Zhongqiong Yin

First Report of a Ranavirus Associated with Morbidity and Mortality in Farmed Chinese Giant Salamanders (Andrias davidianus)

From February to May 2010, an outbreak of disease occurred amongst farmed Chinese giant salamanders (Andrias davidianus) in Hanzhong County, Shanxi Province, China. Clinical signs included anorexia, lethargy, ecchymoses and swollen areas on the head and limbs, and skin ulceration. The aim of this study was to determine the cause of this disease. Necropsy examination revealed subcutaneous and intramuscular oedema, swollen and pale livers with multifocal haemorrhage, swollen kidneys with multifocal haemorrhage and distended fluid-filled intestines with areas of haemorrhage. Light microscopy revealed intracytoplasmic inclusions suggestive of a viral infection in a variety of organs, as well as degeneration and necrosis of these organs. Electron microscopy of ultrathin sections of the same tissues revealed iridovirus-like particles within the inclusions. Of the six specimens tested, all were positive for ranavirus major capsid protein (MCP) gene. Sequence alignments of the ranavirus MCP gene from these specimens showed 95-98% similarity with published ranavirus data. The virus, provisionally designated as Chinese giant salamander virus (CGSV), was isolated from tissue homogenates of diseased salamanders following inoculation of epithelioma papilloma cyprini cells. Sequence analysis of the MCP genes showed that the isolated virus was a ranavirus with marked sequence identity to other members of the genus Ranavirus. Kochs postulates were fulfilled by infecting healthy Chinese giant salamanders with the CGSV. These salamanders all died within 6-8 days. This is the first report of ranavirus infection associated with mass mortality in Chinese giant salamanders.

Toxicological assessment of combined lead and cadmium: acute and sub-chronic toxicity study in rats.

The exposure to chemical mixtures is a common and important determinant of toxicity and receives concern for their introduction by inhalation and ingestion. However, few in vivo mixture studies have been conducted to understand the health effects of chemical mixtures compared with single chemicals. In this study, the acute and 90day sub-chronic toxicity tests of combined Pb and Cd were conducted. In the acute toxicity test, the LD50 value of Pb(NO3)2 and CdCl2 mixture by the oral route was 2696.54mg/kg by Bliss method. The sub-chronic treatment revealed that the low-dose combination of Pb and Cd exposures can significantly change the physiological and biochemical parameters of the blood of Sprague-Dawley (SD) rats with dose-response relationship and causes microcytic hypochromic anemia and the damages of liver and kidney of the SD rats to various degrees. Histopathological exams showed that the target organs of Pb and Cd were testicle, liver, and kidneys. These observations suggest that Pb and Cd are practically additive-toxic for the SD rats in oral acute toxicity studies. The lowest observed adverse-effect level in rats may be lower than a dose of 29.96mg/(kgbwday) when administered orally for 90 consecutive days.

Quantification of metallothionein on the liver and kidney of rats by subchronic lead and cadmium in combination

The combined subchronic effects of exposure to lead acetate and cadmium chloride on oxidative stress and metallothionein (MT) gene expression were detected in the liver and kidney of rats to investigate the hazards of environmentally relevant, low-dose exposure to these compounds. Pb and Cd co-induced oxidative stress in liver and kidney tissues. This result was indicated by a significant (P<0.01) increase in the maleic dialdehyde level and decreased levels of reduced glutathione, superoxide dismutase, catalase, and glutathione peroxidase. MT mRNA and protein significantly increased (P<0.01) in the liver and kidney of rats. Furthermore, the expression levels of MT-1 mRNA and MT-2 mRNA differed between the liver and kidney. The findings indicate that Pb combined with Cd induced oxidative damage in the liver and kidney of rats, and MT may be a biochemical environmental indicator.

