Genomic and Virulence Investigations of a Novel Porcine Deltacoronavirus Strain Identified in South Korea

Figure 1

Cytopathology and growth properties of PDCoV strains KNU-1607 and GNU-2105. (a and b) Phenotypic characteristics of KNU-1607 and GNU-2105. ST (a) or IPEC-J2 (b) cells were mock-infected or infected with each virus at an MOI of 0.1. PDCoV-specific CPE was monitored daily, and cells were photographed at 6 hpi using an inverted microscope at a magnification of 200× (left panels). For immunostaining, infected cells were fixed at 6 hpi and incubated with MAb against the PDCoV N protein, followed by incubation with Alexa green-conjugated goat antimouse secondary antibody (second panels). The cells were then counterstained with DAPI (third panels) and examined under a fluorescence microscope at 200× magnification. (c) Representative images showing the plaque morphology phenotypes of KNU-1607 and GNU-2105. Monolayers of ST (top panels) or IPEC-J2 (bottom panels) cells were infected with each strain. The cells were maintained in agar overlay medium and incubated for 1 day. Plaques were stained with crystal violet and photographed at 24 hpi. (d) Growth kinetics of KNU-1607 and GNU-2105. At the indicated time points postinfection, culture supernatants were harvested, and virus titers were determined. The results are expressed as the mean of three independent experiments performed in duplicate, and the error bars show the SDM.

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