RESUMO
To determine the extent and nature of genetic variation present in independent isolates of HTLV-III/LAV, the nucleotide sequences of the entire envelope gene and parts of gag and pol were determined for two AIDS viruses. The results indicated that variation throughout the viral genome is extensive and that the envelope gene in particular is most highly variable. Within the envelope, changes were most prevalent within the extracellular region where clustered nucleotide substitutions and deletions/insertions were evident. Based on predicted secondary protein structure and hydrophilicity, these hypervariable regions represent potential antigenic sites. In contrast to the hypervariable regions, other sequences in the extracellular envelope and the overall envelope structure (including 18 of 18 cysteine residues), as well as most of the transmembrane region, were highly conserved.
Assuntos
Deltaretrovirus/genética , Genes Virais , Proteínas do Envelope Viral/genética , Síndrome da Imunodeficiência Adquirida/microbiologia , Sequência de Aminoácidos , Sequência de Bases , Deltaretrovirus/isolamento & purificação , Produtos do Gene gag , Variação Genética , Conformação de Ácido Nucleico , DNA Polimerase Dirigida por RNA/genética , Proteínas dos Retroviridae/genética , Homologia de Sequência do Ácido Nucleico , Proteínas Virais/genéticaRESUMO
The authors have determined TdT levels in a case of Ph1-positive AML. Peripheral blood cells and bone marrow cells taken during the various phases of the disease were examined. Liquor cells were analyzed when symptomatic central nervous system involvement occurred. High TdT levels were found in all of the phases of the disease including the liquor. TdT eluted at various isoelectric points indicating a shifting of the activity to greater molarity during progress of the disease. Two different forms of TdT were present in the liquor. The authors speculate about the existence of a relation between TdT levels and Ph1-positive leukemia. They point out the importance of TdT levels as functional criterion of remission in acute leukemia. Finally, the existence of different forms of TdT could be the expression of a clonal selection caused by therapy or of a spontaneous clonal competition.
