Antiviral activity of sulfated Chuanminshen violaceum polysaccharide against duck enteritis virus in vitro

Alpiniae oxyphyllae fructus polysaccharide 3 inhibits porcine epidemic diarrhea virus entry into IPEC-J2 cells

Porcine epidemic diarrhea virus (PEDV) is deadly for suckling piglets and is a significant threat to most pig farms. Alpiniae oxyphyllae fructus polysaccharide 3 (AOFP3) shows antiviral activity against PEDV. However, the anti-PEDV mechanism of AOFP3 is unknown. Entering the host cell is important for viral infection, and many drugs play antiviral roles by inhibiting this process. To understand the antiviral mechanism of AOFP3 against PEDV, the effect of AOFP3 on PEDV entering IPEC-J2 cells was investigated in the present study. Real-time PCR and immunofluorescence were used to study the effect of AOFP3 on PEDV binding and penetrating IPEC-J2 cells. The effect of PEDV on AOFP3 attachment to IPEC-J2 cells was also investigated. Afterward, the effect of AOFP3 on PEDV spike (S) protein binding to porcine aminopeptidase was tested by using coimmunoprecipitation, and the effect of AOFP3 on the cholesterol level of IPEC-J2 cells was detected. The results showed that AOFP3 competitively inhibited PEDV adsorption on IPEC-J2 cells by blocking PEDV S protein binding to porcine aminopeptidase in IPEC-J2 cells. Furthermore, AOFP3 decreased PEDV penetration into host cells by decreasing the cholesterol level in IPEC-J2 cells.

Polysaccharides and Тheir Derivatives as Potential Antiviral Molecules

In the current context of the COVID-19 pandemic, it appears that our scientific resources and the medical community are not sufficiently developed to combat rapid viral spread all over the world. A number of viruses causing epidemics have already disseminated across the world in the last few years, such as the dengue or chinkungunya virus, the Ebola virus, and other coronavirus families such as Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS-CoV). The outbreaks of these infectious diseases have demonstrated the difficulty of treating an epidemic before the creation of vaccine. Different antiviral drugs already exist. However, several of them cause side effects or have lost their efficiency because of virus mutations. It is essential to develop new antiviral strategies, but ones that rely on more natural compounds to decrease the secondary effects. Polysaccharides, which have come to be known in recent years for their medicinal properties, including antiviral activities, are an excellent alternative. They are essential for the metabolism of plants, microorganisms, and animals, and are directly extractible. Polysaccharides have attracted more and more attention due to their therapeutic properties, low toxicity, and availability, and seem to be attractive candidates as antiviral drugs of tomorrow.

Identification of the amino acids residues involved in hemagglutinin-neuraminidase of Newcastle disease virus binding to sulfated Chuanmingshen violaceum polysaccharides

The antiviral mechanism of sulfated polysaccharides is supposed to prevent virus entry, which is mediated by the interactions of anionic charges on sulfated polysaccharides with positively charged domains of viral envelope glycoproteins, leading to shielding of the functional domain involved in virus attachment to cell surface receptors. But, few direct evidences were reported. In the previous study, we found that sulfated Chuanmingshen violaceum polysaccharides (sCVPS) possessed remarkable inhibitory effect against Newcastle disease virus (NDV) through inhibition of NDV attachment to host cells. Whether sCVPS bound to hemagglutinin-neuraminidase (HN) leading to inhibition of NDV attachment needs to be further clarified. The present study conducted site-directed mutagenesis of possible positively charged residues of HN, and found that mutants R197G, H199G, R363G, and R523G could significantly decrease the inhibitory effects of sCVPS on receptor binding ability through hemadsorption assay, especially R363G which suggested that binding to R363 is more effective to shield the sialic acid binding sites. Dual mutants (R363G/R197G, R363G/H199G and R363G/R523G) induced more decreased inhibitory effect of sCVPS than single mutants. The immunofluorescence study using FITC-labeled sCVPS found that the fluorescence intensity of mutants R363G and R363G/H199G were significantly decreased. The binding kinetics of sCVPS to HN measured by surface plasmon resonance indicated that sCVPS had a higher binding affinity for wild-type HN than mutants R363G and R363G/H199G. Plaque reduction study was performed using recombinant NDV with mutant HN_R363G and HN_R363G/H199G, which showed significantly decreased inhibitory effects of sCVPS against mutant NDV adsorption to BHK-21 cells. These results suggested that the residues R197, H199, R363, and R523 were the binding sites for sCVPS, especially R363 act as the main interaction site. The present study provided direct evidence for the theory that antiviral mechanism of sulfated polysaccharides attributed to anionic groups binding to the positively charged residues of viral proteins which led to the shielding of receptor binding sites.

