Human endogenous retrovirus K in the respiratory tract is associated with COVID-19 physiopathology

BACKGROUND

Critically ill 2019 coronavirus disease (COVID-19) patients under invasive mechanical ventilation (IMV) are 10 to 40 times more likely to die than the general population. Although progression from mild to severe COVID-19 has been associated with hypoxia, uncontrolled inflammation, and coagulopathy, the mechanisms involved in the progression to severity are poorly understood.

METHODS

The virome of tracheal aspirates (TA) from 25 COVID-19 patients under IMV was assessed through unbiased RNA sequencing (RNA-seq), and correlation analyses were conducted using available clinical data. Unbiased sequences from nasopharyngeal swabs (NS) from mild cases and TA from non-COVID patients were included in our study for further comparisons.

RESULTS

We found higher levels and differential expression of human endogenous retrovirus K (HERV-K) genes in TA from critically ill and deceased patients when comparing nasopharyngeal swabs from mild cases to TA from non-COVID patients. In critically ill patients, higher HERV-K levels were associated with early mortality (within 14 days of diagnosis) in the intensive care unit. Increased HERV-K expression in deceased patients was associated with IL-17-related inflammation, monocyte activation, and an increased consumption of clotting/fibrinolysis factors. Moreover, increased HERV-K expression was detected in human primary monocytes from healthy donors after experimental SARS-CoV-2 infection in vitro.

CONCLUSION

Our data implicate the levels of HERV-K transcripts in the physiopathology of COVID-19 in the respiratory tract of patients under invasive mechanical ventilation. Video abstract.

Neuraminidase from Influenza A and B Viruses is Susceptible to the Compound 4-(4-Phenyl-1H-1,2,3-Triazol-1-yl)-2,2,6,6-Tetramethylpiperidine-1- Oxyl

Background:

Since the influenza virus is the main cause of acute seasonal respiratory infections and pandemic outbreaks, antiviral drugs are critical to mitigate infections and impair chain of transmission. Neuraminidase inhibitors (NAIs) are the main class of anti-influenza drugs in clinical use. Nevertheless, resistance to oseltamivir (OST), the most used NAI, has been detected in circulating strains of the influenza virus. Therefore, novel compounds with anti-influenza activity are necessary.

Objective:

To verify whether the NA from influenza A and B virus is susceptible to the compound 4-(4- phenyl-1H-1,2,3-triazol-1-yl)-2,2,6,6-tetramethylpiperidine-1-oxyl (Tritempo).

Methods:

Cell-free neuraminidase inhibition assays were performed with Tritempo, using wild-type (WT) and OST-resistant influenza strains. Cell-based assays in MDCKs were performed to confirm Tritempo`s antiviral activity and cytotoxicity. Multiple passages of the influenza virus in increasing concentrations of our compound, followed by the sequencing of NA gene and molecular docking, were used to identify our Tritempo’s target.

Results/Discussion:

Indeed, Tritempo inhibited the neuraminidase activity of WT and OSTresistant strains of influenza A and B, at the nanomolar range. Tritempo bound to WT and OST-resistant influenza NA isoforms at the sialic acid binding site with low free binding energies. Cell-free assays were confirmed using a prototypic influenza A infection assay in MDCK cells, in which we found an EC50 of 0.38 µM, along with very low cytotoxicity, CC50 > 2,000 µM. When we passaged the influenza A virus in the presence of Tritempo, a mutant virus with the G248P change in the NA was detected. This mutant was resistant to Tritempo but remained sensitive to OST, indicating no cross-resistance between the studied and reference drugs.

Conclusion:

Our results suggest that Tritempo’s chemical structure is a promising one for the development of novel antivirals against influenza.

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.

HIV-1 and its gp120 inhibits the influenza A(H1N1)pdm09 life cycle in an IFITM3-dependent fashion

HIV-1-infected patients co-infected with A(H1N1)pdm09 surprisingly presented benign clinical outcome. The knowledge that HIV-1 changes the host homeostatic equilibrium, which may favor the patient resistance to some co-pathogens, prompted us to investigate whether HIV-1 infection could influence A(H1N1)pdm09 life cycle in vitro. We show here that exposure of A(H1N1)pdm09-infected epithelial cells to HIV-1 viral particles or its gp120 enhanced by 25% the IFITM3 content, resulting in a decrease in influenza replication. This event was dependent on toll-like receptor 2 and 4. Moreover, knockdown of IFITM3 prevented HIV-1 ability to inhibit A(H1N1)pdm09 replication. HIV-1 infection also increased IFITM3 levels in human primary macrophages by almost 100%. Consequently, the arrival of influenza ribonucleoproteins (RNPs) to nucleus of macrophages was inhibited, as evaluated by different approaches. Reduction of influenza RNPs entry into the nucleus tolled A(H1N1)pdm09 life cycle in macrophages earlier than usual, limiting influenza's ability to induce TNF-α. As judged by analysis of the influenza hemagglutin (HA) gene from in vitro experiments and from samples of HIV-1/A(H1N1)pdm09 co-infected individuals, the HIV-1-induced reduction of influenza replication resulted in delayed viral evolution. Our results may provide insights on the mechanisms that may have attenuated the clinical course of Influenza in HIV-1/A(H1N1)pdm09 co-infected patients during the recent influenza form 2009/2010.

