Influenza A virus is a particularly problematic virus because of its ability to cause high levels of morbidity on a global scale within a remarkably short period of time. It also has the potential to kill very large numbers of people as occurred in the Spanish influenza pandemic in 1918. Options for antiviral therapy are limited because of the paucity of available drugs and the rapid mutation rate of the virus leading to the emergence of drug-resistant strains. The current H1N1 pandemic and potential threats posed by other strains highlight the need to develop novel therapeutic and prophylactic strategies. Here, we summarize the current state and recent developments of peptide-based inhibitors of influenza A virus.
Chikungunya virus (CHIKV) outbreaks have led to a serious economic burden, as the available treatment strategies can only alleviate disease symptoms, and no effective therapeutics or vaccines are currently available for human use. Here, we report the use of a new cost-effective approach involving production of a recombinant antiviral peptide-fusion protein that is scalable for the treatment of CHIKV infection. A peptide-fusion recombinant protein LATA-PAP1-THAN that was generated by joining Latarcin (LATA) peptide with the N-terminus of the PAP1 antiviral protein, and the Thanatin (THAN) peptide to the C-terminus, was produced in Escherichia coli as inclusion bodies. The antiviral LATA-PAP1-THAN protein showed 89.0% reduction of viral plaque formation compared with PAP1 (46.0%), LATA (67.0%) or THAN (79.3%) peptides alone. The LATA-PAP1-THAN protein reduced the viral RNA load that was 0.89-fold compared with the untreated control cells. We also showed that PAP1 resulted in 0.44-fold reduction, and THAN and LATA resulting in 0.78-fold and 0.73-fold reductions, respectively. The LATA-PAP1-THAN protein inhibited CHIKV replication in the Vero cells at an EC50 of 11.2μg/ml, which is approximately half of the EC50 of PAP1 (23.7μg/ml) and protected the CHIKV-infected mice at the dose of 0.75mg/ml. We concluded that production of antiviral peptide-fusion protein in E. coli as inclusion bodies could accentuate antiviral activities, enhance cellular internalisation, and could reduce product toxicity to host cells and is scalable to epidemic response quantities.
Doxycycline is an antibiotic derived from tetracycline that possesses antimicrobial and anti-inflammatory activities. Antiviral activity of doxycycline against dengue virus has been reported previously; however, its anti-dengue properties need further investigation. This study was conducted to determine the potential activity of doxycycline against dengue virus replication in vitro. Doxycycline inhibited the dengue virus serine protease (DENV2 NS2B-NS3pro) with an IC50 value of 52.3 ± 6.2 μM at 37 °C (normal human temperature) and 26.7 ± 5.3 μM at 40 °C (high fever temperature). The antiviral activity of doxycycline was first tested at different concentrations against DENV2 using a plaque-formation assay. The virus titter decreased significantly after applying doxycycline at levels lower than its 50 % cytotoxic concentration (CC50, 100 μM), showing concentration-dependent inhibition with a 50 % effective concentration (EC50) of approximately 50 μM. Doxycycline significantly inhibited viral entry and post-infection replication of the four dengue serotypes, with serotype-specific inhibition (high activity against DENV2 and DENV4 compared to DENV1 and DENV3). Collectively, these findings underline the need for further experimental and clinical studies on doxycycline, utilizing its anti-dengue and anti-inflammatory activities to attenuate the clinical symptoms of dengue virus infection.
