RESUMEN

Early after seroconversion, macrophage-tropic human immunodeficiency virus type 1 (HIV-1) variants are predominantly found, even when a mixture of macrophage-tropic and non-macrophage-tropic variants was transmitted. For virus contracted by sexual transmission, this is presently explained by selection at the port of entry, where macrophages are infected and T cells are relatively rare. Here we explore an additional mechanism to explain the selection of macrophage-tropic variants in cases where the mucosa is bypassed during transmission, such as blood transfusion, needle-stick accidents, or intravenous drug abuse. With molecularly cloned primary isolates of HIV-1 in irradiated mice that had been reconstituted with a high dose of human peripheral blood mononuclear cells, we found that a macrophage-tropic HIV-1 clone escaped more efficiently from specific cytotoxic T-lymphocyte (CTL) pressure than its non-macrophage-tropic counterpart. We propose that CTLs favor the selective outgrowth of macrophage-tropic HIV-1 variants because infected macrophages are less susceptible to CTL activity than infected T cells.

Asunto(s)

Infecciones por VIH/virología , VIH-1/fisiología , Macrófagos/virología , Linfocitos T Citotóxicos/inmunología , Animales , Modelos Animales de Enfermedad , Productos del Gen rev/inmunología , Enfermedad Injerto contra Huésped/inmunología , Enfermedad Injerto contra Huésped/virología , Infecciones por VIH/inmunología , VIH-1/genética , Humanos , Leucocitos Mononucleares/virología , Ratones , Ratones Endogámicos CBA , Mutación , Replicación Viral , Productos del Gen rev del Virus de la Inmunodeficiencia Humana

RESUMEN

The antiviral activity of a CD8(+) cytotoxic T-lymphocyte (CTL) clone (TCC108) directed against a newly identified HLA-B14-restricted epitope, human immunodeficiency virus type 1 (HIV-1) Rev(67-75) SAEPVPLQL, was analyzed with respect to its kinetics of target cell lysis and inhibition of HIV-1 production. Addition of TCC108 cells or CD8(+) reverse transcriptase-specific CTLs to HLA-matched CD4(+) T cells at different times after infection with HIV-1 IIIB showed that infected cells became susceptible to CTL-mediated lysis before peak virus production but after the onset of progeny virus release. When either of these CTLs were added to part of the infected cells immediately after infection, p55 expression and virus production were significantly suppressed. These data support a model in which CTLs, apart from exerting cytolytic activity which may prevent continued virus release, can interfere with viral protein expression during the eclipse phase via noncytolytic mechanisms. TCC108-mediated inhibition of virus replication in peripheral blood mononuclear cells caused rapid selection of a virus with a mutation (69E-->K) in the Rev(67-75) CTL epitope which abolished recognition by TCC108 cells. Taken together, these data suggest that both cytolytic and noncytolytic antiviral mechanisms of CTLs can be specifically targeted to HIV-1-infected cells.

Asunto(s)

Infecciones por VIH/inmunología , VIH-1/inmunología , Linfocitos T Citotóxicos/inmunología , Secuencia de Aminoácidos , Línea Celular , Pruebas Inmunológicas de Citotoxicidad , Productos del Gen rev/inmunología , Infecciones por VIH/sangre , Transcriptasa Inversa del VIH/inmunología , VIH-1/crecimiento & desarrollo , VIH-1/fisiología , Antígenos HLA-A/inmunología , Antígenos HLA-B/inmunología , Humanos , Cinética , Datos de Secuencia Molecular , Replicación Viral , Productos del Gen rev del Virus de la Inmunodeficiencia Humana

RESUMEN

Three experimental vaccines against feline immunodeficiency virus (FIV), all based on viral antigens presented via immune stimulating complexes (iscoms), were tested for their capacity to induce protection in cats from FIV infection. The respective vaccines consisted of FIV propagated in Crandell feline kidney (CrFK) cells (FIV-iscoms); FIV-iscoms spiked with recombinant vaccinia virus expressed FIV envelope glycoprotein incorporated into iscoms (FIV-iscoms + vGR657x15-iscoms) and vGR657x15-iscoms spiked with recombinant FIV Gag protein incorporated into iscoms (vGR657x15-iscoms + FIV-Gag-iscoms). Simian immunodeficiency virus envelope glycoprotein incorporated into iscoms, iscoms prepared with uninfected CrFK cells, and PBS served as controls. All cats vaccinated with vGR657x15-iscoms combined with FIV-iscoms or FIV-Gag-iscoms developed Env-specific plasma antibody responses. These antibodies neutralised FIV infection in CrFK cells, but failed to neutralise FIV infection in primary feline thymocytes. FIV-iscoms induced poor Env-specific responses and only one out of six cats developed antibodies that neutralised FIV in the CrFK cell based assay. Four weeks after challenge all cats proved to be infected, showing that none of the vaccine preparations provided protection. In contrast, 2 weeks after infection, virus infected peripheral blood mononuclear cells were only observed in cats vaccinated with FIV-iscoms + vGR657x15-iscoms or CrFK-iscoms and to a lesser extent in cats vaccinated with FIV-iscoms and vGR657x15-iscoms + FIV-Gag-iscoms, but not in cats vaccinated with SIV-iscoms or PBS. The differences found in cell associated virus loads amongst the respective groups are discussed in the light of antibody mediated enhancement of infectivity and protective effects provided by Gag-specific T cell responses.