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

Duck enteritis virus (DEV) of the family Herpesviridae is one of the main diseases in waterfowl. Despite the wide use of vaccines to control the disease, infection with the virus cannot be completely prevented. Therefore, antiviral agents against DEV should be developed. This study presents a novel sulfated polysaccharide from Chuanminshen violaceum (sCVPS), which exhibits significant antiviral activity against DEV with 50% inhibitory concentrations (IC₅₀) ranging from 77.12 μg/mL to 104.81 μg/mL. sCVPS is more effective than heparan sulfate (HS, as a positive control) with IC₅₀=132.61 μg/mL. sCVPS and HS inhibit viral activity by preventing virus adsorption with IC₅₀ values ranging from 82.83 μg/mL to 109.28 μg/mL for sCVPS and 150.22 μg/mL for HS. Direct immunofluorescence assay and transmission electron microscopy demonstrated that the mechanism of action was the interference with virus adsorption. The amount of inhibited virus during adsorption was quantified using fluorescent quantitative polymerase chain reaction, which revealed that both sCVPS and HS can significantly reduce all viruses attached to cells. sCVPS also prevented the cell-to-cell spread of DEV. These results indicated that sCVPSs perform more effectively than does HS as antiviral agents against DEV and can be further examined for potential effects as an alternative control measure for DEV infection.

Acaricidal activity of petroleum ether extract of neem (Azadirachta indica) oil and its four fractions separated by column chromatography against Sarcoptes scabiei var. cuniculi larvae in vitro.

The petroleum ether extract of neem oil and its four fractions separated by column chromatography was diluted at different concentrations with liquid paraffin. The acaricidal bioassay was conducted using a dipping method. The results indicated that the median lethal concentration (LC50) of the petroleum ether extract (at the concentration of 500.0ml/l) was 70.9ml/l, 24h after treatment. At concentrations of 500.0, 250.0, 125.0, 62.5 and 31.2ml/l, the median lethal times (LT50) of the petroleum ether extract were 8.7, 8.8, 10.8, 11.5 and 13.1h, respectively. Thin-layer chromatography (TLC) showed that the petroleum ether extract of neem oil separated into four fractions (F1-F4). Acaricidal activity of 68.3% and 100.0% in the F2 and F4 was confirmed. These results suggest that petroleum ether extracts of neem oil and its four fractions possess useful acaricidal activity in vitro.

The enhancement of immune function and activation of NF-κB by resveratrol-treatment in immunosuppressive mice.

Resveratrol, a kind of natural product found in over 70 plants, possesses both immunomodulatory and anticancer effects. Many reports have shown that resveratrol has the bidirectional regulation effects on antigen presenting and cellular immunity. However, few reports have evaluated the effects of resveratrol on reinforcing immunity recovery via activating nuclear factor -κappa B (NF-κB). In the present study, we investigated the effects of resveratrol on recovery and reconstruction of immune function by detecting nonspecific and specific immunity in immunosuppressive mice. We found that, compared to the immunosuppressive mice, the spleen index and spleen lymphocyte proliferation of resveratrol-treated mice (30 mg/kg body weight) were enhanced. After resveratrol-treatment (15 mg/kg body weight), the function of peritoneal macrophages was enhanced and the CD4+ cells were increased in peripheral blood. The expressions of serum cytokines related to immune function, including interleukin (IL)-1α/β, IL-2, tumor necrosis factor-α and NF-κB were up-regulated in a dose-dependent manner. The expression of the transcription factor NF-κB in spleen was enhanced after resveratrol-treatment. The immuno-enhancement effects of resveratrol were similar to that of levamisole (served as positive control). These results demonstrated that resveratrol had potent immune enhancement activity in immunosuppressive mice, and one possible mechanism of action was to activate the NF-κB.

Toxicological evaluation of neem (Azadirachta indica) oil: acute and subacute toxicity.

Neem (Azadirachta indica), popularly known as traditional medicine is a native plant in India. Neem oil is a vegetable oil derived from seeds or fruits of the neem tree through pressing or solvent extraction, and largely used in popular medicine to have antifungal, antibacterial, antimalarial, antiparasitic, anti-inflammatory, as well as immunemodulatory properties in different animal species. In the present study, acute and 28-day subacute toxicity tests were carried out. In the acute toxicity test, the LD50 values of neem oil were found to be 31.95g/kg. The subacute treatment with neem oil failed to change body weight gain, food and water consumption. Serum biochemistry analysis showed no significant differences in any of the parameters examined under the dose of 1600mg/kg/day. Histopathological exams showed that the target organs of neem oil were testicle, liver and kidneys up to the dose of 1600mg/kg/day.

