An enzyme-linked immunosorbent assay for detection of avian influenza virus subtypes H5 and H7 antibodies

Background

Avian influenza virus (AIV) subtypes H5 and H7 attracts particular attention because of the risk of their potential pathogenicity in poultry. The haemagglutination inhibition (HI) test is widely used as subtype specific test for serological diagnostics despite the laborious nature of this method. However, enzyme-linked immunosorbent assays (ELISAs) are being explored as an alternative test method.H5 and H7 specific monoclonal antibodies were experimentally raised and used in the development of inhibition ELISAs for detection of serological response specifically directed against AIV subtypes H5 and H7. The ELISAs were evaluated with polyclonal chicken anti-AIV antibodies against AIV subtypes: H1N2, H5N2, H5N7, H7N1, H7N7, H9N9, H10N4 and H16N3.

Results

Both the H5 and H7 ELISA proved to have a high sensitivity and specificity and the ELISAs detected H5 and H7 antibodies earlier during experimental infection than the HI test did. The reproducibility of the ELISA’s performed at different times was high with Pearson correlation coefficients of 0.96-0.98.

Conclusions

The ELISAs are a potential alternative to the HI test for screening of large amounts of avian sera, although only experimental sera were tested in this study.

     

Plant community composition steers grassland vegetation via soil legacy effects

Soil legacy effects are commonly highlighted as drivers of plant community dynamics and species co‐existence. However, experimental evidence for soil legacy effects of conditioning plant communities on responding plant communities under natural conditions is lacking. We conditioned 192 grassland plots using six different plant communities with different ratios of grasses and forbs and for different durations. Soil microbial legacies were evident for soil fungi, but not for soil bacteria, while soil abiotic parameters did not significantly change in response to conditioning. The soil legacies affected the composition of the succeeding vegetation. Plant communities with different ratios of grasses and forbs left soil legacies that negatively affected succeeding plants of the same functional type. We conclude that fungal‐mediated soil legacy effects play a significant role in vegetation assembly of natural plant communities.     

Monosialoganglioside Increases Catalase Activity in Cerebral Cortex of Rats

Monosialoganglioside (GM1) is a neuroprotective agent that has been reported to scavenge free radicals generated during reperfusion and to protect receptors and enzymes from oxidative damage. However, only a few studies have attempted to investigate the effects of GM1 on enzymatic antioxidant defenses of the brain. In the present study, we evaluate the effects of the systemic administration of GM1 on the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), and on spontaneous chemiluminescence and total radical-trapping potential (TRAP) in cerebral cortex of rats ex vivo. The effects of GM1 on CAT activity and spontaneous chemiluminescence in vitro were also determined.

Animals received two injections of GM1 (50?mg/kg, i.p.) or saline (0.85% NaCl, i.p.) spaced 24?h apart. Thirty minutes after the second injection the animals were sacrificed and enzyme activities and spontaneous chemiluminescence and TRAP were measured in cell-free homogenates. GM1 administration reduced spontaneous chemiluminescence and increased catalase activity ex vivo, but had no effect on TRAP, SOD or GSH-Px activities. GM1, at high concentrations, reduced CAT activity in vitro. We suggest that the antioxidant activity of GM1 ganglioside in the cerebral cortex may be due to an increased catalase activity.