HIV treatment strategies against viral enzymes are continuously hampered by viral drug resistance. Recent findings show that viral substrate Gag contributes to HIV-1 Protease Inhibitor (PI) resistance, leading to demands for new strategies in HIV treatment where Gag is recognized as a drug target. To successfully target Gag, there is a need of in-depth understanding of the Gag polyprotein and the effects of Gag mutations. Here, we propose new strategies in designing novel Gag inhibitors against existing and novel emerging Gag mutations via a structural understanding of the Gag-Protease relationship in PI resistance. In this review, we discuss the role of both novel and previously reported mutations, revealing insights to how they aid in PI resistance, and how new Gag inhibitors can be designed.

Recent studies revealing varied responses of infected cells to LRAs underscore the limited effectiveness of these agents and emphasize the wide array of determinants contributing to the heterogeneity of reservoirs, including virus genetic background, cell model, cell type, silencing mechanisms, tissue reservoirs, integration sites, patient, and gender specific factors. The enhancer region of the HIV-1 LTR contains two adjacent NF-κB binding sites that play a central role in mediating inducible HIV-1 gene expression. Beyond the involvement of various transcription factors, such as NF-κB, epigenetic constraints also play a pivotal role in suppressing the initiation of latent HIV transcription. Consequently, even latent viruses containing functional NF-κB sites remain unresponsive to drugs that activate NF-κB. Thus, it is evident that the activation of NF-κB alone does not suffice to trigger latent HIV, contradicting the central hypothesis of this study. The author used bioinformatics methods to analyze the viral proteins and their primer binding sites. The results show that the amino acid sequence ARG of Gag proteins of HTLV-1, HTLV-2, STLV-1 and STLV-2 match their primer binding site GGGGGCTCG in the 3'-to-5' direction and that the amino acid sequence SPR of Gag proteins of HIV-1, HIV-2, SIV and FIV match their primer binding site GGCGCCCGA in the 3'-to-5' direction. Related studies have shown that the genomic Gag/Gag-Pol complex recruits the LysRS/tRNA complex. The selective packaging of the tRNA primer requires HIV-1 Gag and Gag-Pol, and an interaction between LysRS and Gag is observed in vitro. In HIV-1, Gag/LysRS interaction depends on Gag sequences within the CTD of CA around amino acids 283-363 and motif 1 of LysRS around amino acids 208-259. It should be noted that the amino acid sequence SPR of the Gag protein is located at amino acids 148-150 within the NTD of CA, specifically at the NTD-NTD interface 1. Although this research is purely bioinformatics analysis, the relevant studies have demonstrated that Gag proteins match the HIV-1 primer binding site and possess the potential to directly activate dormant retroviruses.

HIV-1 assembly is a complex mechanism taking place at the plasma membrane of the host cell. It requires nice spatial and temporal coordination to end up with a full immature virus. Researchers have extensively studied HIV-1 assembly molecular mechanism during the past decades, in order to dissect the respective roles of viral proteins, viral genome and host cell factors. Nevertheless, the time course of the process has been observed in living cells only a decade ago. The very recent revolution of optical microscopy, combining high speed and high spatial resolution now permit to study assemblies and their consequences at the single molecule level within (living) cells. In this review, after a short description of these new approaches, we will show how HIV-1 assembly in cells has been revisited using these advanced super resolution microscopy techniques and how much it could make a bridge in studying assembly from the single molecule to the host cell.

Background: The molecular domestication of the gag gene of retrotransposons and retroviruses gave rise to the Gagr gene in the genome of Drosophila. The Gagr protein has a conservative structure in all Drosophila species, suggesting an essential function. As we previously shown, the Gagr gene may play a part in immune response and processes linked to stress reactions. Methods: Tub-GAL4>UAS-Gagr flies, which had the Gagr gene knockdown in all tissues, were compared with the control hybrid Tub-GAL4>w1118. Gagr gene function was verified by RNA-sequencing followed by RT-PCR and physiological tests. Results: In contrast to the control strain, we observed that flies with the Gagr gene knockdown had a shorter lifespan, but the mutant strain was more resistant to heat stress. Also, the Gagr knockdown strain had higher level of transcription of the immune response genes, according to a transcriptome analysis. It has been shown that the ammonium persulfate used to induce stress causes the Toll, Jal-STAT, and Jnk/MAPK signaling pathways to become activated, which results in a systemic response in numerus tissues in the control strain. Conversely, the Gagr gene mutant strain exhibits low expression of the stress response. Enrichment of the molecular function of genes overexpressed under ammonium persulfate stress in the control strain, but not in the Gagr knockdown mutant, revealed a category with 19 transcription factors involved in the control of organism development, morphogenesis and the functioning of the central nervous system. Their expression pattern and the Gagr gene's expression pattern match. The data obtained demonstrates the importance Gagr is to maintaining both the body's immune system and homeostasis.

The structural transitions RNAs undergo during trafficking are not well-understood. Here, we used the well-developed yeast Ty1 retrotransposon to provide the first structural model of genome (g) RNA in the nucleus from a retrovirus-like transposon. Through a detailed comparison of nuclear Ty1 gRNA structure with those established in the cytoplasm, virus-like particles (VLPs), and synthesized in vitro, we detected Ty1 gRNA structural alternations that occur during retrotransposition. Full-length Ty1 gRNA serves as the mRNA for Gag and Gag-Pol proteins and as the genome that is reverse transcribed within VLPs. We show that about 60% of base pairs predicted for the nuclear Ty1 gRNA appear in the cytoplasm, and active translation does not account for such structural differences. Most of the shared base pairs are represented by short-range interactions, while the long-distance pairings seem unique for each compartment. Highly structured motifs tend to be preserved after nuclear export of Ty1 gRNA. In addition, our study highlights the important role of Ty1 Gag in mediating critical RNA:RNA interactions required for retrotransposition.