Dengue virus infects millions of people worldwide, and there is no vaccine or anti-dengue therapeutic available. Antimicrobial peptides have been shown to possess effective antiviral activity against various viruses. One of the main limitations of developing these peptides as potent antiviral drugs is the high cost of production. In this study, high yield production of biologically active plectasin peptide was inexpensively achieved by producing tandem plectasin peptides as inclusion bodies in E. coli. Antiviral activity of the recombinant peptide towards dengue serotype-2 NS2B-NS3 protease (DENV2 NS2B-NS3pro) was assessed as a target to inhibit dengue virus replication in Vero cells. Single units of recombinant plectasin were collected after applying consecutive steps of refolding, cleaving by Factor Xa, and nickel column purification to obtain recombinant proteins of high purity. The maximal nontoxic dose (MNTD) of the recombinant peptide against Vero cells was 20 μM (100 μg/mL). The reaction velocity of DENV2 NS2B-NS3pro decreased significantly after increasing concentrations of recombinant plectasin were applied to the reaction mixture. Plectasin peptide noncompetitively inhibited DENV2 NS2B-NS3pro at Ki value of 5.03 ± 0.98 μM. The percentage of viral inhibition was more than 80% at the MNTD value of plectasin. In this study, biologically active recombinant plectasin which was able to inhibit dengue protease and viral replication in Vero cells was successfully produced in E. coli in a time- and cost- effective method. These findings are potentially important in the development of potent therapeutics against dengue infection.
Chikungunya virus (CHIKV) infection is a persistent problem worldwide due to efficient adaptation of the viral vectors, Aedes aegypti and Aedes albopictus mosquitoes. Therefore, the absence of effective anti-CHIKV drugs to combat chikungunya outbreaks often leads to a significant impact on public health care. In this study, we investigated the antiviral activity of drugs that are used to alleviate infection symptoms, namely, the non-steroidal anti-inflammatory drugs (NSAIDs), on the premise that active compounds with potential antiviral and anti-inflammatory activities could be directly subjected for human use to treat CHIKV infections. Amongst the various NSAID compounds, Mefenamic acid (MEFE) and Meclofenamic acid (MECLO) showed considerable antiviral activity against viral replication individually or in combination with the common antiviral drug, Ribavirin (RIBA). The 50% effective concentration (EC50) was estimated to be 13 μM for MEFE, 18 μM for MECLO and 10 μM for RIBA, while MEFE + RIBA (1:1) exhibited an EC50 of 3 μM, and MECLO + RIBA (1:1) was 5 μM. Because MEFE is commercially available and its synthesis is easier compared with MECLO, MEFE was selected for further in vivo antiviral activity analysis. Treatment with MEFE + RIBA resulted in a significant reduction of hypertrophic effects by CHIKV on the mouse liver and spleen. Viral titre quantification in the blood of CHIKV-infected mice through the plaque formation assay revealed that treatment with MEFE + RIBA exhibited a 6.5-fold reduction compared with untreated controls. In conclusion, our study demonstrated that MEFE in combination with RIBA exhibited significant anti-CHIKV activity by impairing viral replication in vitro and in vivo. Indeed, this finding may lead to an even broader application of these combinatorial treatments against other viral infections.
Lack of vaccine and effective antiviral drugs against chikungunya virus (CHIKV) outbreaks have led to significant impact on health care in the developing world. Here, we evaluated the antiviral effects of tetracycline (TETRA) derivatives and other common antiviral agents against CHIKV. Our results showed that within the TETRA derivatives group, Doxycycline (DOXY) exhibited the highest inhibitory effect against CHIKV replication in Vero cells. On the other hand, in the antiviral group Ribavirin (RIBA) showed higher inhibitory effects against CHIKV replication compared to Aciclovir (ACIC). Interestingly, RIBA inhibitory effects were also higher than all but DOXY within the TETRA derivatives group. Docking studies of DOXY to viral cysteine protease and E2 envelope protein showed non-competitive interaction with docking energy of -6.6±0.1 and -6.4±0.1 kcal/mol respectively. The 50% effective concentration (EC50) of DOXY and RIBA was determined to be 10.95±2.12 μM and 15.51±1.62 μM respectively, while DOXY+RIBA (1:1 combination) showed an EC50 of 4.52±1.42 μM. When compared, DOXY showed higher inhibition of viral infectivity and entry than RIBA. In contrast however, RIBA showed higher inhibition against viral replication in target cells compared to DOXY. Assays using mice as animal models revealed that DOXY+RIBA effectively inhibited CHIKV replication and attenuated its infectivity in vivo. Further experimental and clinical studies are warranted to investigate their potential application for clinical intervention of CHIKV disease.
