Edelfosine reactivates latent HIV-1 reservoirs in myeloid cells through activation of NF-κB and AP1 pathway.

The persistence of latent HIV-1 reservoirs in cells presents a formidable challenge towards a complete HIV cure. Edelfosine is an FDA-approved investigational, anti-neoplastic drug. In this study, we aimed to investigate its role as a HIV-1 Latency Reversal Agent (LRA) using latency model cell lines. Our findings demonstrated that edelfosine reactivated latent HIV-1 viruses in myeloid cells in a dose and time-dependent manner. The mechanism of reactivation by edelfosine involved the activation of NF-κB and AP1 pathways in these cells. The reactivated virus was non-infectious. Delineating the mechanism of non-infectious virus production revealed an increased stabilization of cellular APOBEC3G protein as well as its enhanced incorporation into the released viruses. Thus, our study demonstrated for the first time an additional role of edelfosine in reactivation of latent HIV-1 and production of non-infectious virus. Our results have paved the way for repurposing of edelfosine as a novel HIV-1 latency reversal agent.

Construction and characterization of a full-length, replication-competent and infectious enhanced green fluorescence protein-tagged HIV-1 subtype C molecular clone.

HIV-1 subtype C virus accounts for nearly 50% of the total HIV infections globally. Despite this high prevalence, our understanding of subtype C specific infections remains limited due to lack of an in vitro model system. This is the first report of construction and characterization of a full-length and infectious EGFP-tagged HIV-1 subtype C molecular clone. The EGFP gene was inserted in-frame between the Nef and Env sequence in the HIV genome. The recombinant virus displayed expression of viral genes, infectivity and replication kinetics similar to the parental virus. VSV-G pseudotyping of the recombinant virus led to enhancement of HIV infection. The presence of the EGFP gene provides a rapid, easy and quantitative measure of HIV infection by flow cytometry and fluorescence microscopy. This clone will serve as an extremely beneficial tool to study HIV-1 subtype C specific infections.

Two cationic meso-thiophenium porphyrins and their zinc-complexes as anti-HIV-1 and antibacterial agents under non-photodynamic therapy (PDT) conditions.

The anti-HIV-1 and antimicrobial activities of novel cationic meso-thiophenium porphyrins and their zinc-complex are reported under in vitro non-photodynamic (PDT) conditions. While all the cationic porphyrins led to the inhibition of de novo virus infection, the Zn(II)-complexes of T2(OH)2M (A2B2-type) and T(OH)3M (AB3-type) displayed potent inhibition of HIV-1 entry with T2(OH)2MZn displaying maximal anti-HIV activity. The Zinc complex of both the thiophenium porphyrins T2(OH)2M and T(OH)3M also depicted antibacterial activities against Escherichia coli (ATCC 25922) and more prominently against Staphylococcus aureus (ATCC 25923). Again, the antibacterial activity was more potent for T2(OH)2MZn. Our study highlighted that the presence of two thiophenium groups at the meso-positions of the A2B2-type porphyrins along with zinc strongly enhanced anti-HIV and antimicrobial properties of these novel thiophenium porphyrins under non-PDT conditions.

Maturation inhibitors facilitate virus assembly and release of HIV-1 capsid P224 mutant.

HIV-1 Maturation inhibitors (MIs) bind to the C-terminal domain of capsid protein (CA-CTD) and spacer peptide 1 (SP1) in HIV-1 Gag and inhibit the CA-SP1 cleavage by stabilizing the immature Gag. The ß-turn motif, GVGGP in the HIV CA-CTD (residues 220-224) is one of the key determinants of HIV Gag assembly. In the present study, we mutated each residue of HIV-1 ß-turn motif to alanine and observed complete inhibition of virus release of all mutants. This defect in virus release was rescued in the presence of maturation inhibitors; BVM and PF-46396 for P224A mutant. To our knowledge, this is the first report of identification of BVM and PF-46396-dependent capsid mutant. Our results highlight the importance of the core ß-turn motif residues in immature virus assembly and suggest that the presence of MIs enhances Gag membrane binding and multimerization thereby restoring virus release of HIV Gag P224 mutant.

Novel host restriction factors implicated in HIV-1 replication.

Human immunodeficiency virus-1 (HIV-1) is known to interact with multiple host cellular proteins during its replication in the target cell. While many of these host cellular proteins facilitate viral replication, a number of them are reported to inhibit HIV-1 replication at various stages of its life cycle. These host cellular proteins, which are known as restriction factors, constitute an integral part of the host's first line of defence against the viral pathogen. Since the discovery of apolipoprotein B mRNA-editing enzyme 3G (APOBEC3G) as an HIV-1 restriction factor, several human proteins have been identified that exhibit anti-HIV-1 restriction. While each restriction factor employs a distinct mechanism of inhibition, the HIV-1 virus has equally evolved complex counter strategies to neutralize their inhibitory effect. APOBEC3G, tetherin, sterile alpha motif and histidine-aspartate domain 1 (SAMHD1), and trim-5α are some of the best known HIV-1 restriction factors that have been studied in great detail. Recently, six novel restriction factors were discovered that exhibit significant antiviral activity: endoplasmic reticulum α1,2-mannosidase I (ERManI), translocator protein (TSPO), guanylate-binding protein 5 (GBP5), serine incorporator (SERINC3/5) and zinc-finger antiviral protein (ZAP). The focus of this review is to discuss the antiviral mechanism of action of these six restriction factors and provide insights into the probable counter-evasion strategies employed by the HIV-1 virus. The recent discovery of new restriction factors substantiates the complex host-pathogen interactions occurring during HIV-1 pathogenesis and makes it imperative that further investigations are conducted to elucidate the molecular basis of HIV-1 replication.