Fer de Lance virus (FDLV): a probable paramyxovirus isolated from a reptile.

A new virus has been isolated by inoculation of lung tissues of diseased snakes into snake embryos. Homogenates of infected embryo tissues caused c.p.e. in cell cultures incubated at 30 degrees C. The virus replicates in a wide variety of reptilian or mammalian cell types incubated at 30 degrees C, inducing either syncytium formation or minimal or no cytopathic changes. Efficient replication occurs in embryonated hens' eggs at 27 to 30 degrees C. The virus haemagglutinates guinea pig and chick erythrocytes; it possesses a neuraminidase similar to the receptor-destroying enzyme of Vibrio cholera. Electron microscopic observations of infected cells examined in thin section revealed pleomorphic viruses 146 to 321 nm in diam. resembling known myxoviruses. Internal nucleocapsid strands are 15 to 16 nm in diam.; nucleocapsid observed in negatively stained preparations measures 14 nm in diam. The virus was determined to possess a nucleoprotein core containing a 50S single-stranded unsegmented RNA genome. All characters of the virus are similar to those of the paramyxovirus group except that the nucleocapsid diam. is intermediate between that of paramyxoviruses and pneumoviruses. The virus is antigenically distinct from known myxoviruses and is unique among myxoviruses in its restriction to growth at temperature below 37 degrees C.

Ultrastructural studies of cell-virus interaction in reptilian cell lines. IV. Effects of chloramphenicol and ethidium bromide on VSW cell mitochondria and associated virions.

Structural effects of chloramphenicol (CAP) and ethidium bromide (EB) on VSW cell mitochondria and intramitochondrial virions (IMV) have been studied on a comparative basis by thin-section electron microscopy. CAP-treated cells show a wide variety of mitochondrial alterations, frequently involving swelling of the organelle and loss of cristae orientation. IMV are generally severely disrupted, particularly in peripheral regions. In such configurations, strand-like material radiates in a spokelike fashion from the shell zone to adjacent cristae-matrix area. EB-treated cells also display considerable mitochondrial distortion evidenced primarily by the formation of small, localized multimembrane regions. IMV exposed to EB, however, are less structurally damaged than CAP-treated ones. The relative incidence of IMV production is enhanced approximately fourfold in EB-treated cells compared to CAP-treated ones, suggesting that virion synthesis may be under nuclear, rather than mitochondrial, control.

Intracytoplasmic type A particles in viper spleen cells.

Structures resembling typical type A particles were observed in paranuclear inclusions in cultured C-type particle-producing viper cells (VSW cell line). The incidence of type A particle inclusions was low (approximately 0.5% of cell profiles examined) in untreated cells, but both the incidence and size of the inclusions were slightly increased in cells treated with ethidium bromide. This is apparently the first observation of type A particles in cells of a poikilothermic vertebrate.

Studies of mitochondria and mitochondrial DNA extracted from organelles harboring an intramitochondrial virus.

(1) Two viper cells lines were investigated, one which harbors IMV in the mitochondria (VSW cells) and one without detectable IMV (VH3 cells). (2) The size of closed circular mtDNA molecules from both VSW and VH3 cells was found to be significantly greater (5.4 to 5.6 micron) than the contour lengths of typical mammalian cells (4.8 to 5.2 micron). (3) A small percentage of mini-circles ranging in size from 0.1 to 0.6 micron was observed to band with closed circular mtDNA from both cell lines. Minicircles were especially abundant in VH3 cells. (4) MtDNA from VSW cells contained 34.1% dimers plus oligomers (10.2% oligomers), whereas VH3 cells had only 14.8% dimeric and oligomeric forms (5.4% oligomers). (5) Treatment of VSW cells with 1 microng/ml ethidium bromide for 48 hours resulted in an increased incidence of IMV (IMV in 15% of mitochondrial sections) as compared with untreated VSW cells (IMV in 3% of mitochondrial sections).

An ultrastructural study and model of membrane-intramitochondrial virus relationships.

Intramitochondrial virions (IMV), in many respects structurally similar to 'C-type' viruses of higher organisms, are synthesized in close topographical association with inner mitochondrial membranes of the viper spleen cell line, VSW. Cristal membranes contribute to the formation of a trilaminar viral envelope, whereas the outer mitochondrial membrane does not appear to play any structural role in virion maturation. Two schematic models, correlated with electron microscopic images, are presented to depict: (a) the relative location of the particles within a three-dimensional view of the mitochondrion, and (b) the sequence of virion-mitochondrial membrane relationships during morphogenesis.

Host effect on vesicular stomatitis virus morphogenesis and "T" particle formation in reptilian, avian, and mammalian cell lines.

The morphogenesis of vesicular stomatitis virus (VSV) in three reptilian cell lines (turtle heart, gecko lung, and viper spleen) was studied by thin section electron microscopy. Simultaneous growth studies were conducted in reptilian, chick embryo fibroblast, and BHK/21 cells to compare the yields of infectious VSV during serial passages. The mean length of gecko lung cell VSV measured from electron micrographs is statistically significantly shorter than that of VSV replicating in other reptilian systems studied. This observation, along with comparative growth studies, suggests the predilection of gecko lung cells to form "auto-interfering" truncated "T" rather than infectious "B" VS virions.