Repeat dose and reproductive toxicity of thrombopoietin mimic peptide in Sprague-Dawley rats.

Thrombopoietin mimic peptide (TMP) is a novel thrombopoietin receptor agonist. In this report, we evaluated the potential toxicity of TMP in repeat-dose toxicity and reproductive/developmental toxicity studies (segment Ⅰ, Ⅱ, Ⅲ). TMP was administered subcutaneously to Sprague-Dawley (SD) rats at 5, 15 or 50 mcg/kg. In repeat-dose toxicity study, the rats were administrated three times a week for 26 week with a 4-week recovery. TMP could produce anti-drug antibodies and induce platelet counts increase, megakaryocyte proliferation. While platelet counts decreased gradually and returned to normal after 4 weeks in male rats. Other significant findings included myelofibrosis of bone marrow, hepatic extramedullary hematopoiesis, splenic lymphocytic depletion and bone hyperostosis. All treatment-related effects were reversed following recovery. The NOAEL of repeat-dose toxicity in female rats is 5 mcg/kg. In the reproductive/developmental toxicity (segment Ⅰ, Ⅲ), no deaths occurred, and no general toxicological effects or abnormal reproductive functions were observed. In embryo-fetal developmental toxicity study (segment Ⅱ), the number of resorbed fetuses in the 50 mcg/kg group was significantly increased. The NOAEL as related to reproductive/developmental toxicity in these rats was 15 mcg/kg.

Engineered Gut Symbiotic Bacterium-Mediated RNAi for Effective Control of Anopheles Mosquito Larvae.

Anopheles mosquitoes are the primary vectors for the transmission of malaria parasites, which poses a devastating burden on global public health and welfare. The recent invasion of Anopheles stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides. To address this issue, we developed a new approach for mosquito larvae control using gut microbiota-mediated RNA interference (RNAi). We engineered a mosquito symbiotic gut bacterium, Serratia fonticola, by deleting its RNase III gene to produce double-stranded RNAs (dsRNAs) in the mosquito larval gut. We found that the engineered S. fonticola strains can stably colonize mosquito larval guts and produce dsRNAs dsMet or dsEcR to activate RNAi and effectively suppress the expression of methoprene-tolerant gene Met and ecdysone receptor gene EcR, which encode receptors for juvenile hormone and ecdysone pathways in mosquitoes, respectively. Importantly, the engineered S. fonticola strains markedly inhibit the development of A. stephensi larvae and leads to a high mortality, providing an effective dsRNA delivery system for silencing genes in insects and a novel RNAi-mediated pest control strategy. Collectively, our symbiont-mediated RNAi (smRNAi) approach offers an innovative and sustainable method for controlling mosquito larvae and provides a promising strategy for combating malaria. IMPORTANCE Mosquitoes are vectors for various diseases, imposing a significant threat to public health globally. The recent invasion of A. stephensi in Africa has made malaria eradication more challenging due to its outdoor biting behavior and widespread resistance to insecticides. RNA interference (RNAi) is a promising approach that uses dsRNA to silence specific genes in pests. This study presents the use of a gut symbiotic bacterium, Serratia fonticola, as an efficient delivery system of dsRNA for RNAi-mediated pest control. The knockout of RNase III, a dsRNA-specific endonuclease gene, in S. fonticola using CRISPR-Cas9 led to efficient dsRNA production. Engineered strains of S. fonticola can colonize the mosquito larval gut and effectively suppress the expression of two critical genes, Met and EcR, which inhibit mosquito development and cause high mortality in mosquito larvae. This study highlights the potential of exploring the mosquito microbiota as a source of dsRNA for RNAi-based pest control.

Developmental and reproduction toxicity studies of Biolimus A9 in SD rats.

