RT Journal Article SR Electronic(1) A1 Mittelholzer, Christian A1 Moser, Christian A1 Tratschin, Jon-Duri A1 Hofmann, Martin A.YR 1998 T1 Porcine cells persistently infected with classical swine fever virus protected from pestivirus-induced cytopathic effect JF Journal of General Virology, VO 79 IS 12 SP 2981 OP 2987 DO https://doi.org/10.1099/0022-1317-79-12-2981 PB Microbiology Society, SN 1465-2099, AB Cytopathogenicity of classical swine fever virus (CSFV) depends on the presence of defective particles containing a subgenomic (sg) RNA with a defined deletion. In a previous report we described the spontaneous generation of this sg RNA and therefore of cytopathogenic (cp) CSFV in porcine kidney cell cultures persistently infected with CSFV. Frequently, some cells survived the CPE and could be further propagated. They remained positive for viral antigen and continued to shed complete virus and in most cases also defective virus particles. SK- 6 cells that had survived the CPE (CPEsurv cells) were used to investigate these findings further. In contrast to persistently infected cells that had not experienced a CPE, CPEsurv cells were protected from the CPE when superinfected with cp CSFV or with cp bovine viral diarrhoea virus. Similarly, cells which were rescued and further propagated after acute infection with cp CSFV also proved to be protected from the CSFV-induced CPE. When either virus obtained from CPEsurv cells that had spontaneously lost the sg RNA or virus from which defective particles had been removed was used to establish persistently infected cells, these cells were also protected from the CPE after superinfection with cp CSFV. These findings suggest that the virus contained in CPEsurv cells confers on the host cell the ability to resist the CSFV-induced CPE. However, when naive cells were infected with supernatants from CPEsurv cells that contained defective virus particles, the CPE reappeared within three to five virus passages, indicating that the sg RNA retained its cytopathogenic potential., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-79-12-2981