This study draws on a general framework of proactive motivation to propose and test a model that evaluates the influence of the individualized consideration dimension of transformational leadership ...and organizational climate on change-oriented organizational citizenship behavior. In this model, individuals' cognitive emotional states (role breadth self-efficacy and felt responsibility for constructive change) act as mediating variables. For the first time in the literature, this paper develops a model of leadership and organizational climate antecedents of organizational citizenship behavior. Using a sample of 602 Spanish employees with higher education, the structural equation modeling indicates that the proposed model fits reasonably well to the data. Research results show that all hypotheses are significant, thus confirming the results of previous research that finds mediated relations between transformational leadership and other dimensions of organizational citizenship behavior.
We developed a noncompetitive two-site sandwich ELISA to quantitate monoclonal antibodies in culture supernatant. This assay measures the initial enzyme activity rate during the first minute of the ...reaction, which ensures linear velocity relative to time and a progress curve slope proportional to analyte concentration. During this period, the enzyme substrate is in large excess relative to the analyte/antibody-enzyme complex, and enzyme catalysis proceeds in steady-state conditions. Analyses of repeatability gave coefficients of variation between 4.4 and 9.7 (interassay) and 4.4 and 6.4 (intra-assay), and analyte detectability ranged from 5.8 to 12 ng/ml. The Z-factor calculated for analyte samples at their end dilution yielded mean values from 0.57 to 0.87, which confirmed assay robustness. This initial velocity-based sandwich ELISA is a simple, sensitive, reproducible method to quantitate bi-epitopic antigens.
•Antibody quantitation by measuring initial velocity of enzyme product formation•Initial rate measurements ensure ELISA velocity proportional to analyte concentration.•A mAb isotype-matched standard curve could reduce antiglobulin heterogenous reactivity.
Attaining and maintaining the Official Tuberculosis Free status continues to be a challenge when several domestic and wild hosts contribute to the maintenance of the Mycobacterium tuberculosis ...complex (MTC). Local tuberculosis hotspots are sometimes identified in cattle in low-prevalence regions. We have, therefore, studied one such hotspot in depth in order to produce an epidemiological diagnosis. Host population size and MTC prevalence were estimated in selected wildlife and in livestock, while on-cattle environmental DNA detection was additionally used as a proxy for risk of exposure at the farm (herd) level. Positive skin test reactors were found on16 of the 24 cattle farms studied in the period 2012-2016. Although all goats tested negative to the skin test during this period, MTC was confirmed in four sheep at slaughter, thus indicating an unknown prevalence of infection in this host species. With regard to wildlife, the prevalence of MTC infection based on culture was 8.8% in the case of wild boar (Sus scrofa), and the only road-killed badger (Meles meles) submitted for culture tested positive. Two criteria were employed to divide the cattle farms into higher or lower risk: tuberculosis testing results and environmental DNA detection. Environmental MTC DNA detection yielded significant differences regarding "use of regional pastures" and "proximity to woodland". This study suggests that on-animal environmental DNA sampling may help when assessing contact risk as regards MTC in livestock at the herd level. This tool opens up new avenues of epidemiological research in complex multi-host settings.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We developed a two-step ELISA to determine the immunoreactive fraction of monoclonal antibodies in conditions of antigen excess. An antibody aliquot at limiting dilution was incubated in wells coated ...with increasing amounts of antigen up to concentrations that bind 100% of antibody. At equilibrium, a supernatant aliquot was transferred to a second plate coated with excess of antiglobulin, and the captured antibody was incubated with peroxidase-conjugated anti-IgG. Antibody was quantitated from the enzyme velocity gradient in a kinetic ELISA, and the immunoreactive fraction calculated as (1 - gradienti/gradientT) x 100, where i and T are the gradients for the free and total antibody fractions. For four distinct monoclonal antibodies (anti-diphtheria toxoid, −cholera toxin, −bovine serum albumin (BSA), and -trinitrophenyl-BSA), measurement of inter-assay variability yielded values ranging from 3.1 to 7.4 (% coefficient of variation), which supports method repeatability. This ELISA is simple, precise, and applicable to mono- and polyclonal antibodies.
•Antibody quantitation by measuring initial velocity of enzyme product formation.•Initial rate measurements ensure ELISA velocity proportional to analyte concentration.•A mAb isotype-matched standard curve could reduce antiglobulin heterogenous reactivity.