Matched MeSH terms: Antiviral Agents/pharmacology*; Antiviral Agents/therapeutic use
Dengue virus (DENV) and Zika virus (ZIKV) are flaviviruses transmitted to humans by their common vector, Aedes mosquitoes. DENV infection represents one of the most widely spread mosquito-borne diseases whereas ZIKV infection occasionally re-emerged in the past causing outbreaks. Although there have been considerable advances in understanding the pathophysiology of these viruses, no effective vaccines or antiviral drugs are currently available. In this study, we evaluated the antiviral activity of carnosine, an endogenous dipeptide (β-alanyl-l-histidine), against DENV serotype 2 (DENV2) and ZIKV infection in human liver cells (Huh7). Computational studies were performed to predict the potential interactions between carnosine and viral proteins. Biochemical and cell-based assays were performed to validate the computational results. Mode-of-inhibition, plaque reduction, and immunostaining assays were performed to determine the antiviral activity of carnosine. Exogenous carnosine showed minimal cytotoxicity in Huh7 cells and rescued the viability of infected cells with EC50 values of 52.3 and 59.5 μM for DENV2 and ZIKV infection, respectively. Based on the mode-of-inhibition assays, carnosine inhibited DENV2 mainly by inhibiting viral genome replication and interfering with virus entry. Carnosine antiviral activity was verified with immunostaining assay where carnosine treatment diminished viral fluorescence signal. In conclusion, carnosine exhibited significant inhibitory effects against DENV2 and ZIKV replication in human liver cells and could be utilized as a lead peptide for the development of effective and safe antiviral agents against DENV and ZIKV.
Dengue virus infects millions of people worldwide and there is no vaccine or anti-dengue therapeutic available. Screening large numbers of medicinal plants for anti-dengue activities is an alternative strategy in order to find the potent therapeutic compounds. Therefore, this study was designed to identify anti-dengue activities in nineteen medicinal plant extracts that are used in traditional medicine. Local medicinal plants Vernonia cinerea, Hemigraphis reptans, Hedyotis auricularia, Laurentia longiflora, Tridax procumbers and Senna angustifolia were used in this study. The highest inhibitory activates against dengue NS2B-NS3pro was observed in ethanolic extract of S. angustifolia leaves, methanolic extract of V. cinerea leaves and ethanol extract of T. procumbens stems. These findings were further verified by in vitro viral inhibition assay. Methanolic extract of V. cinerea leaves, ethanol extract of T. procumbens stems and at less extent ethanolic extract of S. angustifolia leaves were able to maintain the normal morphology of DENV2-infected Vero cells without causing much cytopathic effects (CPE). The percentage of viral inhibition of V. cinerea and T. procumbens extracts were significantly higher than S. angustifolia extract as measured by plaque formation assay and RT-qPCR. In conclusion, The outcome of this study showed that the methanolic extract of V. cinerea leaves and ethanol extract of T. procumbens stems possessed high inhibitory activates against dengue virus that worth more investigation.
Dengue viruses, mosquito-borne members of the Flaviviridae family, are the causative agents of dengue fever and its associated complications, dengue haemorrhagic fever and dengue shock syndrome. To date, more than 2.5 billion people in over 100 countries are at risk of infection, and approximately 20 million infections were reported annually. There is currently no treatment or vaccine available for dengue infection. This study employed a whole-cell organism model or in vitro methods to study the inhibitory property of the flavanoid-derived compounds against DENV2 activity. Results showed that at concentration not exceeding the maximum non-toxic dose (MNTD), these compounds completely prevented DENV2 infection in HepG2 cells as indicated by the absence of cytophatic effects. The in vitro antiviral activity assessed in HepG2 cells employing virus inhibition assay showed high inhibitory activity in a dose dependent manner. At concentration below MNTD, compounds exhibited inhibitory activity against DENV2 with a range of potency strengths of 72% to 100%. The plaque forming unit per ml (pfu/ml) was reduced prominently with a maximum reduction of 98% when the infected HepG2 cells were treated with the highest non-toxic dose of compounds. The highly potent activity of the compounds against DENV2 infection strongly suggests their potential as a lead antiviral agent for dengue.
