Retrovirus particles with type C morphology were found in two T-cell lymphoblastoid cell lines, HUT 102 and CTCL-3, and in fresh peripheral blood lymphocytes obtained from a patient with a cutaneous T-cell lymphoma (mycosis fungoides). The cell lines continuously produce these viruses, which are collectively referred to as HTLV, strain CR(HTLVCR). Originally, the production of virus from HUT 102 cells required induction with 5-iodo-2′-deoxyuridine, but the cell line became a constitutive producer of virus at its 56th passage. Cell line CTCL-3 has been a constitutive producer of virus from its second passage in culture. Both mature and immature extracellular virus particles were seen in thin-section electron micrographs of fixed, pelleted cellular material; on occasion, typical type C budding virus particles were seen. No form of intracellular virus particle has been seen. Mature particles were 100-110 nm in diameter, consisted of an electron-dense core surrounded by an outer membrane separated by an electron-lucent region, banded at a density of 1.16 g/ml on a continuous 25-65% sucrose gradient, and contained 70S RNA and a DNA polymerase activity typical of viral reverse transcriptase (RT; RNA-dependent DNA nucleotidyltransferase). Under certain conditions of assay, HTLVCR RT showed cation preference for Mg2+ over Mn2+, distinct from the characteristics of cellular DNA polymerases purified from human lymphocytes and the RT from most type C viruses. Antibodies to cellular DNA polymerase γ and anti-bodies against RT purified from several animal retroviruses failed to detectably interact with HTLVCR RT under conditions that were positive for the respective homologous DNA polymerase, demonstrating a lack of close relationship of HTLVCR RT to cellular DNA polymerases γ or RT of these viruses. Six major proteins, with sizes of approximately 10,000, 13,000, 19,000, 24,000, 42,000, and 52,000 daltons, were apparent when doubly banded, disrupted HTLVCR particles were chromatographed on a NaDodSO4/polyacrylamide gel. The number of these particle-associated proteins is consistent with the expected proteins of a retrovirus, but the sizes of some are distinct from those of most known retroviruses of the primate subgroups.

https://www.pnas.org/content/pnas/77/12/7415.full.pdf

Detection and isolation of type C retrovirus particles from fresh and cultured lymphocytes of a patient with cutaneous T-cell lymphoma

Acquired immune deficiency syndrome (AIDS) is characterized by opportunistic infections and by 'opportunistic neoplasms' (for example, Kaposi's sarcoma). Persistent generalized lymphadenopathy (PGL) is epidemiologically associated with AIDS, especially in male homosexuals. A subset of T lymphocytes positive for the CD4 antigen (also termed T4 antigen), is depleted in AIDS and PGL patients. A retrovirus found in T-cell cultures from these patients is strongly implicated in the aetiology of AIDS because of the high frequency of isolation and the prevalence of specific antibodies in the patients. Here we have detected cell-surface receptors for the AIDS retrovirus (human T-cell leukaemia virus-III (HTLV-III) and lymphadenopathy-associated virus-1 (LAV-1) isolates) by testing the susceptibility of cells to infection with pseudotypes of vesicular stomatitis virus bearing retroviral envelope antigens, and by the formation of multinucleated syncytia on mixing virus-producing cells with receptor-bearing cells. Receptors were present only on cells expressing CD4 antigen; among 155 monoclonal antibodies tested, each of the 14 anti-CD4 antibodies inhibited formation of syncytia and blocked pseudotypes. Productive infection of CD4+ cells with HTLV-III or LAV-1 markedly reduced cell-surface expression of CD4. In contrast, receptors for HTLV-I and HTLV-II were not restricted to CD4+ cells, were not blocked by anti-CD4 antibodies; cells productively infected with HTLV-I and HTLV-II expressed surface CD4. Hence, we conclude that the CD4 antigen is an essential and specific component of the receptor for the causative agent of AIDS.

The CD4 (T4) antigen is an essential component of the receptor for the AIDS retrovirus

Peripheral blood lymphocytes from patients with the acquired immunodeficiency syndrome (AIDS) or with signs or symptoms that frequently precede AIDS (pre-AIDS) were grown in vitro with added T-cell growth factor and assayed for the expression and release of human T-lymphotropic retroviruses (HTLV). Retroviruses belonging to the HTLV family and collectively designated HTLV-III were isolated from a total of 48 subjects including 18 of 21 patients wih pre-AIDS, three of four clinically normal mothers of juveniles with AIDS, 26 of 72 adult and juvenile patients with AIDS, and from one of 22 normal male homosexual subjects. No HTLV-III was detected in or isolated from 115 normal heterosexual subjects. The number of HTLV-III isolates reported here underestimates the true prevalence of the virus since many specimens were received in unsatisfactory condition. Other data show that serum samples from a high proportion of AIDS patients contain antibodies to HTLV-III. That these new isolates are members of the HTLV family but differ from the previous isolates known as HTLV-I and HTLV-II is indicated by their morphological, biological, and immunological characteristics. These results and those reported elsewhere in this issue suggest that HTLV-III may be the primary cause of AIDS.