Asunto(s)

Virus de la Inmunodeficiencia Felina/inmunología , Infecciones por Lentivirus/prevención & control , Vacunas Virales/administración & dosificación , Animales , Anticuerpos Antivirales/sangre , Antígenos Virales/inmunología , Gatos , Infecciones por Lentivirus/inmunología , Vacunación , Viremia/inmunología , Viremia/prevención & control

RESUMEN

Two experimental feline immunodeficiency virus (FIV) vaccines were tested, either alone or in combination, in four groups of cats (A-D). One vaccine (SL3261-FIV) was composed of live attenuated Salmonella typhimurium aroA (SL3261) strains expressing the capsid (Gag) and part of the envelope (Env) proteins of FIV. The other was composed of FIV Gag and Env proteins incorporated into immune-stimulating complexes (iscom-FIV). Cats of group A were immunized four times with SL3261-FIV. Cats of group B were immunized twice with SL3261-FIV and then twice with iscom-FIV. Cats of group C were immunized twice with SL3261 expressing the B subunit of cholera toxin (SL3261-CtxB) and then twice with iscom-FIV. Cats of group D, which served as negative controls, were immunized twice with SL3261-CtxB and then twice with iscom into which the Gag and Env proteins of simian immunodeficiency virus (SIV) had been incorporated (iscom-SIV). Two weeks after the last immunization, all cats were challenged with FIV. At this time, cats immunized with iscom-FIV (groups B and C) showed strong plasma antibody responses to Gag and Env, whilst these responses were weak or undetectable in the cats immunized four times with SL3261-FIV (group A). Seven weeks after FIV challenge, Env-specific antibody responses had increased considerably in cats of all groups except group A. The mean virus loads in the cats of this group proved to be lower than those of the other groups at all time points, indicating partial protection.

Asunto(s)

Síndrome de Inmunodeficiencia Adquirida del Felino/inmunología , Virus de la Inmunodeficiencia Felina/inmunología , Salmonella typhimurium/inmunología , Vacunas Sintéticas , Vacunas Virales , Animales , Gatos , Síndrome de Inmunodeficiencia Adquirida del Felino/prevención & control , Salmonella typhimurium/genética , Proteínas del Envoltorio Viral/genética , Proteínas del Envoltorio Viral/inmunología , Carga Viral

RESUMEN

Immunological correlates of AIDS-free survival after human immunodeficiency virus type 1 (HIV-1) infection are largely unknown. Cytotoxic T lymphocyte (CTL) responses are generally believed to be a major component of protective immunity against viral infections. However, the relationship between HIV-1-specific CTL responses and disease progression rate is presently unclear. Here we show in twelve HIV-1-infected individuals that detection of Rev-specific CTL precursors (CTLp) early in the asymptomatic stage, as well as detection of Rev- and Tat-specific CTLp later during follow-up, inversely correlate with rapid disease progression. No such correlation was found for detection of CTLp against Gag, RT or Nef. Further studies are required to determine whether a protective mechanism is indeed the basis of the observed correlation. The data presented are in agreement with the hypothesis that CTL against proteins that are important for early viral transcription and translation are of particular importance in protection from rapid disease progression.

Asunto(s)

Síndrome de Inmunodeficiencia Adquirida/fisiopatología , Productos del Gen rev/inmunología , Productos del Gen tat/inmunología , Seropositividad para VIH/fisiopatología , VIH-1/inmunología , Antígenos HLA-A/inmunología , Antígeno HLA-B8/inmunología , Linfocitos T Citotóxicos/inmunología , Síndrome de Inmunodeficiencia Adquirida/inmunología , Alelos , Secuencia de Aminoácidos , Recuento de Linfocito CD4 , Cartilla de ADN , Progresión de la Enfermedad , Estudios de Seguimiento , Productos del Gen rev/química , Seropositividad para VIH/inmunología , Antígenos HLA-A/genética , Antígeno HLA-A1/genética , Antígeno HLA-A1/inmunología , Antígeno HLA-A2/genética , Antígeno HLA-A2/inmunología , Antígeno HLA-B8/genética , Prueba de Histocompatibilidad , Humanos , Reacción en Cadena de la Polimerasa , Factores de Tiempo , Productos del Gen rev del Virus de la Inmunodeficiencia Humana , Productos del Gen tat del Virus de la Inmunodeficiencia Humana