Antiviral activity against porcine epidemic diarrhea virus of Pogostemon cablin polysaccharide

ETHNOPHARMACOLOGICAL RELEVANCE

The dry overground parts of Pogostemon cablin (Blanco) Benth. is widely used in China as a traditional Chinese medicine for the treatment of diarrhea, vomiting, nausea and fever. Polysaccharide is an important component of Pogostemon cablin (Blanco) Benth. but has not been studied. Pogostemon cablin (Blanco) Benth. is used to treat porcine epidemic diarrhea. But it is not known whether Pogostemon cablin polysaccharides (PCPs) has the antiviral activities against porcine epidemic diarrhea virus (PEDV).

AIM OF THE STUDY

The purpose of present study is to investigate the structural characterization and the anti-PEDV activities of PCPs.

MATERIALS AND METHODS

PCPs were prepared by water extraction and alcohol precipitation method and purified with DEAE-52 cellulose column and Sephadex G-100 column. Then, the structural characterization of the polysaccharides including the infrared spectrum, molecular weight and monosaccharide composition were analyzed. Afterwards, the antiviral effect of PCPs against PEDV on IPEC-J2 cells was studied by MTT method and real-time PCR method. Additionally, the effects of PCPs on PEDV adsorption, penetration and replication were analyzed by real-time PCR method. Furthermore, we also investigate whether the anti-oxidative effects of PCPs were important to the anti-PEDV activities.

RESULTS

Four polysaccharides were obtained and named as PCP1.1 (31.3 kDa), PCP1.2 (3.5 kDa), PCP2.1 (9.1 kDa) and PCP2.2 (8.3 kDa). PCP1.1, PCP1.2 and PCP2.1 were composed of fucose, arabinose, galactose, glucose, mannose, galacturonic acid and glucuronic acid; and PCP2.2 was composed of arabinose, galactose, glucose, galacturonic acid and glucuronic acid. All PCPs showed anti-PEDV activities. PCP1.1 and PCP1.2 inhibited PEDV replication, while PCP2.1 and PCP2.2 inhibited PEDV penetration and replication. All PCPs showed anti-oxidative effects, which were important to the anti-PEDV activities.

CONCLUSIONS

The treatment effect of Pogostemon cablin (Blanco) Benth. on porcine epidemic diarrhea might be related to the anti-PEDV effect of PCPs. Furthermore, the anti-oxidative effects of PCPs play important roles in their antiviral activities against PEDV.

Assessment of the Effect of Baicalin on Duck Virus Hepatitis

BACKGROUND

Duck virus hepatitis (DVH) caused by duck hepatitis A virus type 1 (DHAV-1) is a malignant disease in ducklings, causing economic losses in the duck industry. However, there is still no antiviral drug against DHAV-1 in the clinic.

OBJECTIVE

Our aim is to investigate the anti-DHAV-1 effect of baicalin, which is a flavonoid derived from the Chinese medicinal herb huangqin (Scutellaria baicalensis Georgi).

METHODS

Here, we first detected its anti-DHAV-1 ability in vitro and in vivo. At the same time, the inhibition of baicalin on DHAV-1 reproduction was determined. Finally, we tested and verified the anti-oxidative and immuno-enhancing roles of baicalin on its curative effect on DVH.

RESULTS

Baicalin possessed anti-DHAV-1 effect. It improved the cytoactive of DEH which was infected by DHAV-1 as well as reduced the DHAV-1 reproduction in DEH. Under baicalin treatment, mortality of ducklings infected by DHAV-1 decreased, additionally the DHAV-1 level and liver injury in such ducklings were significantly reduced or alleviated. The in vitro mechanism study indicated baicalin inhibited DHAV-1 reproduction via interfering the viral replication and release. Furthermore, the in vivo mechanism study manifested both the anti-oxidative and immuno-enhancing abilities of baicalin, which played crucial roles in its curative effect on DVH.

