Nelfinavir impairs glycosylation of herpes simplex virus 1 envelope proteins and blocks virus maturation

Nelfinavir inhibition of Kaposi's sarcoma-associated herpesvirus protein expression and capsid assembly

BACKGROUND

Antiviral therapies that target herpesviruses are clinically important. Nelfinavir is a protease inhibitor that targets the human immunodeficiency virus (HIV) aspartyl protease. Previous studies demonstrated that this drug could also inhibit Kaposi's sarcoma-associated herpesvirus (KSHV) production. Our laboratory demonstrated nelfinavir can effectively inhibit herpes simplex virus type 1 (HSV-1) replication. For HSV-1 we were able to determine that virus capsids were assembled and exited the nucleus but did not mature in the cytoplasm indicating the drug inhibited secondary envelopment of virions.

METHODS

For KSHV, we recently derived a tractable cell culture system that allowed us to analyze the virus replication cycle in greater detail. We used this system to further define the stage at which nelfinavir inhibits KSHV replication.

RESULTS

We discovered that nelfinavir inhibits KSHV extracellular virus production. This was seen when the drug was incubated with the cells for 3 days and when we pulsed the cells with the drug for 1-5 min. When KSHV infected cells exposed to the drug were examined using ultrastructural methods there was an absence of mature capsids in the nucleus indicating a defect in capsid assembly. Because nelfinavir influences the integrated stress response (ISR), we examined the expression of viral proteins in the presence of the drug. We observed that the expression of many were significantly changed in the presence of drug. The accumulation of the capsid triplex protein, ORF26, was markedly reduced. This is an essential protein required for herpesvirus capsid assembly.

CONCLUSIONS

Our studies confirm that nelfinavir inhibits KSHV virion production by disrupting virus assembly and maturation. This is likely because of the effect of nelfinavir on the ISR and thus protein synthesis and accumulation of the essential triplex capsid protein, ORF26. Of interest is that inhibition requires only a short exposure to drug. The source of infectious virus in saliva has not been defined in detail but may well be lymphocytes or other cells in the oral mucosa. Thus, it might be that a "swish and spit" exposure rather than systemic administration would prevent virion production.

Novel inhibitors of HSV-1 protease effective in vitro and in vivo

Herpes simplex virus type 1 (HSV-1) is a widespread human pathogen known to cause infections of diverse severity, ranging from mild ulceration of mucosal and dermal tissues to life-threatening viral encephalitis. In most cases, standard treatment with acyclovir is sufficient to manage the disease progression. However, the emergence of ACV-resistant strains drives the need for new therapeutics and molecular targets. HSV-1 VP24 is a protease indispensable for the assembly of mature virions and, as such, constitutes an interesting target for the therapy. In this study, we present novel compounds, KI207M and EWDI/39/55BF, that block the activity of VP24 protease and consequently inhibit HSV-1 infection in vitro and in vivo. The inhibitors were shown to prevent the egress of viral capsids from the cell nucleus and suppress the cell-to-cell spread of the infection. They were also proven effective against ACV-resistant HSV-1 strains. Considering their low toxicity and high antiviral potency, the novel VP24 inhibitors could provide an alternative for treating ACV-resistant infections or a drug to be used in combined, highly effective therapy.

Predicting the Animal Susceptibility and Therapeutic Drugs to SARS-CoV-2 Based on Spike Glycoprotein Combined With ACE2

