- Volume 13, Issue 3, 1971

The replication of herpes simplex virus type 1 and herpes simplex virus type 2 was studied in two isolated hamster cell lines. These lines developed after being treated with herpes simplex virus type 2 inactivated with 7,12-dimethylbenz(a)-anthracene. One cell line that developed, HDC-22, had a hypodiploid chromosome number and was missing a D-group chromosome. Growth studies revealed that this cell line did not support the replication of herpes simplex virus type 2 but did support the replication of herpes simplex virus type 1. The other cell line, HDC-17, had a normal karyotype and proved susceptible to both herpes simplex virus type 1 and herpes simplex virus type 2. These hamster cell lines afford an opportunity to study specific resistance to herpes simplex virus and the differences in the replicative cycles of type 1 and type 2 herpesviruses.

Semliki Forest virus was thermally inactivated between 20° and 50° by two processes, one of which predominated at temperatures below 41° and the other at higher temperatures. At pH 6.5, the rates of inactivation were greater than at pH 7.5 but the nature of the reactions was unchanged. The stability of the virus in phosphate buffer solutions was greatly reduced at lower concentrations of protein in the suspending medium. The rate of inactivation was reduced in the dark. At higher temperatures, a change occurred in the surface properties of the virus that did not, of itself, cause loss of infectivity.

It is suggested that at the higher temperatures the inactivation was a consequence of a structural breakdown of a surface unit in the virus; at lower temperatures a more subtle change in the substructure was responsible for inactivation.

The inactivation of Semliki Forest virus in solutions of guanidine hydrochloride and urea shows an anomalous dependence on concentration. Under some circumstances the inactivation is reversible. This reactivation is non-cooperative and extracellular and can be induced by incubation at high, or at negligible inactivant concentrations. It is suggested that changes in the surface structure of the virus particle take place before or during inactivation and that modifications of the conformation of the virus are involved in the reversible reactions.

When HeLa cells were pre-labelled with tritiated thymidine and infected with the wr or ihd strain of vaccinia virus, the host-cell DNA was broken down and reutilized for virus particle DNA biosynthesis. This phenomenon did not occur in LM cells, and was not explained by pseudovirus particle formation. Utilization of host-cell DNA, pre-labelled with [14C]-thymidine did not occur. Therefore, breakdown and re-utilization of host-cell DNA in HeLa cells resulted from intranuclear irradiation of the cells. Under these circumstances there was a markedly increased activity in the cells of an exonuclease with a pH optimum of 9.2, a requirement for magnesium ion, and which used denatured DNA as a substrate. The activity of this enzyme in such cells was directly proportional to the amount of irradiation, measured as the specific activity of the pre-labelled host-cell DNA. Associated with the vaccinia virus particles obtained from intranuclearly irradiated HeLa cells was an alkaline DNase inhibited by magnesium ion.

The inactivation of bacteriophages and myxoviruses by oxidized spermine, acrolein and glutaraldehyde has been studied. Oxidized spermine inactivated T5 and not T2 coliphages, while acrolein was more effective against T-even phages. Myxoviruses also differed in their sensitivity to the various aldehydes. This was determined by plaque counting or by assaying the haemagglutination activity after propagation in embryonated eggs.

High-molecular (condensation?) products, which were formed when spermine was oxidized for several hours by small quantities of enzyme also inactivated viruses.

These experiments stress the uniqueness of oxidized spermine as a virucidal agent, and do not support the hypothesis that its antivirus activity is due to the formation of acrolein as a spontaneous degradation product.

When L cells were infected with fowl plague virus, virus haemagglutinin, neuraminidase and complement-fixing antigen, but no infectious virus, were produced. Comparison with infection of chick cells showed that, in both cases, there was an early period of sensitivity to actinomycin and that infection caused depression of host-cell protein synthesis. There was no difference in the distribution of newly synthesized virus RNA between the nucleus and cytoplasm in both chick cells and L cells, and all the virus proteins synthesized in chick cells were also synthesized in L cells. However, the two proteins found in the nucleus did not appear to move out of the nuclei of L cells.

X-ray diffraction studies of oriented gels and electron microscope studies of stained sections of the campinas strain of tobacco rattle virus are described. The X-ray diffraction patterns are similar to those obtained by Finch (1965) and are interpreted in the same way. They show that the virus has a helical arrangement of protein subunits of pitch 25.5 ± 0.5 Å and that there is an integral number (3q + 1), in three turns of the helix. The cylindrically averaged diameter is 205 ± 5 Å. The electron miscroscope studies show that the particles pack together with a centre-to-centre distance of 203 ± 10 Å in the dried state. Two dark annular rings, of radii 41 ± 2 Å and 80 ± 4 Å, are seen in the transverse sections. The larger of these probably represents the radial position of the nucleic acid.

A direct study of the complement-fixing reactivity of cell membranes, soluble components of cell membranes and cell interiors of lymphoblast cell lines showed that with highly concentrated levels of antigen, complement-fixing reactivity could be measured consistently between the cell interior of lymphoma (IM1), leukaemic (4265) and Burkitt lymphoma (P3) cultured cells and sera from patients with infectious mononucleosis or Burkitt lymphoma. A measurable complement-fixing reactive cell-membrane antigen appeared to be present in IM1 and 4265 cells. Complement-fixing activity was also recovered in a soluble fraction of 4265 cell membranes after sonication and separation by Sephadex gel filtration. Separation of the complement-fixing reactive component from HL-A antigens was achieved by gel electrophoresis.

L’analyse des protéines extraites des virions d’une souche thermosensible, ts 23, du virus de la stomatite vésiculaire a été faite sur gel de polyacrylamide. Elle a permis par un double marquage des virions, associé à un changement de température, de mettre en évidence, pour ce clone, une protéine affectée par la mutation. C’est la plus légère des protéines structurales du virion; elle correspond à la protéine d’enveloppe S.

The susceptibility to infectious RSV(RAV-O) of pure-bred and incross-bred chick embryos from the inbred Reaseheath c and i lines was studied, and a genetic hypothesis is proposed to explain the observed segregation of susceptible and resistant embryos. The results suggest (1) the presence of a dominant autosomal gene for susceptibility to RSV(RAV-O), designated es , in the 1 line, and of its recessive allele, es , in the c line, and (2) the presence in the 1 line of an unlinked dominant, autosomal epistatic gene Ie , which inhibits the expression of es , and of its recessive allele, ie , in the c line. The two loci are designated ‘tumour virus e (tve)’ and ‘inhibitor e (Ie )’.

Previous work, (Subak-Sharpe & Hay, 1965, Subak-Sharpe, Shepherd & Hay, 1966), depending on the hybridization of [32P]4s RNA from herpes virus infected cells to herpes DNA and analysis of the aminoacyloligonucleotide fragments produced after RNase T 1 digestion of [14C]- and [3H]-arginyl tRNA, suggested the presence, in infected cells of a herpes-specified arginyl tRNA. The present study indicates that these results were due to the presence of (a) radioactive RNA other than tRNA in the [32P] 4sRNA, and (b) radioactive contaminants in the [3H]-arginine used to aminoacylate the tRNA. Further purification of the aminoacyl tRNA removes these [3H]-arginine contaminants. Protection of the aminoacyl tRNA ester bond by N-acetylation improved the sensitivity of the aminoacyloligonucleotide analyses and permitted tRNA-specific molecular hybridization. Using these techniques, no herpes-specified arginyl tRNA was detected in cells 7 to 9 hr post infection.