The Development of Vaccinia Virus in Earle's L Strain Cells as Examined by Electron Microscopy

Abstract

A favorable system which is amenable to frequent and reproducible sampling, consisting of suspension cultures of strain L cells and vaccinia virus, was employed to study the animal virus-mammalian host cell relationship. The three principal aspects investigated concerned the adsorption and penetration of vaccinia into the host, the relationship between the sequence of virus development and the production of infectious particles, and the changes in the fine structure of the host cells. Experiments in which a very high multiplicity of infection was used revealed that vaccinia is phagocytized by L cells in less than 1 hour after being added to the culture, without any apparent loss of its outer limiting membranes. Regions of dense fibrous material, thought to be loci of presumptive virus multiplication, appear in the cytoplasm 2 hours after infection. A correlation between electron microscope studies and formation of infectious particles shows that although immature forms of the virus appear 4 hours after infection, infectious particles are produced 6 hours after infection of the culture, at the time when mature forms of vaccinia appear for the first time in thinly sectioned cells. Spread of the infection is gradual until eventually, after 24 hours, virus is being elaborated throughout the cytoplasm. Addition of vaccinia to monolayer cultures induced fusion of L cells and rapid formation of muhinucleate giant forms. In both suspension and stationary cultures infected cells elaborate a variety of membranous structures not present in normal L cells. These take the form of tube-like lamcllar and vesicular formations, or appear as complex reticular networks or as multi-laminar membranes within degenerating mitochondria.

Ligand-induced and nonfusogenic dissolution of a viral membrane

“…This antibody (Hu anti-VACV Ab) originated from an individual who had been vaccinated five times against smallpox and contained 52% of anti-IMV and 3% of anti-EEV activity compared with Rb anti-VACV Ab (43). The results demonstrated the benefit of HP in combination with human antibody (versus Hu anti-VACV Ab alone; P Ͻ 0.05 for weight loss and signs of illness, days [4][5][6][7][8][9][10]. This suggested that PAs may be used in conjunction with vaccinia-immune globulin in treating smallpox and vaccinerelated complications.…”

“…IMV is surrounded by one lipid membrane (5)(6)(7)(8)(9) and is physically robust to aid virus transmission between hosts. CEV and EEV are IMV particles wrapped with an additional membrane derived from the trans-Golgi network (10) or endosomes (11) and are responsible for virus dissemination within the host (4).…”

Structure and Replication of the Trachoma Agent in Cell Cultures, as shown by Electron Microscopy

“…It is now certain that information on this could be expected only from close study of infected cells at a stage earlier than any in the present series. The demonstration recently of the phagocytosis and subsequent breakdown of vaccinia virus particles (Dales & Siminovitch, 1961) encourages the speculation that infectious particles of trachoma, and others in the psittacosis group, may be taken into the cell in this way. Certainly, the finding of conspicuous lysosome aggregates 6 hr.…”

The Effect of Gold Sodium Thiomalate in Adult Swiss/A2G Mice Infected with Togaviruses and Flaviviruses

“…An induced membrane proliferation is also observed with Russian spring-summer encephalitis, St. Louis encephalitis and dengue-2 viruses (Murphy, 1980). In other virus infections such as mengovirus (Amako & Dales, 1967), vaccinia virus (Dales & Siminovitch, 1961) and poliovirus (Caliguiri & Tamm, 1970), initiation of RNA synthesis is associated with smooth membranes.…”