Recently, a few animals have been frequently reported to have been diagnosed with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Whether they are SARS-CoV-2 intermediate hosts is worthy of great attention. The interaction of SARS-CoV-2 spike protein and its acceptor protein ACE2 is an important issue in determining viral host range and cross-species infection, while the binding capacity of Spike protein to ACE2 of different species is unknown. Here, we used the atomic structure model of SARS-CoV-2 and human ACE2 to assess the receptor utilization capacity of ACE2s from 10 kinds of animals. Results show that chimpanzees, domestic cats and cattles are more susceptible to infection by SARS-CoV-2. Cats in particular, such as pet cats and stray cats, interact very closely with humans, implying the necessity to carefully evaluate the risk of cats during the current COVID-19 pandemic. Furthermore, based on ACE2(cats)-SARS-CoV-2-RBD model, through high-throughput screening methods using a pool of 30,000 small molecules, eight compounds were selected for binding free energy calculations. All the eight compounds can effectively interfere with the binding of ACE2 and Spike protein, especially Nelfinavir, providing drug candidates for the treatment and prevention of SARS-CoV-2, suggesting further assessment of the anti-SARS-CoV-2 activity of these compounds in cell culture. Although we only reported the results of the simulation, and more laboratory and epidemiological investigation are required. Like cats are a risk factor, we can further detect SARS-CoV-2 according to the susceptibility of different animals, find the potential host of infection, and completely cut off the living space of the virus. Especially, cats could be a choice of animal model for screening antiviral drugs or vaccine candidates against SARS-CoV-2.

The FDA-Approved Drug Nelfinavir Inhibits Lytic Cell-Free but Not Cell-Associated Nonlytic Transmission of Human Adenovirus

Adenoviruses (AdVs) are prevalent and give rise to chronic and recurrent disease. Human AdV (HAdV) species B and C, such as HAdV-C2, -C5, and -B14, cause respiratory disease and constitute a health threat for immunocompromised individuals. HAdV-Cs are well known for lysing cells owing to the E3 CR1-β-encoded adenovirus death protein (ADP). We previously reported a high-throughput image-based screening framework and identified an inhibitor of HAdV-C2 multiround infection, nelfinavir mesylate. Nelfinavir is the active ingredient of Viracept, an FDA-approved inhibitor of human immunodeficiency virus (HIV) aspartyl protease that is used to treat AIDS. It is not effective against single-round HAdV infections. Here, we show that nelfinavir inhibits lytic cell-free transmission of HAdV, indicated by the suppression of comet-shaped infection foci in cell culture. Comet-shaped foci occur upon convection-based transmission of cell-free viral particles from an infected cell to neighboring uninfected cells. HAdV lacking ADP was insensitive to nelfinavir but gave rise to comet-shaped foci, indicating that ADP enhances but is not required for cell lysis. This was supported by the notion that HAdV-B14 and -B14p1 lacking ADP were highly sensitive to nelfinavir, although HAdV-A31, -B3, -B7, -B11, -B16, -B21, -D8, -D30, and -D37 were less sensitive. Conspicuously, nelfinavir uncovered slow-growing round HAdV-C2 foci, independent of neutralizing antibodies in the medium, indicative of nonlytic cell-to-cell transmission. Our study demonstrates the repurposing potential of nelfinavir with postexposure efficacy against different HAdVs and describes an alternative nonlytic cell-to-cell transmission mode of HAdV.

[Modern ethiotropic chemotherapy of human cytomegalovirus infection: clinical effectiveness, molecular mechanism of action, drug resistance, new trends and prospects. Part 1.]

Modern chemotherapy of cytomegalovirus (CMV) infections has a very limited arsenal of first-line drugs. These are preparations of ganciclovir (GCV) belonging to the class of modified nucleosides and its metabolic precursor ganciclovir valine ester. After three-step phosphorylation, GCV, as a structural analogue of the natural nucleotide, competes with it for binding to DNA polymerase and, due to its structural features, inhibits its activity. However, with prolonged use of GCV, mainly under conditions of immunosuppression, the virus develops drug resistance associated in most cases with changes in pUL97 catalyzing the first stage of GCV phosphorylation, as well as in the catalytic subunit of DNA polymerase. When variants of viruses resistant to GCV appear, second-line drugs are used: pyrophosphate analog of foscarnet and nucleotide cidofovir. Resistance to second-line drugs is due to mutations in the pol-gene and in a number of cases leads to multiresistance, which makes it impossible to use traditional anti-CMV drugs. In addition, the use of all of the above drugs is accompanied by the development of severe side effects. All of the above determines the need to search for new compounds that can effectively inhibit the reproduction of the virus, harmless to the macroorganism, convenient to use, overcoming the drug resistance barrier in viruses.As a result of the search in international databases (PubMed, MedLine, eLIBRARY.RU, ClinicalTrials.gov, etc.), the main trends in the search for new anti-CMV agents were identified. In the first part of the review, we concentrated on compounds that are modifications of known antiviral agents currently used in clinical practice, the most promising for the development of drug anti-CMV drugs.