Biolimus A9 (BA9) is a novel rapamycin derivative. In this report we evaluated the potential toxicity of BA9 in a developmental and reproduction toxicity study (segment Ⅰ, Ⅱ, Ⅲ). In segment I, body weight gains in F0 rats receiving 0.80 mg/kg/day were decreased. A lower fertility index of males was observed and females failed to become pregnant in the 0.80 mg/kg/day group. The number of live fetuses and implantations were decreased while the number of dead fetuses, resorptions, and implantation losses were increased in the 0.12 mg/kg/day group. In segment Ⅱ, maternal toxicity: body weight gains in F0 females receiving 0.036 and 0.090 mg/kg/day group were decreased. Embryo toxicity: In the 0.090 mg/kg/day group, weights and body lengths of fetuses were decreased, the numbers of viable fetuses was decreased and resorbed fetuses increased. Teratogenic effects: The percent of visceral variations and skeletal variations were both increased in the 0.090 mg/kg/day group. In segment Ⅲ, dosing F0 rats with BA9 at dose levels of 0.12 and 0.80 mg/kg/day resulted in reproductive and maternal toxicity, consisting of prolonged labor, dystocia, increased mortality, along with reductions in lactation food consumption. F1 rats in the 0.12 mg/kg/day group showed reproductive and developmental toxicity consisting of body weight decreases, decreased food consumption after weaning and a reduction in the gestation index of pregnant rats. Based on these findings, the no-observed-adverse-effect-level (NOAEL) of BA9 toxicity in segment Ⅰ and Ⅲ was 0.02 mg/kg/day. The NOAEL in segment Ⅱ was 0.015 mg/kg/day.

Expression of mosquito miRNAs in entomopathogenic fungus induces pathogen-mediated host RNA interference and increases fungal efficacy.

The growing threat of insecticide resistance prompts the urgent need to develop additional tools for mosquito control. Entomopathogenic fungi provide an eco-friendly alternative to chemical insecticides. One limitation to the use of mycoinsecticides is their relatively low virulence. Here, we report an approach for suppressing mosquito immunity and increasing fungal virulence. We engineered Beauveria bassiana to express Aedes immunosuppressive microRNAs (miRNAs) to induce host RNA interference (RNAi) immune responses. We show that engineered strains can produce and deliver the miRNAs into host cells to activate cross-kingdom RNAi during infection and suppress mosquito immunity by targeting multiple host genes, thereby dramatically increasing fungal virulence against Aedes aegypti and Galleria mellonella larvae. Importantly, expressing host miRNAs also significantly increases fungal virulence against insecticide-resistant mosquitoes, creating potential for insecticide-resistance management. This pathogen-mediated RNAi (pmRNAi)-based approach provides an innovative strategy to enhance the efficacy of fungal insecticides and eliminate the likelihood of resistance development.

Recombinant adeno-associated virus serotype 9 AAV-RABVG expressing a Rabies Virus G protein confers long-lasting immune responses in mice and non-human primates.

Three or four intramuscular doses of the inactivated human rabies virus vaccines are needed for pre- or post-exposure prophylaxis in humans. This procedure has made a great contribution to prevent human rabies deaths, which bring huge economic burdens in developing countries. Herein, a recombinant adeno-associated virus serotype 9, AAV9-RABVG, harbouring a RABV G gene, was generated to serve as a single dose rabies vaccine candidate. The RABV G protein was stably expressed in the 293T cells infected with AAV9-RABVG. A single dose of 2 × 1011 v.p. of AAV9-RABVG induced robust and long-term positive seroconversions in BALB/c mice with a 100% survival from a lethal RABV challenge. In Cynomolgus Macaques vaccinated with a single dose of 1 × 1013 v.p. of AAV9-RABVG, the titres of rabies VNAs increased remarkably from 2 weeks after immunity, and maintained over 31.525 IU/ml at 52 weeks. More DCs were activated significantly for efficient antigen presentations of RABV G protein, and more B cells were activated to be responsible for antibody responses. Significantly more RABV G specific IFN-γ-secreting CD4+ and CD8+ T cells, and IL-4-secreting CD4+ T cells were activated, and significantly higher levels of IL-2, IFN-γ, IL-4, and IL-10 were secreted to aid immune responses. Overall, the AAV9-RABVG was a single dose rabies vaccine candidate with great promising by inducing robust, long-term humoral responses and both Th1 and Th2 cell-mediated immune responses in mice and non-human primates.

