The combination of pleconaril, rupintrivir, and remdesivir efficiently inhibits enterovirus infections in vitro, delaying the development of drug-resistant virus variants

Enteroviruses are a significant global health concern, causing a spectrum of diseases from the common cold to more severe conditions like hand-foot-and-mouth disease, meningitis, myocarditis, pancreatitis, and poliomyelitis. Current treatment options for these infections are limited, underscoring the urgent need for effective therapeutic strategies. To find better treatment option we analyzed toxicity and efficacy of 12 known broad-spectrum anti-enterovirals both individually and in combinations against different enteroviruses in vitro. We identified several novel, synergistic two-drug and three-drug combinations that demonstrated significant inhibition of enterovirus infections in vitro. Specifically, the triple-drug combination of pleconaril, rupintrivir, and remdesivir exhibited remarkable efficacy against echovirus (EV) 1, EV6, EV11, and coxsackievirus (CV) B5, in human lung epithelial A549 cells. This combination surpassed the effectiveness of single-agent or dual-drug treatments, as evidenced by its ability to protect A549 cells from EV1-induced cytotoxicity across seven passages. Additionally, this triple-drug cocktail showed potent antiviral activity against EV-A71 in human intestinal organoids. Thus, our findings highlight the therapeutic potential of the pleconaril-rupintrivir-remdesivir combination as a broad-spectrum treatment option against a range of enterovirus infections. The study also paves the way towards development of strategic antiviral drug combinations with virus family coverage and high-resistance barriers.

Effect of castalagin against HSV-1 infection in newborn mice

We tested in vivo anti-herpetic effect of castalagin, an ellagitannin compound, extracted from pedunculate oak (Quercus robur). Previous investigations found that castalagin possesses a strong inhibitory effect in vitro against HSV-1/2 equal to acyclovir (ACV). It is also effective against ACV-resistant mutants and shows a synergistic effect with ACV. We study castalagin's activity towards HSV-1 infection in newborn mice. Acute toxicity determination in mice showed LD50 value of 295 mg/kg. Prolonged toxicity was also constructed. Castalagin manifested a marked activity against HSV-1 (LD90/0.02 ml) administered in 7-day course at 0.02 ml s.c. doses of 7.5 or 10 mg/kg (PI 57-58%). ACV course demonstrated a marked activity at 20 mg/kg. The selectivity ratio LD50/ED50 (295/7.5) could be accepted as ≥ 33.

Nutritional composition of different cape gooseberry genotypes (Physalis peruviana L.) – a comparative study

Cape gooseberry (Physalis peruviana L.) is a South American fruit with high nutrient content, pleasant taste and antioxidant properties. However, its consumption in some countries is underеvalued. The aim of this study was to determine the nutritional composition of two genotypes of Cape gooseberry fruit produced in Bulgaria (CG-F and CG-P) and to compare it with imported Colombian fruits (CG-C). The samples were assayed for size, diameter, moisture, ash, titratable acidity, pH, protein, lipid, carbohydrate, natural pigments, and mineral content. Bulgarian genotypes were smaller in size than the imported Colombian fruits. The protein content (2.54-1.88 g/100 g) was relatively higher in the imported variety, compared with the locally produced fruit. Carbohydrate content (10.23-14.13 g/100 g) slightly varied between the genotypes. The sweetness of the fruit was due to the main detected sugars – sucrose, glucose and fructose. CG-F and GC-C genotypes had similar sweetness indices, and fruit taste was evaluated as sweet-sour. Pectin content did not exceed 1.85%; the cellulose content varied between 4.29% and 6.64%. Moreover, all investigated fruit had a low lipid content (below 1.00%). The total chlorophyll and carotenoids levels were the highest in the local genotype CG-P (3.62 and 22.36 µg/g). Potassium was the predominant macro-element in all genotypes; there were numerical differences in the rest of the minerals (Ca, Mg, Fe, Cu, Zn, Mn), while the heavy metals, Pb, Cd and Cr, were generally absent. Cape gooseberry fruit of Bulgarian origin was evaluated as a low-calorie nutrient, compatible with the imported Colombian fruit.

Lipid composition of different parts of Cape gooseberry (Physalis peruviana L.) fruit and valorization of seed and peel waste

The consumption of Cape gooseberry (Physalis peruviana L.) fruit (CG), fresh or processed, is gaining popularity worldwide, due to its nutritional and medicinal benefits. This study was based on the analysis of the lipid fraction of different parts of CG fruit and on further valorization of the resulting CG waste. The content of glyceride oil in CG seeds, peels and seed/peel waste, as well as the individual fatty acid, sterol and tocopherol composition of the oils was determined. CG seeds and seed/peel waste were a rich source of oil (up to 22.93%), which is suitable for nutritional application, due to its high proportions of unsaturated fatty acids (up to 83.77%), sterols (campesterol, Δ5-аvenasterol, β-sitosterol) and tocopherols (β-, δ- and γ-tocopherols). Seed/peel waste and the extracted seed cakes contained macro- and microminerals (K, Mg, Na, Fe, Zn, Mn, Cu) which are important for human and animal nutrition. Seed cakes had relatively high protein (24.32%) and cellulose (42.94%) contents, and an interesting amino acid profile. The results from the study contribute to a deeper understanding of the composition of CG fruit, and might be of practical relevance in the development of functional foods and feeds.

