Antiviral potential of ivermectin against foot-and-mouth disease virus, serotype O, A and Asia-1

Dual effects of ipecac alkaloids with potent antiviral activity against foot-and-mouth disease virus as replicase inhibitors and direct virucides

Foot-and-Mouth Disease (FMD) is a contagious, blistering disease caused by the Foot-and-Mouth Disease virus (FMDV), which affects livestock globally. Currently, no commercial antiviral agent is available for effective disease control. This study investigated the antiviral potential of natural-derived alkaloids against FMDV in BHK-21 cells. Twelve alkaloids were assessed for their antiviral activities at various stages of FMDV infection, including pre-viral entry, post-viral entry, and prophylactic assays, as well as attachment and penetration assays by evaluating cytopathic effect reduction and directed-virucidal effects. The results showed that ipecac alkaloids, cephaeline (CPL) and emetine (EMT), exhibited dual effects with robust antiviral efficacy by reducing cytopathic effect and inhibiting FMDV replication in a dose-dependent manner. Evaluation through immunoperoxidase monolayer assay and RT-PCR indicated effectiveness at post-viral entry stage, with sub-micromolar EC50 values for CPL and EMT at 0.05 and 0.24 µM, respectively, and high selective indices. Prophylactic effects prevented infection with EC50 values of 0.23 and 0.64 µM, respectively. Directed-virucidal effects demonstrated significant reduction of extracellular FMDV, with CPL exhibiting a dose-dependent effect. Furthermore, the replicase (3Dpol) inhibition activity was identified using the FMDV minigenome assay, which revealed strong inhibition with IC50 values of 0.15 µM for CPL and 4.20 µM for EMT, consistent with the decreased negative-stranded RNA production. Molecular docking confirmed the interaction of CPL and EMT with residues in the active site of FMDV 3Dpol. In conclusion, CPL and EMT exhibited promising efficacy through their dual effects and provide an alternative approach for controlling FMD in livestock.

Ivermectin ameliorates acute myocarditis via the inhibition of importin-mediated nuclear translocation of NF-κB/p65

BACKGROUND

Myocarditis is an important clinical issue which lacks specific treatment by now. Ivermectin (IVM) is an inhibitor of importin α/β-mediated nuclear translocation. This study aimed to explore the therapeutic effects of IVM on acute myocarditis.

METHODS

Mouse models of coxsackie B3 virus (CVB3) infection-induced myocarditis and experimental autoimmune myocarditis (EAM) were established to evaluate the effects of IVM. Cardiac functions were evaluated by echocardiography and Millar catheter. Cardiac inflammatory infiltration was assessed by histological staining. Cytometric bead array and quantitative real-time PCR were used to detect the levels of pro-inflammatory cytokines. The macrophages and their M1/M2 polarization were analyzed via flow cytometry. Protein expression and binding were detected by co-immunoprecipitation, Western blotting and histological staining. The underlying mechanism was verified in vitro using CVB3-infected RAW264.7 macrophages. Cyclic polypeptide (cTN50) was synthesized to selectively inhibit the nuclear translocation of NF-κB/p65, and CVB3-infected RAW264.7 cells were treated with cTN50.

RESULTS

Increased expression of importin β was observed in both models. IVM treatment improved cardiac functions and reduced the cardiac inflammation associated with CVB3-myocarditis and EAM. Furthermore, the pro-inflammatory cytokine (IL-1β/IL-6/TNF-α) levels were downregulated via the inhibition of the nuclear translocation of NF-κB/p65 in macrophages. IVM and cTN50 treatment also inhibited the nuclear translocation of NF-κB/p65 and downregulated the expression of pro-inflammatory cytokines in RAW264.7 macrophages.

CONCLUSIONS

Ivermectin inhibits the nuclear translocation of NF-κB/p65 and the expression of major pro-inflammatory cytokines in myocarditis. The therapeutic effects of IVM on viral and non-viral myocarditis models suggest its potential application in the treatment of acute myocarditis.

