Six-month repeated dose toxicity of orally administered metacavir in rhesus monkeys.

OBJECTIVE: To explore the toxicities of metacavir, a novel deoxyguanosine analog with an anti-hepatitis B virus (HBV) potential, in a 6-month repeated dosing in rhesus monkeys. METHODS: Rhesus monkeys were divided into four groups with eight animals in each group. Metacavir or blank vehicles were given for up to 6-month, and then the animals were euthanized 3 and 6 months later. Biochemical and hematological parameters, general symptoms, ECG, serum antibodies, and tissue pathology were observed and recorded. RESULTS: No biologically meaningful influences on body weight, body temperature, ocular examination, ECG, and organ weight were observed. The main toxic effects included: obvious gastrointestinal toxicities were observed in metacavir 200 mg/kg group, in which animals experienced vomiting and decrease in food consumption. Along with the increase of dosing times, animals gradually tolerated the drug and all these effects gradually abated. Hematological damages included increased damage of red blood cells, decrease of red blood cell count and hemoglobin levels. Hepatic functions were also damaged at certain levels, including the decreases in total protein, albumin, and glucose and the fatty degeneration in hepatocytes. Mild stenosis and exfoliation of gastric and duodenal mucosa was observed. The mild necrosis and exfoliation of renal tubules epithelia was found 6 months after the start of dosing. All these toxic effects were dose dependent. CONCLUSION: The main target organs of the toxic effects of metacavir are gastrointestinal tract, liver, blood, and kidneys. The no-observed-adverse-effect-level (NOAEL) of metacavir for rhesus monkey were considered to be 50 mg/kg/day.

Development of a fluorescent quantitative real-time polymerase chain reaction assay for the detection of Goose parvovirus in vivo.

BACKGROUND: Goose parvovirus (GPV) is a Dependovirus associated with latent infection and mortality in geese. Currently, it severely affects geese production worldwide. The objective of this study was to develop a fluorescent quantitative real-time polymerase chain reaction (PCR) (FQ-PCR) assay for fast and accurate quantification of GPV DNA in infected goslings, which can aid in the understanding of the regular distribution pattern and the nosogenesis of GPV in vivo. RESULTS: The detection limit of the assay was 2.8 x 10(1) standard DNA copies, with a sensitivity of 3 logs higher than that of the conventional gel-based PCR assay targeting the same gene. The real-time PCR was reproducible, as shown by satisfactory low intraassay and interassay coefficients of variation. CONCLUSION: The high sensitivity, specificity, simplicity, and reproducibility of the GPV fluorogenic PCR assay, combined with a high throughput, make this method suitable for a broad spectrum of GPV etiology-related applications.

New strategies for electrophoresis analysis of enterobacterial repetitive intergenic consensus PCR in animal intestinal microflora.

Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) is a molecular biological technology that can be used to study microbial community diversity and dynamics. In many reports, investigations of microbial diversity from environmental samples were based on the agarose gel electrophoresis (AGE) patterns of ERIC-PCR amplified products. This is not a sound practice, since bands with identical positions can contain different sequences; thus, this practice could possibly exaggerate the similarities or diversities among samples. To mitigate this issue, we employed a denaturing gradient gel electrophoresis (DGGE) strategy to explore DNA bands with the same size, between ERIC-PCR profiles of samples. DPS software was used with Shannon-Wiener diversity index (H') to analyze ERIC-PCR fingerprint profiles. H' revealed that the microbial community diversity at DGGE was higher than with AGE. The results of this study suggest that the ERIC-PCR assays with DGGE can provide a better assessment of electrophoresis pattern with regards to the structure of an intestinal microbial community.

A simple and rapid method for extracting bacterial DNA from intestinal microflora for ERIC-PCR detection.

AIM: To develop a simple and convenient method for extracting genomic DNA from intestinal microflora for enterobacterial repetitive intergenic consensus (ERIC)-PCR detection. METHODS: Five methods of extracting bacterial DNA, including Tris-EDTA buffer, chelex-100, ultrapure water, 2% sodium dodecyl sulfate and 10% Triton-100 with and without sonication, were compared with the commercial fecal DNA extraction kit method, which is considered as the gold standard for DNA extraction. The comparison was based on the yield and purity of DNA and the indexes of the structure and property of micro-organisms that were reflected by ERIC-PCR. RESULTS: The yield and purity of DNA obtained by the chelex method was similar to that obtained with the fecal DNA kit. The ERIC-PCR results obtained for the DNA extracted by the chelex method and those obtained for DNA extracted with the fecal DNA kit were basically the same. CONCLUSION: The chelex method is recommended for ERIC-PCR experiments in view of its simplicity and cost-effectiveness; and it is suitable for extracting total DNA from intestinal micro-organisms, particularly for handling a large number of samples.