Effect of interferon on Vero cells persistently infected with SSPE virus and lytically infected with measles virus

Abstract

The effect of lymphoblastoid interferon (IFN) on viral polypeptides synthesized in a Vero cell culture persistently infected with subacute sclerosing panencephalitis virus (SSPE-Vero) was compared to that of Vero cells infected with exogenous measles virus. After IFN treatment there was no significant decrease in the synthesis of SSPE viral proteins, but inhibition of synthesis of measles polypeptides was readily seen. In Vero and SSPE-Vero cells IFN was able to inhibit replication of Sindbis virus although the effect in Vero cells was significantly more sensitive. In both cell lines IFN was able to stimulate 2'--5' oligoadenylate synthetase (E enzyme) but not the protein kinase system. The SSPE-Vero cells showed a lower basal level of E enzyme activity than the Vero cells.

Effect of interferon on Vero cells persistently infected with Sendai virus compared to Vero cells persistently infected with SSPE virus

“…Endogenous IFN production by these persistently infected cells has been shown to be low or absent [20,30,14]. We have shown previously that Vero cells persistently infected with SSPE virus are significantly less susceptible to the antiviral action of IFN when compared to uninfected Vero cells [6]. A change in the susceptibility to the antiviral and antiproliferative actions of IFN of cells persistently infected with Sendai virus has also been previously reported [11][12][13].…”

“…Incorporation of 3H-leucine was inhibited by 78% in Vero cells and 65% in Sendai-Vero cells when the cells were exposed to a concentration of 10-6M of 2-5A. Previously we have shown that SSPEVero cells reacted to 2-5A in a similar manner with significant inhibition of 3H-leucine incorporation [6]. .…”

“…SSPE-Vero and Sendai-Vero cells also had a very low basal level of E enzyme, which was approximately ten times lower than the uninfected Vero cells. A low basal level of E enzyme has previously been seen in an established SSPE-Vero cell line [6]. Thus a major difference between uninfected Vero cells and those persistently infected with SSPE or Sendai virus appears to be the level to which the E enzyme is activated.…”

“…Protein kinase activity was determined by the phosphorylation of ~-eIF-2 as described by Samuel [24]. Details of these assays have been given previously [6].…”

Suppression of Interferon-induced Oligo-2',5'-adenylate Synthetase Induction in Persistent Infection

“…The kinase inhibitors produced by virus infection are already defined in cells infected with adenovirus, vaccinia virus and reovirus (Whitaker-Dowling & Youngner, 1983;Palz & Esteban, 1984;Rice & Kerr, 1984;Schneider & Shenk, 1987;Imani & Jacobs, 1988). On the other hand, Crespi et al (1986) reported that Vero cells persistently infected with Sendai and subacute sclerosing panencephalitis (SSPE) viruses acquired a resistance to IFN because of the reduced induction of 2-5AS in spite of the normal level of IFN receptor. It has been also reported that failure to induce 2-5AS activity was observed in K562 cells persistently infected with measles and mumps viruses, and BALB3T3 cells persistently infected with Moloney murine leukaemia virus.…”