Thiago Moreno L. Souza

The clinically approved antiviral drug sofosbuvir inhibits Zika virus replication.

Zika virus (ZIKV) is a member of the Flaviviridae family, along with other agents of clinical significance such as dengue (DENV) and hepatitis C (HCV) viruses. Since ZIKV causes neurological disorders during fetal development and in adulthood, antiviral drugs are necessary. Sofosbuvir is clinically approved for use against HCV and targets the protein that is most conserved among the members of the Flaviviridae family, the viral RNA polymerase. Indeed, we found that sofosbuvir inhibits ZIKV RNA polymerase, targeting conserved amino acid residues. Sofosbuvir inhibited ZIKV replication in different cellular systems, such as hepatoma (Huh-7) cells, neuroblastoma (SH-Sy5y) cells, neural stem cells (NSC) and brain organoids. In addition to the direct inhibition of the viral RNA polymerase, we observed that sofosbuvir also induced an increase in A-to-G mutations in the viral genome. Together, our data highlight a potential secondary use of sofosbuvir, an anti-HCV drug, against ZIKV.

The Effects of the Diterpenes Isolated from the Brazilian Brown Algae Dictyota pfaffii and Dictyota menstrualis against the Herpes Simplex Type-1 Replicative Cycle

We describe in this paper that the diterpenes 8,10,18-trihydroxy-2,6-dolabelladiene ( 1) and (6 R)-6-hydroxydichotoma-4,14-diene-1,17-dial ( 2), isolated from the marine algae DICTYOTA PFAFFII and D. MENSTRUALIS, respectively, inhibited HSV-1 infection in Vero cells. We initially observed that compounds 1 and 2 inhibited HSV-1 replication in a dose-dependent manner, resulting in EC (50) values of 5.10 and 5.90 microM, respectively, for a multiplicity of infection (MOI) of 5. Moreover, the concentration required to inhibit HSV-1 replication was not cytotoxic, resulting in good selective index (SI) values. Next, we found that compound 1 sustained its anti-herpetic activity even when added to HSV-1-infected cells at 6 h after infection, while compound 2 sustained its activity for up to 3 h after infection, suggesting that these compounds inhibit initial events during HSV-1 replication. We also observed that both compounds were incapable of impairing HSV-1 adsorption and penetration. In addition, the tested molecules could decrease the contents of some HSV-1 early proteins, such as UL-8, RL-1, UL-12, UL-30 and UL-9. Our results suggest that the structures of compounds 1 and 2, Brazilian brown algae diterpenes, might be promising for future antiviral design.

Design, synthesis, and biological evaluation of new 3-hydroxy-2-oxo-3-trifluoromethylindole as potential HIV-1 reverse transcriptase inhibitors

The trifluoromethyl group (CF3) is present in commercially available drugs of various therapeutic classes owing to its ability to modify and frequently improve their biological activities. Efavirenz is a trifluoromethylated inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) that shows good results in anti-HIV chemotherapy. With the objective of developing efficient non-nucleoside compounds, we have designed and synthesized some new 3-hydroxy-2-oxo-3-trifluoromethylindole as potential RT inhibitors. We used different substituted isatins as starting materials. The final products contain the group CF3, present in Efavirenz, and a pharmacophoric group, oxoindole. We have used molecular docking with HIV-1 RT as a tool to design putative non-nucleoside reverse transcriptase inhibitors (NNRTIs). Based on the calculation results obtained, a series of new 3-hydroxy-2-oxo-3-trifluoromethylindoles were synthesized as a novel class of potential RT inhibitors. The results showed that these compounds are capable of important interactions with the NNRT binding site, which encouraged us to submit them for biological assay. All compounds studied are significantly active in the RNA-dependent DNA-polymerase (RDDP) assay, and were not toxic toward the Vero cell line. Hence, the designed molecules represent good starting structures for further modification and structure–activity relationship (SAR) studies.

The nerve growth factor reduces APOBEC3G synthesis and enhances HIV-1 transcription and replication in human primary macrophages

Macrophages infected with HIV-1 sustain viral replication for long periods of time, functioning as viral reservoirs. Therefore, recognition of factors that maintain macrophage survival and influence HIV-1 replication is critical to understanding the mechanisms that regulate the HIV-1-replicative cycle. Because HIV-1-infected macrophages release the nerve growth factor (NGF), and NGF neutralization reduces viral production, we further analyzed how this molecule affects HIV-1 replication. In the present study, we show that NGF stimulates HIV-1 replication in primary macrophages by signaling through its high-affinity receptor Tropomyosin-related Kinase A (TrKA), and with the involvement of reticular calcium, protein kinase C, extracellular signal-regulated kinase, p38 kinase, and nuclear factor-κB. NGF-induced enhancement of HIV-1 replication occurred during the late events of the HIV-1-replicative cycle, with a concomitant increase in viral transcription and production. In addition, NGF reduced the synthesis of the cellular HIV-1 restriction factor APOBEC3G and also overrode its interferon-γ-induced up-regulation, allowing the production of a well-fitted virus. Because NGF-TrKA signaling is a crucial event for macrophage survival, it is possible that NGF-induced HIV-1 replication plays a role in the maintenance of HIV-1 reservoirs. Our study may contribute to the understanding of the immunopathogenesis of HIV-1 infection and provide insights about approaches aimed at limiting viral replication in HIV-1 reservoirs.