In the global 2009 H1N1 influenza pandemic, children are particularly vulnerable to severe disease. During the winter (May through July 2009) in Buenos Aires, the death rate associated with 2009 H1N1 ...influenza in children was 10 times that associated with seasonal influenza in 2007 (1.1 vs. 0.1 per 100,000 children).
During the winter (May through July 2009) in Buenos Aires, the death rate associated with 2009 H1N1 influenza in children was 10 times that associated with seasonal influenza in 2007.
Three times in the past century, pandemic influenza viruses have circulated globally and caused increased morbidity and mortality among persons who were not generally at risk for severe seasonal influenza.
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In March 2009, a new strain of pandemic influenza A (H1N1) virus emerged in Mexico, where it caused extensive disease in young adults,
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and was associated with increased morbidity in the United States.
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The 2009 H1N1 virus spread rapidly across the Southern Hemisphere.
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Morbidity and mortality were particularly high in Argentina, with numbers of confirmed cases and deaths second only to those in the United States. Although . . .
Antibody-antigen interactions are mediated by the same molecular recognition mechanisms as those of an enzyme and its substrate. On this basis, we developed a competitive inhibition kinetic ELISA to ...measure monoclonal antibody (mAb) inhibition constants. Serially diluted samples of ligand (mAb) and inhibitor (soluble antigen) were incubated to equilibrium in ELISA plates coated with a fixed concentration of antigen (receptor). Plates were washed, and bound mAb measured with antiglobulin-peroxidase. Initial velocity data of receptor-bound mAb at various ligand and inhibitor concentrations were analyzed with enzyme linear competitive inhibition methods by non-linear regression (NLR), linear transformations (Cornish-Bowden, Lineweaver-Burk, Hanes-Woolf, Dixon, Cortés 1/i0.5 vs. Vi/Vmax, Ascenzi Ks/Vmax/Ks,0/Vmax vs. I) and NLR IC50 plots, to derive mAb inhibition constants (Ki). We obtained similar mAb Ki and Kd values by ELISA and surface plasmon resonance, which confirmed the accuracy of the ELISA method. This competitive inhibition ELISA is a simple (it requires no labeling or prior knowledge of antibody concentration), sensitive (it detects Ki values in the low nanomolar range by conventional colorimetry), and reproducible method with which to calculate mAb inhibition constants.
•Antibody affinity can be determined using simple ELISA-based enzyme kinetic methods•Kinetic ELISA is universally accessible when SPR-like technologies are unavailable•mAb research, immunotherapy, and diagnosis require knowledge of antibody affinity
Of the numerous animal species affected by the SARS-CoV-2 virus, cats are one of the most susceptible, and cat-to-cat transmission has been described. Although cat-to-human infection has not, as yet, ...been demonstrated, preventive measures should be taken in order to avoid both viral infection in cats and transmission among them. In this respect, the application of an effective vaccine to at-risk populations would be a useful tool for controlling the disease in this species. Here, we test a new vaccine prototype based on the Spike protein of the virus in order to prevent infection and infectious virus shedding in cats. The vaccine employed in experimentation, and which is easily produced, triggered a strong neutralizing antibody response in vaccinated animals. In contrast to that which occurred with control animals, no infectious virus was detected in the oropharyngeal or rectal swabs of vaccinated cats submitted to a SARS-CoV-2 challenge. These results are of great interest as regards future considerations related to implementing vaccination programs in pets. The value of cats as vaccination trial models is also described herein.
•Preventive measures should be implemented to avoid SARS-CoV-2 viral infection in cats.•The vaccine candidate tested prevented infectious virus shedding in cats.•The subunit vaccine based on the Spike protein of the virus triggered a strong neutralizing antibody response in vaccinated animals.