Evaluation of genotoxic effect via expression of DNA damage responsive gene induced by ivermectin on MDBK cell line

Ivermectin (IVM) is an anti-parasitic drug which is used for treating parasitic infestations. It has been used in humans for treating intestinal strongyloidiasis and onchocerciasis however, currently researchers are investigating its potential for treating coronavirus SARS-CoV-2. Due to its broad-spectrum activities, IVM is being used excessively in animals which has generated an interest for researchers to investigate its toxic effects. Cytotoxic and genotoxic effects have been reported in animals due to excessive usage of IVM. Therefore, this study aims to evaluate the cytotoxic and genotoxic effects of IVM on the Madin-Darby-Bovine-Kidney (MDBK) cell line by examining the expression of a DNA damage-responsive gene (OGG1). Cytotoxicity of IVM was tested using an assay (MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), whereas the genotoxicity was evaluated using comet assay along with micronucleus assay. Moreover, the gene expression of DNA damage response gene (OGG1) was measured by qRT-PCR, after extraction of RNA from the MDBK cell line using the TRIzol method and its conversion to cDNA by reverse-transcriptase PCR. During the experiment, cell viability percentage was measured at different doses of IVM i.e., 25%, 50%, 75%, along with LC50/2, LC50 and LC50*2. It was observed that the gene expression of OGG1 increased as the concentration of IVM increased. It was concluded that IVM has both cytotoxic and genotoxic effects on the MDBK cell line. Furthermore, it is recommended that studies related to the toxic effects of IVM at molecular level and on other model organisms should be conducted to combat its hazardous effects.

Prophylactic treatment with PEGylated bovine IFNλ3 effectively bridges the gap in vaccine-induced immunity against FMD in cattle

Foot-and-mouth disease (FMD) is a vesicular disease of cloven-hoofed animals with devastating economic implications. The current FMD vaccine, routinely used in enzootic countries, requires at least 7 days to induce protection. However, FMD vaccination is typically not recommended for use in non-enzootic areas, underscoring the need to develop new fast-acting therapies for FMD control during outbreaks. Interferons (IFNs) are among the immune system's first line of defense against viral infections. Bovine type III IFN delivered by a replication defective adenovirus (Ad) vector has effectively blocked FMD in cattle. However, the limited duration of protection-usually only 1-3 days post-treatment (dpt)-diminishes its utility as a field therapeutic. Here, we test whether polyethylene glycosylation (PEGylation) of recombinant bovine IFNλ3 (PEGboIFNλ3) can extend the duration of IFN-induced prevention of FMDV infection in both vaccinated and unvaccinated cattle. We treated groups of heifers with PEGboIFNλ3 alone or in combination with an adenovirus-based FMD O1Manisa vaccine (Adt-O1M) at either 3 or 5 days prior to challenge with homologous wild type FMDV. We found that pre-treatment with PEGboIFNλ3 was highly effective at preventing clinical FMD when administered at either time point, with or without co-administration of Adt-O1M vaccine. PEGboIFNλ3 protein was detectable systemically for >10 days and antiviral activity for 4 days following administration. Furthermore, in combination with Adt-O1M vaccine, we observed a strong induction of FMDV-specific IFNγ+ T cell response, demonstrating its adjuvanticity when co-administered with a vaccine. Our results demonstrate the promise of this modified IFN as a pre-exposure prophylactic therapy for use in emergency outbreak scenarios.

Evaluation of Antiviral Activity of Ivermectin against Infectious Bovine Rhinotracheitis Virus in Rabbit Model

Infectious bovine rhinotracheitis (IBR) caused by bovine herpes virus 1 (BoHV-1) can lead to enormous economic losses in the cattle industry. Vaccine immunization is preferentially used to decrease its transmission speed and resultant clinical signs, rather than to completely stop viral infection. Therefore, a drug effective in treating IBR is urgently needed. Our previous work demonstrated that ivermectin significantly inhibited viral replication in a cell infection model. This study aimed to investigate its antiviral effects in vivo by using a rabbit infection model. The viral inhibition assay was first used to confirm that ivermectin at low concentrations (6-25 nM) could reduce viral titers (TCID50) significantly (p < 0.001) at 24 h post-infection. In rabbits, ivermectin was administrated with one to three doses, based on the recommended anti-parasite treatment dosage (0.2 mg/kg bodyweight) through subcutaneous injection at different days post-infection in the treated IBRV infection groups, while non-treated infection group was used as the control. The infected rabbits showed hyperthermia and other clinical signs, but the number of high-fever rabbits in the ivermectin treatment groups was significantly lower than that in the non-treated infection group. Furthermore, in ivermectin treatment groups, the cumulative clinical scores correlated negatively with drug doses and positively with delay of administration time post-infection. The overall nasal shedding time in ivermectin-treated groups was two days shorter than the non-treated challenge group. At the same time point, the titer of neutralizing antibodies in the treatment group with triple doses was higher than the other two-dose groups, but the difference between the treatment groups decreased with the delay of drug administration. Correspondingly, the serious extent of lung lesions was negatively related to the dosage, but positively related to the delay of drug administration. The qPCR with tissue homogenates showed that the virus was present in both the lung tissues and trigeminals of the infected rabbits. In conclusion, ivermectin treatment had therapeutic effect by decreasing clinical signs and viral shedding, but could not stop virus proliferation in lung tissues and trigeminals.

