Respiratory syncytial virus infections recur throughout life despite induction of immunity by the first natural infection. An effective vaccine has long been sought but no vaccine is currently licensed, although promising candidates are currently being developed based on greater knowledge of the virus properties. However, there are significant populations that may not be protected adequately by a vaccine or are unable to be vaccinated. Thus, there is a continued need for effective therapeutic agents to treat the infection, especially in higher-risk individuals, a perspective presented in this article.
Brivudin, (( E)-5-(2-bromovinyl)-2’-deoxyuridine (BVDU) can be considered the gold standard for the treatment of varicella-zoster virus (VZV) infections, such as herpes zoster (shingles). It is available for clinical use in most European countries (except for the UK) and over the whole world (except for the US and Canada). Besides VZV its activity spectrum also includes various other herpesviruses, such as herpes simplex virus type 1 (HSV-1). Its activity against VZV and HSV-1 depends on phosphorylation by the virus-encoded thymidine kinase (TK). In its active form (BVDU TP or BVDU 5’-triphosphate), it can act as both substrate and inhibitor of the viral (i.e., HSV-1) DNA polymerase. It has proven to be effective against herpes zoster, including post-herpetic neuralgia (PHN). It is contra-indicated in patients concomitantly treated by 5-fluorouracil (FU), since its degradation product, ( E)-5-(2-bromovinyl)uracil, is inhibitory to the catabolism of FU, which may enhance the toxicity of the latter. A new compound, the bicyclic nucleoside analogue (BCNA) Cf-1743, has been described, which is a more potent inhibitor of VZV replication than BVDU and which does not interfere with the catabolism of FU. It is applicable orally, as its 5’-valine ester FV-100 (Fermavir), but has not (yet) been marketed for clinical use.
As a result of the multiple gathering and travels restrictions during the SARS-CoV-2 pandemic, the annual meeting of the International Society for Antiviral Research (ISAR), the International Conference on Antiviral Research (ICAR), could not be held in person in 2021. Nonetheless, ISAR successfully organized a remote conference, retaining the most critical aspects of all ICARs, a collegiate gathering of researchers in academia, industry, government and non-governmental institutions working to develop, identify, and evaluate effective antiviral therapy for the benefit of all human beings. This article highlights the 2021 remote meeting, which presented the advances and objectives of antiviral and vaccine discovery, research, and development. The meeting resulted in a dynamic and effective exchange of ideas and information, positively impacting the prompt progress towards new and effective prophylaxis and therapeutics.
Chronic hepatitis B virus (HBV) infection affects 240 to 300 million people worldwide. In the nucleus of infected hepatocytes, the HBV genome is converted to covalently closed circular DNA (cccDNA), which persists and serves as a transcriptional template for viral progeny. Therefore, a long-term cure for chronic HBV infection will require elimination of cccDNA. Although currently available nucleos(t)ide analogues (eg, tenofovir disoproxil fumarate, tenofovir alafenamide, entecavir) effectively control HBV replication, they are seldom curative (functional cure rate ∼10%) and require lifelong treatment for most patients. As such, antiviral agents with novel mechanisms of action are needed. Active site polymerase inhibitor nucleotides (ASPINs) noncompetitively distort the HBV polymerase active site to completely inhibit all polymerase functions, unlike traditional chain-terminating nucleos(t)ide analogues, which only target select polymerase functions and are consumed in the process. Clevudine, a first-generation ASPIN, demonstrated potent and prolonged HBV suppression in phase 2 and 3 clinical studies, but long-term treatment was associated with reversible myopathy in a small number of patients. ATI-2173, a novel next-generation ASPIN, is structurally similar to clevudine but targets the liver and demonstrates potent anti-HBV activity on and off treatment, and may ultimately demonstrate an improved pharmacokinetic and safety profile by significantly reducing systemic clevudine exposure. Thus, ATI-2173 is currently in clinical development as an agent for HBV cure. Here, we review the mechanism of action and preclinical and clinical profiles of clevudine and ATI-2173 to support the role of ASPINs as part of curative regimens for chronic HBV infection.