In the wake of the COVID-19 pandemic caused by SARS-CoV-2, questions emerged about the potential effects of Bacillus Calmette-Guérin (BCG) vaccine on the immune response to SARS-CoV-2 infection, ...including the neurodegenerative diseases it may contribute to. To explore this, an experimental study was carried out in BCG-stimulated and non-stimulated k18-hACE2 mice challenged with SARS-CoV-2. Viral loads in tissues determined by RT-qPCR, histopathology in brain and lungs, immunohistochemical study in brain (IHC) as well as mortality rates, clinical signs and plasma inflammatory and coagulation biomarkers were assessed. Our results showed BCG-SARS-CoV-2 challenged mice presented higher viral loads in the brain and an increased frequency of neuroinvasion, with the greatest differences observed between groups at 3-4 days post-infection (dpi). Histopathological examination showed a higher severity of brain lesions in BCG-SARS-CoV-2 challenged mice, mainly consisting of neuroinflammation, increased glial cell population and neuronal degeneration, from 5 dpi onwards. This group also presented higher interstitial pneumonia and vascular thrombosis in lungs (3-4 dpi), BCG-SARS-CoV-2 mice showed higher values for TNF-α and D-dimer values, while iNOS values were higher in SARS-CoV-2 mice at 3-4 dpi. Results presented in this study indicate that BCG stimulation could have intensified the inflammatory and neurodegenerative lesions promoting virus neuroinvasion and dissemination in this experimental model. Although k18-hACE2 mice show higher hACE2 expression and neurodissemination, this study suggests that, although the benefits of BCG on enhancing heterologous protection against pathogens and tumour cells have been broadly demonstrated, potential adverse outcomes due to the non-specific effects of BCG should be considered.
Effective vaccines against tuberculosis (TB) are needed in order to prevent TB transmission in human and animal populations. Evaluation of TB vaccines may be facilitated by using reliable animal ...models that mimic host pathophysiology and natural transmission of the disease as closely as possible. In this study, we evaluated the immunogenicity and efficacy of two attenuated vaccines, BCG and MTBVAC, after each was given to 17 goats (2 months old) and then exposed for 9 months to goats infected with M. caprae. In general, MTBVAC-vaccinated goats showed higher interferon-gamma release than BCG vaccinated goats in response to bovine protein purified derivative and ESAT-6/CFP-10 antigens and the response was significantly higher than that observed in the control group until challenge. All animals showed lesions consistent with TB at the end of the study. Goats that received either vaccine showed significantly lower scores for pulmonary lymph nodes and total lesions than unvaccinated controls. Both MTBVAC and BCG vaccines proved to be immunogenic and effective in reducing severity of TB pathology caused by M. caprae. Our model system of natural TB transmission may be useful for evaluating and optimizing vaccines.
•Both ELISAs provide 100% specificity for TB diagnosis in intensive-managed pigs.•P22 ELISA had better specificity and sensitivity than bPPD ELISA in free-ranging suids.•TB sero-diagnostic tests are ...valuable tools in the control of the disease in suids.
Animal tuberculosis (TB) is a multi-host disease involving a wide variety of domestic and wild mammals and causing a significant economic burden and sanitary problems. Wild boar and domestic pigs (Sus scrofa) are indicators of the circulation of the Mycobacterium tuberculosis complex (MTC) and can play a role in its maintenance. The proper diagnosis of MTC contact in these species is, therefore, a key factor as regards controlling TB. The objective of the current study is to evaluate the diagnostic performance of the protein complex P22 as a candidate for use in an in-house ELISA to identify M. tuberculosis complex-specific antibodies for the diagnosis of TB in comparison to the commonly used bPPD-based ELISA (bPPD ELISA) in suids.
We conducted a retrospective study. Sera were collected from wild boar during hunting season and from domestic pigs during routine handling, and all the animals underwent reference standard tests (detailed necropsy followed by bacteriological culture and isolation). Animal TB was confirmed to be positive in 277 animals and negative in 366 animals based on both reference standard tests. Sera from those animals were tested by P22 ELISA as well as bPPD ELISA.
Both ELISAs yielded a good diagnostic value, however, a higher sensitivity (Se) and specificity (Sp) was achieved with the P22 ELISA (Se: 84.1%; CI95%: 79.3–88.2% / Sp: 98.4%; CI95%:96.5–99.4%) when compared to the bPPD ELISA (Se: 77.3%; CI95%: 71.9–82.2% / Sp: 97.3%; CI95%: 95–98.3%). An optimum Sp of 100% (CI95%: 98.54–100%) was attained with white pigs for both the bPPD and the P22 ELISA.
The results suggest that serological tests for MTC-antibody detection, and particularly the P22 ELISA, are valuable tools in the diagnosis of TB in wild boar and domestic pigs when attempting to detect contact with MTC and thereby facilitate TB control and management.
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