Matched MeSH terms: Antiviral Agents/pharmacology*; Antiviral Agents/therapeutic use
The Asia-Pacific region has disparate hepatitis C virus (HCV) epidemiology, with prevalence ranging from 0·1% to 4·7%, and a unique genotype distribution. Genotype 1b dominates in east Asia, whereas in south Asia and southeast Asia genotype 3 dominates, and in Indochina (Vietnam, Cambodia, and Laos), genotype 6 is most common. Often, availability of all-oral direct-acting antivirals (DAAs) is delayed because of differing regulatory requirements. Ideally, for genotype 1 infections, sofosbuvir plus ledipasvir, sofosbuvir plus daclatasvir, or ombitasvir, paritaprevir, and ritonavir plus dasabuvir are suitable. Asunaprevir plus daclatasvir is appropriate for compensated genotype 1b HCV if baseline NS5A mutations are absent. For genotype 3 infections, sofosbuvir plus daclatasvir for 24 weeks or sofosbuvir, daclatasvir, and ribavirin for 12 weeks are the optimal oral therapies, particularly for patients with cirrhosis and those who are treatment experienced, whereas sofosbuvir, pegylated interferon, and ribavirin for 12 weeks is an alternative regimen. For genotype 6, sofosbuvir plus pegylated interferon and ribavirin, sofosbuvir plus ledipasvir, or sofosbuvir plus ribavirin for 12 weeks are all suitable. Pegylated interferon plus ribavirin has been replaced by sofosbuvir plus pegylated interferon and ribavirin, and all-oral therapies where available, but cost and affordability remain a major issue because of the absence of universal health coverage. Few patients have been treated because of multiple barriers to accessing care. HCV in the Asia-Pacific region is challenging because of the disparate epidemiology, poor access to all-oral therapy because of availability, cost, or regulatory licensing. Until these problems are addressed, the burden of disease is likely to remain high.
A simple high-performance liquid chromatographic method using fluorescence detection was developed for the determination of acyclovir in human plasma. The method entailed direct injection of the plasma sample after deproteination. It is both specific and sensitive with a detection limit of 30 ng/ml at a signal-to-noise ratio of 3:1, and is thus suitable for use in pharmacokinetic studies of acyclovir. The method had a mean absolute recovery of 96%, while the within-day and between-day coefficients of variation and percentages error were all less than 8%. The calibration curve was linear over a concentration range of 62.5-4000 ng/ml.
Introduction: The incidence of antimicrobial resistance (AMR) has increased worldwide including Malaysia, which may be attributed partly to inappropriate prescribing of antimicrobials. Antimicrobial prescribing form has been introduced to mandate appropriate antimicrobial prescription including documented indication as a key standard of antimicrobial stewardship practice. Hence, this current study aimed to determine the usage and completeness of the designated antimicrobial prescribing form that had been implemented in the General Intensive Care Unit (GICU), Universiti Kebangsaan Malaysia Medical Centre (UKMMC). Methods: This prospective observational study was carried out in GICU UKMMC from 30 August 2018 to 30 November 2018 by convenience sampling. The information that was recorded in the antimicrobial prescribing form was collected by using the designated data collection form. A total of 68 patients were included and 205 antimicrobial prescribing forms were evaluated. Results: There were 100% usage of antimicrobial prescribing forms found in this study. However, only 81 ± 8 % of these forms were completely filled. Indication for the antimicrobial prescription was not filled in 47% of the forms. Almost two thirds of the antimicrobial prescriptions were empirically indicated and one percent de-escalation of antimicrobial therapy was filled in the forms. These prescriptions comprised of 91.7% antibiotics, 7.8% antifungals and 0.5% antivirals. The suspected site of infections were primarily from the lungs (27%), gastrointestinal (16%), blood (16%) and central nervous system (14%). Piperacillin/Tazobactam was the most frequent antibiotic prescribed (21%), followed by third and fourth generation cephalosporins (20%). Conclusion: This study provided an overview of the uptake of the antimicrobial prescribing form implementation and highlighted the requirement for supplementary efforts to maximize the compliance of this form.