Research progress on neutralizing epitopes and antibodies for the Rabies virus.

Rabies is a zoonotic infectious disease with a high fatality rate. It is caused by a virus in the genus Lyssavirus and is a global public health threat. The rabies virus invades and infects cells mainly via a glycoprotein, which may involve multiple receptors. Neutralizing antibodies against the rabies virus function by blocking the binding of the glycoprotein to a receptor or preventing the membrane fusion process. Vaccination combined with anti-rabies virus neutralizing antibodies is essential for postexposure prophylaxis for category III exposure to the rabies virus. In this review, we discussed the neutralizing epitopes of the rabies virus and the neutralization mechanism of monoclonal antibodies. The neutralizing antibodies that have been commercialized or are under development are also summarized. Our review would provide a basis for the further development of safe and effective broad-spectrum neutralizing antibodies to replace the rabies virus immunoglobulin in rabies post-exposure prophylaxis.

Recombinant Human Adenovirus Type 5 Co-expressing RABV G and SFTSV Gn Induces Protective Immunity Against Rabies Virus and Severe Fever With Thrombocytopenia Syndrome Virus in Mice.

Both severe fever with thrombocytopenia syndrome (SFTS) and rabies are severe zoonotic diseases. As co-hosts of rabies virus (RABV) and SFTS virus (SFTSV), dogs and cats could not only be infected but also transmit the virus to human. Hence, developing a bivalent vaccine against both SFTS and rabies is urgently needed. In this study, we generated a recombinant replication-deficient human adenovirus type 5 (Ad5) co-expressing RABV G and SFTSV Gn (Ad5-G-Gn) and evaluated its immunogenicity and efficacy in mice. Ad5-G-Gn immunization activated more dendritic cells (DCs) and B cells in lymph nodes (LNs) and induced Th1-/Th2-mediated responses in splenocytes, leading to robust production of neutralizing antibodies against SFTSV and RABV. In addition, single dose of Ad5-G-Gn conferred mice complete protection against lethal RABV challenge and significantly reduced splenic SFTS viral load. Therefore, our data support further development of Ad5-G-Gn as a potential bivalent vaccine candidate against SFTS and rabies for dog and cat use.

Pharmacokinetics and tissue distribution of four major bioactive components in rats after oral administration of Xianglian pill.

Xianglian pill, a TCM prescription, consists of Rhizome Coptidis and Radix Aucklandiae, and has been used to treat gastrointestinal disease for many years. Berberine, jatrorrhizin, coptisine and palmatine are four representative alkaloids in Xianglian pill. Knowing that the drug disposal process in vivo is closely related to the toxicity and efficacy of a drug, it is important to classify the disposal properties of these alkaloids. In this study, the pharmacokinetics and tissue distribution of the four alkaloids were investigated. The analytical samples were analyzed using a validated HPLC-MS/MS method. The results showed that the four alkaloids could be slowly absorbed. The Cmax values of berberine, jatrorrhizin, coptisine and palmatine were 11.420, 2.287, 2.584 and 3.102 ng/ml, respectively. Subsequently, the tissue distribution studies showed that they were quickly distributed to various tissues with rich blood flow in the body.

Assembly of pigeon circovirus-like particles using baculovirus expression system.

Pigeon circovirus (PiCV) is able to infect racing and meat pigeons of all ages and is a key factor that triggers young pigeon disease syndrome (YPDS). PiCV vaccine research has been impeded because PiCV cannot be grown or propagated in cell cultures. Virus-like particles (VLPs), which can be generated by a wide range of expression systems, have been shown to have outstanding immunogenicity and constitute promising vaccines against a wide range of pathogens. Cap protein, which contains neutralizing antibody epitopes, is the only capsid protein of PiCV. In this study, the baculovirus expression system was utilized to express the PiCV Cap protein, which was self-assembled into VLPs with a spherical morphology and diameters of 15-18 nm. Specific antibodies against the Cap protein were induced after BALB/c mice immunized intramuscularly (i.m.) with VLPs combined with adjuvant. Based on these findings, PiCV VLPs may be a promising candidate vaccine against PiCV.

