Optimization by orthogonal array design and humoral immunity of the bivalent vaccine against Aeromonas hydrophila and Vibrio fluvialis infection in crucian carp (Carassius auratus L.)

Aeromonas hydrophila and Vibrio fluvialis are the causative agents of a serious haemorrhagic septicaemia that affects a wide range of freshwater fish in China. In order to develop a bivalent anti-A. hydrophila and anti-V. fluvialis formalin-killed vaccine to prevent this disease, an orthogonal array design (OAD) method was used to optimize the production conditions, using three factors, each having three levels. The effects of these factors and levels on the relative per cent survival for crucian carp were quantitatively evaluated by analysis of variance. The final optimized formulation was established. The data showed that inactivation temperature had a significant effect on the potency of vaccine, but formalin concentration did not. The bivalent vaccine could elicit a strong humoral response in crucian carp (Carassius auratus L.) against both A. hydrophila and V. fluvialis simultaneously, which peaked at 3 or 5 weeks respectively. Antibody titres remained high until week 12, the end of the experiment, after a single intraperitoneal injection. The verification experiment confirmed that an optimized preparation could provide protection for fish at least against A. hydrophila infection, and did perform better than the non-optimized vaccine judged by the antibody levels and protection rate, suggesting that OAD is of value in the development of improved vaccine formulations.

A combined phage display ScFv library against Myxobolus rotundus infecting crucian carp, Carassius auratus auratus (L.), in China

Immunological methods have been developed for the diagnosis of Myxobolus rotundus but their use has been limited for the prevention and therapy of this serious parasitic pathogen. Phage display antibody libraries are a powerful technique for the development of antibodies to molecules of interest and have advantages over traditional hybridroma approaches. In the present study, four antigen fractions related to M. rotundus were prepared and a combined phage display single-chain antibody fragments (ScFv) library was constructed against this parasite. Preliminary analysis indicated that a combined antibody library of about 2.08 X 10(5) individual clones and high diversity was generated. After four rounds of screening (bio-panning) against soluble spore protein prepared from lysed, intact, mature M rotundus spores, a strain monoclonal phage display ScFv, termed pCAN-6H9, with better affinity, was isolated. The pCAN-6H9 gene fragment was sequenced and analysed. The specificity of pCAN-6H9 was further demonstrated by dot-blot. In competition enzyme-linked immunosorbent assay, both the original and enriched phage-displayed ScFv repertoire showed significant inhibition of mouse anti-M rotundus serum binding to coated antigen, while the inhibition rate of monoclonal pCAN-6H9 phage particles was only 11.83%.

Humoral immune responses of the grouper Eninephelus akaara against the microsporidium Glugea epinephelusis

The humoral immune responses of grouper Epinephelus akaara to a natural infection with Glugea epinephelusis was studied by ELISA utilizing intact mature spores as the coated antigen. Results showed that a specific humoral immune response was elicited, but the intensity of infection (in terms of the number of cysts) was not related to the antibody level in naturally infected hosts. The differences in the antigenicity of intact mature spores and soluble spore proteins derived from cracked mature spores were also analyzed. Results suggested that similar antigen epitopes existed between the 2 groups. Additionally, antigen component patterns and the distribution of antigen with immunogenicity were investigated by using the western blot and the immunofluorescent antibody technique (IFAT). The new parasitic microsporidium has specific polypeptide patterns comparable to the reported fish microsporidians. The main antigenic substances are concentrated on the surface of spores, and are mostly located on the anterior and posterior end of the spore bodies. Most surface components of the G. epinephelusis spores are soluble, The potential role of the surface components in initiating infection was also discussed.

Quantitative structure-property relationships for octanol-air partition coefficients of polychlorinated naphthalenes, chlorobenzenes and p,p '-DDT

The octanol-air partition coefficient (K-OA) is a key descriptor of chemicals partitioning between the atmosphere and environmental organic phases. Quantitative structure-property relationships (QSPR) are necessary to model and predict KOA from molecular structures. Based on 12 quantum chemical descriptors computed by the PM3 Hamiltonian, using partial least squares (PLS) analysis, a QSPR model for logarithms of K-OA to base 10 (log K-OA) for polychlorinated naphthalenes (PCNs), chlorobenzenes and p,p'-DDT was obtained. The cross-validated Q(cum)(2) value of the model is 0.973, indicating a good predictive ability of the model. The main factors governing log K-OA of the PCNs, chlorobenzenes, and p,p'-DDT are, in order of decreasing importance, molecular size and molecular ability of donating/accepting electrons to participate in intermolecular interactions. The intermolecular dispersive interactions play a leading role in governing log K-OA. The more chlorines in PCN and chlorobenzene molecules, the greater the log K-OA values. Increasing E-LUMO (the energy of the lowest unoccupied molecular orbital) of the molecules leads to decreasing log K-OA values, implying possible intermolecular interactions between the molecules under study and octanol molecules. (C) 2002 Elsevier Science Ltd. All rights reserved.