Lack of antiviral activity of ivermectin against foot-and-mouth disease virus serotype O in BALB/c mice

Ivermectin is an FDA approved drug and showed in vitro antiviral activity against different serotypes of Foot-and-mouth disease virus (FMDV). We here assessed the effect of ivermectin in 12 day old female BALB/c mice infected with 50LD50 FMDV serotype O intraperitoneally. Initially FMDV was adopted on 3-day old BALB/c mice by blind passages. After successful adaptation of virus mice showed hind limb paralysis. Mice were divided in 6 different groups and each group has 6 mice. Ivermectin was given at clinically prescribed dose of 500 μg/kg subcutaneously at different time interval. Ivermectin was given at 0 h post infection (hpi) and 12 hpi. Moreover we compared commercially available ivermectin with purified ivermectin preparation in sterilized DMSO. Viral load was evaluated through RT-qPCR and ELISA in different groups. Results showed that positive control and negative control has CT-value 26.28 and 38 respectively. Treated groups at 0hpi, 12hpi, purified ivermectin and pre-post treatment group has CT values 24.89, 29.44, 27.26 and 26.69 respectively that showed there was no significant reduction in virus load in treated groups as compare to positive control. In histopathology of lung tissue perialveolar capillaries were congested and alveoli were altelactic. Some emphysema was seen in alveoli and mild thickening in the alveolar wall was observed. In the alveolar epithelium mononuclear cells infiltration was seen. There was discoloration haemorrhages and enlargement of heart. Degeneration, fragmentation and loss of sarcoplasm were seen in the cardiac muscle fibers. Above results showed that ivermectin did not lessen lung and heart viral load. This study contributes that ivermectin does not have a significant antiviral effect when used in mice against FMDV serotype O, according to a growing body of research.

Inhibition of bovine and ovine capripoxviruses (Lumpy skin disease virus and Sheeppox virus) by ivermectin occurs at different stages of propagation in vitro

Capripoxvirus diseases are listed as reportable diseases by World Organization for Animal Health (OIE). Lumpy skin disease virus (LSDV) and sheeppox virus (SPPV), which can only be distinguished by molecular analysis, cause moderately, severe, or sometimes fatal infections in cattle and sheep. Even though vaccines are the most effective way to control the infection, their effectiveness may decrease in some cases. Therefore, it is significant to explore antiviral drugs against these diseases along with the vaccine. This study aimed to investigate the antiviral efficiency of ivermectin (IVM) at different stages of in vitro replication of LSDV and SPPV. For this purpose, viral titers (TCID₅₀/mL) of the viruses not treated with IVM (0.0 μM) and treated with non-cytotoxic concentrations of IVM (1.0 and 2.5 μM) were compared during a nine-day (216 h) post-infection period by viral titration assay. At 2.5 μM concentrations of IVM, the mean viral titer was significantly (P<0.05) reduced by approximately three logs for the replication stage of LSDV and SPPV. To evaluate the antiviral activity of IVM against LSDV and SPPV by treatment at the virus attachment and penetration stages, the titers of the virus either untreated or treated with 2,5 μM IVM were compared by virus titration assay. The number of infectious virions for LSDV and SPPV were decreased by 99.82% and 99.87% at the viral replication stage, 68.38% and 25.01% at the attachment stage, and 57.83% and 0.0% at the penetration stage, respectively. It was determined that ivermectin is statistically more effective on LSDV than SPPV at the virus attachment and penetration stages (P<0.05). This study found that the drug IVM can inhibit capripoxviruses, including LSDV and SPPV at various stages of the propagation. Moreover, this research predicted the in vitro antiviral ability of IVM against capripoxvirus infections for the first time.