RESUMEN
Numerous virus-specific, class I-restricted cytotoxic T lymphocyte (CTL) epitopes have been identified, yet little information is available regarding the specificity of the CTL response in persons of the same human histocompatibility leukocyte antigen (HLA) type. In this study, the human immunodeficiency virus (HIV) 1 envelope-specific CTL response was evaluated in five HLA-B14-positive persons. CTL responses specific for a previously described nine-amino acid epitope in gp41 (aa 584-592, ERYLKDQQL) could be identified in all subjects, and CTL clones specific for this epitope could be isolated from four persons. Despite heterogeneous T cell receptor usage, the fine specificity of the clones was similar, as defined by recognition of alanine-substituted peptides as well as peptides representing natural HIV-1 sequence variants. Correlation with in vivo virus sequences revealed that the dominant species in two of the subjects represented poorly recognized variants, with a K-->Q substitution at amino acid 588, whereas no variants were observed in the other two subjects. Although clonal type-specific responses to these dominant variants could be identified, the magnitude of these responses remained small, and the dominant CTL response was directed at the minor in vivo variant. These studies indicate that despite similar epitope-specific immunologic pressure in persons of the same HLA type, the in vivo quasispecies may differ, and that the major in vivo immune response to a given CTL epitope can be directed at a minor variant.
Asunto(s)
Proteína gp41 de Envoltorio del VIH/inmunología , Infecciones por VIH/inmunología , VIH-1/inmunología , Antígenos HLA-B/inmunología , Fragmentos de Péptidos/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Linfocitos T Citotóxicos/inmunología , Secuencia de Aminoácidos , Antígenos Virales/genética , Antígenos Virales/inmunología , Secuencia de Bases , Células Clonales , Variación Genética , Proteína gp41 de Envoltorio del VIH/genética , VIH-1/genética , Antígeno HLA-B14 , Prueba de Histocompatibilidad , Humanos , Epítopos Inmunodominantes/genética , Epítopos Inmunodominantes/inmunología , Masculino , Datos de Secuencia Molecular , Fragmentos de Péptidos/genética , Análisis de Secuencia de ADN , Homología de Secuencia , Especificidad de la Especie , Linfocitos T Citotóxicos/citologíaRESUMEN
Human immunodeficiency virus 1 (HIV-1) infection is associated with a vigorous cellular immune response that allows detection of cytotoxic T lymphocyte (CTL) activity using freshly isolated peripheral blood mononuclear cells (PBMC). Although restricting class I antigens and epitopes recognized by HIV-1-specific CTL have been defined, the effector cells mediating this vigorous response have been characterized less well. Specifically, no studies have addressed the breadth and duration of response to a defined epitope. In the present study, a longitudinal analysis of T cell receptor (TCR) gene usage by CTL clones was performed in a seropositive person using TCR gene sequences as a means of tracking responses to a well-defined epitope in the glycoprotein 41 transmembrane protein. 10 CTL clones specific for this human histocompatibility leukocyte antigen-B14-restricted epitope were isolated at multiple time points over a 31-mo period. All clones were derived from a single asymptomatic HIV-1-infected individual with a vigorous response to this epitope that was detectable using unstimulated PBMC. Polymerase chain reaction amplification using V alpha and V beta family-specific primers was performed on each clone, followed by DNA sequencing of the V-D-J regions. All 10 clones utilized V alpha 14 and V beta 4 genes. Sequence analysis of the TCR revealed the first nine clones isolated to also be identical at the nucleotide level. The TCR-alpha junctional region sequence of the tenth clone was identical to the junctional region sequences of the other nine, but this clone utilized distinct D beta and J beta gene segments. This study provides evidence that the observed high degree of HIV-1-specific CTL activity may be due to monoclonal or oligoclonal expansion of specific effector cells, and that progeny of a particular CTL clone may persist for prolonged periods in vivo in the presence of a chronic productive viral infection. The observed limited TCR diversity against an immunodominant epitope may limit recognition of virus variants with mutations in regions interacting with the TCR, thereby facilitating immune escape.
Asunto(s)
VIH-1/inmunología , Receptores de Antígenos de Linfocitos T/genética , Linfocitos T Citotóxicos/inmunología , Secuencia de Aminoácidos , Secuencia de Bases , Línea Celular Transformada , Células Clonales , ADN Viral , Proteína gp41 de Envoltorio del VIH/inmunología , Seropositividad para VIH/inmunología , Seropositividad para VIH/microbiología , Humanos , Epítopos Inmunodominantes/inmunología , Estudios Longitudinales , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Receptores de Antígenos de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Receptores de Antígenos de Linfocitos T alfa-beta/inmunología , Homología de Secuencia de Ácido NucleicoRESUMEN
We longitudinally measured T-cell receptor transcript frequencies of human immunodeficiency virus type 1 (HIV-1) specific cytotoxic T lymphocytes (CTL) in an individual with rapidly progressive disease and high levels of viremia. CTL clones elicited during acute HIV-1 infection were present at the time of death, despite absent functional CTL responses, arguing against clonal deletion as a mechanism for the decline of CTL responses observed during HIV-1 infection.