Construction and characterization of a novel recombinant single-chain variable fragment antibody against White Spot Syndrome Virus from shrimp

An antibody phage display library against White Spot Syndrome Virus (WSSV) was constructed. After four rounds of panning against WSSV, 192 out of 480 clones displayed WSSV binding activity. One of the positive clones, designated A1, had relatively higher activity specifically binding to WSSV A1-soluble, single-chain fragment variable (scFv) antibody has an affinity constant (K-aff) of 2.02 +/- 0.42 x 10(9) M-1. Dot blot assays showed that A1-soluble scFv could detect WSSV directly from shrimp hemolymph after 24-h feeding infection by WSSV. A1 scFv has potential for the development of a cheap, simple and sensitive diagnostic kit for WSSV in the field. (C) 2003 Elsevier Science B.V. All rights reserved.

Introduction of the human lactoferrin gene into grass carp (Ctenopharyngodon idellus) to increase resistance against GCH virus

Haemorrhage can be an epidemic and fatal condition in grass carp. It is known now that the Grass Carp Haemorrhage Virus (GCHV) triggers haemorrhage. Human lactoferrin (hLF) plays an important role in the non-specific immune system, making some organisms more resistant to some viruses. Sperm of grass carp was mixed with linearized pCAhLFc, which is a DNA construct containing an hLF cDNA and the promoter of common carp beta-actin gene, and then electroporated. Then, mature eggs were fertilized in vitro with the treated sperm cells. The fry were sampled and analyzed by polymerase chain reaction (PCR). Results indicated that the foreign gene had been transferred successfully into the cells of some fry. Under optimal electroporation conditions, the efficiency of gene transfer was as high as 46.8%. About 35.7% of treated 5-month-old grass carp contained foreign genes. Most transgenic fry demonstrated significant delays in onset of symptoms of haemerrhage after injection of GCHV, suggesting a significant positive relationship between hLF cDNA and levels of disease resistance (P < 0.01). Results suggest that transgenic grass carp could be bred for increased resistance to haemorrhage. (C) 2002 Elsevier Science B.V. All rights reserved.

Quantitative structure-property relationships for octanol-air partition coefficients of polychlorinated biphenyls

Based on nine quantum chemical descriptors computed by PM3 Hamiltonian, using partial least squares analysis, a significant quantitative structure-property relationship for the logarithm of octanol-air partition coefficients (log K-OA) of polychlorinated biphenyls (PCBs) was obtained. The cross-validated Q(cum)(2) value of the model is 0.962, indicating a good predictive ability. The intermolecular dispersive interactions and thus the size of the PCB molecules play a key role in governing log K-OA. The greater the size of PCB molecules, the greater the log K-OA values. Increasing E-LUMO (the energy of the lowest unoccupied molecular orbital) values of the PCBs leads to decreasing log K-OA values, indicating possible interactions between PCB and octanol molecules. Increasing Q(Cl)(+) (the most positive net atomic charges on a chlorine atom) and Q(C)(-) (the largest negative net atomic charge on a carbon atom) values of PCBs results in decreasing log K-OA values, implying possible intermolecular electrostatic interactions between octanol and PCB molecules. (C) 2002 Elsevier Science Ltd. All rights reserved.

Quantitative structure-property relationships (QSPRs) on direct photolysis of PCDDs

By the use of partial least squares (PLS) method and 27 quantum chemical descriptors computed by PM3 Hamiltonian, a statistically significant QSPR were obtained for direct photolysis quantum yields (Y) of selected Polychlorinated dibenzo-p-dioxins (PCDDs). The QSPR can be used for prediction. The direct photolysis quantum yields of the PCDDs are dependent on the number of chlorine atoms bonded with the parent structures, the character of the carbon-oxygen bonds, and molecular polarity. Increasing bulkness and polarity of PCDDs lead to decrease of log Y values. Increasing the frontier molecular orbital energies (E-lumo and E-homo) and heat of formation (HOF) values leads to increase of log Y values. (C) 2001 Elsevier Science Ltd. All rights reserved.