Simultaneous Quantification of Brigatinib and Brigatinib-Analog in Rat Plasma and Brain Homogenate by LC-MS/MS: Application to Comparative Pharmacokinetic and Brain Distribution Studies.

Brigatinib and brigatinib-analog are potent and selective ALK inhibitors with the similar structure. A simple and sensitive high-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of brigatinib and brigatinib-analog in rat plasma and brain homogenate was developed and validated. Chromatographic separation was carried out on an ODS column with acetonitrile and 0.1% formic acid in water as the mobile phase with gradient elution at a flow rate of 0.5 mL/min. Detections were performed using a TSQ Quantum Ultra mass spectrometric detector with electrospray ionization (ESI) interface, which was operated in the positive ion mode. A simple protein precipitation preparation process was used. The lower limits of quantification (LLOQs) were 1.0 ng/mL and 0.5 ng/mL for analytes in rat plasma and brain homogenate, respectively. The intrabatch and interbatch precision and accuracy of brigatinib and brigatinib-analog were well within the acceptable limits of variation. The simple and sensitive LC-MS/MS method was successfully applied to the pharmacokinetic and brain distribution studies following a single oral administration of brigatinib and brigatinib-analog to rats. The above studies would lay a good foundation for the further applications of brigatinib and brigatinib-analog.

A fungal pathogen deploys a small silencing RNA that attenuates mosquito immunity and facilitates infection.

Insecticidal fungi represent a promising alternative to chemical pesticides for disease vector control. Here, we show that the pathogenic fungus Beauveria bassiana exports a microRNA-like RNA (bba-milR1) that hijacks the host RNA-interference machinery in mosquito cells by binding to Argonaute 1 (AGO1). bba-milR1 is highly expressed during fungal penetration of the mosquito integument, and suppresses host immunity by silencing expression of the mosquito Toll receptor ligand Spätzle 4 (Spz4). Later, upon entering the hemocoel, bba-milR1 expression is decreased, which avoids induction of the host proteinase CLIPB9 that activates the melanization response. Thus, our results indicate that the pathogen deploys a cross-kingdom small-RNA effector that attenuates host immunity and facilitates infection.

Antiviral efficacy of favipiravir against canine distemper virus infection in vitro.

BACKGROUND: Canine distemper (CD) is an acute infectious disease with high morbidity rates caused by a highly contagious pathogen (Canine Morbillivirus, also known as canine distemper virus, CDV). CDV can infect a broad range of carnivores resulting in complex clinical signs. Currently, there is no effective method to treat for CDV infections. Favipiravir (T-705), a pyrazine derivative, was shown to be an effective antiviral drug against RNA viruses, acting on RNA-dependent RNA polymerase (RdRp). However, whether the T-705 has antiviral effects following CDV infection is unclear. Here, we investigated the antiviral effect of T-705 against CDV-3 and CDV-11 strains in Vero and DH82 cell lines. RESULTS: Our data demonstrated that T-705 significantly inhibited the replication of CDV-3 and CDV-11 in both Vero and DH82 cells at different concentrations, ranging from 2.441 µg/ml to 1250 µg/ml. Additionally, T-705 exhibited efficacious antiviral effects when administered at different time points after virus infection. Cytotoxicity tests showed a slight decline in viability in Vero cells after T-705 treatment, and no apparent cytotoxicity was detected in T-705 treated DH82 cells. Comparison of anti-CDV polyclonal serum only inhibition of CDV in supernatant, T-705 directly inhibited viral replication in cells, and indirectly reduced the amount of virions in supernatant. The combination application of T-705 and anti-CDV polyclonal serum exhibited a rapid and robust inhibition against virions in supernatant and virus replication in cells. CONCLUSIONS: Our data strongly indicated that T-705 effectively inhibited viral replication following CDV infection in vitro, and could be a potential candidate for treatment for CD.