RESUMEN

Human immunodeficiency virus type 1 (HIV-1) Gag-specific cytotoxic T lymphocyte (CTL) responses were studied in seven seropositive long-term asymptomatic individuals (CDC A1) with stable CD4 counts for more than 8 years. Using a set of partially overlapping peptides covering the whole Gag, five 15-20-mer peptides were found to contain CTL epitopes. Further characterization of these epitopes revealed a new HLA-A25-restricted CTL epitope in p24, p24(203-212) ETINEEAAEW. This region of Gag is highly conserved in clades B and D of HIV-1. Naturally occurring amino acid sequences, containing p24(203)D (consensus HIV-1 clades A, C, F, G and H) or p24(204)I (HIV-2ROD) were not recognized by CTL recognizing the index peptide. No virus variants with mutations in this sequence were found in peripheral blood mononuclear cells from the HIV-1-infected individual concerned during the 8 year observation period, indicating that the virus had not escaped from the observed CTL response.

Asunto(s)

Secuencia Conservada , Epítopos de Linfocito T , Productos del Gen gag/inmunología , VIH-1/inmunología , Linfocitos T Citotóxicos/inmunología , Secuencia de Aminoácidos , Mapeo Epitopo , Variación Genética , Proteína p24 del Núcleo del VIH/inmunología , Infecciones por VIH/inmunología , Antígenos HLA-A/inmunología , Antígenos de Histocompatibilidad Clase I , Humanos , Leucocitos Mononucleares/inmunología , Datos de Secuencia Molecular , Sobrevivientes

Asunto(s)

Productos del Gen env/inmunología , Virus de la Inmunodeficiencia Felina/inmunología , Infecciones por Lentivirus/inmunología , Infecciones por Lentivirus/virología , Vacunas Virales/inmunología , Viremia , Animales , Anticuerpos Antivirales/sangre , Gatos , Línea Celular , Cricetinae , Expresión Génica , Productos del Gen env/genética , Productos del Gen gag/inmunología , Virus de la Inmunodeficiencia Felina/crecimiento & desarrollo , Recombinación Genética , Factores de Tiempo , Vacunación , Virus Vaccinia/genética , Virus Vaccinia/inmunología

RESUMEN

A type-specific human immunodeficiency virus type 1 (HIV-1)-neutralizing human monoclonal antibody (HuMAb MN215) is described that reacts with the V3 domain of a number of subtype B virus strains. Pepscan analysis indicated that amino acids at both sides of the tip of the V3 loop were involved in the binding of HuMAb MN215. The minimum epitope in a V3 sequence, obtained from the donor from whom the cell line originated, was 9 amino acids long and proved to be located at the C-terminal side of the tip of the loop. In a replacement Pepscan analysis, individual amino acids of the V3 loop important for binding of HuMAb MN215 were identified. Amino acids at positions 15 (H), 16 (I), 17 (G) and 18 (P) were found to be essential for binding of the antibody, whereas changes at positions 19 of G to N, 20 of R to K and 23 of F to L, as well as the addition of a negative charge at the C terminus, improved binding. Thus, amino acids involved in the binding of HuMAb MN215 are primarily located within highly variable regions of the V3 loop. HuMAb MN215 showed a higher affinity for the V3 domain sequences and recombinant envelope glycoproteins derived from non-syncytium-inducing strains than for those derived from syncytium-inducing strains.

Asunto(s)

Anticuerpos Monoclonales/química , VIH-1/inmunología , VIH-1/patogenicidad , Estructura Terciaria de Proteína , Secuencia de Aminoácidos , Aminoácidos/inmunología , Anticuerpos Monoclonales/biosíntesis , Linfocitos B/virología , Sitios de Unión de Anticuerpos , Línea Celular , Reacciones Cruzadas , Epítopos/inmunología , Glicoproteínas/inmunología , Humanos , Masculino , Datos de Secuencia Molecular , Pruebas de Neutralización , Péptidos/inmunología , Fenotipo , Especificidad de la Especie