Effect of Consecutive Alternating Administration of a Triple Combination of Anti-Enteroviral Compounds in Mice Infected with Coxsackievirus B3

A novel approach for treatment of enterovirus infections was characterized. Application of treatment course of consecutive alternating administration (CAA) of triple combination of enterovirus replication inhibitors in experimental infections (20 MLD50) with coxsackievirus B3 (CVB3) strains in newborn mice is presented. It was established that in infection with cardiotropic Woodruff strain the combination of pleconaril, МDL-860 and oxoglaucine (PMO) subjected to the CAA scheme, a significant protective effect was observed. Monotherapeutic courses as well as simultaneously daily applied PMO were without effect. Analogous data were observed at experimental infection with the neurotriopic Nancy strain of CVB3. Following IC50 values of virus samples taken every day from target organs of infected animals during the whole period of study, a drug-resistance was established in monotherapy with compounds-partners in the PMO combination. At courses by the treatment scheme CAA of PMO development of drug-resistance was not established, but an increased susceptibility to the effect of the inhibitor-components in the combination was proven. Toxicity of PMO applied via the CAA scheme and in the monotherapeutic courses in both healthy and CVB3 infected animals was recorded. All data obtained prove the potential of the CAA treatment scheme for development of effective chemotherapy of enterovirus infections.

Genome analysis of coxsackievirus B1 isolates during the consecutive alternating administration course of triple antiviral combination in newborn mice

Background

We 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.

Methods

Brain 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.

Results

Samples 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.

Conclusions

The results reveal that the high anti-enteroviral efficacy of the CAA course is substantiated by the appearance of specific changes in the viral genome.

Anti-enteroviral triple combination of viral replication inhibitors: activity against coxsackievirus B1 neuroinfection in mice

BACKGROUND

Chemotherapy is an important tool for controlling enterovirus infections, but clinically effective anti-enterovirus drugs do not currently exist, mainly due to the development of drug resistance. We investigated the combination effects of enterovirus replication inhibitors in order to limit this process. In previous studies, we showed the efficacy of consecutive alternating administration of the triple combinations disoxaril/guanidine/oxoglaucine and pleconaril/guanidine/oxoglaucine against coxsackievirus B1 infection in newborn mice. Drug sensitivity tests of the viral brain isolates showed that these drug combinations prevented the development of drug resistance.

METHODS

In the current study, we replaced guanidine-HCl with enteroviral RNA synthesis inhibitor MDL-860 to test the effect of a new triple combination-pleconaril/MDL-860/oxoglaucine-applied via consecutive alternating administration in newborn mice infected subcutaneously with 20 MLD₅₀ of coxsackievirus B1.

RESULTS

The pleconaril/MDL-860/oxoglaucine combination via consecutive alternating administration showed high activity at the 75 mg/kg MDL-860 dose: a protective effect of 50% and a pronounced suppression of brain virus titers. Moreover, along with prevention of drug resistance, a phenomenon of increased drug sensitivity was established. MDL-860 sensitivity in pleconaril/MDL-860/oxoglaucine increased 8.2 times vs. placebo (29 times vs. monotherapy) on day 7 and oxoglaucine sensitivity-4.9 times vs. placebo (by 6.8 times vs. monotherapy) on day 13. As concerns pleconaril, a demonstrable prevention of drug resistance was registered without increase of drug sensitivity. Daily, simultaneous administration of pleconaril/MDL-860/oxoglaucine showed no protective effects and led to a rapid development of drug resistance.

CONCLUSIONS

These results add new support for using consecutive alternating administration treatment courses to achieve clinically effective chemotherapy of enterovirus infections.

Effect of consecutive alternating administration (CAA) of a triple anti-enteroviral combination on Coxsackievirus B1 neuroinfection in mice