Evaluation of pharmacokinetics, bioavailability and urinary excretion of scopolin and its metabolite scopoletin in Sprague Dawley rats by liquid chromatography-tandem mass spectrometry.

We aimed to investigate the pharmacokinetics, bioavailability and urinary excretion of scopolin and its metabolite scopoletin in rats. An LC-tandem mass spectrometry (MS/MS) method for simultaneous determination of scopolin and scopoletin in rat biomatrices was developed and validated over a plasma and urine concentration range of 5.0-2000 ng/mL. Chromatographic separation was performed on a Hypersil GOLD C18 column with acetonitrile and 0.1% formic acid in water as mobile phase with gradient elution. Detection was performed in the positive ionization and selected reaction monitoring mode. The intra- and inter-batch precision and accuracy, extraction recovery and matrix effect and stability of scopolin and scopoletin were well within the acceptable limits of variation. There was no gender-related difference in the pharmacokinetic profiles of scopolin. There were significant differences in total area under the concentration-time curve (AUC), time required to achieve a maximal concentration (Tmax ) and apparent clearance from plasma (Cl/F) of scopoletin between the male and female rats (p < .05). The bioavailability (F) of scopolin was exceptionally low. The maximal excretion rates were 7.61 µg/h and 7.15 µg/h for scopolin and 31.68 µg/h and 25.58 µg/h for scopoletin in male and female rats, respectively. The LC-MS/MS method was successfully applied to the pharmacokinetic, bioavailability and urinary excretion studies of scopolin and its metabolite scopoletin following a single administration of scopolin to rats.

A UPLC-MS/MS method for comparative pharmacokinetics study of morusin and morin in normal and diabetic rats.

The aim of this study was to establish and validate a rapid, selective and reliable ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for simultaneous quantitations of morin and morusin, and to investigate their pharmacokinetics difference between normal and diabetic rats after oral administration. Plasma samples were pretreated via protein precipitation with acetonitrile. Genkwanin was used as internal standard (IS). Analytes and IS were separated on a Thermo Hypersil Gold C18 column (50 × 4.6 mm, 3 µm) using gradient elution. The mobile phase consisted of acetonitrile and 0.1% formic acid in water at a flow rate of 0.5 mL/min. Mass spectrometry detection was carried out by means of negative electrospray ionization source and multipe-reaction monitoring mode. The transitions of m/z 300.9 → 151.2 for morin, m/z 419.2 → 297.1 for morusin and m/z 283.1 → 268.2 for IS were chosen for quantification. Calibration curves were linear in the range of 1.01-504.2 ng/mL (r2 ≥ 0.99) for morin and 1.02-522.3 ng/mL (r2 ≥ 0.99) for morusin. The lower limit of quantification was 1.02 ng/mL for morin and 1.05 ng/mL for morusin. The extraction recovery was >85.1% for each analyte. No obvious matrix effect was observed under the present UPLC-MS/MS conditions during all of the bioanalysis. The stability study demonstrated that morin and morusin remained stable during the whole analytical procedure. The method was successfully applied to support the pharmacokinetic comparisons of morin and morusin between normal and diabetic rats.

Determination of tubuloside B by LC-MS/MS and its application to a pharmacokinetic study in rats.

Tubuloside B, a novel neuroprotective phenylethanoid, is a major active constituent of Cistanche tubulosa and Cistanche deserticola. A specific and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantification of tubuloside B in rat plasma. Sample preparation was conducted through a protein-precipitation extraction with methanol using tubuloside A as internal standard (IS). Chromatographic separation was achieved using a Capcell Pak C18 column (2.0 × 50 mm, 5 µm) with a mobile phase of methanol-10 mm ammonium acetate buffer (70:30, v/v) in an isocratic elution. Mass spectrometry analysis was performed in negative ionization mode with selected reaction monitoring transitions at m/z 665.1 → 160.9 for tubuloside B, and m/z 827.1 → 160.9 for IS. Calibration curves were linear over the range of 1.64-1640 ng/mL for plasma samples samples (R2 > 0.990). The lower limit of quantification (LLOQ) was 1.64 ng/mL. The intra- and inter-day accuracy was between 92.3 and 113.0% with the RSD <9.23% at all LLOQ and quality control levels. Finally, this method was successfully applied in the pharmacokinetics study of tubuloside B after intravenous administration.