CONCLUSION

This study may provide a scientific basis for developing baicalin as one or a part of the anti-DHAV-1 drugs.

Discrimination of Chuanminshen violaceum Sheh et Shen from different regions based on fatty acid profiles of roots and leaves

Objectives

The purpose of this paper was to construct a reliable methodology to discriminate the geographical origins of Chuanminshen violaceum Sheh et Shan planted in different regions in Sichuan, China.

Materials and methods

Fatty acid profiles of roots and leaves of C. violaceum planted in various regions of Sichuan Province in China, namely Guangyuan (GY), Langzhong (LZ), Jintang (JT), Bazhong (BZ), and Shuangling (SL), were determined using GC-MS followed by multivariate statistical analyses, including orthogonal partial least-squares discriminant analysis and hierarchical clustering analysis.

Results

Leaves of C. violaceum showed the highest contents of hexadecatrienoic acid (3.21 g/kg), linoleic acid (6.62 g/kg), and α-linolenic acid (7.24 g/kg), which were all higher than those contained in roots. Chuanminshen violaceum samples collected from LZ, JT, and GY could be clearly distinguished based on fatty acid profiles of leaves and those collected from LZ, GY, and BZ could be clearly distinguished based on fatty acid profiles of roots.

Conclusions

Chemometric method is used as a potential approach for analyses of fatty acid profiles of roots and leaves to control the quality of C. violaceum and their powered products.

The inhibitory effect of phosphorylated Codonopsis pilosula polysaccharide on autophagosomes formation contributes to the inhibition of duck hepatitis A virus replication

Duck hepatitis A virus type 1 (DHAV) infection causes duck viral hepatitis and results in enormous loss to poultry farming industry. We reported that phosphorylated Codonopsis pilosula polysaccharide (pCPPS) inhibited DHAV genome replication. Here we further explored its underlying antiviral mechanisms. Autophagosomes formation is essential for the genome replication of picornaviruses. In this study, Western blot, confocal microscopy observation, and ELISA methods were performed to analyze polysaccharides' effects on autophagy by the in vitro and in vivo experiments. Results obtained from in vitro and in vivo experiments showed that Codonopsis pilosula polysaccharide did not play a role in regulating autophagy and had no therapeutic effects on infected ducklings. However, pCPPS treatment downregulated LC3-II expression level activated by DHAV and rapamycin, indicating the inhibition of autophagosomes formation. The interdiction of autophagosomes formation resulted in the inhibition of DHAV genome replication. Further study showed that pCPPS treatment reduced the concentration of phosphatidylinositol-3-phosphate (PI3P), an important component of membrane, in cells and serum, and consequently, autophagosomes formation was downregulated. In vivo experiments also verified the therapeutic effect of pCPPS. Phosphorylated Codonopsis pilosula polysaccharide treatment increased the infected ducklings' survival rate and alleviated hepatic injury. Our studies verified the effects of pCPPS against DHAV infection in duck embryo hepatocytes and ducklings and confirmed that phosphorylated modification enhanced the bioactivities of polysaccharides. The results also stated pCPPS's antiviral mechanisms, provided fundamental basis for the development of new anti-DHAV agents.

Role of primary metabolites in plant defense against pathogens

Plants under natural environment facing various pathogens, tend to produce defense to maintain their fitness and minimize pathogenic damage. Plant-pathogens interaction is gaining more importance by researches as, their means of the fight are primary metabolites. The ultimate result of either means of defense is pathogenesis or resistance. Plant defense mechanisms can be grouped either into inducible and constitutive defense or chemical, structural and morphological defense. Majority of defense mechanisms have a passive role, i.e. only defensive against pathogens, but a few are very active. Plant primary metabolites are catching interest in their immunity role. Deep information of molecular mechanisms involved during the plant-pathogen system is need of the day for future disease control. This review will highlight the role of primary metabolites and their mechanism of action in plant defense.

