- Volume 22, Issue 2, 1974

Antisera raised in rabbits against RK13 cells infected with herpes simplex virus type 1 were capable of specifically precipitating proteins synthesized after infection of BHK-21 cells with the virus. Analysis of these immune precipitates by polyacrylamide gel electrophoresis demonstrated ≧ 15 polypeptides with mol. wt. from 25 to 100000. A number of these polypeptides were not detected in purified preparations of virus particles.

Precipitates formed with two ‘monoprecipitin’ antisera were also analysed. Antiserum to the structural antigen Band II precipitated a major polypeptide of mol. wt. 47000, which was glycosylated, and corresponded in mobility to a minor component polypeptide of the herpes virus particle. The other monoprecipitin antiserum, to the herpes-specified thymidine kinase, precipitated a polypeptide with a mol. wt. of 44000. The thymidine kinase polypeptide was not glycosylated.

Cells from the F1 and F2 embryos derived from a cross between C/AC and C/O parents were examined for the degree of linkage between the tva and tvc loci. Genetic analysis of the results suggested that in the population under study these two loci are closely but not completely linked. The linkage value estimated on a pooled sex basis was 0.08 ± 0.03.

A bacteriophage containing DNA and which is active on Caulobacter vibrioides CV6 has been shown to attach to the flagellum of the motile cell type. Attachment to the flagellum appears to be a necessary preliminary step to irreversible attachment to the cell wall at the base of the flagellum. The possible use of such a phage in the study of cellular differentiation in this diphasic bacterium is suggested.

The sera of several animal species neutralize Friend leukaemia virus. Among 54 serum samples taken from 16 different species only those of mouse, rat and sheep were found to be devoid of this property. The neutralizing activity is partially heat-labile and appears to require the presence of complement. Its biological significance might be considerable.

Messenger RNA (mRNA) with sequences of polyriboadenylic acid (poly A) has been isolated from the cytoplasm of vaccinia virus-infected cells after a short pulse label with radioactive uridine. No labelled RNA containing poly A was isolated from mock-infected cells under the same conditions. mRNA synthesized at various times during the replicative cycle was examined by polyacrylamide gel electrophoresis and compared with the mRNA synthesized in the presence of inhibitors of protein and DNA synthesis. No difference was detected between ‘class 1’ and ‘class 2 early’ mRNA species although ‘late’ RNA species were on average considerably larger than the ‘early’ species.

Extracts of the leaves of Phytolacca americana and partially purified preparations of such extracts caused marked inhibition of the infection of Chenopodium quinoa by cucumber mosaic virus (CMV) and of the infection of monkey kidney cells and embryonated hen eggs by the A2/Hong Kong/1/68 (H3N2) strain of influenza virus.

Both viruses became non-infective when mixed with preparations of the extracts but infectivity was regained when the viruses were separated from them by centrifuging.

Raspberry ringspot virus has two RNA species, of mol. wt. about 2.4 × 106 (RNA-1) and 1.4 × 106 (RNA-2). In experiments with four naturally occurring strains, virus hybrids were made by mixing RNA-1 and RNA-2 preparations from different strains. Parent strains were regenerated by crossing appropriate hybrids. In the crosses, both serological specificity and transmissibility by the nematode Longidorus elongatus were determined by RNA-2, suggesting that the protein surface of the virus particles is involved in the transmission process. Ability of isolates to cause systemic yellowing in Petunia hybrida, previously found to be also controlled by RNA-2, was shown to be associated with distinctive ultrastructural changes in the chloroplasts. Severity of systemic symptoms in Chenopodium quinoa and other herbaceous hosts, ability to infect Lloyd George raspberry and ability to invade the non-inoculated leaves of Phaseolus vulgaris, were all determined by RNA-1. Both RNA species played a part in determining lesion type in inoculated leaves of Chenopodium amaranticolor and C. quinoa, and in some crosses the two kinds of hybrid were respectively less virulent and more virulent than either parent. The determinant for systemic symptoms in Petunia hybrida that is carried by RNA-2 was not expressed when in association with RNA-1 from the strain able to infect Lloyd George raspberry. Some genes of raspberry ringspot virus are probably pleiotropic.

At 30 to 60 min after infection of primary rabbit kidney cells with Shope fibroma virus, the majority of virus particles were found within dense granules identified as lysosomes, whereas by 24 h no particles could be observed. The lysosomes appeared to become more fragile as infection proceeded, cellular proteins being progressively released from 7 to 24 h. Extracted lysosomal enzymes had no effect on purified Shope fibroma virus.

Alliaria mosaic virus (AIMV), a possible member of the PVY group, easily undergoes a partial disruption during the last stages of purification or upon standing of purified virus preparations. Protein dissociation from the virus particles usually gives random aggregates and can, in some cases, organize itself into helical structures. Two main kinds of helical structures have been observed in electron micrographs of purified virus suspensions: single and double helices. Both helical structures have a diam. of 28 nm and a pitch of 70 nm.