Development of an LC-MS/MS method for quantification of two isomeric phenylpropenes and the application to pharmacokinetic studies in rats.

Isomers ß-asarone and α-asarone have recently been demonstrated to have differential pharmacological activities. Here, we report an LC-MS/MS method developed using acetonitrile to extract two isomeric phenylpropenes from rat plasma. Separation was achieved using a XDB-C18 column (100 × 2.1 mm; i.d., 1.8 µm) with a mobile phase of methanol-0.1% formic acid (55:45, v/v) at a flow rate of 0.3 mL/min. Calibration curves ranging from 5.20 to 2080 ng/mL for ß-asarone and from 3.68 to 1470 ng/mL for α-asarone were linear (r2 ≥ 0.9938) with the lower limits of quantification being 5.20 and 3.68 ng/mL for both isomers. Intravenous administration of ß-asarone (2.22 mg/kg) and α-asarone (2.36 mg/kg) in rats yielded half-lives of 13.40 ± 4.11 and 28.88 ± 7.82 min with clearance values of 0.196 ± 0.062 mL/min/kg and 0.112 ± 0.012 mL/min/kg for ß-asarone and α-asarone, respectively.

Quantification of morusin using LC-MS in rat plasma: Application to a pharmacokinetic study.

A sensitive LC-MS method was developed for the quantification of morusin in rat plasma using praeruptorin C as internal standard. After extraction with diethyl ether, post-treatment samples were chromatographed on a Hypersil C18 column. An isocratic mobile phase consisting of methanol-water (70:30, v/v) was applied at a flow rate of 0.4 mL/min. Detection was performed via electrospray ionization source with positive ion mode using selected ion monitoring mode at m/z 443.1 for morusin and m/z 451.0 for IS. Acceptable linearity (r2 ≥ 0.99) was observed over the concentration range of 1.5-800 ng/mL. This method was successfully applied in the pharmacokinetics study of morusin in rats.

Development and Validation of a Rapid and Sensitive LC-MS/MS Method for the Pharmacokinetic Study of Osimertinib in Rats.

Osimertinib is a new-generation epidermal growth factor inhibitor for the treatment of non-small cell lung cancer. In the present study, a rapid and sensitive LC with tandem MS method was developed and validated for the determination of osimertinib in rat plasma. Chromatographic separation was carried out on a C18 column using acetonitrile and water containing 0.1% formic acid. The assay was validated over a concentration range of 1.0-1000 ng/mL for osimertinib, with a lower LOQ of 1.0 ng/mL. The intra- and interday accuracy values for osimertinib ranged from 92.66 to 101.50% and from 97.08 to 99.15%, respectively, and the intra- and interday precision values for osimertinib ranged from 6.25 to 10.34% and from 3.43 to 10.44%, respectively. The method was successfully applied in a pharmacokinetic study of osimertinib after oral administration of osimertinib (4.5 mg/kg) to rats.

Determination of AZD3759 in rat plasma and brain tissue by LC-MS/MS and its application in pharmacokinetic and brain distribution studies.

A simple and sensitive high performance liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for determination of AZD3759, a novel epidermal growth factor receptor tyrosine kinase inhibitor, in rat plasma and brain homogenate was developed and validated over the range of 1.0-1000ng/mL. Chromatographic separation was carried out on a C18 column with acetonitrile and 0.1% formic acid in water as mobile phase with gradient elution at a flow rate of 0.4mL/min. The lower limits of quantification (LLOQs) were 1.0ng/mL for AZD3759 in both rat plasma and brain homogenate. The intra-day and inter-day precision and accuracy of AZD3759 were well within the acceptable limits of variation. The simple and sensitive LC-MS/MS method was successfully applied to the pharmacokinetic and brain distribution studies following an oral administration of AZD3759 to rats.