Antiviral effect of baicalin phospholipid complex against duck hepatitis A virus type 1

Duck hepatitis A virus type 1 (DHAV-1) is one of the main pathogens of ducklings and causes a high mortality rate. Baicalin (BA) has potent antiviral effect, but the solubility is very poor. In order to increase the absorption, solubility, and pharmacological activity, the phospholipid complex was used to modify BA in present study. Therefore, BA phospholipid complex (BAPC) was prepared. The anti-DHAV-1 abilities of BA and BAPC in vitro was evaluated by cell counting kit-8 and reverse transcription quantitative PCR. The curative effects of BA and BAPC on ducklings which were infected by DHAV-1 in addition to the ALT and AST levels were also detected. The results indicated the anti-DHAV-1 ability of BAPC was stronger than that of BA both in vitro and in vivo. To explore the anti-DHAV-1 mechanism, the influence of BAPC on DHAV-1 adsorption, replication, and release was studied. Furthermore, the anti-oxidative and immuno-enhancing abilities of BAPC in the treatment of infected ducklings were also determined. The results showed BAPC inhibited DHAV-1 adsorption, replication and release. Furthermore, it played anti-oxidative and immno-enhancing roles in the treatment, and the immno-enhancing role was crucial to the treatment.

Aloe Polysaccharides Inhibit Influenza A Virus Infection-A Promising Natural Anti-flu Drug

Influenza A virus causes periodic outbreaks and seriously threatens human health. The drug-resistant mutants have shown an epidemic trend because of the abuse of chemical drugs. Aloe polysaccharides (APS) extracted from Aloe vera leaves have evident effects on the therapy of virus infection. However, the activity of APS in anti-influenza virus has yet to be investigated. Here, we refined polysaccharides from A. vera leaf. In vitro test revealed that APS could inhibit the replication of a H1N1 subtype influenza virus, and the most obvious inhibitory effect was observed in the viral adsorption period. Transmission electron microscopy indicated that APS directly interacted with influenza virus particles. Experiments on PR8 (H1N1) virus infection in mice demonstrated that APS considerably ameliorated the clinical symptoms and the lung damage of the infected mice, and significantly reduced the virus loads and mortality. Our findings provided a theoretical basis for the development of novel natural anti-influenza agents.

The antiviral activity of polysaccharides and their derivatives

Viral infectious diseases are seriously endangering human health. In the search for effective antiviral drugs, people have found that polysaccharides have good antiviral activity. As an effective and low-toxic antiviral component, polysaccharides have broad prospects for medicinal use and are deserved for further study. Herein, the antiviral activity and action mechanisms of polysaccharides and their various derivatives were summed up and analyzed.

Total Synthesis of the Flavonoid Natural Product Houttuynoid A

The first total synthesis of the antiviral flavonoid houttuynoid A (1) has been achieved from aryl ketone 6 and benzofuran aldehyde 5 in nine linear steps. The C₆-C₃-C₆ structure of the flavonoid was synthesized by an I₂-catalyzed oxa-Michael addition of a chalcone intermediate, generated by the Claisen-Schmidt condensation of 5 and 6. This work provides a method for the synthesis of houttuynoids and provides a reference for the synthesis of the remaining members of the houttuynoid family.

Phyto-metabolites; An Impregnable Shield against Plant Viruses

Worldwide, economically important crops are under continuous threat from plant viruses as they reproduce within the host and spread via various biological and non biological means. The problem can be minimized via application of integrated management approaches involving utilization of resistant genotypes and reducing the insect vector population. But such strategies are rarely applied in developing countries and farmers prefer to use chemicals against all type of diseases. But increasing use of pesticides is a leading cause of disaster to our ecosystem so alternative means such as phyto-metabolites should be explored for eco friendly management of plant viruses. So here we have reviewed about different phyto-metabolites that can be effectively and potentially used against various plant virus diseases. We further explained about the various primary and secondary metabolites such as alkaloids, essential oils, flavonoids, polysaccharides and proteins. The review highlights the recent advances in the field of phyto-metabolites utilization against plant viruses and sums up via hoping through prospects that future drugs will be safer for human beings and our ecosystem.

Anti-DHAV-1 reproduction and immuno-regulatory effects of a flavonoid prescription on duck virus hepatitis

CONTEXT

The flavonoid prescription baicalin-linarin-icariin-notoginsenoside R1 (BLIN) has a curative effect on duck virus hepatitis (DVH) caused by duck hepatitis A virus type 1 (DHAV-1). However, the mechanism of this curative effect is not understood.