Currently, clinically effective antivirals for use in the treatment of enteroviral (EV) infections do not exist. The main reason is the development of drug resistance, the principle obstacle in the development of EV infection chemotherapy, based til now on monotherapy. The most important achievement of our previous studies was the development of a novel scheme for in vivo application of a triple combination of EV inhibitors with different modes of action against Coxsackievirus B (CVB) infections in mice. It consists of consecutive alternating administration (CAA) of the substances in the combination. Here, we tested the effect of the triple combination pleconaril, guanidine-HCl, and oxoglaucine (PGO) via CAA in newborn mice infected with a neurotropic strain of CVB1 (20 LD50 per mouse). This combination manifested a considerable protective effect with pleconaril doses of 25-200mg/kg: it decreased mortality rate (protection index, PI, between 31.3% and 67.7%) and increased mean survival time (MST) by 4-6days. Pleconaril monotherapy demonstrated activity similar to that of PGO via CAA, as measured by PI values, but MST values were slightly lower. However, it also greatly suppressed growth of infected suckling mice, especially at 200mg/kg. This toxic effect was avoided with CAA of PGO at pleconaril doses of 25-100mg/kg. Pleconaril monotherapy administered every 3days was ineffective. The PGO with CAA treatment course decreased infectious virus content, whereas pleconaril monotherapy did not. Analysis of drug-sensitivity in brain samples from CVB1 infected mice, based on IC50 (50% inhibitory concentration) values from cell culture experiments, showed that the CAA course counteracted the development of drug resistance to pleconaril and oxoglaucine in the triple PGO combination and increased drug sensitivity. In contrast, pleconaril and oxoglaucine monotherapies resulted in drug resistance. This data clearly proves the effectiveness of the proposed novel approach-the CAA treatment course-for combined application of EV replication inhibitors.

Antiviral Combination Approach as a Perspective to Combat Enterovirus Infections

Human enteroviruses distributed worldwide are causative agents of a broad spectrum of diseases with extremely high morbidity, including a series of severe illnesses of the central nervous system, heart, endocrine pancreas, skeleton muscles, etc., as well as the common cold contributing to the development of chronic respiratory diseases, including the chronic obstructive pulmonary disease. The above mentioned diseases along with the significantly high morbidity and mortality in children, as well as in the high-risk populations (immunodeficiencies, neonates) definitely formulate the chemotherapy as the main tool for the control of enterovirus infections. At present, clinically effective antivirals for use in the treatment of enteroviral infection do not exist, in spite of the large amount of work carried out in this field. The main reason for this is the development of drug resistance. We studied the process of development of resistance to the strongest inhibitors of enteroviruses, WIN compounds (VP1 protein hydrophobic pocket blockers), especially in the models in vivo, Coxsackievirus B (CV-B) infections in mice. We introduced the tracing of a panel of phenotypic markers (MIC50 value, plaque shape and size, stability at 50℃, pathogenicity in mice) for characterization of the drug-mutants (resistant and dependent) as a very important stage in the study of enterovirus inhibitors. Moreover, as a result of VP1 RNA sequence analysis performed on the model of disoxaril mutants of CVB1, we determined the molecular basis of the drug-resistance. The monotherapy courses were the only approach used till now. For the first time in the research for anti-enterovirus antivirals our team introduced the testing of combination effect of the selective inhibitors of enterovirus replication with different mode of action. This study resulted in the selection of a number of very effective in vitro double combinations with synergistic effect and a broad spectrum of sensitive enteroviruses. The most prospective attainment in our examinations in this field was the development of a novel scheme for the combined application of anti-enteroviral substances in coxsackievirus B1 neuroinfection in newborn mice. It consisted of a consecutive, alternating and non simultaneous administration of the substances in the combination. The triple combination - disoxaril- guanidine. HCl-oxoglaucine (DGO) showed a high effectiveness expressed in the marked reduction of the mortality rate in infected mice as compared both to the placebo group, and to the partner compounds used alone every day, and to the same combination applied simultaneously every day. The studies of the drug sensitivity of viral brain isolates from mice treated with DGO combination showed not only preserved, but even increased sensitivity to the drugs included in the combination. Obviously, the consecutive alternating administration of anti-enteroviral substances hinders the occurrence of drug-resistance in the course of the experimental enteroviral infections in mice.

Glanzmann's thrombasthenia in 11 cases of one family

We report here the largest family in Bulgaria with Glanzmann's thrombasthenia which is inherited in an autosomal recessive manner. Eleven children in four successive generations were followed up. Clinically, the disease manifested in mucocutaneous haemorrhages. Five of the children died due to severe haemorrhagic episodes. The diagnosis was confirmed by haemostasic investigation; in some of the children the thrombocytes were examined by electron microscopy. Necessity of prenatal diagnosis is suggested.

Solid tumours in newborns and infants

Thirty two cases of solid tumours in newborns and infants were observed by the authors over a 15 year period. The most common type of tumours were soft tissue tumours (n = 8), neuroblastomas (n = 7), nephroblastomas (n = 5) and germ cell tumours (n = 5). Other types of embryonal tumours such as retinoblastoma and hepatoblastoma were observed in four children and non-Hodgkin's lymphomas in three children. Of 25 children followed up 18 survived. Five children died of their tumours and two children died of causes unrelated to their basic disease. Analysis of the fate of the patients and the effect of the therapy is made. It is concluded that malignant tumours prevail in infancy (90.6% of all cases). The percentage of patients treated successfully with insignificant risk for consequences from radiotherapy and chemotherapy is also high (72%).