Viral Induced Oxidative and Inflammatory Response in Alzheimer's Disease Pathogenesis with Identification of Potential Drug Candidates: A Systematic Review using Systems Biology Approach

Alzheimer's disease (AD) is genetically complex with multifactorial etiology. Here, we aim to identify the potential viral pathogens leading to aberrant inflammatory and oxidative stress response in AD along with potential drug candidates using systems biology approach. We retrieved protein interactions of amyloid precursor protein (APP) and tau protein (MAPT) from NCBI and genes for oxidative stress from NetAge, for inflammation from NetAge and InnateDB databases. Genes implicated in aging were retrieved from GenAge database and two GEO expression datasets. These genes were individually used to create protein-protein interaction network using STRING database (score≥0.7). The interactions of candidate genes with known viruses were mapped using virhostnet v2.0 database. Drug molecules targeting candidate genes were retrieved using the Drug- Gene Interaction Database (DGIdb). Data mining resulted in 2095 APP, 116 MAPT, 214 oxidative stress, 1269 inflammatory genes. After STRING PPIN analysis, 404 APP, 109 MAPT, 204 oxidative stress and 1014 inflammation related high confidence proteins were identified. The overlap among all datasets yielded eight common markers (AKT1, GSK3B, APP, APOE, EGFR, PIN1, CASP8 and SNCA). These genes showed association with hepatitis C virus (HCV), Epstein- Barr virus (EBV), human herpes virus 8 and Human papillomavirus (HPV). Further, screening of drugs targeting candidate genes, and possessing anti-inflammatory property, antiviral activity along with a suggested role in AD pathophysiology yielded 12 potential drug candidates. Our study demonstrated the role of viral etiology in AD pathogenesis by elucidating interaction of oxidative stress and inflammation causing candidate genes with common viruses along with the identification of potential AD drug candidates.

KSHV oral shedding and plasma viremia result in significant changes in the extracellular tumorigenic miRNA expression profile in individuals infected with the malaria parasite

Kaposi's sarcoma herpesvirus (KSHV) is the etiological agent of Kaposi’s sarcoma (KS). Both KSHV and HIV infections are endemic in Uganda, where KS is among the most common cancers in HIV-infected individuals. Recent studies examined the use of small RNAs as biomarkers of disease, including microRNAs (miRNAs), with viral and tumor-derived miRNAs being detected in exosomes from individuals with KSHV-associated malignancies. In the current study, the host and viral extracellular mature miRNA expression profiles were analyzed in blood of KS-negative individuals in Uganda, comparing those with or without KSHV detectable from the oropharynx. We observed increased levels of cellular oncogenic miRNAs and decreased levels of tumor-suppressor miRNAs in plasma of infected individuals exhibiting oral KSHV shedding. These changes in host oncomiRs were exacerbated in people co-infected with HIV, and partially reversed after 2 years of anti-retroviral therapy. We also detected KSHV miRNAs in plasma of KSHV infected individuals and determined that their expression levels correlated with KSHV plasma viremia. Deep sequencing revealed an expected profile of small cellular RNAs in plasma, with miRNAs constituting the major RNA biotype. In contrast, the composition of small RNAs in exosomes was highly atypical with high levels of YRNA and low levels of miRNAs. Mass spectrometry analysis of the exosomes revealed eleven different peptides derived from the malaria parasite, Plasmodium falciparum, and small RNA sequencing confirmed widespread plasmodium co-infections in the Ugandan cohorts. Proteome analysis indicated an exosomal protein profile consistent with erythrocyte and keratinocyte origins for the plasma exosomes. A strong correlation was observed between the abundance of Plasmodium proteins and cellular markers of malaria. As Plasmodium falciparum is an endemic pathogen in Uganda, our study shows that co-infection with other pathogens, such as KSHV, can severely impact the small RNA repertoire, complicating the use of exosome miRNAs as biomarkers of disease.