The Compound 6-Chloro-1,4-Dihydro-4-Oxo-1-(β-D-Ribofuranosyl) Quinoline-3-Carboxylic Acid Inhibits HIV-1 Replication by Targeting the Enzyme Reverse Transcriptase

We describe in this paper that the chloroxoquinolinic ribonucleoside 6-chloro-1,4-dihydro-4-oxo-1-(beta-D-ribofuranosyl)-quinoline-3-carboxylic acid (compound A) inhibits the HIV-1 replication in human primary cells. We initially observed that compound A inhibited HIV-1 infection in peripheral blood mononuclear cells (PBMCs) in a dose-dependent manner, resulting in an EC(50) of 1.5 +/- 0.5 microM and in a selective index of 1134. Likewise, compound A blocked HIV-1(BA-L) replication in macrophages in a dose-dependent manner, with an EC(50) equal to 4.98 +/- 0.9 microM. The replication of HIV-1 isolates from subtypes C and F was also inhibited by compound A with the same efficiency. Compound A inhibited an early event of the HIV-1 replicative cycle, since it prevented viral DNA synthesis in PBMCs exposed to HIV-1. Kinetic assays demonstrated that compound A inhibits the HIV-1 enzyme reverse transcriptase (RT) in dose-dependent manner, with a K(I) equal to 0.5 +/- 0.04 microM. Using a panel of HIV-1 isolates harboring NNRTI resistance mutations, we found a low degree of cross-resistance between compound A and clinical available NNRTIs. In addition, compound A exhibited additive effects with the RT inhibitors AZT and nevirapine, and synergized with the protease inhibitor atazanavir. Our results encourage continuous studies about the kinetic impact of compound A towards different catalytic forms of RT enzyme, and suggest that our nucleoside represents a promising molecule for future antiretroviral drug design.

The chloroxoquinolinic derivative 6-chloro-1,4-dihydro-4-oxo-1-(β-D-ribofuranosyl) quinoline-3-carboxylic acid inhibits HSV-1 adsorption by impairing its adsorption on HVEM

SummaryIn this paper, we describe that the oxoquinolinic acid derivative (compound A) inhibited HSV-1 adsorption on Vero cells. This effect was achieved with an EC50 value of 10 ± 2.0 µM and with low cytotoxicity, since the CC50 value for compound A was >1000 µM. Moreover, we demonstrate for the first time that adsorption inhibition was due to the blockage of the interactions between HSV-1 and the cellular receptor herpes virus entry mediator (HVEM). These results show that compound A can prevent HSV-1 infection in Vero cells, encouraging further studies to determine at what level compound A inhibits HSV-1-HVEM interactions.

The effects of neurotrophins and the neuropeptides VIP and PACAP on HIV-1 infection: histories with opposite ends.

The nerve growth factor (NGF) and other neurotrophins, and the neuropeptides vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) are largely present in human tissue and can exert modulatory activities on nervous, endocrine and immune system functions. NGF, VIP and PACAP receptors are expressed systemically in organisms, and thus these mediators exhibit pleiotropic natures. The human immunodeficiency virus type 1 (HIV-1), the causal agent of the acquired immunodeficiency syndrome (AIDS), infects immune cells, and its replication is modulated by a number of endogenous factors that interact with HIV-1-infected cells. NGF, VIP and PACAP can also affect HIV-1 virus particle production upon binding to their receptors on the membranes of infected cells, which triggers cell signaling pathways that modify the HIV-1 replicative cycle. These molecules exert opposite effects on HIV-1 replication, as NGF and other neurotrophins enhance and VIP and PACAP reduce viral production in HIV-1-infected human primary macrophages. The understanding of AIDS pathogenesis should consider the mechanisms by which the replication of HIV-1, a pathogen that causes chronic morbidity, is influenced by neurotrophins, VIP and PACAP, i.e. molecules that exert a broad spectrum of physiological activities on the neuroimmunoendocrine axis. In this review, we will present the main effects of these two groups of mediators on the HIV-1 replicative cycle, as well as the mechanisms that underlie their abilities to modulate HIV-1 production in infected immune cells, and discuss the possible repercussion of the cross talk between NGF and both neuropeptides on the pathogenesis of HIV-1 infection.

Corrigendum: The clinically approved antiviral drug sofosbuvir inhibits Zika virus replication

Scientific Reports 7: Article number: 40920; published online 18 January 2017; updated on 24 April 2017 The Competing Financial Interests section in this Article is incorrect and should read: “Dr. Karin Bruning is a member of the BMK consortium, able to produce sofosbuvir”.