OBJECTIVE

This study investigates the mechanism of the curative effect of BLIN on DVH caused by DHAV-1. We analyzed the anti-DHAV-1 reproduction mechanism and immuno-regulatory effect of BLIN.

MATERIALS AND METHODS

The anti-DHAV-1 reproduction effects of BLIN at 20, 10, 5 and 2.5 μg/mL in vitro, as well as the influence of BLIN at 20 μg/mL on DHAV-1 adsorption, replication and release were tested using the qRT-PCR method. The promotion abilities of BLIN at 20, 10, 5 and 2.5 μg/mL on T- and B-lymphocyte proliferation were investigated by the MTT method. IL-2 and IFN-γ levels and total anti-DHAV-1 antibody secretion after treatment with DHAV-1 for 4, 8 and 54 h were determined by ELISA.

RESULTS

BLIN showed a dose-dependent DHAV-1 reproduction inhibitory effect. The inhibitory effect was highest at 20 μg/mL, where DHAV-1 adsorption and release were significantly lower. Meanwhile, BLIN at 5 μg/mL significantly increased T and B lymphocyte proliferation. BLIN stimulated total anti-DHAV-1 antibody secretion in ducklings at the dosage of 4 mg per duckling, but did not stimulate IL-2 and IFN-γ secretion significantly.

CONCLUSIONS

BLIN inhibits DHAV-1 reproduction by suppressing its adsorption and release. Additionally, BLIN promoted the duckling antiviral response.

Duck virus enteritis (duck plague) - a comprehensive update

Duck virus enteritis (DVE), also called duck plague, is one of the major contagious and fatal diseases of ducks, geese and swan. It is caused by duck enteritis virus (DEV)/Anatid herpesvirus-1 of the genus Mardivirus, family Herpesviridae, and subfamily Alpha-herpesvirinae. Of note, DVE has worldwide distribution, wherein migratory waterfowl plays a crucial role in its transmission within and between continents. Furthermore, horizontal and/ or vertical transmission plays a significant role in disease spread through oral-fecal discharges. Either of sexes from varying age groups of ducks is vulnerable to DVE. The disease is characterized by sudden death, vascular damage and subsequent internal hemorrhage, lesions in lymphoid organs, digestive mucosal eruptions, severe diarrhea and degenerative lesions in parenchymatous organs. Huge economic losses are connected with acute nature of the disease, increased morbidity and mortality (5%-100%), condemnations of carcasses, decreased egg production and hatchability. Although clinical manifestations and histopathology can provide preliminary diagnosis, the confirmatory diagnosis involves virus isolation and detection using serological and molecular tests. For prophylaxis, both live-attenuated and killed vaccines are being used in broiler and breeder ducks above 2 weeks of age. Since DEV is capable of becoming latent as well as shed intermittently, recombinant subunit and DNA vaccines either alone or in combination (polyvalent) are being targeted for its benign prevention. This review describes DEV, epidemiology, transmission, the disease (DVE), pathogenesis, and advances in diagnosis, vaccination and antiviral agents/therapies along with appropriate prevention and control strategies.

Taishan Pinus massoniana pollen polysaccharide inhibits subgroup J avian leucosis virus infection by directly blocking virus infection and improving immunity

Subgroup J avian leucosis virus (ALV-J) generally causes neoplastic diseases, immunosuppression and subsequently increases susceptibility to secondary infection in birds. The spread of ALV-J mainly depends on congenital infection and horizontal contact. Although ALV-J infection causes enormous losses yearly in the poultry industry worldwide, effective measures to control ALV-J remain lacking. In this study, we demonstrated that Taishan Pinus massoniana pollen polysaccharide (TPPPS), a natural polysaccharide extracted from Taishan Pinus massoniana pollen, can significantly inhibit ALV-J replication in vitro by blocking viral adsorption to host cells. Electron microscopy and blocking ELISA tests revealed that TPPPS possibly blocks viral adsorption to host cells by interacting with the glycoprotein 85 protein of ALV-J. Furthermore, we artificially established a congenitally ALV-J-infected chicken model to examine the anti-viral effects of TPPPS in vivo. TPPPS significantly inhibited viral shedding and viral loads in immune organs and largely eliminated the immunosuppression caused by congenital ALV-J infection. Additionally, pre-administration of TPPPS obviously reduced the size and delayed the occurrence of tumors induced by acute oncogenic ALV-J infection. This study revealed the prominent effects and feasible mechanisms of TPPPS in inhibiting ALV-J infection, thereby providing a novel prospect to control ALV-J spread.

