Effects of RNA interference therapy against herpes simplex virus type 1 encephalitis

Flexible nano-liposomes-encapsulated recombinant UL8-siRNA (r/si-UL8) based on bioengineering strategy inhibits herpes simplex virus-1 infection

Herpes simplex virus-1 (HSV-1) infection can cause various diseases and the current therapeutics have limited efficacy. Small interfering RNA (siRNA) therapeutics are a promising approach against infectious diseases by targeting the viral mRNAs directly. Recently, we employed a novel tRNA scaffold to produce recombinant siRNA agents with few natural posttranscriptional modifications. In this study, we aimed to develop a specific prodrug against HSV-1 infection based on siRNA therapeutics by bioengineering technology. We screened and found that UL8 of the HSV-1 genome was an ideal antiviral target based on RNAi. Next, we used a novel bio-engineering approach to manufacture recombinant UL8-siRNA (r/si-UL8) in Escherichia coli with high purity and activity. The r/si-UL8 was selectively processed to mature si-UL8 and significantly reduced the number of infectious virions in human cells. r/si-UL8 delivered by flexible nano-liposomes significantly decreased the viral load in the skin and improved the survival rate in the preventive mouse zosteriform model. Furthermore, r/si-UL8 also effectively inhibited HSV-1 infection in a 3D human epidermal skin model. Taken together, our results highlight that the novel siRNA bioengineering technology is a unique addition to the conventional approach for siRNA therapeutics and r/si-UL8 may be a promising prodrug for curing HSV-1 infection.

Nanosystems for gene therapy targeting brain damage caused by viral infections

Several human pathogens can cause long-lasting neurological damage. Despite the increasing clinical knowledge about these conditions, most still lack efficient therapeutic interventions. Gene therapy (GT) approaches comprise strategies to modify or adjust the expression or function of a gene, thus providing therapy for human diseases. Since recombinant nucleic acids used in GT have physicochemical limitations and can fail to reach the desired tissue, viral and non-viral vectors are applied to mediate gene delivery. Although viral vectors are associated to high levels of transfection, non-viral vectors are safer and have been further explored. Different types of nanosystems consisting of lipids, polymeric and inorganic materials are applied as non-viral vectors. In this review, we discuss potential targets for GT intervention in order to prevent neurological damage associated to infectious diseases as well as the role of nanosized non-viral vectors as agents to help the selective delivery of these gene-modifying molecules. Application of non-viral vectors for delivery of GT effectors comprise a promising alternative to treat brain inflammation induced by viral infections.

Liposomal siRNA Formulations for the Treatment of Herpes Simplex Virus-1: In Vitro Characterization of Physicochemical Properties and Activity, and In Vivo Biodistribution and Toxicity Studies

Herpes simplex virus-1 (HSV-1) is highly contagious, and there is a need for a therapeutic means to eradicate it. We have identified an siRNA (siHSV) that knocks down gene expression of the infected cell protein 0 (ICP0), which is important in the regulation of HSV infection. The selected siHSV was encapsulated in liposomes to overcome its poor stability, increase cell permeability, and prolonging siRNA circulation time. Several siRNAs against ICP0 have been designed and identified. We examined the role of various parameters, including formulation technique, lipids composition, and ratio. An optimal liposomal siHSV formulation (LipDOPE-siHSV) was characterized with desirable physiochemical properties, in terms of nano-size, low polydispersity index (PDI), neutral surface charge, high siHSV loading, spherical shape, high stability in physiologic conditions in vitro, and long-term shelf-life stability (>1 year, 4 °C). The liposomes exhibited profound internalization by human keratinocytes, no cytotoxicity in cell cultures, no detrimental effect on mice liver enzymes, and a gradual endo-lysosomal escape. Mice biodistribution studies in intact mice revealed accumulation, mainly in visceral organs but also in the trigeminal ganglion. The therapeutic potential of siHSV liposomes was demonstrated by significant antiviral activity both in the plaque reduction assay and in the 3D epidermis model, and the mechanism of action was validated by the reduction of ICP0 expression levels.

