Lymphadenopathy/AIDS virus: genetic organization and relationship to animal lentiviruses

This article presents data obtained by our group in the molecular characterization of the probable agent of the acquired immune deficiency syndrome (AIDS), the lymphadenopathy/AIDS virus (LAV). Molecular cloning and complete nucleotide sequencing of LAV allows a detailed comparison with other AIDS virus isolates, as well as other human and animal retroviruses. We have now molecular evidence that the AIDS virus is closely related to visna virus, prototype of the lentiviruses, whereas the other human retroviruses, i.e., human T-cell leukemia viruses type I and II (HTLV-I and II), are quite remote in the evolution.

Nucleotide sequence of the visna lentivirus: relationship to the AIDS virus

We have determined the complete 9202 nucleotide sequence of the visna lentivirus. The deduced genetic organization most closely resembles that of the AIDS retrovirus in that there is a novel central region separating pol and env. Moreover, there is a close phylogenetic relationship between the conserved reverse transcriptase and endonuclease/integrase domains of the visna and AIDS viruses. These findings support the inclusion of the AIDS virus in the retroviral subfamily Lentivirinae.

Nucleotide sequence of the AIDS virus, LAV

The complete 9193-nucleotide sequence of the probable causative agent of AIDS, lymphadenopathy-associated virus (LAV), has been determined. The deduced genetic structure is unique: it shows, in addition to the retroviral gag, pol, and env genes, two novel open reading frames we call Q and F. Remarkably, Q is located between pol and env and F is half-encoded by the U3 element of the LTR. These data place LAV apart from the previously characterized family of human T cell leukemia/lymphoma viruses.

Molecular cloning of lymphadenopathy-associated virus

Lymphadenopathy-associated virus (LAV) is a human retrovirus first isolated from a homosexual patient with lymphadenopathy syndrome, frequently a prodrome or a benign form of acquired immune deficiency syndrome (AIDS). Other LAV isolates have subsequently been recovered from patients with AIDS or pre-AIDS and all available data are consistent with the virus being the causative agent of AIDS. The virus is propagated on activated T lymphocytes and has a tropism for the T-cell subset OKT4 (ref. 6), in which it induces a cytopathic effect. The major core protein of LAV is antigenically unrelated to other known retroviral antigens. LAV-like viruses have more recently been independently isolated from patients with AIDS and pre-AIDS. These viruses, called human T-cell leukaemia/lymphoma virus type III (HTLV-III) and AIDS-associated retrovirus (ARV), seem to have many characteristics in common with LAV and probably represent independent isolates of the LAV prototype. We have sought to characterize LAV by the molecular cloning of its genome. A cloned LAV complementary DNA was used to screen a library of recombinant phages constructed from the genomic DNA of LAV-infected T lymphocytes. Two families of clones were characterized which differ in a restriction site. The viral genome is longer than any other human retroviral genome (9.1-9.2 kilobases).

Lymphadenopathy associated virus and its etiological role in AIDS

Lymphadenopathy associated virus (LAV) is a novel human retrovirus first reported in 1983. It was isolated from the lymph node lymphocytes of a French homosexual patient with generalized hyperplasic lymphadenopathy. Subsequently LAV was isolated from patients with frank acquired immune deficiency syndrome (AIDS) coming from all the different high-risk groups, while anti-LAV antibodies were detected equally in individuals from all "at-risk" groups. Such a profile is consistent with the virus being the major etiological agent of AIDS. Furthermore its biological properties, namely its cytopathic effect in vitro, its T4-cell tropism as well as the role of the T4 molecule in virus infection explain, at least in part, the pathophysiology of AIDS. The major core (gag) proteins are p18, p25, and p13 which are products of a Pr55 precursor. The major envelope (env) glycoprotein is unusually large (gp110) for a retrovirus and comparable to those of the lentiviruses. Recently the virus has been molecularly cloned. The genome is 9.2 kb long, longer than any other known replication competent retrovirus apart from the lentiviruses. The absence of molecular hybridization between cloned LAV and human T-cell leukemia/lymphoma virus (HTLV) genomes compounds the original and extensive differences noted between these viruses and demonstrates that LAV is a prototype of a new class of human retrovirus.

The rabbit uteroglobin gene. Structure and interaction with the progesterone receptor

The study of the regulation of uteroglobin gene in the rabbit endometrium constitutes a model for analyzing the mechanism of action of progesterone in mammals. The gene has been cloned into lambda phage and sequenced. Comparison of the sequence of the gene with the amino acid sequence of preuteroglobin and the three-dimensional structure of uteroglobin established by crystal x-ray diffraction showed that the 3 exons correspond to different functional domains of the protein and that at least one of the splice junctions does not map at the surface of the protein. S1 mapping allowed us to define the RNA polymerase initiation site. No difference was observed when analyzing premessengers from the endometrium, where the gene is controlled by progesterone and estradiol, and from lung where the gene is constitutively expressed and not controlled by these hormones. In addition, S1 mapping revealed the existence of several minor transcription initiation sites. In the 5' flanking region between positions -33 and -24 there is the sequence AATACAAAAA which may correspond to a Goldberg-Hogness box. Two other A- and T-rich sequences were found further upstream from the gene, one of these preceding by about 30 nucleotides a minor start of transcription. No obvious feature, possibly related to steroid regulation, was observed in the nucleotide sequence. A fragment of the gene containing the "promoter" region (from nucleotide +10 to nucleotide -394) was preferentially retained on nitrocellulose filters after incubation with purified rabbit uterine receptor. A competitive binding assay was used to compare the affinity for the receptor of various DNA fragments. Labeled "promoter" region DNA was incubated with receptor and various concentrations of nonlabeled competing DNA, and the nitrocellulose-bound radioactivity was measured. This method showed the existence of several high affinity binding sites in the 5' part of the gene and in adjacent regions. However, no high affinity binding sites were observed in the 3' part of the gene. Also, within the "promoter" region there were at least two high affinity binding sites for the receptor.