A Defined Antigen Skin Test That Enables Implementation of BCG Vaccination for Control of Bovine Tuberculosis:Proof of Concept

In most low- and middle-income countries (LMICs), bovine tuberculosis (bTB) remains endemic due to the absence of control programs. This is because successful bTB control and eradication programs have relied on test-and-slaughter strategies that are socioeconomically unfeasible in LMICs. While Bacillus Calmette–Guérin (BCG) vaccine-induced protection for cattle has long been documented in experimental and field trials, its use in control programs has been precluded by the inability to differentiate BCG-vaccinated from naturally infected animals using the OIE-prescribed purified protein derivative (PPD)-based tuberculin skin tests. In the current study, the diagnostic specificity and capability for differentiating infected from vaccinated animals (DIVA) of a novel defined antigen skin test (DST) in BCG-vaccinated (Bos taurus ssp. taurus x B. t. ssp. indicus) calves were compared with the performance of traditional PPD-tuberculin in both the skin test and in vitro interferon-gamma release assay (IGRA). The IFN-γ production from whole blood cells stimulated with both PPDs increased significantly from the 0 week baseline levels, while DST induced no measurable IFN-γ production in BCG-vaccinated calves. None of the 15 BCG-vaccinated calves were reactive with the DST skin test (100% specificity; one-tailed lower 95% CI: 82). In contrast, 10 of 15 BCG-vaccinated calves were classified as reactors with the PPD-based single intradermal test (SIT) (specificity in vaccinated animals = 33%; 95% CI: 12, 62). Taken together, the results provide strong evidence that the DST is highly specific and enables DIVA capability in both skin and IGRA assay format, thereby enabling the implementation of BCG vaccine-based bTB control, particularly in settings where test and slaughter remain unfeasible

Optical and Structural Characterization of Hydrogenated Aluminium Nitride Thin-films Synthesized at Low Temperature

A fundamental study of the optical and structural properties of hydrogenated aluminium nitride (AlN:H) films is presented. It is shown that incorporation of hydrogen within aluminium nitride (AlN) enables inherent optical tunability and leads to enhancement in its optical transmittance. It is revealed through microscopy studies (SEM, AFM and TEM) that the AlN:H films have an amorphous-nanocrystalline character, undergo non-columnar growth, and have reduced surface roughness, and feature size. Examination of the infrared vibrational modes indicate enhancement in chemical stability and robustness of the AlN:H films. Optical tunability coupled with excellent physical, structural and chemical properties of the AlN:H films enabled its successful integration in spectrally selective coatings (SSCs) wherein these multilayer stacks are synthesized with the fewest layers in comparison to the state-of-the-art and have been experimentally demonstrated to provide optimal solar energy control and rapid active uniform heating with inherent stability against degradation from ambient moisture and oxygen.M.A.S.2019-11-03 00:00:0