Detection of the influenza A(H1N1)pdm09 virus carrying the K-15E, P83S and Q293H mutations in patients who have undergone bone marrow transplant

The 2009 pandemic influenza A(H1N1)pdm09 virus emerged and caused considerable morbidity and mortality in the third world, especially in Brazil. Although circulating strains of A(H1N1)pdm09 are A/California/04/2009-like (CA-04-like) viruses, various studies have suggested that some mutations in the viral hemagglutinin (HA) may be associated with enhanced severity and fatality. This phenomenon is particularly challenging for immunocompromised individuals, such as those who have undergone bone marrow transplant (BMT), because they are more likely to display worse clinical outcomes to influenza infection than non-immunocompromised individuals. We studied the clinical and viral aspects of post-BMT patients with confirmed A(H1N1)pdm09 diagnosis in the largest cancer hospital in Brazil. We found a viral strain with K-15E, P83S and Q293H polymorphisms in the HA, which is presumably more virulent, in these individuals. Despite that, these patients showed only mild symptoms of infection. Our findings complement the discovery of mild cases of infection with the A(H1N1)pdm09 virus with the K-15E, P83S and Q293H mutations in Brazil and oppose other studies that have linked these changes with increased disease severity. These results could be important for a better comprehension of the impact of the pandemic influenza in the context of BMT.

Herpes simplex type 1 activates glycolysis through engagement of the enzyme 6-phosphofructo-1-kinase (PFK-1)

Viruses such as HIV, HCV, Mayaro and HCMV affect cellular metabolic pathways, including glycolysis. Although some studies have suggested that the inhibition of glycolysis affects HSV-1 replication and that HSV-1-infected eyes have increased lactate production, the mechanisms by which HSV-1 induces glycolysis have never been investigated in detail. In this study, we observed an increase in glucose uptake, lactate efflux and ATP content in HSV-1-infected cells. HSV-1 triggered a MOI-dependent increase in the activity of phosphofructokinase-1 (PFK-1), a key rate-limiting enzyme of the glycolytic pathway. After HSV-1 infection, we observed increased PFK-1 expression, which increased PFK-1 total activity, and the phosphorylation of this enzyme at serine residues. HSV-1-induced glycolysis was associated with increased ATP content, and these events were critical for viral replication. In summary, our results suggest that HSV-1 triggers glycolysis through a different mechanism than other herpesviruses, such as HCMV. Thus, this study contributes to a better understanding of HSV-1 pathogenesis and provides insights into novel targets for antiviral therapy.

HIGHLIGHTS

►HSV-1 activates glycolysis by PFK-1 activation. ►In HSV-1-infected cells PFK-1 synthesis is up-regulated and phosphorylated at serine residues. ►PFK-1 knockdown impairs HSV-1 replication. ►HSV-1-mediated glycolysis activation increases ATP content.

Synthesis and anti-HSV-1 activity of new 1,2,3-triazole derivatives

In this work, a new series of arysulfonylhydrazine-1H-1,2,3-triazole derivatives were synthesized, and their ability to inhibit the in vitro replication of HSV-1 was evaluated. Among the 1,2,3-triazole derivatives, 1-[(5″-methyl-1″-(4‴-fluorophenylamino)-1H-1,2,3-triazol-4″-yl)carbonyl]-2-(4'-methylphenylsulfonyl)hydrazine and 1-[(5'-methyl-1'-(2″,5″-dichlorophenylamino)-1H-1,2,3-triazol-4'-yl)carbonyl]-2-(phenylsulfonyl)hydrazine, with IC(50) values of 1.30 and 1.26 μM, respectively, displayed potent activity against HSV-1. Because these compounds have low cytotoxicity, their selectivity indices are high. Under the assay conditions, they have better performance than does the reference compound acyclovir. The structures of all of the compounds were confirmed by one- and two-dimensional NMR techniques ((1)H, (13)C-APT, COSY-(1)H×(1)H and HETCOR (1)J(CH)) and by elemental analysis.

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.

The alkaloid 4-methylaaptamine isolated from the sponge Aaptos aaptos impairs Herpes simplex virus type 1 penetration and immediate-early protein synthesis

We describe in this paper that the alkaloid 4-methylaaptamine, isolated from the marine sponge Aaptos aaptos, inhibited HSV-1 infection. We initially observed that 4-methylaaptamine inhibited HSV-1 replication in Vero cells in a dose-dependent manner with an EC50 value of 2.4 microM. Moreover, the concentration required to inhibit HSV-1 replication was not cytotoxic, since the CC50 value of 4-methylaaptamine was equal to 72 microM. Next, we found that 4-methylaaptamine sustained antiherpetic activity even when added to HSV-1-infected Vero cells at 4 h after infection, suggesting that this compound inhibits initial events during HSV-1 replication. We observed that 4-methylaaptamine impaired HSV-1 penetration without affecting viral adsorption. In addition, the tested compound could inhibit, in an MOI-dependent manner, the expression of an HSV-1 immediate-early protein, ICP27, thus preventing the inhibition of macromolecular synthesis induced by this virus. Our results warrant further investigation on the pharmacokinetics of 4-methylaaptamine and propose that this alkaloid could be considered as a potential compound for HSV-1 therapy.