Sendai virus mediated fusion of adenovirus type 12 (Ad. 12) transformed cells (HTC) and permissive cells (HEp-2) was used to (i) rescue Ad. 12, (ii) determine if a repressor is present in the HTC cells. No evidence of virus rescue was observed. The presence of repressor in the transformed cells was tested by superinfecting heterokaryocytes of HTC and HEp-2 cells, with Ad. 12. Inclusion bodies and virus antigens were observed in both types of nuclei of heterokaryocytes demonstrating the absence of Ad. 12 specific repressor in the HTC cells.

Following the adsorption of u.v.-inactivated Sendai virus at high multiplicity on to HeLa-S3 or L-929 cells there was a transient inhibition of uptake of amino acids into the cells, but no inhibition of protein synthesis. The uptake of amino acids into virus-treated cells was maximally inhibited at the end of the adsorption period, but within a few hours returned to control level.

The changes in the uptake of amino acids occurred concomitantly with enhanced potassium uptake and with inhibition of DNA synthesis, but were of longer duration.

Poly(I).poly(C) adsorbed to rabbit red blood cells (RRBC) has been shown to stimulate interferon production in primary rabbit kidney (PRK) cell cultures. The interferon titres obtained could not be accounted for by the amounts of poly(I). poly(C) released from the red blood cells into the supernatant fluids during their incubation with the PRK cells. However, they could be fully accounted for by the amounts of polynucleotide picked up by the PRK cells upon their contact with poly(I).poly(C)-coated RRBC.

At identical dosage levels poly(I).poly(C) attached to RRBC proved more efficient in inducing interferon than free poly(I).poly(C). This increased interferon-inducing efficiency correlated well with an increased accessibility of PRK cell-associated polymer to extraneous ribonuclease treatment.

Comparative studies by the ferritin-labelled antibody technique showed differences between the surface antigens of RD-114 and feline leukaemia viruses (FeLV). Guinea pig and rabbit antisera to RD-114 virus reacted with RD-114 virus but not with FeLV. Dog antiserum to FeLV reacted with FeLV but not with RD-114 virus.

The caliciviruses (feline picornavirus and vesicular exanthema virus) have a diam. of 35 to 40 nm and possess a distinctive morphology which clearly distinguishes them from the other members of the family Picornaviridae. They also differ in having an E 260/280 ratio of about 1.52 compared with 1.65 to 1.70 for the picornaviruses. More significantly, they are unique among the mammalian viruses in containing only one major polypeptide, mol. wt. about 65 × 103. Feline picornavirus and vesicular exanthema virus differ from each other in their behaviour in caesium chloride gradients and in the base composition of their RNAs. Our evidence suggests that the two viruses are not typical picornaviruses but are in fact distinct members of a new virus family, the Caliciviridae.

Three immuno-peroxidase techniques (direct, indirect and peroxidase-antiperoxidase) were compared for their potential in foot-and-mouth disease research. Each technique was shown to offer a simple and efficient means for the detection of the virus of foot-and-mouth disease and of virus-infection-associated (VIA) antigen in infected cells.

The sensitivity to actinomycin D of the early steps of the in vitro replication of murine sarcoma virus (Moloney) (M-MSV) was investigated by treating infected mouse cells with the antibiotic (0.25 µg/ml) for 6 h periods at several times after infection. The results obtained indicate that M-MSV production is inhibited when actinomycin D is added within 2½ h of infection.

Herpes simplex virus was highly purified from host cell material with little loss of infectivity by the combination of isopycnic centrifuging in a three layered silica gradient and rate zonal centrifuging in dextran T 70 gradient. By layering three solutions of colloidal silica (24, 18 and 12%, w/v) on top of each other in the centrifuge tube prior to ultracentrifuging, a linear type of gradient was obtained. Virus particles and nucleocapsids seemed to be distinctly separated in this three-layered silica gradient. The overall reduction of host proteins and sphingolipids was 1250 to 2000 times and 350 to 600 times, respectively. The reduction of virus specified non-particulate proteins was approx. 500 times. The recovery of infectivity was 55 to 70%.

Samples taken from either rhinovirus- or poliovirus-infected suspensions of L132 cells at various times during the growth cycle were assayed for intra- and extracellular virus infectivity, trypan blue uptake and release of acid phosphatase from lysosomes. At similar times infected L132 cell monolayers were observed for cell rounding (virus c.p.e.). At 16 h after infection with rhinovirus 2, cells showed no change in the distribution of acid phosphatase activity but had undergone extreme cytopathogenic changes; at this time 99% of the virus was intracellular and few cells took up trypan blue. Poliovirus-infected cells showed no change in the distribution of acid phosphatase at 6 h after infection when cytopathogenic changes were extreme, but 2 h later when cells began to take up trypan blue and release virus, acid phosphatase was released from the lysosomes.

It is suggested that lysosomal enzymes have no role in the induction of virus c.p.e. but are involved at a later stage of degeneration of the cell.