Dendritic cells and the promise of therapeutic vaccines for human immunodeficiency virus (HIV)-1

Treatment of human immunodeficiency virus (HIV)-1 infection with potent antiretroviral medications has provided considerable clinical benefit. However because of the limitations of current therapy, innovative approaches are needed to better control HIV-1 infection. Several studies have suggested that robust CD4+ T helper and CD8+ T cell responses may contribute to the immunologic control of HIV-1 infection in certain individuals. Most chronically infected patients, however, cannot control the infection and may benefit from stimulation of cellular immunity with immunotherapy. Dendritic cells (DCs) are potent professional antigen-presenting cells (APCs) and have a central role in directing the adaptive immune response to pathogens. The ability of DCs to stimulate naive T cells has long been thought to be crucial in initiating an effective immune response. As DCs are uniquely situated at the interface between the innate and adaptive immune systems, they are currently under intense scrutiny as potential adjuvants for vaccines in many clinical settings. Studies in healthy volunteers and patients with cancer have shown that antigen-pulsed DCs can boost both CD8+ and CD4+ T cell responses in vivo. Based on these promising findings, ex vivo antigen-pulsed DCs are being actively investigated in studies aimed at developing a therapeutic vaccine for individuals with HIV-1 infection.     

NIH conference. Development and evaluation of a vaccine for human immunodeficiency virus (HIV) infection

The development of a safe and effective vaccine for infection with human immunodeficiency virus (HIV) is complicated by several unique scientific, logistic, and ethical issues. These issues include a lack of understanding of protective immunity to HIV and disease development, the absence of an adequate and convenient animal model for studying HIV infection, and difficulties in phase III evaluation of candidate vaccines. Because HIV can be transmitted as either a cell-free or cell-associated virus, a protective immune response against HIV infection will likely require both humoral and cell-mediated immunity. A neutralizing antibody against HIV and an antibody involved in antibody-dependent cellular cytotoxicity have been shown in HIV-infected persons, but their precise relation to protection is unclear. Cytotoxic lymphocytes from HIV-infected persons have been shown to lyse target cells expressing HIV or its proteins. Cloned T cells have been developed that manifest HIV-specific, major histocompatibility-complex class I-restricted cytotoxic capabilities that are broadly specific. Thus far, all attempts to protect chimpanzees, currently the only suitable animal model, from HIV infection have failed. Ongoing vaccine studies in humans include phase I trials of recombinant proteins of the HIV envelope in uninfected persons as well as the administration of whole killed virus to persons already infected with HIV. Rapid progress is being made in the development of new animal models for HIV infection. The establishment of alternative animal models, both primate and small animal models, will greatly facilitate the development of a vaccine for HIV infection.     

Human immunodeficiency virus (HIV) seropositivity among uninfected HIV vaccine recipients

Since 1987, >10,000 individuals worldwide have received immunizations with human immunodeficiency virus (HIV) preventive vaccine constructs. Many constructs elicit antibodies detected by standard serologic tests (enzyme immunoassays, rapid tests, and Western blots) and result in vaccine recipients' serum being identified as reactive and indicative of HIV infection. To determine the frequency of vaccine-induced HIV antibody among uninfected HIV vaccine trial participants and to identify factors associated with these results, serum samples from HIV-uninfected participants from selected United States phase I/II HIV-1 vaccine trials were tested with 6 serologic screening tests. Reactive specimens were tested by use of Western blot. Overall, 490 serum specimens from 461 vaccine recipients were tested; 100 (20.4%) reacted on at least 1 serologic test, and 65 (13%) were determined to be positive by Western blot. Canarypox or vaccinia vaccine recipients' serum with or without HIV envelope glycoprotein (gp120 or gp160) boosts accounted for all positive Western blot results; no positive Western blot results were obtained from gp120 subunit recipients. The potential for vaccine recipients being misclassified as HIV infected increased with vaccine complexity.     