The idea to start the Rega Foundation was conceived in 1971 at an informal meeting organized by Prof. Piet De Somer (where Prof. Alfons Billiau, Prof. André Vlerick and I were also present), before the Foundation was formally created in 1972. From the early years some antiviral compounds, such as BVDU and the aminoacyl esters of acyclovir (from which ultimately valacyclovir evolved) originated. The advent of AIDS in 1981 and the discovery of the etiologic agent (HIV) thereof in 1983 have led to the identification of an avalanche of anti-HIV compounds in which the Rega Institute has played a primordial role. Foremost among these compounds was tenofovir, discovered in collaboration with Antonín Holý from the IOCB (Institute of Organic Chemistry and Biochemistry) in Prague. Tenofovir laid the basis for the treatment of HIV (AIDS) and hepatitis B virus (HBV) infections, and in combination with emtricitabine it was the first chemical ever approved by the US FDA (Food and Drug Administration) for the prophylaxis of HIV infections.
BACKGROUND:Bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV). and bovine coronavirus (BCV) threaten the productivity of cattle worldwide. Development of therapeutics that can control the spread of these viruses is an unmet need. The present research was designed to explore the in vitro antiviral activity of the Nerium oleander derived cardiac glycoside oleandrin and a defined N. oleander plant extract (PBI-05204) containing oleandrin.METHODS:Madin Darby Bovine Kidney (MDBK) cells, Bovine Turbinate (BT) cells, and Human Rectal Tumor-18 (HRT-18) cells were used as in vitro culture systems for BVDV, BRSV and BCV, respectively. Cytotoxicity was established using serial dilutions of oleandrin or PBI-05204. Noncytotoxic concentrations of each drug were used either prior to or at 12 h and 24 h following virus exposure to corresponding viruses. Infectious virus titers were determined following each treatment.RESULTS:Both oleandrin as well as PBI-05204 demonstrated strong antiviral activity against BVDV, BRSV, and BCV, in a dose-dependent manner, when added prior to or following infection of host cells. Determination of viral loads by PCR demonstrated a concentration dependent decline in virus replication. Importantly, the relative ability of virus produced from treated cultures to infect new host cells was reduced by as much as 10,000-fold at noncytotoxic concentrations of oleandrin or PBI-05204.CONCLUSIONS:The research demonstrates the potency of oleandrin and PBI-05204 to inhibit infectivity of three important enveloped bovine viruses in vitro. These data showing non-toxic concentrations of oleandrin inhibiting infectivity of three bovine viruses support further investigation of in vivo antiviral efficacy.
The water-based combination of two inorganic chemical compounds such as sodium tungstate dihydrate-Na 2 WO 4 × 2H 2 O and Aluminum sulfate octadecahydrate-Al 2 (SO 4 ) 3 × 18H 2 O that we have conditionally named ‘Vomifal’ has a broad antiviral activity in various DNA and RNA viruses, including Human Herpes Virus (HHV), African Swine Fever Virus (ASFV), Vaccinia Virus (VV), Hepatitis C Virus (HCV), Foot and Mouth Disease Virus (FMDV), Influenza A virus (A/Aichi/2/68 (H3N2)). In vitro and In vivo assays in several tissue cultures as well as in laboratory animals, conformed ‘Vomifal’ has a very low toxicity and the antiviral properties partially are due to its ability to induce gamma-IFN. Based on the results obtained, we can assume the presence of at least two mechanisms of the antiviral action of the studied drug. First or early stage - an unknown mechanism, possibly related to the effect on cellular receptors. Second or late stage – main antiviral properties probably associated with an interferonogenic effect.
BACKGROUND:In our previous study, the semi-synthetic analog of andrographolide, 3,19-isopropylideneandrographolide (IPAD), acts more effectively against herpes simplex virus (HSV) infection in cell culture than does acyclovir. IPAD inhibits cytopathic effect and production of HSV wild types and drug-resistant strains. Its effect is associated with the reduction of immediate-early regulatory protein (ICP27) and early proteins (ICP8 and UL42), indicating a mode of action different from that of acyclovir. Therefore, studies of the anti-HSV activity of IPAD in animal models are required before further application.MATERIAL & METHOD:Prednisolone-treated BALB/c mice were cutaneously infected with HSV-1 wild-type KOS strain. Experimental groups included control groups (untreated or treated only with the cream base) and treatment groups (with acyclovir or IPAD creams). Creams were applied four times daily for 10 days after infection to the relevant groups. The skin lesion score was assessed twice a day for 10 days. In addition, the effect of IPAD on HSV copy number and HSV late gene (gD) expression was investigated in skin lesion cells by quantitative real-time polymerase chain reaction.RESULT:IPAD cream was significantly effective in delaying the development of skin lesions and regression of the skin lesion score by day 5 (P < 0.01) compared with untreated controls. In addition, this IPAD cream significantly reduced HSV DNA copy number and gD gene expression (P < 0.01). No signs of irritation were observed at the application site.CONCLUSION:Topical administration of IPAD cream reduced skin lesions in mice cutaneously infected with HSV-1 KOS.
