A novel swine enteric alphacoronavirus, swine acute diarrhoea syndrome coronavirus (SADS‐CoV), related to Rhinolophus bat CoV HKU2 in the subgenus Rhinacovirus emerged in southern China in 2017, ...causing diarrhoea in newborn piglets, and critical questions remain about the pathogenicity, cross‐species transmission and potential animal reservoirs. Our laboratory's previous research has shown that SADS‐CoV can replicate in various cell types from different species, including chickens. Here, we systematically explore the susceptibility of chickens to a cell‐adapted SADS‐CoV strain both in vitro and in vivo. First, evidence of SADS‐CoV replication in primary chicken cells, including cytopathic effects, immunofluorescence staining, growth curves and structural protein expression, was proven. Furthermore, we observed that SADS‐CoV replicated in chicken embryos without causing gross lesions and that experimental infection of chicks resulted in mild respiratory symptoms. More importantly, SADS‐CoV shedding and viral distribution in the lungs, spleens, small intestines and large intestines of infected chickens were confirmed by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. The genomic sequence of the original SADS‐CoV from the pig source sample in 2017 was determined to have nine nucleotide differences compared to the cell‐adapted strain used; among these were three nonsynonymous mutations in the spike gene. These results collectively demonstrate that chickens are susceptible to SADS‐CoV infection, suggesting that they are a potential animal reservoir. To our knowledge, this study provides the first experimental evidence of cross‐species infection in which a mammalian alphacoronavirus is able to infect an avian species.
Porcine deltacoronavirus (PDCoV) causes severe diarrhea and vomiting in affected piglets. The aim of this study was to establish the basic, in vitro characteristics of the life cycle such as ...replication kinetics, cellular ultrastructure, virion morphology, and induction of autophagy of PDCoV. Time-course analysis of viral subgenomic and genomic RNA loads and infectious titers indicated that one replication cycle of PDCoV takes 5 to 6 h. Electron microscopy showed that PDCoV infection induced the membrane rearrangements with double-membrane vesicles and large virion-containing vacuoles. The convoluted membranes structures described in alpha- and beta-coronavirus were not observed. PDCoV infection also increased the number of autophagosome-like vesicles in the cytoplasm of cells, and the autophagy response was detected by LC3 I/II and p62 Western blot analysis. For the first time, this study presents the picture of the PDCoV infection cycle, which is crucial to help elucidate the molecular mechanism of deltacoronavirus replication.
Tryptophan is a fluorescent amino acid common in proteins. Its absorption is largest for wavelengths λ ≲ 290 nm and its fluorescence emissions peak around 300-350 nm, depending upon the local ...environment. Here we report the observation of red fluorescence near 600 nm emerging from 488-nm continuous-wave (CW) laser photoexcitation of dry tryptophan (Trp) particles. With an excitation intensity below 0.5 kW/cm
, dry Trp particles yield distinctive Raman scattering peaks in the presence of relatively weak and spectrally broad emissions with λ ∼500-700 nm, allowing estimation of particle temperature at low excitation intensities. When the photoexcitation intensity is increased to 1 kW/cm
or more for a few minutes, fluorescence intensity dramatically increases by more than two orders of magnitude. The fluorescence continues to increase in intensity and gradually shift to the red when photoexcitation intensity and the duration of exposure are increased. The resulting products absorb at visible wavelengths and generate red fluorescence with λ ∼ 650-800 nm with 633-nm CW laser excitation. We attribute the emergence of orange and red fluorescence in the Trp products to a photochemical transformation that is instigated by weak optical transitions to triplet states in Trp with 488-nm excitation and which may be expedited by a photothermal effect.
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•An optical trap for both transparent and absorbing particles in air.•Fast and effective fluorescence bleaching in single particles.•Observation of the entire evolution from strong ...fluorescence to clean Raman spectra.•A new method to study dynamic changes of single particles in air.
We observe the entire temporal evolution process of fluorescence and Raman spectra of single solid particles optically trapped in air. The spectra initially contain strong fluorescence with weak Raman peaks, then the fluorescence was bleached within seconds, and finally only the clean Raman peaks remain. We construct an optical trap using two counter-propagating hollow beams, which is able to stably trap both absorbing and non-absorbing particles in air, for observing such temporal processes. This technique offers a new method to study dynamic changes in the fluorescence and Raman spectra from a single optically trapped particle in air.
We present a broad assessment on the studies of optically-trapped single airborne aerosol particles, particularly chemical aerosol particles, using laser technologies. To date, extensive works have ...been conducted on ensembles of aerosols as well as on their analogous bulk samples, and a decent general description of airborne particles has been drawn and accepted. However, substantial discrepancies between observed and expected aerosols behavior have been reported. To fill this gap, single-particle investigation has proved to be a unique intersection leading to a clear representation of microproperties and size-dependent comportment affecting the overall aerosol behavior, under various environmental conditions. In order to achieve this objective, optical-trapping technologies allow holding and manipulating a single aerosol particle, while offering significant advantages such as contactless handling, free from sample collection and preparation, prevention of contamination, versatility to any type of aerosol, and flexibility to accommodation of various analytical systems. We review spectroscopic methods that are based on the light-particle interaction, including elastic light scattering, light absorption (cavity ring-down and photoacoustic spectroscopies), inelastic light scattering and emission (Raman, laser-induced breakdown, and laser-induced fluorescence spectroscopies), and digital holography. Laser technologies offer several benefits such as high speed, high selectivity, high accuracy, and the ability to perform in real-time, in situ. This review, in particular, discusses each method, highlights the advantages and limitations, early breakthroughs, and recent progresses that have contributed to a better understanding of single particles and particle ensembles in general.
Light scattering from spiral particles Surkov, Yehor; Shkuratov, Yuriy; Pan, Yong-Le ...
Journal of quantitative spectroscopy & radiative transfer,
April 2023, 2023-04-00, Volume:
298
Journal Article
Peer reviewed
•We calculate the light-scattering spiral particles.•The magnitude of the circular-polarization signal can be greater than 10%.•A circular polarization opposition effect is observed for the first ...time.
We calculate the light-scattering Mueller matrix elements of left-handed and right-handed spiral particles that have morphological chirality. For such orientation-averaged systems, none of the Mueller matrix elements are equal to zero, although basic relations do exist between enantiomers. The magnitude of the circular-polarization signal can be greater than 10%; however, in the backscattering region it can be significantly greater due to a manifestation of the coherent-backscattering mechanism. The magnitude of this circular-polarization opposition effect decreases with particle absorption and its width decreases with decreasing wavelength, which is consistent with the linear-polarization opposition effect and the intensity opposition effect.
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