Enhanced immunity to human immunodeficiency virus (HIV) envelope elicited by a combined vaccine regimen consisting of priming with a vaccinia recombinant expressing HIV envelope and boosting with gp160 protein.

Transmission studies have suggested that an optimal human immunodeficiency virus type 1 (HIV-1) vaccine should induce both neutralizing antibodies and cytolytic T cells to eliminate free virus and infected cells. A phase I trial in healthy HIV-1-seronegative persons was conducted with a combination HIV-1 vaccine regimen (strain IIIB) consisting of priming with a recombinant vaccinia (vac/env) virus expressing HIV-1 envelope and boosting with a gp160 glycoprotein derived from a recombinant baculovirus (rgp160). T-cell and antibody responses detected after immunization with either vac/env alone or rgp160 alone were generally of low magnitude and transient, and no subject developed neutralizing antibodies. In contrast, recipients of the combination regimen demonstrated in vitro T-cell proliferative responses to homologous HIV-1 antigens that were 3- to 10-fold higher than responses with either vaccine alone, and these responses were sustained for > 18 months in 75% of recipients. Moreover, both CD8+ and CD4+ cytolytic T cells were detected. Antibody responses (titer, 1:800 to 1:102,400) to homologous HIV envelope developed in all recipients of the combination regimen, and neutralizing antibodies were detected in 7 of 13. Thus, immunization with a live virus vaccine followed by boosting with a soluble protein offers promise for inducing the broad immunity needed in an HIV vaccine.     

HIV (human immunodeficiency virus) and HIV-associated diseases

The discovery of the Human Immunodeficiency Virus (HIV), the characterization of its molecular biology and the development of serologic methods for detecting antibodies have led to a better understanding of HIV-associated clinical syndromes. Recently, the Centre of Disease Control has proposed a classification of HIV-related conditions. This classification forms the basis for this review. It is completed by remarks on antiviral and immunomodulating drugs and its effects on HIV. Difficulties in development of vaccines are discussed.     

Monoclonal antibodies against human immunodeficiency virus (HIV) type 2 core proteins: cross-reactivity with HIV type 1 and simian immunodeficiency virus.

Four mouse monoclonal antibodies were developed after immunization with one human immunodeficiency virus (HIV) type 2 isolate and were tested for reactivity with different HIV-1, HIV-2, and simian immunodeficiency virus (SIV) isolates in an immunofluorescence assay and by immunological blot analysis. One of them, an anti-capsid (p24) antibody, called R1C7, reacted with all HIV-1, HIV-2, and SIV isolates tested, thus identifying an epitope shared by all HIV and SIV. Another anti-capsid antibody, named A4F6, reacted with three HIV-2 isolates (HIV-2NIH-Z, LAV-2Rod, and LK001 ST9), some SIV isolates (STLV-IIIAGM, SIV-251, and SIV-309), but no HIV-1 isolates. Two anti-matrix (p16) antibodies, named R5C4 and R5F6, reacted strongly only with the HIV-2 isolates. The use of these monoclonal antibodies for rapid discrimination and identification of acquired immunodeficiency syndrome-related retroviruses is discussed.     

Male genital tract compartmentalization of human immunodeficiency virus type 1 (HIV)

We present phylogenetic evidence supporting viral compartmentalization between the blood (peripheral blood mononuclear cells or plasma) and multiple genitourinary sites in HIV-infected men. Four of the five subjects evaluated demonstrated compartmentalization of viral sequences between urogenital tract specimens (tissue or fluid) and at least one blood category. HIV sequence migration from blood to urogenital tract was detected in four of five men, with migration from urogenital tract to blood in the fifth, and cross migration between both compartments noted in one man. These observations add 5 additional cases to the 27 total reported cases in which male urogenital tract compartmentalization has been studied, investigate surgical samples/specimens that have not been evaluated previously, and provide further evidence for restricted flow of HIV between the blood and the genital tract. As such, our study findings are important for understanding the long-term response to antiretroviral therapy, the design of vaccines, and the sexual transmission of HIV.     