Inhibitory Effect of Resveratrol against Duck Enteritis Virus In Vitro

Duck viral enteritis (DVE) is an acute, contagious herpesvirus infection of ducks, geese, and swans of all ages and species. This disease has been responsible for significant economic losses in domestic and wild waterfowl as a result of mortality, and decreased egg production. Resveratrol is a naturally occurring phytoalexin in specific plants and exhibits inhibitory activity against many kinds of virus. In this paper, resveratrol was found to inhibit duck enteritis virus (DEV) replication in a dose-dependent manner, with a 50% inhibition concentration of 3.85 μg/mL. The inhibition in virus multiplication in the presence of resveratrol was not attributed to direct inactivation or inhibition of virus attachment to the host cells, but to the inhibition of viral multiplication in host cells. The assay of the time of addition limited the drug effect during the first 8 h of infection. This conclusion was supported by the ultrastructure images of the early stage of DEV infection, which showed that the replication of virus nucleic acid and the formation of the capsid in the cell nucleus were suppressed. In the indirect immunofluorescence assay, proteins expression in DEV infected duck embryo fibroblasts (DEFs) within 24 h post-infection (p.i.) was also effectively suppressed by resveratrol. In summary, the resveratrol has a good activity against DEV infection in vitro, which could be attributed to that fact that several essential immediate early viral proteins for virus replication were impacted by resveratrol.

Identification, genotyping, and molecular evolution analysis of duck circovirus.

Duck circovirus (DuCV) is a contagious immunosuppressive virus affecting many duck species, which is responsible for multiple outbreaks in poultry industries worldwide. In this study, the first DuCV isolate GH01 was identified in Sichuan by PCR, which shared a high level of nucleotide identity (81.8-99.4%) with sequences of other DuCV isolates available in GenBank. Comparative phylogenetic and pairwise sequence comparison analyses indicated that DuCV could be divided into two genotypes (DuCV-1 and DuCV-2) and six subtypes (1a, 1b, 1c, 2a, 2b and 2c) based on the complete genome sequence. The results revealed that both DuCV-1 and DuCV-2 had evolved from the same ancestor but undergone divergent evolution. Interestingly, phylogenetic analyses indicated that three isolates were classified into a cluster DuCV-2a using complete DuCV genome sequence and cap gene, except rep gene. Recombination analyses revealed that DuCV-2a arose from recombination between DuCV-1a and DuCV-2b isolates within the rep genes, and the recombination events mainly occur both in non-structural protein coding region and structural protein coding region. In addition, the mechanisms of recombination supporting the genetic variability in DuCV isolates were investigated. Likewise, selective pressure indicated that purifying selection had been a major driving force in maintaining diversity among the DuCV isolates. Because eradicating the virus from commercial ducks is impossible, it is necessary to take effective control measures and implement them throughout the world.

Fermented Yupingfeng polysaccharides enhance immunity by improving the foregut microflora and intestinal barrier in weaning rex rabbits

Yupingfeng (YPF) is a kind of Astragali radix-based ancient Chinese herbal supplemented with Atractylodis Macrocephalae Rhizoma and Radix Saposhnikoviae. Increasing evidence has proven the beneficial immunomodulating activity of YPF. However, the action mechanism(s) of it is not known. Here, we explored the immunomodulatory activity of unfermented Yupingfeng polysaccharides (UYP) and fermented Yupingfeng polysaccharides (FYP) obtained using Rhizopus oligosporus SH in weaning Rex rabbits. The results showed that both UYP and FYP exhibited notable growth-promoting and immune-enhancing activities, improvement of the intestinal flora homeostasis, and maintenance of intestinal barrier integrity and functionality. Notably, compared with UYP, FYP effectively enhanced average daily gain, organ indices, interleukin-2 (IL-2), IL-4, IL-10, tumor necrosis factor-alpha (TNF-α), TLR2, and TLR4 mRNA levels in spleen, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12, TNF-α, and IFN-γ protein concentrations in serum, and TLR2 and TLR4 mRNA expressions in the gastrointestinal tract (GIT). Moreover, FYP exhibited greater beneficial effects in improving the intestinal flora, including augment flora diversity and the abundance of cellulolytic bacteria, reduction the abundance of Streptococcus spp. and Enterococcus spp. in the GIT, particularly the foregut and maintaining the intestinal barrier integrity and functionality by upregulating zonula occludens 1, claudin, polymeric immunoglobulin receptor, trefoil factor, and epidermal growth factor mRNA levels in the jejunum and ileum. Our results indicated the immunoenhancement effect of FYP is superior over that of UYP, which is probably related with the amelioration of the intestinal microflora and intestinal barrier in the foregut.