Human norovirus is the main cause of viral gastroenteritis, resulting annually in ∼ 700 million infections and 200,000 deaths, of whom most are children <5 years. Mouse norovirus-infected macrophages are the most widely used in vitro system to screen and characterize the antiviral effect of norovirus-targeting small molecules. We have previously established antiviral assays using this system, identified novel inhibitors and performed additional studies in order to have a first insight into their mechanism of action. As potent and safe anti-norovirus small molecules are urgently needed, we here describe the detailed protocol for a set of assays that will allow the identification of novel norovirus inhibitors.
Background Drug repurposing is a cost-effective strategy to identify drugs with novel effects. We searched for drugs exhibiting inhibitory activity to Herpes Simplex virus 1 (HSV-1). Our strategy utilized gene expression data generated from HSV-1-infected cell cultures which was paired with drug effects on gene expression. Gene expression data from HSV-1 infected and uninfected neurons were analyzed using BaseSpace Correlation Engine (Illumina®). Based on the general Signature Reversing Principle (SRP), we hypothesized that the effects of candidate antiviral drugs on gene expression would be diametrically opposite (negatively correlated) to those effects induced by HSV-1 infection. Results We initially identified compounds capable of inducing changes in gene expression opposite to those which were consequent to HSV-1 infection. The most promising negatively correlated drugs (Valproic acid, Vorinostat) did not significantly inhibit HSV-1 infection further in African green monkey kidney epithelial cells (Vero cells). Next, we tested Sulforaphane and Menadione which showed effects similar to those caused by viral infections (positively correlated). Intriguingly, Sulforaphane caused a modest but significant inhibition of HSV-1 infection in Vero cells (IC50 = 180.4 µM, p = 0.008), but exhibited toxicity when further explored in human neuronal progenitor cells (NPCs) derived from induced pluripotent stem cells. Conclusions These results reveal the limits of the commonly used SRP strategy when applied to the identification of novel antiviral drugs and highlight the necessity to refine the SRP strategy to increase its utility.
Introduction Maraviroc inhibits CCR5-tropic HIV-1 across different subtypes in vitro and has demonstrated efficacy in clinical trials. V3-loop amino acid variants observed in individual maraviroc-resistant viruses have not been found to be predictive of reduced susceptibility. Sequence-database searches have demonstrated that approximately 7.3% of viruses naturally encode these variants, raising concerns regarding potential pre-existing resistance. A study from Russia reported that combinations of these same amino acids are present in the V3 loops of the Russian variant subtype A (IDU-A, now A6) with a much greater prevalence (range: 74.4%–92.3%) depending on the combination. However, these studies and database searches did not include phenotypic evaluation. Methods Sixteen Russian HIV-1 isolates (including sub-subtype A6 viruses) were assessed for V3 loop sequence and phenotypic susceptibility to maraviroc. Results All 12 of the A6 viruses and 2/4 subtype B isolates encoded V3-loop variants that have previously been identified in individual virus isolates with reduced susceptibility to maraviroc. However, despite the prevalence of these V3-loop amino acid variants among the tested viruses, phenotypic sensitivity to maraviroc was observed in all instances. Similarly, reduced susceptibility to maraviroc was not found in virus from participants who experienced virologic failure in a clinical study of maraviroc in Russia (A4001101, [NCT01275625]). Discussion Altogether, these data confirm that the presence of individual or combinations of V3-loop amino acid residues in sub-subtype A6 viruses alone does not predict natural resistance to maraviroc and that V3-loop genotype analysis of R5 virus prior to treatment is not helpful in predicting clinical outcome.