Non-cryptosporidial diarrhoea in human immunodeficiency virus (HIV) infected patients.

Thirty of 81 consecutive HIV antibody positive patients referred with non-cryptosporidial diarrhoea had no potential infectious cause; most had AIDS related complex rather than the full blown syndrome. Opportunistic infections with cytomegalovirus (CMV), mycobacterium avium-intracellulare (MAI), and herpes simplex virus (HSV), which allowed a diagnosis of AIDS to be made, were found in 19 patients and were the presenting features of AIDS in five. Other potential pathogenic species included entamoeba, giardia, campylobacter, and salmonella (without septicaemia). Cytomegalovirus infection was often accompanied by abdominal pain. Severe weight loss (greater than 10 kg) at presentation was found in patients with CMV infection and MAI. Bloody diarrhoea was confined to the group with HSV procitis. Malignant causes of diarrhoea were rare. Two patients developed a squamous carcinoma of the anorectal margin and one a non-Hodgkin's lymphoma. In only two of 12 patients who had Kaposi's sarcoma was this considered as a cause of diarrhoea. Rigid sigmoidoscopy showed macroscopic abnormalities in over a third (32) of the 81 patients with non-cryptosporidial diarrhoea. Most commonly this was severe inflammation (17) or discrete ulceration (four) [three of whom had CMV colitis]. Kaposi's sarcoma was identified in 11 patients. Non-specific inflammation was seen histologically in 40 of the 60 patients with no sigmoidoscopic inflammatory changes. Barium enema only revealed an abnormality in a minority of the patients and a colonoscopy only revealed information additional to rigid sigmoidoscopy in two patients--one with CMV ulcers in the transverse colon and the other with evidence of Kaposi's sarcoma not seen in the rectum. Ten patients had a rectal biopsy examined by electron microscopy as no infective cause of diarrhoea was uncovered. In four of these microtubular structures which are commonly seen in viral infections were found and two had prelymphomatous changes and in one of these frank lymphoma has developed. We recommend multiple stool analysis, sigmoidoscopy and rectal biopsy as the initial investigations in these patients reserving tests of malabsorption, colonoscopy, and barium enema for the small number of more difficult cases.     

Studies of antibody-dependent enhancement of human immunodeficiency virus (HIV) type 1 infection mediated by Fc receptors using sera from recipients of a recombinant gp160 experimental HIV-1 vaccine.

Subneutralizing concentrations of sera from human immunodeficiency virus (HIV)-1-infected patients augment HIV infection mediated by Fc receptor uptake by human monocytes and the monocytic cell line U937. Antibody-dependent enhancement (ADE) and neutralization activity were studied in the sera of HIV-1 antibody-negative volunteers who had been immunized with three 40-micrograms doses of a recombinant gp160 (rgp160) candidate HIV vaccine. Volunteers were vaccinated with rgp160 or a hepatitis B vaccine as a control on days 0, 30, and 180. Sera were obtained before and after three doses of vaccine and were tested for ADE and neutralization activity. Serum samples collected before vaccination showed neither neutralization nor ADE activity. Thirteen sera from volunteers who received gp160 and four from placebo recipients failed to show ADE. Three sera showed low levels of neutralization of strain IIIB of HIV. Vaccination with this dose of rgp160 produced neutralizing antibodies in some subjects but did not induce detectable enhancing antibodies.     