https://science.sciencemag.org/content/sci/224/4648/500.full.pdf

Frequent detection and isolation of cytopathic retroviruses (HTLV-III) from patients with AIDS and at risk for AIDS

A cell system was developed for the reproducible detection of human T-lymphotropic retroviruses (HTLV family) from patients with the acquired immunodeficiency syndrome (AIDS) or with signs or symptoms that frequently precede AIDS (pre-AIDS). The cells are specific clones from a permissive human neoplastic T-cell line. Some of the clones permanently grow and continuously produce large amounts of virus after infection with cytopathic (HTLV-III) variants of these viruses. One cytopathic effect of HTLV-III in this system is the arrangement of multiple nuclei in a characteristic ring formation in giant cells of the infected T-cell population. These structures can be used as an indicator to detect HTLV-III in clinical specimens. This system opens the way to the routine detection of HTLV-III and related cytopathic variants of HTLV in patients with AIDS or pre-AIDS and in healthy carriers, and it provides large amounts of virus for detailed molecular and immunological analyses.

https://science.sciencemag.org/content/sci/224/4648/497.full.pdf

Detection, Isolation, and Continuous Production of Cytopathic Retroviruses (HTLV-III) from Patients with AIDS and Pre-AIDS

1. Developmental Defects of the Oral and Maxillofacial Region 2. Abnormalities of Teeth 3. Pulpal and Periapical Disease 4. Periodontal Diseases 5. Bacterial Infections 6. Fungal and Protozoal Diseases 7. Viral Infections 8. Physical and Chemical Injuries 9. Allergies and Immunologic Diseases 10. Epithelial Pathology 11. Salivary Gland Pathology 12. Soft Tissue Tumors 13. Hematologic Disorders 14. Bone Pathology 15. Odontogenic Cysts and Tumors 16. Dermatologic Diseases 17. Oral Manifestations of Systemic Diseases 18. Facial Pain and Neuromuscular Diseases 19. Forensic Dentistry Appendix: Differential Diagnosis of Oral and Maxillofacial Diseases Part 1: Mucosal and Soft Tissue Pathology: Color Changes Part 2: Mucosal and Soft Tissue Pathology: Surface Alterations Part 3: Mucosal and Soft Tissue Pathology: Masses or Enlargements Part 4: Radiographic Pathology Part 5: Pathology of Teeth

Oral and Maxillofacial Pathology

Eighteen rhesus macaques were inoculated with either an infectious molecularly cloned human immunodeficiency virus type 2 (HIV-2)SBL/ISY, or with one of eight mutants defective in one or more accessory genes. The immune responses generated by the macaques were monitored for up to 2 years postinfection. All the macaques except those that received mutants lacking the vpr or vif genes demonstrated low to moderate antibody titers. Macaques inoculated with vpx- mutants exhibited a persistent serological response, suggesting continuous virus expression even in the absence of detectable virus in the peripheral blood mononuclear cells (PBMCs). Neutralizing antibodies developed in only four macaques. In general, low-level cytotoxic T lymphocyte (CTL) activity, not clearly HIV-2 specific, was detected in PBMCs. However, one virus-negative macaque exhibited significant HIV-2-specific CTL activity in an enriched CD8+ cell population from PBMCs, suggesting clearance of the viral infection. In addition, CTL activity against the Env and Gag/Pol epitopes of HIV-2 by CD8+ lymphocytes from the spleens and lymph nodes of two infected macaques, in one case requiring CD8+ T cell enrichment and in the other clearly evident in unfractionated tissue lymphocytes, was demonstrated for the first time. This sequestration of tissue CTLs occurred in the absence of significant levels of circulating CTLs in the blood. Our results suggest that routine monitoring of PBMCs may sometimes be inadequate for detecting cell-mediated immune responses. Elucidation of immune correlates of vaccine protection may therefore require sampling of lymphoid tissues and assessment of enriched CD8+ populations.

Humoral and Cellular Immune Responses in Rhesus Macaques Infected with Human Immunodeficiency Virus Type 2

On the historical origins of HIV-1 (MN) and (RF).

Des cellules mononucleaires de sang de donneurs normaux ou d'une lignee de cellules T humaine etablie ont ete utilisees pour evaluer l'inhibition de l'infection par HTLV-III/LAV par une association de suramine et d'acyclovie. Des associations mieux tolerees et plus faciles a obtenir in vivo pourraient influencer l'infectivite et la replication des virus. Le traitement associe devrait aussi defavoriser la selection de variants viraux resistants aux medicaments

In Vitro Suppression of HTLV-III/LAV Infectivity by a Combination of Acyclovir and Suramin