Nipah and Hendra virus were first identified in mid 1990s in Australia and Malaysia, caus- ing epidemics with high mortality rate in affected animals and humans. Since their first emer- gence, they continued to re-emerge in Australia and South East Asia almost every year. Nipah and Hendra virus were classified in the new genus Henipavirus because of their un- common features amongst Paramyxoviridae. Henipaviruses are zoonotic paramyxoviruses with a broad tropism, and cause severe acute respiratory disease and encephalitis. Their high virulence and wide host range make them to be given Biosecurity Level 4 status. This review summarizes details of Henipavirus emergence, reservoir hosts and pathology, and introduce recent progress in vaccines and antivirals.
Matched MeSH terms: Antiviral Agents/therapeutic use
Nucleobases serve as essential molecular frameworks present in both natural and synthetic compounds that exhibit notable antiviral activity. Through molecular modifications, novel nucleobase-containing drugs (NCDs) have been developed, exhibiting enhanced antiviral activity against a wide range of viruses, including the recently emerged SARS‑CoV‑2. This article provides a detailed examination of the significant advancements in NCDs from 2015 till current, encompassing various aspects concerning their mechanisms of action, pharmacology and antiviral properties. Additionally, the article discusses antiviral prodrugs relevant to the scope of this review. It fills in the knowledge gap by examining the structure-activity relationship and trend of NCDs as therapeutics against a diverse range of viral diseases, either as approved drugs, clinical candidates or as early-stage development prospects. Moreover, the article highlights on the status of this field of study and addresses the prevailing limitations encountered.
Matched MeSH terms: Antiviral Agents/pharmacology; Antiviral Agents/therapeutic use
Dengue virus (DENV) infection causes mild to severe illness in humans that can lead to fatality in severe cases. Currently, no specific drug is available for the treatment of DENV infection. Thus, the development of an anti-DENV drug is urgently required. Cordycepin (3'-deoxyadenosine), which is a major bioactive compound in Cordyceps (ascomycete) fungus that has been used for centuries in Chinese traditional medicine, was reported to exhibit antiviral activity. However, the anti-DENV activity of cordycepin is unknown. We hypothesized that cordycepin exerts anti-DENV activity and that, as an adenosine derivative, it inhibits DENV replication. To test this hypothesis, we investigated the anti-DENV activity of cordycepin in DENV-infected Vero cells. Cordycepin treatment significantly decreased DENV protein at a half-maximal effective concentration (EC50) of 26.94 μM. Moreover, DENV RNA was dramatically decreased in cordycepin-treated Vero cells, indicating its effectiveness in inhibiting viral RNA replication. Via in silico molecular docking, the binding of cordycepin to DENV non-structural protein 5 (NS5), which is an important enzyme for RNA synthesis, at both the methyltransferase (MTase) and RNA-dependent RNA polymerase (RdRp) domains, was predicted. The results of this study demonstrate that cordycepin is able to inhibit DENV replication, which portends its potential as an anti-dengue therapy.