Brief Report: A Phase 1b/Pharmacokinetic Trial of PTC299, a Novel PostTranscriptional VEGF Inhibitor, for AIDS-Related Kaposi's Sarcoma: AIDS Malignancy Consortium Trial 059

Vascular endothelial growth factor (VEGF) plays an important role in Kaposi's sarcoma (KS). We administered PTC299, a post-transcriptional inhibitor of pathogenic VEGF, to persons with HIV-related KS. Seventeen participants received 3 different doses of PTC299. Adverse events typically observed with VEGF inhibition were absent. Three participants had partial tumor responses and 11 had stable disease. There were no differences in exposure to PTC299 by antiretroviral regimen. Serum VEGF, but not KS-associated herpesvirus DNA, decreased on treatment. Given redundancies in the VEGF feedback loop, future trials should consider combining PTC299 with agents that inhibit different pathways implicated in KS and KS-associated herpesvirus proliferation.

Risk of congenital cytomegalovirus infection among HIV-exposed uninfected infants is not decreased by maternal nelfinavir use during pregnancy

BACKGROUND

Congenital cytomegalovirus (cCMV) infection is common among infants born to HIV-infected women. Nelfinavir (NFV), an antiretroviral drug that is safe during pregnancy, inhibits CMV replication in vitro at concentrations that standard doses achieve in plasma. We hypothesized that infants born to women receiving NFV for prevention of mother-to-child transmission of HIV (PMTCT) would have a reduced prevalence of cCMV infection.

METHODS

The prevalence of cCMV infection was compared among HIV-uninfected infants whose HIV-infected mothers either received NFV for >4 weeks during pregnancy (NFV-exposed) or did not receive any NFV in pregnancy (NFV-unexposed). CMV PCR was performed on infant blood samples collected at <3 weeks from birth.

RESULTS

Of the 1,255 women included, 314 received NFV for >4 weeks during pregnancy and 941 did not receive any NFV during pregnancy. The overall prevalence of cCMV infection in the infants was 2.2%, which did not differ by maternal NFV use. Maternal CD4 T cell counts were inversely correlated with risk of cCMV infection, independent of the time NFV was initiated during gestation. Infants with cCMV infection were born 0.7 weeks earlier (P = 0.010) and weighed 170 g less (P = 0.009) than uninfected infants.

CONCLUSION

Among HIV-exposed uninfected infants, cCMV infection was associated with adverse perinatal outcomes. NFV use in pregnancy was not associated with protection against cCMV. Safe and effective strategies to prevent cCMV infection are needed.

Glycans Instructing Immunity: The Emerging Role of Altered Glycosylation in Clinical Immunology

Protein glycosylation is an important epigenetic modifying process affecting expression, localization, and function of numerous proteins required for normal immune function. Recessive germline mutations in genes responsible for protein glycosylation processes result in congenital disorders of glycosylation and can have profound immunologic consequences. Genetic mutations in immune signaling pathways that affect glycosylation sites have also been shown to cause disease. Sugar supplementation and in vivo alteration of glycans by medication holds therapeutic promise for some of these disorders. Further understanding of how changes in glycosylation alter immunity may provide novel treatment approaches for allergic disease, immune dysregulation, and immunodeficiency in the future.