Semliki Forest Virus Replication in Cultured Aedes albopictus Cells: studies on the Establishment of Persistence

Abstract

SUMMARY Semliki Forest virus (SFV) established a persistent, non-cytopathic infection incultured Aedes albopictus cells with no effect on cumulative cell number as compared with control cultures. All cells were initially infected by SFV as judged by infective centre and immunofluorescence assay and released approx. 5o to 7o p.f.u./cell in the initial a4 h after infection. At 12 h after infection there was a 'shut-down' of virus-specific RNA synthesis followed by a sharp decline in the percentage of cells infected, stabilizing at about 2 % by 48 h. Significant amounts of virus were released from about 2 % of cells in persistently infected cultures. At 8 to lO days a small-plaque, attenuated variant of SFV appeared in infected cultures; it replaced 'wild-type' virus completely by day 16.The establishment of persistence could not be related to (i) the release of interferon-like activity from infected cells, (ii) the presence of a directly antiviral agent in infected cells or medium, or (iii) changes in the total levels or subcellular distribution of acid phosphatase.Subculturing persistently infected cells stimulated cell division and promoted a (reduced) burst of virus production; simultaneous superinfection with SFV gave no increase in virus yields.

Antiviral RNA Interference Responses Induced by Semliki Forest Virus Infection of Mosquito Cells: Characterization, Origin, and Frequency-Dependent Functions of Virus-Derived Small Interfering RNAs

“…Alphaviruses replicate within cytoplasmic replication complexes associated with cellular membranes, and viruses mature by budding (17,45); important differences in replication complex formation between vertebrate and mosquito cells have been described (16). The infection of mosquito cell cultures with alphaviruses usually starts with an acute phase characterized by efficient virus production, followed by the establishment of a persistent infection with low-level virus production (6,10,15).…”

Cell-to-Cell Spread of the RNA Interference Response Suppresses Semliki Forest Virus (SFV) Infection of Mosquito Cell Cultures and Cannot Be Antagonized by SFV

“…Like other arboviruses, SFV infection of cultured mosquito cells usually begins with an acute phase of efficient virus production between 12 and 24 h and then enters a persistent phase during which only a few cells (1 to 2%) produce virus (22). In this study, we used the A. albopictus-derived U4.4 cell line, which has been shown to closely resemble infectivity in the mosquito and has been previously used to study virus-host interactions (19,20,61,68).…”

Demonstration of Interference between Dengue Virus Types in Cultured Mosquito Cells using Monoclonal Antibody Probes

“…This relatively short period is in marked contrast to the 50-week interval reported by Igarashi (1979) for resistance to occur in dengue-1 PI cultures, indicating that we have not observed the same phenomenon. The possibility that the resistance is interferon-mediated is also unlikely, since the induction of resistance was not sensitive to actinomycin D. In addition, other investigators have shown that mosquito cells do not express interferon activity (Peleg, 1969;Murray & Morahan, 1973;Stollar & Shenk, 1973;Davey & Delgarno, 1974;Kascsak & Lyons, 1974).…”

“…These cultures were exposed to [3H]uridine (5 /~Ci/ml) during the 24 h incubation period. The cultures were then rinsed three times with PBS, and the amount of incorporated [3H]uridine determined as described by Davey & Delgarno (1974).…”