Advances and prospects in biogenic substances against plant virus: A review

Plant virus diseases, known as 'plant cancer', are the second largest plant diseases after plant fungal diseases, which have caused great damage to agricultural industry. Since now, the most direct and effective method for controlling viruses is chemotherapeutics, except for screening of anti-disease species. As the occurrence and harm of plant diseases intensify, production and consumption of pesticides have increased year by year, and greatly contributed to the fertility of agriculture, but also brought a series of problems, such as the increase of drug resistance of plant pathogens and the excessive pesticide residues. In recent years, biopesticide, as characterized by environmentally safe due to low residual, safe to non-target organism due to better specificity and not as susceptible to produce drug resistance due to diverse work ways, has gained more attention than ever before and exhibited great development potential. Now much progress has been made about researches on new biogenic anti-plant-virus substances. The types of active components include proteins, polysaccharides and small molecules (alkaloids, flavonoids, phenols, essential oils) from plants, proteins and polysaccharides from microorganisms, polysaccharides from algae and oligochitosan from animals. This study summarized the research advance of biogenic anti-plant-virus substances in recent years and put forward their further development in the future.

The complete chloroplast genome sequence and phylogenetic analysis of Chuanminshen (Chuanminshenviolaceum Sheh et Shan)

Chloroplast genome sequences are very useful for species identification and phylogenetics. Chuanminshen (Chuanminshen violaceum Sheh et Shan) is an important traditional Chinese medicinal plant, for which the phylogenetic position is still controversial. In this study, the complete chloroplast genome of Chuanminshen violaceum Sheh et Shan was determined. The total size of Chuanminshen chloroplast genome was 154,529 bp with 37.8% GC content. It has the typical quadripartite structure, a large single copy (17,800 bp) and a small single copy (84,171 bp) and a pair of inverted repeats (26,279 bp). The whole genome harbors 132 genes, which includes 85 protein coding genes, 37 tRNA genes, eight rRNA genes, and two pseudogenes. Thirty-nine SSR loci, 32 tandem repeats and 49 dispersed repeats were found. Phylogenetic analyses results with the help of MEGA showed a new insight for the Chuanminshen phylogenetic relationship with the reported chloroplast genomes in Apiales plants.

Polysaccharides from Traditional Chinese Medicines: Extraction, Purification, Modification, and Biological Activity

Traditional Chinese Medicine (TCM) has been used to treat diseases in China for thousands of years. TCM compositions are complex, using as their various sources plants, animals, fungi, and minerals. Polysaccharides are one of the active and important ingredients of TCMs. Polysaccharides from TCMs exhibit a wide range of biological activities in terms of immunity- modifying, antiviral, anti-inflammatory, anti-oxidative, and anti-tumor properties. With their widespread biological activities, polysaccharides consistently attract scientist's interests, and the studies often concentrate on the extraction, purification, and biological activity of TCM polysaccharides. Currently, numerous studies have shown that the modification of polysaccharides can heighten or change the biological activities, which is a new angle of polysaccharide research. This review highlights the current knowledge of TCM polysaccharides, including their extraction, purification, modification, and biological activity, which will hopefully provide profound insights facilitating further research and development.

The Antiviral Effect of Baicalin on Enterovirus 71 In Vitro

Baicalin is a flavonoid compound extracted from Scutellaria roots that has been reported to possess antibacterial, anti-inflammatory, and antiviral activities. However, the antiviral effect of baicalin on enterovirus 71 (EV71) is still unknown. In this study, we found that baicalin showed inhibitory activity on EV71 infection and was independent of direct virucidal or prophylactic effect and inhibitory viral absorption. The expressions of EV71/3D mRNA and polymerase were significantly blocked by baicalin treatment at early stages of EV71 infection. In addition, baicalin could decrease the expressions of FasL and caspase-3, as well as inhibit the apoptosis of EV71-infected human embryonal rhabdomyosarcoma (RD) cells. Altogether, these results indicate that baicalin exhibits potent antiviral effect on EV71 infection, probably through inhibiting EV71/3D polymerase expression and Fas/FasL signaling pathways.

