Zika virus protease induces caspase-independent pyroptotic cell death by directly cleaving gasdermin D.

The association of Zika virus (ZIKV) infection with a congenital malformation in fetuses, neurological, and other systemic complications in adults have brought significant global health emergency. ZIKV targets nerve cells in the brain and causes cell death, such as pyroptosis, leading to neuroinflammation. Here we described a novel mechanism of pyroptosis caused by ZIKV protease. We found that ZIKV protease directly cleaved the GSDMD into N-terminal fragment (1-249) leading to pyroptosis in a caspase-independent manner, suggesting a direct mechanism of ZIKV-induced cell death and subsequent inflammation. Our findings might shed new light to explore the pathogenesis of ZIKV infections where ZIKV protease might be a suitable target for the development of antiviral agents.

Development of Monoclonal Antibodies and Antigen-Capture ELISA for Human Parechovirus Type 3.

Human parechovirus type 3 (HPeV3) is an etiologic agent of respiratory diseases, meningitis, and sepsis-like illness in both infants and adults. Monoclonal antibodies (mAbs) can be a promising diagnostic tool for antigenic diseases such as virus infection, as they offer a high specificity toward a specific viral antigen. However, to date, there is no specific mAb available for the diagnosis of HPeV3 infection. In this study, we developed and characterized mAbs specific for HPeV3 capsid protein VP0. We used cell-free, wheat germ-synthesized viral VP0 protein for immunizing BALB/c mice to generate hybridomas. From the resultant hybridoma clones, we selected nine clones producing mAbs reactive to the HPeV3-VP0 antigen, based on enzyme-linked immunosorbent assay (ELISA). Epitope mapping showed that these mAbs recognized three distinct domains in HPeV3 VP0. Six mAbs recognized HPeV3 specifically and the other three mAbs showed cross-reactivity with other HPeVs. Using the HPeV3-specific mAbs, we then developed an ELISA for viral antigen detection that could be reliably used for laboratory diagnosis of HPeV3. This ELISA system exhibited no cross-reactivity with other related viruses. Our newly developed mAbs would, thus, provide a useful set of tools for future research and ensure HPeV3-specific diagnosis.

Prolyl Isomerase Pin1 Regulates the Stability of Hepatitis B Virus Core Protein.

The dynamic interplay between virus and host proteins is critical for establishing efficient viral replication and virus-induced pathogenesis. Phosphorylation-dependent prolyl isomerization by Pin1 provides a unique mechanism of molecular switching to control both protein function and stability. We demonstrate here that Pin1 binds and stabilizes hepatitis B virus core protein (HBc) in a phosphorylation-dependent manner, and promotes the efficient viral propagation. Phos-tag gel electrophoresis with various site-directed mutants of HBc revealed that Thr160 and Ser162 residues within the C terminal arginine-rich domain are phosphorylated concomitantly. GST pull-down assay and co-immunoprecipitation analysis demonstrated that Pin1 associated with phosphorylated HBc at the Thr160-Pro and Ser162-Pro motifs. Chemical or genetic inhibition of Pin1 significantly accelerated the rapid degradation of HBc via a lysosome-dependent pathway. Furthermore, we found that the pyruvate dehydrogenase phosphatase catalytic subunit 2 (PDP2) could dephosphorylate HBc at the Pin1-binding sites, thereby suppressing Pin1-mediated HBc stabilization. Our findings reveal an important regulatory mechanism of HBc stability catalyzed by Pin1 and may facilitate the development of new antiviral therapeutics targeting Pin1 function.

Production and characterization of monoclonal antibodies specific for major capsid VP1 protein of trichodysplasia spinulosa-associated polyomavirus.

Trichodysplasia spinulosa-associated polyomavirus (TSPyV), a newly identified polyomavirus, has been implicated as a causative agent of trychodysplasia spinulosa (TS), a rare proliferative skin disease in severely immunocompromised hosts. Diagnosis using mAbs is a promising tool with high specificity towards the specific antigen. However, thus far, no suitable mAbs for diagnosing TS disease have been identified. In this study, mAbs specific for VP1 of TSPyV were developed and characterized. Wheat germ cell-free synthesized VP1 protein of TSPyV was used to immunize BALB/c mice to generate hybridomas. Screening of the resultant hybridoma clones resulted in selection of five strongly positive clones that produce mAbs that react with the TSPyV-VP1 antigen. Epitope mapping and bioinformatic analysis showed that these mAbs recognized epitopes located within highly conserved C-terminal region of all clinical isolates of TSPyV-VP1. Further, all these mAbs were highly effective for immunofluorescence and immunoprecipitation analysis. Three of the five mAbs exhibited no cross-reactivity with VP1 of other related polyomaviruses. In addition, one of our mAbs (#14) provided immunohistochemical staining of skin tissue of TS disease. It can be concluded that three of the mAbs in this panel of anti-VP1 antibodies may provide a useful set of tools for studying TSPyV infection and making the specific diagnosis.

Preliminary pharmacological activity of the methanolic extract of Premna integrifolia barks in rats.

