Cloning of HTLV-4 and its relation to simian and human immunodeficiency viruses

Although much is now known of the strain variation among the type-1 human immunodeficiency virus (HIV-1), which is the cause of AIDS (acquired immune deficiency syndrome) in the United States, Europe, and Central Africa, much less is yet known about a second group of viruses that have been found in West Africans. One member of this group, named human T-cell lymphotropic virus type 4 (HTLV-4), has been isolated from healthy Senegalese. Another is the virus isolated from West Africans with AIDS-like illness and originally called LAV-2 but now renamed HIV-2. Both these viruses seem to be less closely related to HIV-1 than they are to a virus of healthy African green monkeys, known variously as simian T-cell lymphotropic virus type 3 (STLV-3) or simian immunodeficiency virus (SIV), which in turn is related to viruses isolated from healthy sooty mangabeys and captive macaques with a form of immunodeficiency (to distinguish these viruses they are referred to as STLV-3 (or SIV)agm, STLV-3mac, or STLV-3smm). To clarify the relationship between the various HIVs, STLV-3s and HTLV-4 we are determining and comparing the molecular and biological characteristics of several of them. Following our recent publication of a restriction-site map of STLV-3agm, we now report that the equivalent map of three isolates of HTLV-4 is remarkably similar to it. In addition we present comparative sequence data on the long terminal repeats (LTR) of HTLV-4, STLV-3agm, HIV-1 and HIV-2, together with evidence that cloned HTLV-4 uses the same receptor as HIV-1 and induces some, but not all, of the cytopathic effects attributed to most isolates of HIV-1 and HIV-2.     

Molecular cloning and polymorphism of the human immune deficiency virus type 2

We recently reported the isolation of a novel retrovirus, the human immune deficiency virus type 2 (HIV-2, previously named LAV-2), from patients with acquired immune deficiency syndrome (AIDS) originating from West Africa. This virus is related to HIV-1, the causative agent of the AIDS epidemic now spreading in Central and East Africa, as well as the USA and Europe (see ref. 3 for review) both by its morphology and by its tropism and in vitro cytopathic effect on CD4 (T4) positive cell lines and lymphocytes. But preliminary hybridization experiments indicated that there are substantiated differences between the sequences of the two genomes. Furthermore, the proteins of HIV-1 and HIV-2 have different sizes and their serological cross-reactivity is restricted to the major core protein, as the envelope glycoproteins of HIV-2 are not immunoprecipitated by HIV-1-positive sera. We now report the molecular cloning of the complete 9.5-kilobase (kb) genome of HIV-2, the observation of restriction site polymorphism between different isolates, and a preliminary analysis of the relationship of HIV-2 with other human and simian retroviruses.     

Sequence of simian immunodeficiency virus and its relationship to the human immunodeficiency viruses

The characterization of HIV-1 (HTLV-III/LAV), the human retrovirus associated with AIDS (acquired immune deficiency syndrome) has led to the identification of a group of related human and simian retroviruses which also infect CD4-bearing T lymphocytes. Simian T-lymphotropic virus type III (simian immodeficiency virus) from macaques (STLV-IIIMAC) induces symptoms similar to those of AIDS in infected macaques, but isolates from African green monkeys (STLV-IIIAGM) and mangabeys (STLV-IIMM) appear to be non-pathogenic in these animals. A human virus immunologically related to STLV-IIIAGM (HTLV-IV), reported to have been isolated from healthy humans, has been shown to be almost identical to STLV-IIIAGM, which has called into question the independent origin of these viruses. Here we report the complete DNA sequence of STLV-IIIAGM and analyse its relationship with the genomes of the HTLV-IIIB strain of HIV-1, HIV-2ROD (previously called LAV-2) and several ungulate lentiretroviruses. STLV-IIIAGM and HIV-2 are closely related, and more distantly related to HIV-1.     

Sequence of simian immunodeficiency virus from macaque and its relationship to other human and simian retroviruses

Because of the growing incidence of AIDS (acquired immune deficiency syndrome), the need for studies on animal models is urgent. Infection of chimpanzees with the retroviral agent of human AIDS, the human immunodeficiency virus (HIV), will have only limited usefulness because chimpanzees are in short supply and do not develop the disease. Among non-human primates, both type D retroviruses and lentiviruses can be responsible for immune deficiencies. The D-type retroviruses, although important pathogens in macaque monkey colonies, are not satisfactory as a model because they differ in genetic structure and pathophysiological properties from the human AIDS viruses. The simian lentivirus, previously referred to as simian T-cell lymphotropic virus type III (STLV-III), now termed simian immunodeficiency virus (SIV) is related to HIV by the antigenicity of its proteins and in its main biological properties, such as cytopathic effect and tropism for CD4-bearing cells. Most importantly, SIV induces a disease with remarkable similarity to human AIDS in the common rhesus macaques, which therefore constitute the best animal model currently available. Natural or experimental infection of other monkeys such as African green monkeys or sooty mangabeys has not yet been associated with disease. Molecular approaches of the SIV system will be needed for biological studies and development of vaccines that could be tested in animals. We have cloned and sequenced the complete genome of SIV isolated from a naturally infected macaque that died of AIDS. This SIVMAC appears genetically close to the agent of AIDS in West Africa, HIV-2, but the divergence of the sequences of SIV and HIV-2 is greater than that previously observed between HIV-1 isolates.     