Seasonal flu is caused by influenza infection, a virus that spreads easily in human population with periodical epidemic outbreaks. The high mutational rate of influenza viruses leads to the emergence of strains resistant to the current treatments. Due to that, scientific research is focusing on the development of new anti-influenza agents as alternative or complementary treatments. Olive tree ( Olea europaea L.) has been a source of ancestral remedies due to its antimicrobial activity. Thus, the aim of this study was to test the anti-influenza activity of a standardized olive leaf extract rich in elenolic acid (EA), Isenolic ® , compared with oseltamivir. Isenolic ® extract was characterized by High Performance Liquid Chromatography (HPLC)-Mass Spectrometry and its content in EA was determined by HPLC. Cytotoxicity, viral neuraminidase inhibitor activity and cell viability protection against influenza infection of Isenolic ® were tested in vitro using sialic acid overexpressing Madin-Darby Canine Kidney cells. Isenolic ® formulations showed a 4% and 8% dry basis. Oseltamivir and Isenolic ® extracts showed anti-influenza activity. The 8% Isenolic ® formulation showed a dose-dependent neuraminidase inhibitor activity higher than the 4% formulation, and preserved cell viability under viral infection. Thus, Isenolic ® become a promising natural alternative to existing influenza treatments.
Severe acute respiratory syndrome coronavirus 2 is an RNA virus currently causing a pandemic. Due to errors during replication, mutations can occur and result in cell adaptation by the virus or in the rise of new variants. This can change the attachment receptors' usage, result in different morphology of plaques, and can affect as well antiviral development. Indeed, a molecule can be active on laboratory strains but not necessarily on circulating strains or be effective only against some viral variants. Experiments with clinical samples with limited cell adaptation should be performed to confirm the efficiency of drugs of interest. In this protocol, we present a method to culture severe acute respiratory syndrome coronavirus 2 from nasopharyngeal swabs, obtain a high viral titer while limiting cell adaptation, and assess antiviral efficiency.
Many species of the order Bunyavirales contain potentially fatal viruses that lack effective medical countermeasures and are therefore collectively a major public health threat. Here, we describe a cell-based assay using Bunyamwera virus (BUNV)-mCherry to identify and characterize new antiviral molecules against bunyaviruses. BUNV is the type species for the genus Orthobunyavirus and has been reported to cause mild symptoms in humans, such as fever, joint pain, and rash. One major benefit of using our fluorescence-based assay over classical CPE-based assays is the fact that the antiviral effect of the tested compounds and their effect on the cell viability can be determined within the same assay well. For that reason, this type of assay could significantly advance our preclinical efforts towards finding new antiviral molecules against bunyaviruses.
Viruses from 15 of 35 maraviroc-treated participants with virologic failure and CCR5-tropic (R5) virus in the MOTIVATE studies at Week 24 had reduced maraviroc susceptibility. On-treatment amino acid changes were observed in the viral envelope glycoprotein 120 third variable (V3)–loop stems and tips and differed between viruses. No amino acid change reliably predicted reduced susceptibility, indicating that resistance was genetic context–dependent. Through Week 24, poor adherence was associated with maraviroc-susceptible virologic failure, whereas reduced maraviroc susceptibility was associated with suboptimal background regimen activity, highlighting the importance of overall regimen activity and good adherence. Predictive values of pretreatment V3-loop sequences containing these Week 24 mutations or other variants present at >3% in pretreatment viruses of participants with virologic failure at Week 48 were retrospectively assessed. Week 48 clinical outcomes were evaluated for correlates with pretreatment V3-loop CCR5-tropic sequences from 704 participants (366 responders; 338 virologic failures [83 with R5 virus with maraviroc susceptibility assessment]). Seventy-five amino acid variants with >3% prevalence were identified among 23 V3-loop residues. Previously identified variants associated with resistance in individual isolates were represented, but none were associated reliably with virologic failure alone or in combination. Univariate analysis showed virologic-failure associations with variants 4L, 11R, and 19S ( P < 0.05). However, 11R is a marker for CXCR4 tropism, whereas neither 4L nor 19S was reliably associated with reduced maraviroc susceptibility in R5 failure. These findings from a large study of V3-loop sequences confirm lack of correlation between V3-loop genotype and clinical outcome in participants treated with maraviroc. Clinical trial registration numbers (ClinicalTrials.gov): NCT00098306 and NCT00098722
Human norovirus is the main cause of viral gastroenteritis, resulting annually in ∼ 700 million infections and 200,000 deaths, of whom most are children <5 years. Mouse norovirus-infected macrophages are the most widely used in vitro system to screen and characterize the antiviral effect of norovirus-targeting small molecules. We have previously established antiviral assays using this system, identified novel inhibitors and performed additional studies in order to have a first insight into their mechanism of action. After the identification of novel small molecules with anti-norovirus activity (part 1 of this protocol), we here describe the logical next step which entails the generation of early information of their mode of action. This information together with a continuous improvement of the potency of compounds will contribute to the optimization of a compound class towards in vivo efficacy and a successful preclinical development.