Extraction of crude polysaccharides from Duchesnea indica (Andrews) Focke: optimization by response surface methodology

A full set of optimization procedure was applied to the extraction of anti-viral polysaccharides from Duchesnea indica (Andrews) Focke. By Plackett-Burman factorial design, three parameters (extraction time, extraction temperature, and ratio of water to raw material) were identified as significant to the extraction yield. However, no significant parameters had been identified for antiviral activity. A three-level-three-factor Box-Behnken factorial design was then employed to further optimize the extraction condition. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and also examined using appropriate statistical methods. This led to the construction of a response surface indicating the optimal values for each parameter and response studied. Concerning the extraction yield, an extraction at 98.51 ºC for 6.16 h with a ratio of water to raw material of 30.94 mL/g was found to be optimal. Under the optimized conditions, the experimental yield was 6.430 ± 0.078%, which was well matched with the predicted yield of 6.509%.

Antiviral effect of sulfated Chuanmingshen violaceum polysaccharide in chickens infected with virulent Newcastle disease virus

Newcastle disease virus (NDV) belonging to the Paramyxovirinae subfamily is one of the most devastating pathogens in poultry. Although vaccines are widely applied to control the infection, outbreaks of Newcastle disease (ND) repeatedly happen. Currently, there are no alternative control measures available for ND. In the present study, we found that sulfated Chuanmingshen violaceum polysaccharide (sCVPS) were potent inhibitors of NDV in specific pathogen free chickens infected with a virulent strain. With sCVPS treatment, the survival rate increased by almost 20% and virus titers in test organs, including brain, lung, spleen and thymus, were significantly decreased. The sCVPS also exhibited the ability to prevent viral transmission by reducing the amount of virus shed in saliva and feces. Higher concentrations of interferon α and γ in serum were detected in chickens treated with sCVPS, indicating that one of the antiviral mechanisms may be attributed to the property of immunoenhancement. Histopathological examination showed that sCVPS could alleviate the tissue lesions caused by NDV infection. These results suggest that sCVPS are expected to be a new alternative control measure for NDV infection and further studies could be carried out to evaluate the antiviral activity of sCVPS against other paramyxoviruses.

Adaptation and growth kinetics study of an Indian isolate of virulent duck enteritis virus in Vero cells

Duck virus enteritis, also known as duck plague, is a viral infection of ducks caused by duck enteritis virus (DEV). The control of the disease is mainly done by vaccination with chicken embryo adapted live virus that is known to be poorly immunogenic and elicits only partial protection. Further, the embryo propagated vaccine virus pose a threat of harboring other infectious agents. Seeing these limitations, the present study reports for the first time regarding propagation and adaptation of a virulent Indian isolate of duck enteritis virus in Vero cell line. In this study isolation of an outbreak virus from Kerala state was done in chicken embryo fibroblast cell culture (CEF). Then adapted the DEV isolate in the Vero cell line. The characteristic cytopathic effects (CPE) of clumping and fusion of Vero cells were observed starting from the 7th passage onwards. The presence of the virus and its multiplication in Vero cells was confirmed by detection of viral specific DNA and antigen by using polymerase chain reaction (PCR) and indirect immuno fluorescent assay (IIFA), respectively. PCR detection of DEV using self designed primers for US4 (gD) and UL30 (DNA Polymerase) gene has been reported for the in the present study. The kinetics of DEV in Vero cells revealed a maximum infectivity titer of 10(5.6) TCID 50/ml after 48hr of viral infection. Compared to chicken embryo adapted DVE vaccine virus, the Vero cell culture system is free from other infectious agents. So it will be a good candidate for cultivation and propagation of duck enteritis virus vaccine strain. Further research studies are suggested to explore the feasibility of utilizing this Vero cell culture adapted DEV isolate for developing an attenuated vaccine virus against duck virus enteritis.

