Phillip D. Markham

Intra-Blood–Brain-Barrier Synthesis of HTLV-III-Specific IgG in Patients with Neurologic Symptoms Associated with AIDS or AIDS-Related Complex

Intra-blood-brain-barrier production of virus-specific antibody is good evidence of infection within the blood-brain barrier. Patients with the acquired immuno-deficiency syndrome (AIDS) have an increased incidence of neurologic abnormalities--i.e., unexplained, diffuse encephalopathy manifested clinically as chronic progressive dementia. To define the role of human T-cell lymphotropic virus Type III (HTLV-III), the etiologic agent of AIDS, in the pathogenesis of neurologic dysfunction, we compared cerebrospinal fluid and serum from patients with neurologic symptoms associated with AIDS and the AIDS-related complex for the presence of antibodies directed against HTLV-III. Antibodies directed against HTLV-III antigens were detected by four immunologic tests: a fixed-cell immunofluorescence assay, an enzyme-linked immunosorbent assay, immunoblots of viral lysates, and immunoprecipitation of cellular lysates. All patients were seropositive, and 22 of 23 (96 per cent) had HTLV-III-specific antibodies in their cerebrospinal fluid. Unique oligoclonal IgG bands were detected in the cerebrospinal fluid, and the rate of IgG synthesis within the blood-brain barrier was elevated. In eight of nine patients tested, the enzyme-linked immunosorbent assay showed that the percentage of HTLV-III-specific IgG in cerebrospinal fluid was higher than in serum, suggesting that HTLV-III infection of neurologic tissue occurs in the majority of patients with neurologic disease associated with AIDS or its related complex.

ALVAC-SIV-gag-pol-env-Based Vaccination and Macaque Major Histocompatibility Complex Class I (A*01) Delay Simian Immunodeficiency Virus SIVmac-Induced Immunodeficiency

ABSTRACT T-cell-mediated immune effector mechanisms play an important role in the containment of human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) replication after infection. Both vaccination- and infection-induced T-cell responses are dependent on the host major histocompatibility complex classes I and II (MHC-I and MHC-II) antigens. Here we report that both inherent, host-dependent immune responses to SIVmac251 infection and vaccination-induced immune responses to viral antigens were able to reduce virus replication and/or CD4+ T-cell loss. Both the presence of the MHC-I Mamu-A*01 genotype and vaccination of rhesus macaques with ALVAC-SIV-gag-pol-env (ALVAC-SIV-gpe) contributed to the restriction of SIVmac251 replication during primary infection, preservation of CD4+ T cells, and delayed disease progression following intrarectal challenge exposure of the animals to SIVmac251 (561). ALVAC-SIV-gpe immunization induced cytotoxic T-lymphocyte (CTL) responses cumulatively in 67% of the immunized animals. Following viral challenge, a significant secondary virus-specific CD8+ T-cell response was observed in the vaccinated macaques. In the same immunized macaques, a decrease in virus load during primary infection (P = 0.0078) and protection from CD4 loss during both acute and chronic phases of infection (P = 0.0099 and P = 0.03, respectively) were observed. A trend for enhanced survival of the vaccinated macaques was also observed. Neither boosting the ALVAC-SIV-gpe with gp120 immunizations nor administering the vaccine by the combination of mucosal and systemic immunization routes increased significantly the protective effect of the ALVAC-SIV-gpe vaccine. While assessing the role of MHC-I Mamu-A*01 alone in the restriction of viremia following challenge of nonvaccinated animals with other SIV isolates, we observed that the virus load was not significantly lower in Mamu-A*01-positive macaques following intravenous challenge with either SIVmac251 (561) or SIVSME660. However, a significant delay in CD4+ T-cell loss was observed in Mamu-A*01-positive macaques in each group. Of interest, in the case of intravenous or intrarectal challenge with the chimeric SIV/HIV strains SHIV89.6P or SHIVKU2, respectively, MHC-I Mamu-A*01-positive macaques did not significantly restrict primary viremia. The finding of the protective effect of the Mamu-A*01 molecule parallels the protective effect of the B*5701 HLA allele in HIV-1-infected humans and needs to be accounted for in the evaluation of vaccine efficacy against SIV challenge models.