Dysfunction of CD4 + T cells by HIV infection can cause serious immune defects. Recently, Campbell and colleagues described an intriguing and simple therapeutic method for HIV-infected resting central memory CD4 + T cells (HIV-T CM ), dependently on inhibitor of apoptosis (IAP) family proteins-targeted and second mitochondria-derived activator of caspases (SMAC) mimetics-mediated apoptosis, which is only triggered in HIV-T CM and not uninfected ones. Autophagy induction and subsequent formation of a ripoptosome-like death signaling complex were observed after such treatment, which may partially explain the potential mechanism. However, the direct intracellular inhibitory effects of IAPs on autophagy, as well as the critical roles of autophagy in activating extracellular anti-infection immune responses, warrant further investigation. Thus, this pointer aims to provide potential alternative mechanisms and to suggest important avenues for follow-up study.
Background With the advent of next generation integrase strand transfer inhibitors, the rates of virologic failure in treated subjects are expected to decrease. In this study, we analyzed the mutation patterns leading to virologic failure before and after starting integrase strand transfer inhibitor-based regimen as first-line or salvage therapy. Methods Between 2016 and 2019, blood samples were received from 258 patients with HIV-1 infection. Plasma HIV-1 RNA concentrations, and pol gene sequences were determined at baseline, and 16–48 weeks of treatment with integrase strand transfer inhibitor-based regimen. Only patients who did not achieve viral suppression at 48 weeks of integrase strand transfer inhibitor-based treatment were eligible for the current study. Results Virologic failure was observed in seven patients on raltegravir-based regimen. All patients with virologic failure but one were infected with CRF01_AE virus subtype. Raltegravir based-regimen was offered as first-line therapy for four patients, and as salvage therapy for three patients. M184V mutation associated with high level resistance to lamivudine and emtricitabine was detected in six out of seven patients. Primary mutations (Y143C, N155H, T66I, G118R, E138K) conferring high level resistance to raltegravir were detected in only three patients. Pre-existing polymorphic integrase mutation (T97A) was detected in two patients. Furthermore, two patients reported low adherence to treatment. Conclusions Emergence of primary mutations in the integrase gene can account for virologic failure in less than half of patients on raltegravir-based regimen. Low adherence to treatment, pre-existing accessory mutations, and resistance to reverse transcriptase inhibitors may have some role in virologic outcome.
BackgroundWe developed a new approach for the treatment of enterovirus infections, the consecutive alternating administration (CAA) of a combination of enterovirus inhibitors. On the model of coxsackievirus B1 (CVB1) in mice, two phenomena were observed: absence of drug resistance and increased susceptibility to the antivirals. This study aims to clarify the genetic basis of these phenomena. MethodsBrain samples from CVB1-infected mice subjected to a CAA course with the combination pleconaril/MDL-860/oxoglaucine were used for viral RNA extraction and next generation sequencing. In parallel, samples from monotherapeutic courses of the three substances included in the combination were studied. Whole genome sequence analysis was carried out on all samples. ResultsSamples of pleconaril monotherapy showed mutations in 5′untranslated region, VP3, 2C, 3C and 2A regions of viral RNA, translated in amino acid substitution of the 2A protein. The MDL-860 course induced changes in CVB1 RNA in the VP3 and 2C regions. The oxoglaucine monotherapy samples showed RNA mutation and amino acid substitution in the VP1 region and nucleotide substitution in the 3D region. In the specimens taken from mice subjected to the CAA course with pleconaril/MDL-860/oxoglaucine, the following RNA mutations were established: 5′ untranslated region, 2A, and 2B, and amino acids substitutions in VP3 and 2A, which differ from those mentioned above. These changes could be the reason for the prevention of drug resistance development and also to be considered as the basis for the phenomenon of increased drug susceptibility. ConclusionsThe results reveal that the high anti-enteroviral efficacy of the CAA course is substantiated by the appearance of specific changes in the viral genome.