siRNA intervention inhibiting viral replication and delivery strategies for treating herpes simplex viral infection

The effective treatment of herpes simplex virus (HSV) infections generally involves the use of antiviral nucleoside drugs, but with increasing reports of antiviral resistance, the use of these drugs is challenged. Hence, a need arises to explore alternate treatment options. In this review we have discussed various targets that have been explored to control the HSV replication using siRNA therapeutics. We have also discussed the advantages of targeting a less explored UL10 gene to develop an alternate therapeutic intervention. Gene silencing can induce an inhibitory activity to virus spread and infection. The capacity and suitability of UL10 gene as siRNA induced silencing target in eliciting the desired antiviral effect in patients is identified and particularly discussed. The major challenge associated with the siRNA therapeutics is their delivery. The various viable delivery options, that are being explored in the recent times is summarized and different delivery pathways and strategies are reviewed as a part of the study.

Pharmacokinetics and Drug-Drug Interactions of Lopinavir-Ritonavir Administered with First- and Second-Line Antituberculosis Drugs in HIV-Infected Children Treated for Multidrug-Resistant Tuberculosis

Lopinavir-ritonavir forms the backbone of current first-line antiretroviral regimens in young HIV-infected children. As multidrug-resistant (MDR) tuberculosis (TB) frequently occurs in young children in high-burden TB settings, it is important to identify potential interactions between MDR-TB treatment and lopinavir-ritonavir. We describe the pharmacokinetics of and potential drug-drug interactions between lopinavir-ritonavir and drugs routinely used for MDR-TB treatment in HIV-infected children. A combined population pharmacokinetic model was developed to jointly describe the pharmacokinetics of lopinavir and ritonavir in 32 HIV-infected children (16 with MDR-TB receiving treatment with combinations of high-dose isoniazid, pyrazinamide, ethambutol, ethionamide, terizidone, a fluoroquinolone, and amikacin and 16 without TB) who were established on a lopinavir-ritonavir-containing antiretroviral regimen. One-compartment models with first-order absorption and elimination for both lopinavir and ritonavir were combined into an integrated model. The dynamic inhibitory effect of the ritonavir concentration on lopinavir clearance was described using a maximum inhibition model. Even after adjustment for the effect of body weight with allometric scaling, a large variability in lopinavir and ritonavir exposure, together with strong correlations between the pharmacokinetic parameters of lopinavir and ritonavir, was detected. MDR-TB treatment did not have a significant effect on the bioavailability, clearance, or absorption rate constants of lopinavir or ritonavir. Most children (81% of children with MDR-TB, 88% of controls) achieved therapeutic lopinavir trough concentrations (>1 mg/liter). The coadministration of lopinavir-ritonavir with drugs routinely used for the treatment of MDR-TB was found to have no significant effect on the key pharmacokinetic parameters of lopinavir or ritonavir. These findings should be considered in the context of the large interpatient variability found in the present study and the study's modest sample size.

Topical treatment of herpes simplex virus infection with enzymatically created siRNA swarm

BACKGROUND

Herpes simplex virus (HSV) is a common human pathogen. Despite current antivirals, it causes a significant medical burden. Drug resistant strains exist and they are especially prevalent in immunocompromised patients and in HSV eye infections. New treatment modalities are needed.

METHODS

BALB/c mice were corneally infected with HSV and subsequently treated with a swarm of enzymatically created, Dicer-substrate small interfering RNA (siRNA) molecules that targeted the HSV gene UL29. Two infection models were used, one in which the infection was predominantly peripheral and another in which it spread to the central nervous system. Mouse survival, as well as viral spread, load, latency and peripheral shedding, was studied.

RESULTS

The anti-HSV-UL29 siRNA swarm alleviated HSV infection symptoms, inhibited viral shedding and replication and had a favourable effect on mouse survival.

CONCLUSIONS

Treatment with anti-HSV-UL29 siRNA swarm reduced symptoms and viral spread in HSV infection of mice and also inhibited local viral replication in mouse corneas.

