Noninvasive high-throughput single-cell analysis of HIV protease activity using ratiometric flow cytometry

Retrovirus Drugs-Loaded PEGylated PAMAM for Prolonging Drug Release and Enhancing Efficiency in HIV Treatment

Polyamidoamine dendrimer (PAMAM) with its unique characteristics emerges as a potential drug delivery system which can prolong releasing time, reduce the side effects but still retaining treatment efficiency. In this study, methoxy polyethylene glycol modified PAMAM generation 3.0 (G3.0@mPEG) is prepared and characterized via 1H-NMR, FT-IR, and TEM. Subsequently, two antiretroviral agents (ARV) including lamivudine (3TC) and zidovudine (AZT) are individually encapsulated into G3.0@mPEG. The drug-loading efficiency, drug release profile, cytotoxicity and anti-HIV activity are then evaluated. The results illustrate that G3.0@mPEG particles are spherical with a size of 34.5 ± 0.2 nm and a drug loading content of about 9%. Both G3.0@mPEG and ARV@G3.0@mPEG show no cytotoxicity on BJ cells, and G3.0@mPEG loading 3TC and AZT performs sustained drug release behavior which is best fitted with the Korsmeyer-Peppas model. Finally, the anti-HIV activity of ARV via Enzymatic Assay of Pepsin is retained after being loaded into the G3.0@mPEG, in which about 36% of pepsin activity was inhibited by AZT at the concentration of 0.226 mM. Overall, PAMAM G3.0@mPEG is a promising nanocarrier system for loading ARV in HIV treatment and prevention.

Nanoscale flow cytometry reveals interpatient variability in HIV protease activity that correlates with viral infectivity and identifies drug-resistant viruses

HIV encodes an aspartyl protease that is activated during, or shortly after, budding of viral particles from the surface of infected cells. Protease-mediated cleavage of viral polyproteins is essential to generating infectious viruses, a process known as ‘maturation’ that is the target of FDA-approved antiretroviral drugs. Most assays to monitor protease activity rely on bulk analysis of millions of viruses and obscure potential heterogeneity of protease activation within individual particles. In this study we used nanoscale flow cytometry in conjunction with an engineered FRET reporter called VIral ProteasE Reporter (VIPER) to investigate heterogeneity of protease activation in individual, patient-derived viruses. We demonstrate previously unappreciated interpatient variation in HIV protease processing efficiency that impacts viral infectivity. Additionally, monitoring of protease activity in individual virions distinguishes between drug sensitivity or resistance to protease inhibitors in patient-derived samples. These findings demonstrate the feasibility of monitoring enzymatic processes using nanoscale flow cytometry and highlight the potential of this technology for translational clinical discovery, not only for viruses but also other submicron particles including exosomes, microvesicles, and bacteria.

Molecular Docking, Synthesis and anti-HIV-1 Protease Activity of Novel Chalcones

Background:

Since the beginning of the HIV/AIDS epidemic, 75 million people have been infected with the HIV and about 32 million people have died of AIDS. Investigation of the molecular mechanisms critical to the HIV replication cycle led to the identification of potential drug targets for AIDS therapy. One of the most important discoveries is HIV-1 protease, an enzyme that plays an essential role in the replication cycle of HIV.

Objective:

The aim of the present study is to synthesize and investigate anti-HIV-1 protease activity of some chalcone derivatives with the hope of discovering new lead structure devoid drug resistance.

Methods:

20 structurally similar chalcone derivatives were synthesized and their physico-chemical characterization was performed. Binding of chalcones to HIV-1 protease was investigated by fluorimetric assay. Molecular docking studies were conducted to understand the interactions.

Results:

The obtained results revealed that all compounds showed anti-HIV-1 protease activity. Compound C1 showed the highest inhibitory activity with an IC50 value of 0.001 μM, which is comparable with commercial product Darunavir.

Conclusion:

It is difficult to provide general principles of inhibitor design. Structural properties of the compounds are not the only consideration; ease of chemical synthesis, low molecular weight, bioavailability, and stability are also of crucial importance. Compared to commercial products the main advantage of compound C1 is the ease of chemical synthesis and low molecular weight. Furthermore, compound C1 has a structure that is different to peptidomimetics, which could contribute to its stability and bioavailability.

Function-based mutation-resistant synthetic signaling device activated by HIV-1 proteolysis

The high mutation rate of the human immunodeficiency virus type 1 (HIV-1) virus is a major problem since it evades the function of antibodies and chemical inhibitors. Here, we demonstrate a viral detection strategy based on synthetic biology principles to detect a specific viral function rather than a particular viral protein. The resistance caused by mutations can be circumvented since the mutations that cause the loss of function also incapacitate the virus. Many pathogens encode proteases that are essential for their replication and that have a defined substrate specificity. A genetically encoded sensor composed of a fused membrane anchor, viral protease target site, and an orthogonal transcriptional activator was engineered into a human cell line. The HIV-1 protease released the transcriptional activator from the membrane, thereby inducing transcription of the selected genes. The device was still strongly activated by clinically relevant protease mutants that are resistant to protease inhibitors. In the future, a similar principle could be applied to detect also other pathogens and functions.