OBJECTIVE: Premna integrifolia Linn (Family: Verbenaceae) synonym of Premna serratifolia has tremendous medicinal value. Preliminary pharmacological studies were performed on the methanolic extract of Premna integrifolia (MEPI) bark to investigate neuropharmacological, analgesic, and anti-inflammatory activities. MATERIALS AND METHODS: Neuropharmacology study was done by open field and hole cross test whereas acetic acid writhing test and formalin induced pain was done for analgesic activity of MEPI. Carrageenan induced inflammatory model was considered for anti-inflammatory activity evaluation. RESULTS: A statistically significant (p0.05) decrease in locomotor activity was observed at all doses in the open-field and hole-cross tests. The extract significantly (p0.05) and dose dependently reduced the writhing reflex in the acetic acid-induced writhing test as well as licking response in the formalin induced inflammatory pain. At 200 mg/kg body weight dose, MEPI showed 71.16% inhibition in carrageenan induced anti-inflammatory activity. CONCLUSION: The finding of this study suggests that MEPI will provide scientific support for the use of this species in traditional medicine.

Analgesic, antibacterial and central nervous system depressant activities of Albizia procera leaves

Objective: To ascertain analgesic, antibacterial and central nervous system (CNS) depressant activities of ethyl acetate, dichloromethane and carbon tetrachloride fractions of methanol extract of Albizia procera (A. procera) leaves. Methods: Leaves extracts of A. procera were tested for analgesic activity by acetic acid induced and formalin test method in mice. The in vitro antibacterial activity was performed by agar well diffusion method. CNS depressant activity was evaluated by hole cross and open field tests. Results: All the extracts at 200 mg/kg exhibited significant (P Conclusions: It is concluded that all the extracts possess potential analgesic and CNS depressants activity. This study also showed that different fractions of methanol extract could be potential sources of new antimicrobial agents.

Antibacterial, antidiarrhoeal, and cytotoxic activities of methanol extract and its fractions of Caesalpinia bonducella (L.) Roxb leaves.

BACKGROUND: Caesalpinia bonducella is an important medicinal plant for its traditional uses against different types of diseases. Therefore, the present study investigated the antimicrobial, antidiarrhoeal, and cytotoxic activities of the methanol extract and ethyl acetate, chloroform, and petroleum ether (pet. ether) fractions of C. bonducella leaves. METHODS: The antibacterial potentialities of methanol extract and its fractions of C. bonducella leaves were investigated by the disc diffusion method against four gram-positive and five gram-negative bacteria at 300, 500 and 800 µg/disc. Kanamycin (30 µg/disc) was used as the standard drug. Antidiarrhoeal activities of leaf extracts were evaluated at two doses (200 and 400 mg/kg) and compared with loperamide in a castor oil-induced diarrhoeal model in rat. The fractions were subjected to a brine shrimp lethality test to evaluate their cytotoxicity. RESULTS: The methanol extract and other three fractions exhibited better activities at higher concentrations. Amongst, the chloroform fraction showed maximum activity at all three concentrations (300, 500, and 800 µg/disc) against almost all bacteria. S. aureus and P. aeruginosa showed better sensitivities to all extracts at all three concentrations excluding the pet. ether fraction. Bacillus megaterium and Klebsiella spp. were two bacteria amongst nine that showed lowest sensitivity to the extracts. Maximum zone of inhibition (25-mm) was obtained by the methanol extract at an 800 µg/disc concentration against S. aureus. In the antidiarrhoeal test, all fractions exhibited dose-dependent actions, which were statistically significant (p < 0.05). Ethyl acetate fraction exerted maximum inhibition (51.11%) against defecation, whereas 57.75% inhibition was obtained for loperamide. Moderate cytotoxicity was found for the methanol extract and its three fractions compared with the standard drug vincristine sulfate in the brine shrimp bioassay. In the present study, the LC50 values of the methanol crude extract and ethyl acetate, chloroform, pet. ether fractions and vincristine sulfate were 223.87, 281.84, 112.2, 199.53, and 12.59 µg/mL, respectively. Therefore, the ethyl acetate fraction showed maximum cytotoxicity, whereas minimum cytotoxicity was observed for the chloroform fraction. CONCLUSION: The present study revealed that the ethyl acetate fraction of the C. bonducella leaves has significant antidiarrhoeal properties. The methanol extract and other three fractions of the C. bonducella leaves possess potent antibacterial activities along with moderate cytotoxicities that may lead to new drug development.

Water-soluble Fraction of Abelmoschus esculentus L Interacts with Glucose and Metformin Hydrochloride and Alters Their Absorption Kinetics after Coadministration in Rats.

This study was done to investigate the effects of water-soluble fraction (WSF) of the fruits of Abelmoschus esculentus L (okra/lady's fingers) on absorption of oral glucose as well as metformin from the gastrointestinal tract in the Long Evans rats. WSF of A. esculentus significantly (P < 0.05) reduced the absorption of glucose as studied in the 24 hrs fasting rats. The effect of WSF of A. esculentus on metformin absorption was studied in alloxan-induced diabetic rats. Significant differences (P < 0.05) were observed in the average blood glucose level from 2 to 24 hours after metformin therapy in presence (33.6 to 34.2 mmol/L) or absence (15.2 to 20.2 mmol/L) of oral WSF of A. esculentus. In both of the experiments, Na-carboxymethylcellulose (CMC) was used as positive control. The results of this study indicate that A. esculentus may improve glycemic control but should not be taken concurrently with metformin hydrochloride in controlling diabetes mellitus.