Mucosal AIDS vaccine reduces disease and viral load in gut reservoir and blood after mucosal infection of macaques

Given the mucosal transmission of HIV-1, we compared whether a mucosal vaccine could induce mucosal cytotoxic T lymphocytes (CTLs) and protect rhesus macaques against mucosal infection with simian/human immunodeficiency virus (SHIV) more effectively than the same vaccine given subcutaneously. Here we show that mucosal CTLs specific for simian immunodeficiency virus can be induced by intrarectal immunization of macaques with a synthetic-peptide vaccine incorporating the LT(R192G) adjuvant. This response correlated with the level of T-helper response. After intrarectal challenge with pathogenic SHIV-Ku2, viral titers were eliminated more completely (to undetectable levels) both in blood and intestine, a major reservoir for virus replication, in intrarectally immunized animals than in subcutaneously immunized or control macaques. Moreover, CD4+ T cells were better preserved. Thus, induction of CTLs in the intestinal mucosa, a key site of virus replication, with a mucosal AIDS vaccine ameliorates infection by SHIV in non-human primates.

Viremia control following antiretroviral treatment and therapeutic immunizationduring primary SIV 251 infection of macaques

Prolonged antiretroviral therapy (ART) is not likely to eradicate human immunodeficiency virus type I (HIV-I) infection. Here we explore the effect of therapeutic immunization in the context of ART during primary infection using the simian immunodeficiency virus (SIV251) macaque model. Vaccination of rhesus macaques with the highly attenuated poxvirus-based NYVAC-SIV vaccine expressing structural genes elicited vigorous virus-specific CD4+ and CD8+ T cell responses in macaques that responded effectively to ART. Following discontinuation of a six-month ART regimen, viral rebound occurred in most animals, but was transient in six of eight vaccinated animals. Viral rebound was also transient in four of seven mock-vaccinated control animals. These data establish the importance of antiretroviral treatment during primary infection and demonstrate that virus-specific immune responses in the infected host can be expanded by therapeutic immunization.

Protection against mucosal simian immunodeficiency virus SIV (mac251) challenge by using replicating adenovirus-SIV multigene vaccine priming and subunit boosting

ABSTRACT Whereas several recent AIDS vaccine strategies have protected rhesus macaques against a pathogenic simian/human immunodeficiency virus (SHIV)89.6P challenge, similar approaches have provided only modest, transient reductions in viral burden after challenge with virulent, pathogenic SIV, which is more representative of HIV infection of people. We show here that priming with replicating adenovirus recombinants encoding SIV env/rev, gag, and/or nef genes, followed by boosting with SIV gp120 or an SIV polypeptide mimicking the CD4 binding region of the envelope, protects rhesus macaques from intrarectal infection with the highly pathogenic SIVmac251. Using trend analysis, significant reductions in acute-phase and set point viremia were correlated with anti-gp120 antibody and cellular immune responses, respectively. Within immunization groups exhibiting significant protection, a subset (39%) of macaques have exhibited either no viremia, cleared viremia, or controlled viremia at the threshold of detection, now more than 40 weeks postchallenge. This combination prime-boost strategy, utilizing replication competent adenovirus, is a promising alternative for HIV vaccine development.

Cytokines from activated T cells induce normal endothelial cells to acquire the phenotypic and functional features of AIDS-Kaposi's sarcoma spindle cells.

Kaposis sarcoma (KS) is a proliferative disease of vascular origin particularly frequent in HIV-1-infected homosexual men (AIDS-KS) and characterized by proliferating spindle-shaped cells, angiogenesis, and inflammatory cell infiltration. Previous work has suggested that KS spindle cells are of endothelial cell origin and that chronic immune activation via the release of inflammatory cytokines may cooperate with basic fibroblast growth factor (bFGF) and the HIV-1 Tat protein in the induction and progression of AIDS-KS. Here we show that KS spindle cells have features of activated endothelial cells, and that conditioned media from activated T cells, rich in the same inflammatory cytokines increased in HIV-1-infected individuals, induce normal endothelial cells to acquire the phenotypic and functional features of KS cells. These include (a) acquisition of a similar pattern of cell surface antigen expression; (b) similar proliferative response to bFGF; (c) induction of the responsiveness to the mitogenic effect of extracellular HIV-1 Tat protein that is now able to promote the G1-S transition of endothelial cell cycle; and (d) induction in nude mice of vascular lesions closely resembling early KS as well as the lesions induced by inoculation of KS cells. These results suggest that chronic immune activation, via release of inflammatory cytokines, may play a role in the induction of KS.

