S. Theodore

A novel HIV-1 isolate containing alterations affecting the NF-κB element

Abstract Three molecular clones of HIV-1, derived from a single isolate (Al-1), exhibited distinct replicative and cytopathic properties during propagation in a human T cell line. The phenotypic differences observed were attributable, in large part, to changes affecting the viral LTR. Nucleotide sequence and PCR analyses demonstrated the presence of novel duplications or deletions involving the NF-κB motif. These changes in the enhancer element were identified in the original AL1 virus stock. Subcloning of the variant NF-κB segments into LTR-driven CAT expression vectors confirmed a correlation between promoter activity and replicative/cytopathic capacity.

Molecular characterization of a polymerase mutant human immunodeficiency virus.

A cell line (8E5) containing a single defective copy of human immunodeficiency virus proviral DNA and producing noninfectious viral particles lacking reverse transcriptase (RT) and endonuclease proteins has recently been described (Folks, et al., (1986b) J. Exp. Med. 164, 280-290). In this report, the mutation in a full-length molecular clone of the provirus (p8E5) was mapped to a 1931-bp region of the pol gene encoding RT. The nucleotide sequence of this segment revealed a 1-base deletion 301 codons from the common amino terminus of the 64- and 51-kDa RTs. Expression of the p8E5 RT segment in Escherichia coli generated an enzymatically inactive and truncated 33-kDa protein.

Induction of Disease by a Molecularly Cloned Highly Pathogenic Simian Immunodeficiency Virus/Human Immunodeficiency Virus Chimera Is Multigenic

ABSTRACT One of three full-length infectious molecular clones of SHIVDH12R, designated SHIVDH12R-CL-7 and obtained from productively infected rhesus monkey peripheral blood mononuclear cells, directed rapid and irreversible loss of CD4+ T cells within 3 weeks of its inoculation into Indian rhesus monkeys. Induction of complete CD4+ T-cell depletion by SHIVDH12R-CL-7 was found to be dependent on inoculum size. The acquisition of this pathogenic phenotype was accompanied by the introduction of 42 amino acid substitutions into multiple genes of parental nonpathogenic SHIVDH12. Transfer of the entire SHIVDH12R-CL-7env gene into the genetic background of nonpathogenic SHIVDH12 failed to confer the rapid CD4+ T-lymphocyte-depleting syndrome; similarly, the substitution of gag plus pol sequences from SIVsmE543 for analogous SIVmac239 genes in SHIVDH12R-CL-7 attenuated the pathogenic phenotype. Amino acid changes affecting multiple viral genes are necessary, but insufficient by themselves, to confer the prototypically rapid and irreversible CD4+ T-cell-depleting phenotype exhibited by molecularly cloned SHIVDH12R-CL-7.

Although Macrophage-Tropic Simian/Human Immunodeficiency Viruses Can Exhibit a Range of Pathogenic Phenotypes, a Majority of Isolates Induce No Clinical Disease in Immunocompetent Macaques

ABSTRACT Unlike prototypical lentiviruses like visna and caprine arthritis-encephalitis viruses, which are mainly macrophage tropic (M-tropic), primate lentiviruses primarily target CD4+ T lymphocytes. We previously reported that during the late phase of highly pathogenic chimeric simian/human immunodeficiency virus (SHIV) infections of rhesus macaques, when CD4+ T cells have been systemically eliminated, high levels of viremia are maintained from productively infected macrophages. The availability of several different M-tropic SHIVs from such late-stage immunocompromised animals provided the opportunity to assess whether they might contribute to the immune deficiency induced by their T-cell-tropic parental viruses or possibly cause a distinct disease based on their capacity to infect macrophages. Pairs of rhesus monkeys were therefore inoculated intravenously with six different M-tropic SHIV preparations, and their plasma viral RNA loads, circulating lymphocyte subset numbers, and eventual disease outcomes were monitored. Only one of these six M-tropic SHIVs induced any disease; the disease phenotype observed was the typical rapid, complete, and irreversible depletion of CD4+ T cells induced by pathogenic SHIVs. An analysis of two asymptomatic monkeys, previously inoculated with an M-tropic SHIV recovered directly from alveolar macrophages, revealed that this inoculum targeted alveolar macrophages in vivo, compared to a T-cell-tropic virus, yet no clinical disease occurred. Although one isolate did, in fact, induce the prototypical rapid, irreversible, and complete loss of CD4+ T cells, indicating that M-tropism and pathogenicity may not be inversely related, the majority of M-tropic SHIVs induced no clinical disease in immunocompetent macaques.