Sequence of simian immunodeficiency virus from African green monkey, a new member of the HIV/SIV group

Some wild African green monkeys are known to be naturally infected with a retrovirus related to human immunodeficiency virus (HIV) without having any apparent symptoms of an AIDS-like disease. This simian immunodeficiency virus, designated SIVAGM, may be helpful in clarifying the evolution and pathogenicity of HIV. Some virus strains that were previously reported to be isolated from African green monkeys were shown to be laboratory contaminations of SIVMAC (SIV from a rhesus macaque) Here we report the complete DNA sequence of authentic SIVAGM, which was isolated from a naturally infected African green monkey of Kenyan origin. Comparison of the genome of SIVAGM with those of known HIV/SIVs indicates that the virus is a new simian lentivirus that is approximately equally distantly related to HIV-1 and HIV-2 in contrast to SIVMAC, which is much closer to HIV-2 than to HIV-1 (refs 5, 9).     

云南省野生恒河猴病毒血清流行病学研究

对云南省野生恒河猴作了Ｂ病毒（ＢＶ）、猴爱滋病毒（ＳＩＶ）、猴Ｔ细胞白血病毒（ＳＴＬＶ）、猴Ｄ型逆转录病毒（ＳＲＶ）、轮状病毒（ＳＡｌ）、腺病毒（ＳＡＶ）、痘病毒（Ｍｏｎｋｅｙｐｏｘ）、麻疹病毒（Ｍｅａｓｌｅｓ）、柯赛基病毒Ｂ－１型（ＣｏｘｓａｃｋｉｅＢ１）和人巨细胞病毒（ＨＣＭＶ）等１０种病毒血清抗体及乙型肝炎病毒（ＨＢＶ）检测,结果表明,云南省野生恒河猴中,抗体阳性率较高的有ＳＡ１１（９０％）,ＳＡＶ（８３１％）,ＢＶ（４４６％）和Ｍｏｎｋｅｙｐｏｘｖｉｒｕｓ（２０６％）;３种逆转录病毒的抗体阳性率分别为ＳＴＬＶ－１（８８％）,ＳＲＶ（４７％）,ＳＩＶ（２２％）;未发现Ｍｅａｓｌｅｓ,和ＣｏｘｓａｃｋｉｅＢ－１病毒血清抗体及ＨＢＶ感染,但在１只动物血清中有ＨＣＭＶ抗体．病毒抗体阳性率与动物的年龄有关,成年猴明显高于未成年猴．对来自思茅地区、临沧地区和文山州动物的调查表明,Ｂ病毒相关抗体和逆转录病毒抗体阳性率有地区差异,思茅地区的野生恒河猴,抗体阳性率较高．     

New human and simian HIV-related retroviruses possess functional transactivator (tat) gene

New human retroviruses antigenically related to HIV and even more closely to STLV-III have been recently isolated from individuals from some West African countries. One of these viruses, HTLV-IVP, was reportedly isolated from lymphocytes of a healthy female prostitute. Another isolate, LAV-2FG, was obtained from an AIDS patient and third, SBL-6669, from an individual with lymphadenopathy. Current epidemiological studies indicate that some of these virus isolates cause immune deficiency whereas others may not or may be less efficient at inducing immune deficiency. Similarly, STLV-III apparently does not cause immune deficiency in its natural host, African green monkey. A novel feature of HIV is the possession of a gene termed tat, which is implicated in its pathobiology. We report here that, like HIV, HTLV-IVP, LAV-2FG (HIV-2) and SBL-6669, as well as STLV-IIIAGM possess the putative tat gene, irrespective of their pathogenic potential in vivo. Interestingly, HTLV-IVP/LAV-2FG long terminal repeat (LTR) is equally well transactivated by the HTLV-IVP/LAV-2FG and HTLV-IIIB tat function, HTLV-IIIB LTR responds better to its own tat function.     