Cross-subtype antibody and cellular immune responses induced by a polyvalent DNA prime–protein boost HIV-1 vaccine in healthy human volunteers

An optimally effective AIDS vaccine would likely require the induction of both neutralizing antibody and cell-mediated immune responses, which has proven difficult to obtain in previous clinical trials. Here we report on the induction of Human Immunodeficiency Virus Type-1 (HIV-1)-specific immune responses in healthy adult volunteers that received the multi-gene, polyvalent, DNA prime-protein boost HIV-1 vaccine formulation, DP6-001, in a Phase I clinical trial conducted in healthy adult volunteers of both genders. Robust cross-subtype HIV-1-specific T cell responses were detected in IFNgamma ELISPOT assays. Furthermore, we detected high titer serum antibody responses that recognized a wide range of primary HIV-1 Env antigens and also neutralized pseudotyped viruses that express the primary Env antigens from multiple HIV-1 subtypes. These findings demonstrate that the DNA prime-protein boost approach is an effective immunization method to elicit both humoral and cell-mediated immune responses in humans, and that a polyvalent Env formulation could generate broad immune responses against HIV-1 viruses with diverse genetic backgrounds.

Human B-lymphotropic virus (human herpesvirus-6).

Human B-lymphotropic virus (HBLV), also known as human herpesvirus-6 (HHV-6) was first isolated in 1986 from AIDS patients and patients with other lymphoproliferative disorders. HBLV is distinct from known human herpesviruses, biologically, immunologically and by molecular analysis. HBLV can infect and replicate in fresh and established lines of hemopoietic cells and cells of neural origin, suggesting wide tropism. The prevalence of HBLV antibody in the normal population was 26% though clear differences between different populations were observed. The prevalence of HBLV antibody an elevated antibody titer was higher in sera from certain malignancies, Sjögrens syndrome and sarcoidosis. Antibody to HBLV was also elevated in AIDS patients and patients with chronic fatigue syndrome. HBLV-DNA was detected in some B-cell lymphomas. The broad in vitro tropism, combined with immunological and molecular evidence of HBLV infection in individuals raise the question of the pathogenicity of this virus in some diseases. Because in vitro co-infection of CD4 cells by HBLV and HIV leads to enhanced degeneration, this raises the possibility that infection in AIDS patients by both viruses can aggravate the HIV-induced immunodeficiency. Specific reagents and immunological and molecular assays are currently being investigated, which will aid in virus detection in cells from patients, and in elucidating the possible pathogenesis of HBLV.

Block of AIDS-Kaposi's sarcoma (KS) cell growth, angiogenesis, and lesion formation in nude mice by antisense oligonucleotide targeting basic fibroblast growth factor. A novel strategy for the therapy of KS.

Kaposis sarcoma (KS) is the most frequent tumor of HIV-1-infected individuals (AIDS-KS). Typical features of KS are proliferating spindle-shaped cells, considered to be the tumor cells of KS, and endothelial cells forming blood vessels. Basic fibroblast growth factor (bFGF), a potent angiogenic factor, is highly expressed by KS spindle cells in vivo and after injection in nude mice it induces vascular lesions closely resembling early KS in humans. Similar lesions are induced by inoculating nude mice with cultured spindle cells from AIDS-KS lesions (AIDS-KS cells) which produce and release bFGF. Here we show that phosphorothioate antisense (AS) oligonucleotides directed against bFGF mRNA (ASbFGF) inhibit both the growth of AIDS-KS cells derived from different patients and the angiogenic activity associated with these cells, including the induction of KS-like lesions in nude mice. These effects are due to the block of the production of bFGF which is required by AIDS-KS cells to enter the cell cycle and which, after release, mediates angiogenesis. The effects of ASbFGF are specific, dose dependent, achieved at low (0.1-1 microM), nontoxic, oligomer concentrations, and are reversed by the addition of bFGF to the cells, suggesting that ASbFGF oligomers are promising drug candidates for KS therapy.

Increased immune responses in rhesus macaques by DNA vaccination combined with electroporation

We used optimized DNA expression vectors to compare two gene delivery methodologies in rhesus macaques, namely direct DNA injection and in vivo adaptive constant-current electroporation via the intramuscular route. The use of in vivo electroporation increased levels of gene expression and immune responses. We used an optimized HIV gag expression plasmid to show the development of new cellular immune responses in SIV-infected animals controlling viremia. Furthermore, after vaccination with SIV expression plasmids the recall responses to the SIV antigens were very high, indicating that DNA is a strong boost in the presence of antiretroviral treatment in SIV-infected animals. There was substantial animal-to-animal variability in DNA expression, revealed by plasma measurements of IL-15 produced by co-injected IL-15 DNA. IL-15 expression levels correlated with peak immune responses. Electroporation led to an expansion of antigen-specific CD4+ and CD8+ T cells of both central and effector memory phenotype. These results indicate that improved gene delivery and expression by electroporation dramatically increases immunogenicity of DNA vaccines. Electroporation is thus an important method to improve the effectiveness of DNA vaccination.