Are Prophylactic and Therapeutic Target Concentrations Different?: the Case of Lopinavir-Ritonavir or Lamivudine Administered to Infants for Prevention of Mother-to-Child HIV-1 Transmission during Breastfeeding

The ANRS 12174 trial assessed the efficacy and tolerance of lopinavir (LPV)-ritonavir (LPV/r) prophylaxis versus those of lamivudine (3TC) prophylaxis administered to breastfed infants whose HIV-infected mothers were not on antiretroviral therapy. In this substudy, we assessed LPV/r and 3TC pharmacokinetics to evaluate the percentage of infants with therapeutic plasma concentrations and to discuss these data in the context of a prophylactic treatment. Infants from the South African trial site underwent blood sampling for pharmacokinetic study at weeks 6, 26, and 38 of life. We applied a Bayesian approach to derive the 3TC and LPV pharmacokinetic parameters on the basis of previously published pharmacokinetic models for HIV-infected children. We analyzed 114 LPV and 180 3TC plasma concentrations from 69 infants and 92 infants, respectively. A total of 30 LPV and 20 3TC observations were considered missing doses and discarded from the Bayesian analysis. The overall population analysis showed that 30 to 40% of the infants did not reach therapeutic targets, regardless of treatment group. The median LPV trough concentrations at weeks 6, 26, and 38 were 2.8 mg/liter (interquartile range [IQR], 1.7 to 4.4 mg/liter), 5.6 mg/liter (IQR, 3.2 to 7.7 mg/liter), and 3.4 mg/liter (IQR, 2.3 to 7.3 mg/liter), respectively. The median 3TC area under the curve from 0 to 12 h after the last drug intake were 5.6 mg · h/liter (IQR, 4.1 to 7.8 mg · h/liter), 5.9 mg · h/liter (IQR, 5.1 to 7.5 mg · h/liter), and 7.3 mg · h/liter (IQR, 4.9 to 8.5 mg · h/liter) at weeks 6, 26, and 38, respectively. Use of the therapeutic doses recommended by the WHO would have resulted in a higher proportion of infants achieving the targets. However, no HIV-1 infection was reported among these infants. These results suggest that the prophylactic targets for both 3TC and LPV may be lower than the therapeutic ones. For treatment, the WHO dosing guidelines should be suitable to maintain values above the therapeutic pharmacokinetic targets in most infants. (This study has been registered at ClinicalTrials.gov under identifier NCT00640263.).

Optimization of the strength of the efavirenz/lamivudine/abacavir fixed-dose combination for paediatric patients

BACKGROUND

Child-friendly, low-cost, solid, oral fixed-dose combinations (FDCs) of efavirenz with lamivudine and abacavir are urgently needed to improve clinical management and drug adherence for children.

METHODS

Data were pooled from several clinical trials and therapeutic drug monitoring datasets from different countries. The number of children/observations was 505/3667 for efavirenz. Population pharmacokinetic analyses were performed using a non-linear mixed-effects approach. For abacavir and lamivudine, data from 187 and 920 subjects were available (population pharmacokinetic models previously published). Efavirenz/lamivudine/abacavir FDC strength options assessed were (I) 150/75/150, (II) 120/60/120 and (III) 200/100/200 mg. Monte Carlo simulations of the different FDC strengths were performed to determine the optimal dose within each of the WHO weight bands based on drug efficacy/safety targets.

RESULTS

The probability of being within the target efavirenz concentration range 12 h post-dose (1-4 mg/L) varied between 56% and 60%, regardless of FDC option. Option I provided a best possible balance between efavirenz treatment failure and toxicity risks. For abacavir and lamivudine, simulations showed that for option I >75% of subjects were above the efficacy target.

CONCLUSIONS

According to simulations, a paediatric efavirenz/lamivudine/abacavir fixed-dose formulation of 150 mg efavirenz, 75 mg lamivudine and 150 mg abacavir provided the most effective and safe concentrations across WHO weight bands, with the flexibility of dosage required across the paediatric population.