presumably within regulatory elements of the
HIV-1 genome, can be responsible for significant
biological differences.

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