Prediction of G gene epitopes of viral hemorrhagic septicemia virus and eukaryotic expression of major antigen determinant sequence.

This study aims to express fish Viral hemorrhagic septicemia virus (VHSV) G main antigen domain by using Bac-to-bac expression system. Using bioinformatics tools, B cell epitope of VHSV G gene was predicted, and G main antigen domain was optimized. GM gene was inserted into pFastBac1 vector, then transferred recombinant plasmid into DH10Bac to get recombinant rBacmid-GM. Obtained shuttle plasmid rBacmid-GM was transfected into sf9 cells. GM expression was examined using by PCR and western-blot. Results indicated that G main antigen domain gene of VHSV was successfully cloned and sequenced which contains 1209 bp. PCR proved that shuttle plasmid rBacmid-GM was constructed correctly. SDS-PAGE electrophoresis analysis detected a band of protein about 45kD in expression product of G gene. Obtained recombinant G protein reacted with VHSV-positive serum that was substantiated by western-blot analysis. In conclusion, the main antigen domain of VHSV G was successfully expressed in the Bac-to-Bac baculovirus system.

A physiologically based pharmacokinetic model for quinoxaline-2-carboxylic acid in rats, extrapolation to pigs.

A multi-compartment physiologically based pharmacokinetic (PBPK) model to describe the disposition of cyadox (CYX) and its metabolite quinoxaline-2-carboxylic acid (QCA) after a single oral administration was developed in rats (200 mg/kg b.w. of CYX). Considering interspecies differences in physiology and physiochemistry, the model efficiency was validated by pharmacokinetic data set in swine. The model included six compartments that were blood, muscle, liver, kidney, adipose, and a combined compartment for the rest of tissues. The model was parameterized using rat plasma and tissue concentration data that were generated from this study. Model simulations were achieved using a commercially available software program (ACSLXL ibero version 3.0.2.1). Results supported the validity of the model with simulated tissue concentrations within the range of the observations. The correlation coefficients of the predicted and experimentally determined values for plasma, liver, kidney, adipose, and muscles in rats were 0.98, 0.98, 0.98, 0.99, and 0.95, respectively. The rat model parameters were then extrapolated to pigs to estimate QCA disposition in tissues and validated by tissue concentration of QCA in swine. The correlation coefficients between the predicted and observed values were over 0.90. This model could provide a foundation for developing more reliable pig models once more data are available.

Toxicokinetics of T-2 toxin and its major metabolites in broiler chickens after intravenous and oral administration.

T-2 toxin, one of the most toxic trichothecene mycotoxins, causes economic losses in animal production. Little information is available on the toxicokinetic parameters of T-2 toxin and its major metabolites (i.e., HT-2 toxin and T-2 triol) in broiler chickens. In this study, toxicokinetics of T-2 toxin and its major metabolites were evaluated in broiler chickens after a single intravenous (0.5 mg/kg b.w.) and multiple oral administrations (2.0 mg/kg b.w., every 12 h for 2 days). Plasma concentration profiles of T-2 toxin and its metabolites were analyzed by a noncompartmental model method. Following intravenous administration, the terminal elimination half-lives (t(1/2λz)) of T-2 toxin, HT-2 toxin, and T-2 triol were 17.33 ± 1.07 min, 33.62 ± 3.08 min, and 9.60 ± 0.50 min, respectively. Following multiple oral administrations, no plasma levels above the limit of quantification were observed for HT-2 toxin. The t(1/2λz) of T-2 toxin and T-2 triol was 23.40 ± 2.94 min and 87.60 ± 29.40 min, respectively. Peak plasma concentrations (Cmax ) of 53.10 ± 10.42 ng/mL (T-2 toxin) and 47.64 ± 9.19 ng/mL (T-2 triol) were observed at Tmax of 13.20 ± 4.80 min and 38.40 ± 15.00 min, respectively. T-2 toxin had a low absolute oral bioavailability (17.07%). Results showed that the T-2 toxin was rapidly absorbed and most of the T-2 toxin was extensively transformed to metabolites in broiler chickens.

Pharmacokinetics and bioavailability of valnemulin in broiler chickens.

The objective of this study was to investigate the pharmacokinetics and bioavailability of valnemulin in broiler chickens after intravenous (i.v.), intramuscular (i.m.) and oral administrations of 10 mg/kg body weight (bw). Plasma samples were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Pharmacokinetic characterization was performed by non-compartmental analysis using WinNonlin program. After intravenous administration, distribution was wide with the volume of distribution based on terminal phase(V(z)) of 4.27 ± 0.99 L /kg. Mean valnemulin t(1/2ß)(h), Cl(ß)(L /h /kg), V(ss)(L /kg) and AUC((0-∞))(µg·h /mL) values were 2.85, 0.99, 2.72 and 10.34, respectively. After intramuscular administration, valnemulin was rapidly absorbed with a C(max) of 2.2 µg/mL achieved at 0.43 h (t(max)), and the absolute bioavailability (F) was 88.81%; and for the oral route the same parameters were 0.66 ± 0.15 µg/mL, 1.54 ± 0.27 h and 74.42%. A multiple-peak phenomenon was present after oral administration. The plasma profile of valnemulin exhibited a secondary peak during 2-6 h and a tertiary peak at 32 h. The favorable PK behavior, such as the wide distribution, slow elimination and acceptable bioavailability indicated that it is likely to be effective in chickens.

Multiplex polymerase chain reaction assay for the detection of minute virus of mice and mouse parvovirus infections in laboratory mice.

Mouse parvoviruses are among the most prevalent infectious pathogens in contemporary mouse colonies. To improve the efficiency of routine screening for mouse parvovirus infections, a multiplex polymerase chain reaction (PCR) assay targeting the VP gene was developed. The assay detected minute virus of mice (MVM), mouse parvovirus (MPV) and a mouse housekeeping gene (α-actin) and was able to specifically detect MVM and MPV at levels as low as 50 copies. Co-infection with the two viruses with up to 200-fold differences in viral concentrations can easily be detected. The multiplex PCR assay developed here could be a useful tool for monitoring mouse health and the viral contamination of biological materials.

The infectivity and antigenicity of Toxocara canis eggs can be retained after long-term preservation.

Suspensions of fertilized eggs of Toxocara canis were mixed with 2% neutral formalin and preserved at 4 degrees C. When, after storage for 0, 12, 18, 21 and 24 months, samples of the eggs were incubated at 30 degrees C for 12 days, 96.8%, 92.6%, 74.1%, 51.0% and 19.3% of the eggs in the samples were found to embryonate. The embryonated eggs produced from the fertilized eggs preserved (in 2% neutral formalin at 4 degrees C) for 0, 12, 18 and 21 months were then tested for their infectivity to BALB/c mice, each mouse being given 800 embryonated eggs. The numbers of larvae recovered from the mice and the sites from which they were recovered, 2 or 14 days post-infection, appeared unaffected by the length of storage of the eggs. The infected mice all had similar eosinophil counts in their peripheral blood and similar serum titres of Toxocara-specific IgM and IgG antibodies, and cultures of their spleen cells produced similar amounts of interleukin-4, interleukin-5 and interferon-gamma when stimulated with concanavalin A. The results of SDS-PAGE indicated that egg preservation for at least 21 months had no effect on the excretory-secretory antigens in samples of medium from cultures of infective larvae released from the eggs. In summary, at least 50% of the fertilized eggs preserved in 2% neutral formalin at 4 degrees C for 21 months could fully embryonate and then had the same infectivity and antigenicity as embryonated fresh eggs.