HIV infection of primate lymphocytes and conservation of the CD4 receptor

The CD4 T-lymphocyte differentiation antigen is an essential component of the cell surface receptor for human immunodeficiency viruses (HIVs) causing AIDS (acquired immune deficiency syndrome) (refs 1-3). Peripheral blood lymphocytes of apes, New World and Old World monkeys express cell surface antigens homologous to CD4 of human T-helper lymphocytes. The cells of several of these species can be infected in short term culture with diverse strains of the type-1 or type-2 human immunodeficiency viruses (HIV-1 and HIV-2). HIV-1 is the prototype AIDS virus, and HIV-2 is the second type of AIDS virus, prevalent in West Africa. Infection of the primate cells correlates with evolutionary conservation on CD4 of one particular epitope cluster, and is inhibited by treatment of the cells with monoclonal antibodies to this epitope. The capacity of HIV to replicate in simian cells may provide a means for evaluating antiviral drugs and vaccines.     

The Hardy-Zuckerman 2-FeSV, a new feline retrovirus with oncogene homology to Abelson-MuLV

There is substantial evidence that oncogenes (v-onc) of acute transforming retroviruses have been acquired by transduction of cellular genes (c-onc) with retroviruses. Feline leukaemia virus (FeLV)-associated feline fibrosarcomas have proven to be extremely useful for the isolation of acute transforming retroviruses of a mammalian species. Three different v-onc genes have been identified in five acute transforming feline retroviruses. The Susan McDonough feline sarcoma virus (SMFeSV) contains the oncogene fms (ref. 4). The Snyder-Theilen (ST) and Gardner-Arnstein (GA) FeSVs contain the oncogene fes (ref. 4), which is homologous to the oncogene fps of the avian sarcoma viruses FSV, RRCII, PRCIV and 16L (refs 7, 8). The v-onc sequences of the Parodi-Irgens (PI) FeSV have recently been found to be homologous with the v-sis sequences of the simian sarcoma virus. We report here the isolation of another acute transforming feline retrovirus from a naturally occurring feline fibrosarcoma, designated the Hardy-Zuckerman 2 feline sarcoma virus (HZ2-FeSV) and demonstrate that the HZ2-FeSV and Abelson murine leukaemia virus (A-MuLV) have homologous oncogenes.     

Identification of a protein encoded by the vpu gene of HIV-1

Human immunodeficiency virus 1 (HIV-1) is the aetiological agent of AIDS. The virus establishes lytic, latent and non-cytopathic productive infection in cells in culture. The complexity of virus-host cell interaction is reflected in the complex organization of the viral genome. In addition to the genes that encode the virion capsid and envelope proteins and the enzymes required for proviral synthesis and integration common to all retroviruses, HIV-1 is known to encode at least four additional proteins that regulate virus replication, the tat, art, sor and 3' orf proteins, as well as a protein of unknown function from the open reading frame called R. Close examination of the nucleic acid sequences of the genomes of multiple HIV isolates raised the possibility that the virus encodes a previously undetected additional protein. Here we report that HIV-1 encodes a ninth protein and that antibodies to this protein are detected in the sera of people infected with HIV-1. This protein distinguishes HIV-1 isolates from the other human and simian immunodeficiency viruses (HIV-2 and SIV) that do not have the capacity to encode a similar protein.     

Effect of recombinant soluble CD4 in rhesus monkeys infected with simian immunodeficiency virus of macaques

The CD4 molecule is a high-affinity cell-surface receptor for the human immunodeficiency virus (HIV-1) and a soluble truncated form of CD4 produced by recombinant DNA technology is a potent inhibitor of HIV-1 replication and HIV-1-induced cell fusion in vitro. Rhesus monkeys infected with the simian immunodeficiency virus of macaques (SIVMAC), a virus closely related to HIV-1, develop an AIDS-like syndrome, and so provide an important model for the evaluation of potential AIDS therapies. We have assessed the therapeutic effect of recombinant soluble CD4 in SIVMAC-infected rhesus monkeys. Virus was readily isolated from peripheral blood lymphocytes and bone marrow cells of these animals before starting treatment with soluble CD4, but became difficult to isolate soon after treatment had begun. Moreover the diminished growth of both granulocyte-macrophage and erythrocyte progenitor colonies from the bone marrow of these monkeys rose to normal levels during treatment. These findings indicate that soluble CD4 could prove valuable in the treatment of AIDS.     

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).     

Variable and conserved neutralization antigens of human immunodeficiency virus

Human immunodeficiency virus type 1 (HIV-1, HTLV-III/LAV), the retrovirus responsible for acquired immune deficiency syndrome (AIDS), shows a high degree of genetic polymorphism, particularly in the env gene. We have examined sera from rabbits and guinea pigs immunized with gp130, a recombinant env glycoprotein, and sera from HIV-1-infected subjects, to test their capacity to neutralize a panel of genetically divergent HIV-1 isolates. The sera raised against recombinant antigen specifically neutralized the virus strain from which the env gene was cloned (HTLV-IIIB), but not an independent isolate (HTLV-IIIRF). One rabbit serum tested on seven isolates cross-neutralized two at lower titres. In contrast, human sera from Britain and Uganda, chosen for ability to neutralize HTLV-IIIRF, cross-neutralized six other HIV-1 isolates. When serum and isolate were derived from the same subject, the serum was in some cases effective at slightly lower concentrations (higher titres). Human complement did not affect neutralization titres. These findings indicate that genetically diverse HIV-1 isolates carry both variable and widely conserved antigenic epitopes for neutralizing antibodies. The identification of shared epitopes may help the development of protective vaccines.     