Antiviral Activity of Sulfated Polysaccharide of Adenanthera pavonina against Poliovirus in HEp-2 Cells

Adenanthera pavonina, popularly known as red-bead tree, carolina, pigeon's eye, and dragon's eye, is a plant traditionally used in Brazil for the treatment of several diseases. The present study aimed at evaluating the activity of sulfated polysaccharide from the Adenanthera pavonina (SPLSAp) seeds against poliovirus type 1 (PV-1) in HEp-2 cell cultures. The SPLSAp presented a cytotoxic concentration (CC₅₀) of 500 μg/mL in HEp-2 cell cultures, evaluated by the dimethylthiazolyl-diphenyltetrazolium bromide method (MTT). The SPLSAp exhibited a significant antiviral activity, with a 50% inhibitory concentration (IC₅₀) of 1.18 µg/mL, determined by plaque reduction assay and a high selectivity index (SI) of 423. The maximum inhibition (100%) of PV replication was found when the SPLSAp treatment was concomitant with viral infection (time 0 h), at all tested concentrations. The maximal inhibition was also found when the SPLSAp was used 1 h and 2 h postinfection, albeit at 50 μg/mL and 100 μg/mL. Therefore, we demonstrated that the SPLSAp inhibited PV growth. We also suggested that SPLSAp inhibited PV in more than one step of the replication, as the mechanism of antiviral action. We, therefore, selected the compound as a potential candidate for further development towards the control of the infection.

Comparison of Bush Sophora Root polysaccharide and its sulfate's anti-duck hepatitis A virus activity and mechanism

In order to research the sulfating modification in enhancing the anti-duck hepatitis A virus (DHAV) activity of Bush Sophora Root polysaccharide (BSRPS), sulfated Bush Sophora Root polysaccharide (sBSRPS) was prepared by chlorosulfonic acid-pyridine method. KBr pellets method was applied to analyze their different structures. Anti-DHAV activity was studied by duck embryonic hepatocytes culture in vitro and artificial inoculation method in vivo. Direct immunofluorescence method and Real-time PCR were applied to study the antiviral mechanism of adsorption, replication and release in vitro and the dynamic change of virus content of blood in vivo. The results showed at the most effective content, sBSRPS (7.813 μg/mL) could inhibit both replication and release of DHAV in vitro, BSRPS (500 μg/mL) only inhibit replication. The relative expression of DHAV gene at the 8thh and the mortality rate of sBSRPS group were significantly reduced. These results indicated sBSRPS performed more effectively in anti-DHAV activity than BSRPS.

Antiviral activity of sulfated Chuanmingshen violaceum polysaccharide against Newcastle disease virus

Newcastle disease virus (NDV) is a member of Paramyxovirinae subfamily and can infect most species of birds causing severe economic losses. The current control measure is vaccination, but infections cannot be completely prevented. It remains a constant threat to the poultry industry and new control measures are urgently needed. This study demonstrates that sulfated Chuanmingshen violaceum polysaccharides (sCVPSs) were potent inhibitors of NDV, with 50 % inhibitory concentrations (IC50) ranging from 62.55 to 76.31 µg ml(-1) in Baby hamster kidney fibroblasts clone 21 (BHK-21) and from 101.57 to 125.90 µg ml(-1) in chicken embryo fibroblasts (CEF). sCVPS is more effective than heparan sulfate (HS; as a positive control) with IC50 values of 99.28 µg ml(-1) in BHK-21 and 118.79 µg ml(-1) in CEF. sCVPSs and HS exhibit anti-NDV activity by prevention of the early stages of viral life. The mechanism of action study indicated that virus adsorption in BHK-21, and both virus adsorption and penetration in CEF were inhibited by sCVPSs. When the number of viruses was increased to an m.o.i. of 0.1 in the immunofluorescence study and to an m.o.i. of 1 in the fluorescent quantitative PCR study, viral infection was also significantly suppressed; the antiviral activity of sCVPSs was independent of the m.o.i. sCVPSs also prevented the cell-to-cell spread of NDV. In vivo tests carried out on specific pathogen-free (SPF) chickens showed that sCVPSs also inhibited virus multiplication in heart, liver, spleen, lung and kidney. These results indicated that sCVPSs perform more effectively than HS as antiviral agents against NDV, and can be further examined for their potential as an alternative control measure for NDV infection.