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Purpose of the Study.
In mammalian cells, DNA is transcribed into RNA. “RNA interference” is a mechanism of posttranscriptional gene silencing. Short interfering 21-23-mer double-stranded RNA segments guide messenger RNA (mRNA) degradation in a sequence-specific fashion. The purpose of this study was to investigate the feasibility of using siRNA to suppress the expression of human immunodeficiency virus (HIV) receptors (CD4), a viral structural protein (Gag) and green florescent protein substituted for an HIV regulatory protein (Nef).
siRNAs specific for CD4, p24 (gag) and green fluorescent protein mRNAs were prepared. These were transfected in vitro into cell lines that were permissive for HIV infection. These cell lines were then infected in vitro and the degree of suppression of target proteins was measured.
Silencing the expression of CD4 on target cells decreased HIV entry into target cells. Silencing of Gag polyprotein production inhibited HIV RNA replication. Silencing of viral regulatory gene expression (green florescent protein as a substitute for Nef) reduced viral gene expression in target T-cells.
These results demonstrate that siRNA technology can be used to suppress multiple steps of the HIV life cycle and have potential for therapeutic intervention in HIV infection.
Advances in molecular biology continue to reveal unique cellular pathways that may be manipulated for therapeutic intervention. That RNA interference can occur in human cells has been recognized for <2 years. Yet, this remarkable technology has already been harnessed in a model system to demonstrate it’s potential as a treatment for HIV infection. Highly active retroviral drug therapy (HAART) has been extraordinarily successful in reducing HIV-associated morbidity and mortality. However, the rapid emergence and spread of HIV strains that are resistant to current drugs strongly support the development of other avenues of intervention. As with current gene transfer technology, the delivery of therapeutic nucleic acids into specific target cells will be a great challenge.