Isolation of HTLV-transformed B-lymphocyte clone from a patient with HTLV-associated adult T-cell leukaemia

The human T-cell leukaemia/lymphoma virus (HTLV) is an exogenous retrovirus which has been associated with adult T-cell leukaemia/lymphoma (ATL). This malignancy of T lymphocytes is endemic to southern Japan, the West Indies, and to a lesser extent, the Middle East, Central Africa and the southeastern United States. ATL cells from patients of diverse geographical origins have been found to be infected with HTLV-1 (ref.6). HTLV is normally tropic for mature T lymphocytes, especially those expressing the helper-inducer surface antigen phenotype (OKT4 or Leu-3-positive), and the neoplastic T cells infected with HTLV generally express receptors for T-cell growth factor (detected by reactivity with anti-Tac antibody). However, we report here the isolation of a HTLV-infected B-lymphocyte clone from the peripheral blood of a patient with ATL. This clone is cytogenetically normal and is not infected with Epstein-Barr virus (EBV). Co-culture of cells from this clone with cord blood lymphocytes resulted in transmission of HTLV and the immortalization of either T or B lymphocytes. These results suggest that HTLV may be associated with a broader range of host cells than previously recognized.     

Genome organization and transactivation of the human immunodeficiency virus type 2

Analysis of the nucleotide sequence of the human retrovirus associated with AIDS in West Africa, HIV-2, shows that it is evolutionarily distant from the previously characterized HIV-1. We suggest that these viruses existed long before the current AIDS epidemics. Their biological properties are conserved in spite of limited sequence homology; this may help the determination of the structure-function relationships of the different viral elements.     

Nucleic acid structure and expression of the human AIDS/lymphadenopathy retrovirus

The 9,213-nucleotide structure of the AIDS/lymphadenopathy virus has been determined from molecular clones representing the integrated provirus and viral RNA. The sequence reveals that the virus is highly polymorphic and lacks significant nucleotide homology with type C retroviruses characterized previously. Together with an analysis of the two major viral subgenomic RNAs, these studies establish the coding frames for the gag, pol and env genes and predict the expression of a novel gene at the 3' end of the genome unrelated to the X genes of HTLV-1 and -II.     

Comparison of simian immunodeficiency virus isolates

Information on the extent of genetic variability among non-human primate lentiviruses related to human immunodeficiency virus (HIV) is sorely lacking. Here we describe the isolation of two molecular clones from the simian immunodeficiency virus (SIV) and their use to derive restriction endonuclease maps of five SIV isolates from rhesus macaques and one from a cynomolgus macaque. Although similar, all six viral isolates are readily distinguishable; the single isolate from a cynomolgus macaque is the most different. The restriction endonuclease map of one macaque isolate (SIVMAC-251) is identical to that published by others for STLV-IIIAGM of African green monkeys and for HTLV-IV of humans. Nucleotide sequences from the envelope region of cloned SIVMAC-251 have more than 99% identify to previously published sequences for STLV-IIIAGM (refs 2, 4) and HTLV-IV (ref. 4). These results and other observations provide strong evidence that isolates previously referred to as STLV-IIIAGM and HTLV-IV by others are not authentic, but were derived from cell cultures infected with SIVMAC-251.     

Sequence of a novel simian immunodeficiency virus from a wild-caught African mandrill

Since the isolation of an HIV-2-related virus from captive macaques (SIVMAC), the origin of human immunodeficiency viruses, a much debated subject, has been attributed to monkeys. The sequence of SIVAGM, which is derived from a naturally infected African green monkey, shows equal relatedness to HIV-1 and HIV-2, suggesting that the derivation of these viruses from SIVAGM is unlikely. Recent sequence analysis of SIV from a captive sooty mangabey (SIVMAC), however, shows its close relatedness to HIV-2 and SIVMAC, indicating a possible origin of HIV-2 and SIVMAC from SIVSM (refs 4, 7, 9). We report here the sequence of a novel simian lentivirus, SIVMND, isolated from a wild-caught mandrill in Africa. It is distinct from the three other main groups, HIV-1, HIV-2/SIVMAC/SIVSM and SIVAGM, and therefore represents a fourth main group of primate lentiviruses. Phylogenetic analysis indicates that these four main virus groups might have diverged from a common ancestor at about the same time, long before the spread of AIDS in humans.