Role of temperature-sensitive mutants in persistent infections initiated with vesicular stomatitis virus

Abstract

Noncytocidal persistent infections at 37 C of mouse L cells (LX X) with infective B particles of vesicular stomatitis virus (VSV) could be established only in the presence of large numbers of defective interfering (DI) particles. Under these conditions, there was a rapid spontaneous selection of temperature-sensitive (ts) virus. At 10 days there was an increase to 17.8% in the frequency of ts clones in the virus population; by 17 days this frequency had reached 85.2%, and by 63 days 100% of the clones isolated were ts at 39.5 C, the nonpermissive temperature used. All 34 of the clones isolated from the 84-day fluid had an RNA-phenotype, and 8 clones that were tested all belonged to VSV complementation group I. When tested by an interference assay, L,,fluids did not contain significant numbers of DI particles (<1 DI/PFU). Furthermore, persistent infection of L cells at 37 C could be initiated under conditions in which few, if any, DI particles were present by using low input multiplicities (10-4 and 10-5) of a clonal isolate of an RNA group I mutant obtained from LX ,\ cells. On the basis of these and other results, a mechanism is proposed to explain the role of ts mutants in both the establishment and maintenance of the persistently infected state. MATERIALS AND METHODS Cells. Primary chicken embryo (CE) cells, mouse L cells (clone 929), and a line (BHK-21) of hamster kidney cells were propagated in Eagle minimal essential medium plus 4% calf serum. Viruses. The large-plaque mutant of VSVINI) (L,VSV) described by Wertz and Youngner (22) was grown in BHK-21 cells and assayed in CE cells. Monolayers in 32-ounce (ca. 950-ml) culture bottles were infected with less than 0.01 PFU/cell to avoid production of DI particles. This wild-type virus stock is referred to in the text as VSVe. Analysis of [PH1uridine-labeled viral particles by sucrose gradients failed to detect DI particles in lysates produced under these conditions. ts mutants of VSVINI) 90

In vivo and in vitro models of demyelinating diseases II. Persistence and host-regulated thermosensitivity in cells of neural derivation infected with mouse hepatitis and measles viruses

“…Although the molecular events underlying the maintenance of persistence in the systems under study here remain to be elucidated, in other virus carrier states chronic infections have been explained by effects involving the formation of and competition from defective interfering (DI) particles for host synthetic machinery (Holland et al, 1976;Kawai and Matsumoto, 1977), or by inhibition of virus production due to interferon, sometimes in a cyclical fashion (Wiktor and Clark, 1972), or due to selection of genotypically changed variants of the virus (Thacore and Youngner, 1969;Kawai et al, 1975;Youngner et al, 1976;Truant and Hallum, 1977).…”

“…Replication outgrowth of or selection for a variant progeny virus that is temperature-sensitive for growth (Haspel et al, 1973;Preble and Youngner, 1973;Shenk et al, 1974;Gould and Linton, 1975;Kimura et cd., 1975;Youngner and Quagliana, 1975;Youngner et al, 1976;Armen et al, 1977;Truant and Hallum, 1977). To determine whether a similar appearance of thermolabile progeny occurred in the cell-virus systems being examined here, temperature-shift experiments were conducted after initiating persistent infections.…”

Isolation of a heterogeneous population of temperature-sensitive mutants of measles virus from persistently infected human lymphoblastoid cell lines.

“…Although ts mutant viruses are the most outstanding characteristics of the LCL carrier state, other factors involved in persistent infection, such as interferon and DI particles, cannot yet be excluded. Interferon and DI particles may be more important in the period before establishment of a stable carrier culture, rather than in the maintenance of persistence, as has been suggested (44).…”

“…Clonal analysis has been carried out for progeny virus from a VSV-PI L cell line (44). The 34 VSV clones from this mouse cell line also showed a range of P.E.…”

Establishment and maintenance of a persistent infection of L132 cells by human coronavirus strain 229E

“…A common factor in severM other in vitro persistent virus/host systems is the production of temperature sensitive virus progeny. For example, such mutants have been isolated in persistent infections of measles (2), Newcastle disease virus (14), vesicular stematitis virus (22), and mumps virus (21). Among the Coronaviruses, only mouse hepatitis virus has been reported to dev-elop a persistent infection in vitro (17).…”