Journal of General Virology - Volume 12, Issue 1, 1971

Treatment of chick cells with reovirus resulted in the production of an inhibitor of virus replication which was characterized as an interferon. No infectious virus was released, nor could any virus-specific RNA synthesis be detected in cells receiving virus. The ability of reovirus to induce interferon formation in chick cells was less sensitive to irradiation with ultraviolet light than was its ability to produce infectious virus in L cells. These data suggest that the interferon was induced by the double-stranded RNA of the inoculum virus. Comparison of this system with that induced by a synthetic double-stranded polynucleotide showed that the latter was considerably less sensitive to the effects of metabolic inhibitors, suggesting that the two inducers do not stimulate interferon formation by the same mechanism. The effect of addition of two metabolic inhibitors simultaneously to cells previously treated with a synthetic polynucleotide suggests that their effect is not a direct one on the formation of an interferon messenger RNA and its translation.

Electrophoretic analyses of the polypeptide components of adenovirus indicate that both the hexon and the penton base are degraded during storage of either purified virus preparations or isolated antigens. These two protein components are also degraded by trypsin and the products of tryptic digestion of native hexons were examined in detail. They were shown to consist of six polypeptide species which may result from tryptic action at three distinct sites on the hexon polypeptide.

Both spontaneously degraded and trypsinized hexon and penton base proteins retained their morphological and antigenic characteristics.

To evaluate the latex test for detecting distant serological relationships among plant viruses, latex coated first with antibody and then with virus was used to determine antiserum titres. In tests with latex coated with elongated viruses of the potato virus X group and with isometric viruses of the turnip yellow mosaic virus group the homologous titres of antisera were always much higher than in slide precipitin or agar diffusion tests. Usually, the heterologous titres were also increased and more heterologous reactions were found, especially when the pure γ-globulin fraction was used instead of unfractionated sera, even though this γ-globulin fraction contained relatively few antibodies.

With both groups of viruses, the results corroborate previous observations made using conventional serological methods. In addition, turnip yellow mosaic virus was shown for the first time to be distantly serologically related to Andean potato latent and belladonna mottle viruses. The latex test may offer improved opportunities to detect distant serological relationships among members of other groups of viruses.

Mycophage PS 1, produced by the mould Penicillium stoloniferum, was concentrated and purified by zonal centrifugation or by a combination of isopropanol precipitation and zonal centrifugation. Continuous flow isopycnic banding was accomplished using the K-II zonal centrifuge. Isopropanol precipitates of fermentation broths were further concentrated by continuous flow isopycnic banding in the B-IX rotor followed by rate zonal separation and a second isopycnic banding in the B-XV rotor. Mycophage PS 1 was a potent inducer of interferon. Double-stranded RNA isolated from both the virus-like particle and from the rate zonal gradient also induced interferon. The characters of the double-stranded RNA from both sources were identical.

Infection of primary human embryo kidney cells with adenovirus types 2, 7, 12, 18 and 31, at a multiplicity of infection of 2, resulted in the induction of chromosome aberrations in metaphases examined 24 hr after infection. The aberrations induced by types 2 and 7 were randomly distributed over the karyotype, but types 12 and 31, and to a lesser extent type 18, all induced non-random effects. Both type 12 and type 31 produced chromatid and isochromatid gaps and breaks at a specific site on chromosome no. 17.

Interferon has been demonstrated to be present in vesicles of persons infected with chickenpox and herpes zoster viruses (Wheelock, 1967; Armstrong et al. 1970). Using human foreskin fibroblast monolayers, our studies demonstrate that varicella zoster infection results in interferon production and that interferon or polyinosinic acid:polycytidylic acid (Poly I:C) pre-treatment protects these cell cultures from varicella zoster virus infection.

Varicella zoster virus (ellen strain, supplied by Dr P. Brunell) was grown on human foreskin fibroblast (HFF) monolayers using Minimal Eagle's media (MEM) and 2% inactivated foetal calf serum. Varicella zoster virus infection was passed using intact, infected cells. Vesicular stomatitis virus (VSV, indiana strain, supply by Dr L. Glasgow and Dr S. Baron) and vaccinia virus (ihd strain, Wyeth) were similarly cultured. Media for interferon assay from virus-infected HFF monolayers was collected by aspiration and centrifuged for 2 hr at 100,000g.

Lettuce necrotic yellows virus (LNYV) is very unstable in vitro (Crowley, 1967) and is therefore difficult to store, even by dehydrating virus-infected leaf tissue, a technique which has been particularly successful for the long-term storage of many plant viruses (McKinney & Silber, 1968). Hunt, Gourevitch & Lein (1958) and Perkins (1962) described ways of preserving microbial stock cultures by dehydration with anhydrous silica gel, and these methods have been applied to a range of microorganisms (see Grivell & Jackson, 1969).

In this paper we report that LNYV has been preserved for several years by the technique described by Perkins (1962) for storing fungi, in which a suspension of the fungal spores is mixed with skim-milk and then with anhydrous granular silica gel. Tomato spotted wilt (TSWV), cucumber mosaic (CMV) and cauliflower mosaic (CIMV) viruses have also been stored by this method and later recovered.

Murine sarcoma virus (MSV), which in its natural state is enveloped in a murine leukaemia virus coat, can, under select conditions of aggregation with feline leukaemia virus (FelLV), be made to infect and transform cat embryo cells (Fischinger & O'Connor, 1969). The product of such an infection is a new FelLV pseudotype of sarcoma-MSV (FelLV) which replicates to a high titre in cat cells, possesses a new host range, and is neutralized by FelLV antisera (Fischinger & O'Connor, 1969; Sibal et al. 1970). The infectious capacity of MSV (FelLV) is not limited to cat cells but is also manifest by a morphological transformation of cultured human, dog and pig cells (O'Connor & Fischinger, 1970; Chapman, Fischinger & O'Connor, 1970). The MSV infection of mouse cells is defective in the sense that both focus formation and progeny virus replication are only initiated by an infection of a cell with both MSV and murine leukaemia virus (Hartley & Rowe, 1966; Bassin et al. 1968; O'Connor & Fischinger, 1968).

Recent reports (Gourlay, 1970; Gourlay, Bruce & Garwes, 1971) described the first isolation and gave some characteristics of a virus which infects a member of the order Mycoplasmatales, namely Acholeplasma laidlawii (formerly Mycoplasma laidlawii). This virus, designated Mycoplasmatales virus-laidlawii 1 (MV-L1), was shown to be bacilliform with a mean width of 14·6 nm. and a mean length of 89·8 nm. It was insensitive to ether and detergent and withstood a temperature of 60° for 30 min.; its nucleic acid appeared to be DNA. This report describes the isolation of another virus which infects A. laidlawii and which differs from MV-L 1.