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. 2019 Aug 30;537:226–236. doi: 10.1016/j.virol.2019.08.030

Fig. 2.

Fig. 2

Evaluating the response to type I interferon and the kinetics of FIPV Black replication in Fcwf-4 parent and IFNαR-deficient cells. A) Fcwf-4 CU, Fcwf-4 CU 2.2 Poly, Fcwf-4 CU 2.2 clones 1, 2 and 3 (IRN cells) were treated with 0 or 1000 U feline IFNα for 6 h and ISG54 transcripts were measured by qPCR. B) FIPV Black growth kinetics (MOI = 0.1) at indicated hours post-infection (HPI) in Fcwf-4 CU and IRN cells. C) Nucleocapsid gene transcript levels measured by qPCR during FIPV Black infection (MOI = 0.1) of Fcwf-4 CU or IRN cells. D) FIPV Black growth kinetics (MOI = 0.01) in indicated cells pre-treated with 0 or 1000 U feline IFNα for 8 h. E) Plaque formation induced by FIPV Black in Fcwf-4 CU or IRN cells at 3–4 days post-infection (DPI). Wells display 10−5 virus dilution. F) Plaque sizes (mm2) measured from FIPV Black plaque assays (6-well plates) at 3 and 4 DPI on Fcwf-4 CU and IRN indicator cells at 10−5 and 10−6 virus dilutions. For mRNA expression, Ct values were normalized to β-actin using the 2−ΔCt method and presented as fold expression over mock (A) or relative expression (B). Data represent 3 independent experiments in triplicate. Mean ± SD analyzed by unpaired t-tests. Viral titers (B and D) were calculated from triplicate plaque assays per time point on Fcwf-4 CU indicator cells and represent 3 independent experiments. Mean ± SD plaque-forming units (PFU) per mL analyzed by two-way ANOVA by time (D). Plaque sizes (F) were measured using Adobe Photoshop software and mean ± SD values were analyzed using unpaired t-tests. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.