Quantitative structure-property relationship study on reductive dehalogenation of selected halogenated aliphatic hydrocarbons in sediment slurries

In this study, by the use of partial least squares (PLS) method and 26 quantum chemical descriptors computed by PM3 Hamiltonian, a quantitative structure-property relationship (QSPR) model was developed for reductive dehalogenation rate constants of 13 halogenated aliphatic compounds in sediment slurry under anaerobic conditions. The model can be used to explain the dehalogenation mechanism. Halogenated aliphatic compounds with great energy of the lowest unoccupied molecular orbital (E-lumo), total energy (TE), electronic energy (EE), the smallest bond order of the carbon-halogen bonds (BO) and the most positive net atomic charges on an atom of the molecule (q(+)) values tend to be reductively dehalogenated slow, whereas halogenated aliphatic compounds with high values of molecular weight (Mw), average molecular polarizability (a) and core-core repulsion energy (CCR) values tend to be reductively dehalogenated fastest. (C) 2001 Published by Elsevier Science Ltd.

Quantitative structure-property relationship studies on n-octanol/water partitioning coefficients of PCDD/Fs

Based on some fundamental quantum chemical descriptors computed by PM3 Hamiltonian, by the use of partial least-squares (PLS) analysis, a significant quantitative structure-property relationship (QSPR) model for logK(ow) of polychlorinated dibenzo-p-dioxins and dibenzo-p-furans (PCDD/Fs) was obtained. The QSPR can be used for prediction. The intermolecular dispersive interactions and thus the bulkness of the PCDD/Fs are the main factors affecting the logK(ow). The more chlorines in the PCDD/F molecule, the greater the logK(ow) values. (C) 2001 Elsevier Science Ltd. All rights reserved.

Structure and magnetic property of (Ga,Cr)As films with different Cr contents

We report variations in structure and magnetic property of (Ga,Cr) As films with increasing Cr content x. Due to phase segregation, a tendency towards inhomogeneous distribution with increasing x is confirmed. Barkhausen-like magnetization and large remanent magnetic moment were also clearly observed in the samples with x<5.3%. However, spin-glass-like behaviors were observed in both dc and ac magnetic measurements, which might originate from the competition between magnetic nucleation and frustration of long ferromagnetic order in this inhomogeneous system. All the samples exhibit characteristics of variable-range hopping conductivity at temperature below 150 K. Typical magnetic circular dichroism structure was observed in the sample with x=7.9%.

Investigation of native defects and property of bulk ZnO single crystal grown by a closed chemical vapor transport method

Hall effect, Raman scattering, photoluminescence spectroscopy (PL), optical absorption (OA), mass spectroscopy, and X-ray diffraction have been used to study bulk ZnO single crystal grown by a closed chemical vapor transport method. The results indicate that shallow donor impurities (Ga and Al) are the dominant native defects responsible for n-type conduction of the ZnO single crystal. PL and OA results suggest that the as-grown and annealed ZnO samples with poor lattice perfection exhibit strong deep level green photoluminescence and weak ultraviolet luminescence. The deep level defect in as-grown ZnO is identified to be oxygen vacancy. After high-temperature annealing, the deep level photoluminescence is suppressed in ZnO crystal with good lattice perfection. In contrast, the photoluminescence is nearly unchanged or even enhanced in ZnO crystal with grain boundary or mosaic structure. This result indicates that a trapping effect of the defect exists at the grain boundary in ZnO single crystal. (C) 2007 Elsevier B.V. All rights reserved.

Growth parameter dependence of magnetic property of CrAs thin film

This paper has systematically investigated the substrate temperature and thickness dependence of surface morphology and magnetic property of CrAs compound films grown on GaAs by molecular-beam epitaxy. It finds that the substrate temperature affects the surface morphology and magnetic property of CrAs thin film more potently than the thickness.

Systematic investigation on the influence of the As-4 flux on the magnetic property of (In,Cr)As quantum dots

We study the structure, optical and magnetic characteristics of self-assembled (In,Cr) As diluted magnetic semiconductor quantum dots as a function of the As-4 flux. Increasing the surface energy by increasing the As4 pressure leads to a smaller number of larger dots for a higher As-4 flux. The remanent magnetization measured at 5K also increases with increasing As-4 flux, which is attributed to the enhancement of the effective Cr content due to the As-4-rich condition. We explore the possibility of tailoring magnetism by controlling the As-4/In flux ratio without changing the Cr concentration. Furthermore, extremely low-density QDs have also been successfully grown. Copyright (C) EPLA, 2008