RESUMO
BACKGROUND: HIV-1 is characterized by its rapid genetic evolution and high diversity as a consequence of its error-prone reverse transcriptase and genetic recombination. This latter mechanism is responsible for the creation of circulating recombinant forms (CRFs) found in nature. Previous studies from our lab group have shown that the epidemic in Argentina is characterized by one highly prevalent circulating recombinant form, CRF12_BF, and many related BF recombinant forms. Since transcriptional transactivation of the HIV-1 long terminal repeat (LTR) promoter element requires the essential viral Tat protein, since these genetic structures underwent recombination in variants widely spread in South America, the aim of this work was to study transcriptional activity associated with the recombinant LTR and Tat elements. RESULTS: Differential transcriptional activity was measured for the BF recombinant LTR/Tat complex that is present in widely spread viral variants was demonstrated. This analysis demonstrated a higher activity for the BF complex when compared to its B subtype counterpart. CONCLUSION: This study indicates structural and functional consequences of recombination events within the LTR promoter and Tat transactivator protein of a naturally occurring HIV-1 recombinant form.
Assuntos
Variação Genética , Repetição Terminal Longa de HIV/genética , HIV-1/genética , Ativação Transcricional , Síndrome da Imunodeficiência Adquirida/virologia , Adulto , Linhagem Celular , Criança , Clonagem Molecular , DNA Viral/genética , Produtos do Gene tat/genética , Genes Reporter , HIV-1/classificação , HIV-1/isolamento & purificação , Humanos , Recombinação Genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Produtos do Gene tat do Vírus da Imunodeficiência HumanaRESUMO
To investigate the immunopathogenic mechanisms of type I autoimmune hepatitis in children, we analyzed by quantitative or semiquantitative reverse transcription-polymerase chain reaction the expression of cytokines interferon (IFN)-gamma, interleukin (IL)-12p40, IL-18, IL-4, IL-10, and IL-12R beta 2. In addition, liver and peripheral blood was collected to investigate the expression of the natural killer T (NKT) cell marker V alpha 24. The presence of NKT cells in hepatic lesions were also identified by immunohistochemistry. The analysis was performed on liver biopsies from 25 children with type I autoimmune hepatitis. As disease controls, we included six children with hepatitis C virus-related chronic hepatitis and nine control livers. The expression of IFN-gamma and IL-12p40 was not detected in controls but was clearly upregulated in pathologic biopsies. In addition, these samples showed an increased expression of IL-18 (p = 0.0003), IL-4 (p = 0.0055), and IL-12R beta 2 (p = 0.007). Western blot analysis confirmed the expression of IL-12p40 and IL-18. However, for IL-18, we detected only the immature biologically inactive polypeptide. The V alpha 24 transcripts were found increased in the liver (p = 0.0007) where V alpha 24(+) cells were also localized, but decreased in peripheral blood mononuclear cells (p = 0.041). In addition to a type I immune response, NKT cells might play a substantial role in the pathogenesis of type I autoimmune hepatitis in children.