Defining human immunodeficiency virus (HIV) type 1 immunotypes with six human monoclonal antibodies

Studies of HIV-1 immunological relatedness have revealed that genetic diversity does not parallel antigenic diversity and have recently shown that HIV-1 strains from different geographic regions from around the world can be grouped into a small number of immunologically defined groups (immunotypes). Previously, the binding patterns of 28 monoclonal antibodies (mAbs) (specific for V3 and C5 of gp120 and cluster I of gp41) with 26 HIV-1 virions obtained globally were determined in a virus binding assay. Analysis of the binding patterns of these 728 mAb/virus combinations now reveals that a particular subset containing six of the 28 mAbs can correctly immunotype 24 of the 26 isolates (92%) into three immunotypes. Like the original panel of mAbs, the subset of six mAbs identified was directed against epitopes in the V3 and C5 regions of gp 120 as well as cluster I of gp41. The binding patterns ("profiles") of these six mAbs with 24 additional HIV-1 virions from Cameroon confirmed that epitopes in V3 and C5 of gp120 and cluster I of gp41 are well exposed on these viruses. Multivariate analysis of the binding patterns of these six mAbs with all 50 viruses (26 obtained globally and 24 obtained from Cameroon) indicates that the viruses from Cameroon have binding profiles similar to viruses from the rest of the world and can be classified into the same three immunotypes that were previously described. This study suggests that a vaccine against HIV-1 need not be based on geographic origin of the virus or on clade, but may better be based on antigenic properties that classify the plethora of different HIV-1 viruses into immunologically defined groups.     

Endocrine manifestations of human immunodeficiency virus (HIV) infection

Endocrine manifestations of HIV infection include both pathological changes and disturbances in function. Mechanisms include direct infection of glands by HIV or opportunistic organisms, infiltration by neoplasms, side effects of drugs, and production of humoral factors that may alter metabolism. The adrenal gland is most often affected, but virtually every endocrine system may be involved. Dysfunction is often subtle, with symptoms overlapping those of the HIV infection itself. Endocrine manifestations may be found at any time in the course of the disease, from the asymptomatic HIV-positive stage through full-blown AIDS. Optimal management of these patients may include a careful search for, and appropriate treatment of, associated endocrine abnormalities.     

The safety and immunogenicity of a human immunodeficiency virus type 1 (HIV-1) recombinant gp160 candidate vaccine in humans. NIAID AIDS Vaccine Clinical Trials Network

OBJECTIVE: To evaluate the safety and immunogenicity of a human immunodeficiency virus type 1 (HIV-1) recombinant envelope glycoprotein (rgp 160) candidate vaccine in humans. SUBJECTS: Healthy adults (72) who were seronegative for HIV-1 were randomly assigned to one of four groups. INTERVENTIONS: The subjects were randomly assigned to receive 40 or 80 micrograms of rgp 160, 10 micrograms of hepatitis B vaccine, or placebo in three doses (on days 0, 30, and 180), with an elective, nonblinded administration of a fourth dose on day 540. MEASUREMENTS AND MAIN RESULTS: Neither clinical nor laboratory toxicity was encountered during a follow-up period exceeding 21 months. No effect of immunization was noted on lymphocyte counts, mitogenic responses, or delayed-type hypersensitivity. Serum antibody responses to HIV envelope proteins detected by Western blot were seen in 30 of 33 subjects (91%; 95% CI, 71% to 97%) receiving either 40- or 80-micrograms doses of rgp160 and were most commonly of weakly reactive intensity. Responses were first noted by Western blot after the second dose. They markedly increased in frequency after the third dose and declined over the next 12 to 18 months. The administration of a fourth dose resulted in homologous neutralizing activity in sera from 5 to 24 subjects (21%; CI, 7% to 37%) as well as in complement-mediated antibody-dependent enhancement in sera from 6 of 24 subjects (25%; CI, 10% to 42%). Antibody responses were detected by enzyme-linked immunosorbent assay (ELISA) less frequently than by Western blot, and these responses persisted for a shorter time. CONCLUSIONS: The administration of rgp160 was well tolerated and safe, resulted in a high rate of antibody response by Western blot after the administration of the third and fourth doses, and generated serum neutralizing activity and complement-mediated antibody-dependent enhancement in some subjects after the fourth dose.