In Reply.— Because AIDS has been diagnosed almost exclusively in members of "high-risk" groups, physicians often do not consider the diagnosis of HTLV-III infection in individuals who do not belong to these risk groups. We have looked for evidence of HTLV-III infection in all patients (of either sex) presenting to our infectious disease service with the appropriate signs or symptoms and also their sexual partners. This case-finding methodology is etiologically based and epidemiologically sound. Our report documented the occurrence of HTLV-III disease in non-drug-using heterosexual males and females, thus providing scientifically sound evidence for bidirectional heterosexual transmission. Our report did not purport to define the relative risk of infection that is associated with either multiple heterosexual contacts or prostitute contacts. In a heterosexual population, we suggested that the risk of infection with HTLV-III will be more likely in individuals with multiple sexual partners or in individuals whose sexual contacts (eg,

https://jamanetwork.com/journals/JAMA/articlepdf/403496/jama_255_13_012.pdf

Female-to-Male Transmission of HTLV-III-Reply

Elucidation of host factors that modulate susceptibility to infection with human immunodeficiency virus (HIV) or simian immunodeficiency virus (SIV) and influence disease outcome will not only broaden our understanding of virus-cell interactions but will also have important practical implications. Knowledge of natural host defense mechanisms may lead to their exploitation for therapeutic or prophylactic purposes. Identification of host susceptibility factors may influence treatment decisions and further define risk factors for HIV acquisition. Clarification of host susceptibility and resistance factors in nonhuman primates should limit the variability in experimental groups and lead to improved design of preclinical studies.

A few immunologic and genetic host factors have been identified which influence HIV or SIV infection and viral replication (11). The former includes acquired immunity resulting from viral infection, as well as innate immunity involving many inducible cytokines and chemokines. Genetic factors, such as HLA haplotypes, can influence the host's immune response. Two haplotypes have been associated with rapid disease progression after HIV infection (10), whereas another has been linked to long-term nonprogression (39). A similar protective effect of the rhesus macaque Mamu A*01 genotype has been recently demonstrated (43). The most dramatic genetic influence on HIV transmission and disease progression involves a 32-bp deletion (Δ32) in the CCR5 gene, the major coreceptor for macrophage-tropic, non-syncytium-inducing HIV isolates. This deletion results in a truncated, nonfunctional gene product and is associated with protection against HIV infection in individuals homozygous for the CCR5 Δ32 allele (20, 30, 49) and with delayed disease progression and decreased CCR5 expression on T cells among heterozygous individuals (13, 45, 59). Additional CCR5 polymorphisms exist but have not been shown to modulate HIV infection (37). Polymorphisms in the CCR5 promoter have been associated with accelerated disease progression (34, 36), but the mechanisms for this are unclear. A minor coreceptor mutation, CCR2-64I, with strong linkage disequilibrium with a CCR5 promoter region mutation (25), was initially associated with delayed disease progression (53), although subsequent studies have yielded conflicting results (33, 37, 38).

Alterations in chemokine or cytokine genes or their promoters can also affect the course of HIV disease. Delayed disease progression has been attributed to a polymorphism in the RANTES promoter (29) and to an SDF-1 gene mutation, although the latter finding is controversial (19, 41, 57, 58). Polymorphisms in the interleukin-10 (IL-10) promoter have been linked to AIDS progression (52).

Identification of host factors which contribute to susceptible or resistant phenotypes is difficult in humans. Our observation, summarized below, of unusually strong resistance to SIV infection in a rhesus macaque, presented a unique opportunity for investigating novel host resistance mechanisms. In general, intravaginal infection of rhesus macaques can result in either transient or persistent viremia (40), as well as in occult systemic infection in some cases (35). In earlier preclinical vaccine studies in which rhesus macaques were challenged with infectious, pathogenic SIVmac251, we observed such variable outcomes in both controls and immunized monkeys with regard to infection and disease progression (7, 8). One naive control macaque, 359, resisted two intravaginal exposures with escalating dosages of SIVmac251. Here we report that, after an additional intrarectal challenge with SIVmac32H, macaque 359 became only transiently viremic and cleared virus from the peripheral blood. In vitro studies confirmed that the animal's peripheral blood mononuclear cells (PBMCs) were highly resistant to SIV infection, even though adequate levels of CCR5 were expressed on the surface of the cells. In order to elucidate the basis for the unusually strong resistance of macaque 359 to in vivo and in vitro SIV infection, early events in the viral infection and replication process were examined. We examined several coreceptor genes for mutational changes. Genetic polymorphisms were detected in the CCR5 gene; however, none of the changes led to amino acid substitutions. Investigation of reverse transcription events revealed significant inhibition in the accumulation of early DNA replication intermediates. However, macaque 359 cells were able to fuse with cells expressing a SIVmac251 envelope or a CCR5-tropic HIV envelope as readily as cells from macaques highly susceptible to SIV infection. Taken together, our results indicate that the resistance of macaque 359 to SIV infection is due to postentry inhibition of viral replication and implicate a host cell mechanism in this process.

Phillip D. Markham

Papers

Humoral and Cellular Immune Responses in Rhesus Macaques Infected with Human Immunodeficiency Virus Type 2

On the historical origins of HIV-1 (MN) and (RF).

In Vitro Suppression of HTLV-III/LAV Infectivity by a Combination of Acyclovir and Suramin

Female-to-Male Transmission of HTLV-III-Reply

Rhesus macaque resistance to mucosal simian immunodeficiency virus infection is associated with a postentry block in viral replication.