Defining Mechanisms of HIV-1 Gag:RNA Interactions and Virus Assembly

Division Of Basic Sciences - Nci

Investigators

Linked publications & trials

Abstract

After exiting the nucleus,HIV-1 RNA travels to subcellular locations to carry out its functions. HIV-1 RNA traffic to the plasma membrane,the major virus assembly site to generate infectious particles. HIV-1 Gag protein drives particle assembly and interacts with viral RNA,viral proteins, and host proteins to ensure the packaging of the viral genome and replication machinery, and virus egress. To better understand how Gag recognized RNA,we compared RNA elements in HIV-2 5' untranslated region that are recognized by HIV-1 and HIV-2 Gag. Our study demonstrates that Gag proteins from two different retroviruses recognize and use mostly the same set of cis-acting elements to mediate RNA packaging and provide the mechanistic basis for genome cross-packaging. These studies are published in Viruses in 2025. HIV-1 packages viral RNA genome in two steps,a dimeric RNA is first incorporated into immature virus particles, and during virus maturation, viral RNA needs to be packaged into the newly formed viral core. We are currently studying the mechanisms by which HIV-1 packages RNA in these two steps. It has often been suggested that the interactions of HIV-1 RNA and Gag leading to assembly are initiated in the cytoplasm. We have devised a novel strategy using nonviral RNA as a model to study the location where HIV-1 selects packaging RNA. We found that a major site for packaged RNA selection is in the plasma membrane. We have previously used total internal reflection fluorescence (TIRF) microscopy to study the interaction of HIV-1 RNA and Gag at the plasma membrane. We will continue these live-cell imaging studies to determine the kinetics of HIV-1 and nonviral RNA on the plasma membrane and examine the factors that affect their retention on the plasma membrane. We have shown that not all HIV-1 unspliced RNA are created equal. By using neighboring transcription start sites, HIV-1 generates multiple unspliced RNA species with minor differences at the 5' end can vary in their functions. For example, HIV-1 RNA with one guanosine (1G RNA) is selected over RNA with three guanosines (3G RNA) at the 5' end to be packaged into particles. We have studied the role of HIV-1 RNA during virus assembly. We hypothesize that HIV-1 full-length RNA facilitates the formation of viral particles. To test our hypothesis, we are examining the behaviors of different HIV-1 RNA species in the cells and their interactions with Gag. After exiting the nucleus, HIV-1 RNA travels to subcellular locations to carry out its functions. HIV-1 RNA traffic to the plasma membrane, the major virus assembly site to generate infectious particles. HIV-1 Gag protein drives particle assembly and interacts with viral RNA, viral proteins, and host proteins to ensure the packaging of the viral genome and replication machinery, and virus egress. To better understand how Gag recognized RNA, we compared RNA elements in HIV-2 5' untranslated region that are recognized by HIV-1 and HIV-2 Gag. Our study demonstrates that Gag proteins from two different retroviruses recognize and use mostly the same set of cis-acting elements to mediate RNA packaging and provide the mechanistic basis for genome cross-packaging. These studies are published in Viruses in 2025. HIV-1 packages viral RNA genome in two steps, a dimeric RNA is first incorporated into immature virus particles, and during virus maturation, viral RNA needs to be packaged into the newly formed viral core. We are currently studying the mechanisms by which HIV-1 packages RNA in these two steps. It has often been suggested that the interactions of HIV-1 RNA and Gag leading to assembly are initiated in the cytoplasm. We have devised a novel strategy using nonviral RNA as a model to study the location where HIV-1 selects packaging RNA. We found that a major site for packaged RNA selection is in the plasma membrane. We have previously used total internal reflection fluorescence (TIRF) microscopy to study the interaction of HIV-1 RNA and Gag at the plasma membrane. We will continue these live-cell imaging studies to determine the kinetics of HIV-1 and nonviral RNA on the plasma membrane and examine the factors that affect their retention on the plasma membrane. We have shown that not all HIV-1 unspliced RNA are created equal. By using neighboring transcription start sites, HIV-1 generates multiple unspliced RNA species with minor differences at the 5' end can vary in their functions. For example, HIV-1 RNA with one guanosine (1G RNA) is selected over RNA with three guanosines (3G RNA) at the 5' end to be packaged into particles. We have studied the role of HIV-1 RNA during virus assembly. We hypothesize that HIV-1 full-length RNA facilitates the formation of viral particles. To test our hypothesis, we are examining the behaviors of different HIV-1 RNA species in the cells and their interactions with Gag