C-5-bromo-2-hydroxyphenylcalix[4]-2-methylresorcinarene (I) was synthesized by cyclocondensation of 5-bromo-2-hydroxybenzaldehyde and 2-methylresorcinol in the presence of concentrated HCl. Compound I was characterized by infrared and nuclear magnetic resonance spectroscopic data. X-ray analysis showed that this compound crystallized in a triclinic system with space group of Pī, a = 15.9592(16)Å, b = 16.9417(17)Å, c = 17.0974(17)Å, α = 68.656(3)°, β = 85.689(3)°, γ = 81.631(3)°, Z = 2 and V = 4258.6(7)Å3. The molecule adopts a chair (C2h) conformation. The thermal properties and antioxidant activity were also investigated. It was strongly antiviral against HSV-1 and weakly antibacterial against Gram-positive bacteria. Cytotoxicity testing on Vero cells showed that it is non-toxic, with a CC50 of more than 0.4 mg/mL.
Rhinoviruses (RV), especially Human rhinovirus (HRVs) have been accepted as the most common cause for upper respiratory tract infections (URTIs). Pleconaril, a broad spectrum anti-rhinoviral compound, has been used as a drug of choice for URTIs for over a decade. Unfortunately, for various complications associated with this drug, it was rejected, and a replacement is highly desirable. In silico screening and prediction methods such as sub-structure search and molecular docking have been widely used to identify alternative compounds. In our study, we have utilised sub-structure search to narrow down our quest in finding relevant chemical compounds. Molecular docking studies were then used to study their binding interaction at the molecular level. Interestingly, we have identified 3 residues that is worth further investigation in upcoming molecular dynamics simulation systems of their contribution in stable interaction.
We have developed and characterised a mouse model of Japanese encephalitis virus (JEV) infection via
footpad inoculation in order to better mimic viral transmission by mosquito bites. Two-week-old and
5-week-old mice consistently developed signs of infection such as ruffled fur, weight loss, hunchback
posture, tremors, mask-like facies and occasionally, hindlimb paralysis at 4 days post infection (dpi)
and 11-13 dpi, respectively. Most of the animals died within 24 to 48 hours following the onset of signs
of infection, with mortalities of 100% and 33.3% in 2-week-old and 5-week-old mice, respectively.
Mild meningitis and variable parenchymal inflammation with formation of microglial nodules, focal
necrosis and neuronophagia, and perivascular cuffing by inflammatory cells were observed in the
caudate nucleus, putamen, thalamus, cerebral cortex, brainstem, and spinal cord. Viral antigens/RNA
were demonstrated by immunohistochemisty and in situ hybridization, respectively, in most of these
areas as well as in the hippocampus and cerebellum, albeit more focally. The pathological findings in
this mouse model were generally similar to human Japanese encephalitis (JE) and other established JE
models but perhaps, compared to other JEV mouse models, it demonstrates lethal encephalitic infection
more consistently. We believe that our mouse model should be useful to study the pathogenesis of JE,
and for testing anti-viral drugs and vaccines
The coronavirus pandemic, COVID-19 has a global impact on the lives and livelihoods of people. It is characterized by a widespread infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), where infected patients may develop serious medical complications or even face death. Development of therapeutic is essential to reduce the morbidity and mortality of infected patients. Chitosan is a versatile biomaterial in nanomedicine and exhibits anti-microbial, anti-cancer and immunomodulatory properties. This review highlights the progress in chitosan design and application pertaining to the anti-viral effects of chitosan and chitosan derivatives (hydroxypropyl trimethylammonium, sulfate, carboxymethyl, bromine, sialylglycopolymer, peptide and phosphonium conjugates) as a function of molecular weight, degree of deacetylation, type of substituents and their degree and site of substitution. The physicochemical attributes of these polymeric therapeutics are identified against the possibility of processing them into nanomedicine which can confer a higher level of anti-viral efficacy. The designs of chitosan for the purpose of targeting SARS-CoV-2, as well as the ever-evolving strains of viruses with a broad spectrum anti-viral activity to meet pandemic preparedness at the early stages of outbreak are discussed.