RESUMEN

Cats were immunized three times with different recombinant feline immunodeficiency virus (FIV) candidate vaccines. Recombinant vaccinia virus (rVV)-expressed envelope glycoprotein with (vGR657) or without (vGR657 x 15) the cleavage site and an FIV envelope bacterial fusion protein (beta-Galactosidase-Env) were incorporated into immune-stimulating complexes or adjuvanted with Quil A. Although all immunized cats developed antibodies against the envelope protein, only the cats vaccinated with the rVV-expressed envelope glycoproteins developed antibodies which neutralized FIV infection of Crandell feline kidney cells. These antibodies failed to neutralize infection of thymocytes with a molecularly cloned homologous FIV. After the third immunization the cats were challenged with homologous FIV. Two weeks after challenge the cell-associated viral load proved to be significantly higher in the cats immunized with vGR657 and vGR657 x 15 than in the other cats. The cats immunized with vGR657 and vGR657 x 15 also developed antibodies against the Gag proteins more rapidly than the cats immunized with beta-Galactosidase-Env or the control cats. This suggested that immunization with rVV-expressed glycoprotein of FIV results in enhanced infectivity of FIV. It was shown that the observed enhancement could be transferred to naive cats with plasma collected at the day of challenge.

Asunto(s)

Síndrome de Inmunodeficiencia Adquirida del Felino/inmunología , Glicoproteínas/inmunología , Proteínas del Envoltorio Viral/inmunología , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/biosíntesis , Anticuerpos Antivirales/sangre , Gatos , Línea Celular , Inmunización , Virus de la Inmunodeficiencia Felina/inmunología , Cinética , Monocitos/virología

RESUMEN

Recombinant vaccinia viruses were constructed that expressed the complete env gene of feline immunodeficiency virus with or without the nucleotide sequence encoding the cleavage site between the surface (SU) protein and the transmembrane (TM) protein. The removal of this cleavage site resulted in the expression of a 150K protein that was processed into a 130K protein and was not cleaved into the SU and the TM proteins. Removal of the cleavage site also facilitated incorporation of the SU protein in immune-stimulating complexes (iscoms). Antibody responses to both an SU and a TM peptide representing two immunodominant B cell epitopes were measured. These were higher in cats immunized with iscoms prepared from the cleavage site-deleted envelope protein than in cats immunized with iscoms prepared from the native envelope protein or immunized with the envelope protein and the adjuvant Quil A.

Asunto(s)

Anticuerpos Antivirales/biosíntesis , Antígenos Virales/inmunología , Productos del Gen env/inmunología , Virus de la Inmunodeficiencia Felina/inmunología , Animales , Antígenos Virales/genética , Linfocitos B/inmunología , Secuencia de Bases , Gatos , Síndrome de Inmunodeficiencia Adquirida del Felino/prevención & control , Productos del Gen env/genética , Virus de la Inmunodeficiencia Felina/genética , Epítopos Inmunodominantes/inmunología , Datos de Secuencia Molecular , Procesamiento Proteico-Postraduccional/genética , Proteínas Recombinantes/inmunología , Vacunas Sintéticas/inmunología

RESUMEN

OBJECTIVE: The aim of this study is to characterize antigenic sites on HIV-1 gp120 which may be important for the development of active and passive immunization strategies against HIV-1 infection. DESIGN: Two HIV-1-seropositive individuals were selected from the Amsterdam cohort and Epstein-Barr virus (EBV)-transformed B cells were generated from their peripheral blood mononuclear cells, which produce HIV-1-specific human monoclonal antibodies (HuMAb). METHODS: HuMAb were generated and selected based on their reactivities with native gp120. Reactivity with HIV-1 strains from phylogenetically different subfamilies was determined by immunostaining and virus neutralization assays. Specificity for the CD4-binding site was tested by an inhibition enzyme-linked immunosorbent assay and amino acids (aa) involved in the binding of the HuMAb were identified with a set of gp120 molecules with single aa substitutions. RESULTS: Three HuMAb (GP13, GP44, GP68) were generated, all recognizing a conserved conformation dependent epitope within, or topographically near, the CD4-binding site of gp120. HuMAb GP13 and GP68 neutralized a broad range of HIV-1 strains from phylogenetically different subfamilies, whereas HuMAb GP44 exhibited a more restricted pattern of neutralizing activity. The patterns of gp120 aa involved in their binding were unique for each of these HuMAb. CONCLUSIONS: The pattern of reactivities of these three HIV-1-neutralizing HuMAb developed in these studies is similar to, but distinct from other human and rodent MAb that recognize this antigenic site of HIV-1 gp120.

Asunto(s)

Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/inmunología , Epítopos/inmunología , Proteína gp120 de Envoltorio del VIH/inmunología , VIH-1/inmunología , Adulto , Especificidad de Anticuerpos , Linfocitos B/microbiología , Células Clonales/microbiología , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunohistoquímica , Masculino , Países Bajos , Pruebas de Neutralización