- Volume 33, Issue 1, 1976

The anticellular and antiviral effects of human leukocyte interferons were studied in vitro in the transformed human embryonic cell lines, RSa and RSb. The growth of these cells was inhibited and they began to deteriorate about 48 h after treatment with 500 units/ml of interferon. When interferon was washed out within 48 h, their growth recovered gradually. The effects of interferon on cell growth depended on the amount of interferon added per cell. A subline, named IFr, was isolated which grows in the presence of 2000 units/ml of interferon, whereas growth of vesicular stomatitis virus in these cells is suppressed by 10 units/ml of interferon, just as in the parent cells. The anticellular and antiviral effects of interferon on IFr cells are discussed in relation to cell surface receptors.

Multiplication of the human clonal cell line, RSa, is completely inhibited by human leukocyte interferon preparations. Synthesis of DNA and protein is markedly reduced in these cells in proportion to the concentration of interferon applied. Interferon treatment leads to accumulation of cells of an epithelial morphology which do not enter the division cycle. It is suggested that the growth inhibitory effects of interferon on RSa cells may result from these effects.

Concanavalin A (Con A) concentration dependence of agglutinability of a mutant of Rous sarcoma virus which is temperature-sensitive for transformation was examined. Con A agglutinability of the virion was quantitatively expressed by measuring radioactivities of 60 to 70 S RNA extracted from Con A-agglutinated material. The mutant grown at a permissive temperature (35 °C) agglutinated at a significantly lower concentration of Con A, compared with that at a non-permissive temperature (40 °C).

Some properties of a small RNA virus isolated from larvae of Heteronychus arator [Coleoptera: Scarabaeidae] are described. The virus develops in the cytoplasm of gut and fat body cells and is 30 nm in diameter. The sedimentation coefficient of virus was 137S and the buoyant density was 1.33 g/ml. The single stranded RNA was isolated as two species which sedimented at 22S and 15S, corresponding to mol. wt. of 1.0 and 0.5 × 106 respectively. The base ratios of the two RNA species were 22S:A = 29.0, C = 24.1, G = 22.8, U = 24.1; 15S:A = 26.4, C = 23.8, G = 24.7, U = 25.2. There was one major polypeptide, mol. wt. 40000 and two minor polypeptides in the virus. The virus was infective for Galleria mellonella and some other insects, but was not infective for mice. No evidence was obtained to suggest that the two RNA species were present in different particles.

The sedimentation of radiolabelled 22 nm hepatitis B surface antigen particles was unaffected by treatment with either trypsin or SDS alone, but combined treatment disrupted the particulate nature of the radiolabelled material. Considerable antibody binding activity by the group-specific determinant (a) was preserved after combined SDS and trypsin treatment but was released from the bulk of the radiolabelled protein; gel filtration indicated an approximate mol. wt. of 5000 to 15000 for the released antibody binding material. This material was precipitated by concanavalin A, suggesting the presence of carbohydrate. Its serological activity was remarkably resistant to boiling and to proteolytic digestion, but was partially sensitive to treatment with 0.01 m-periodate or with mixed carbohydrases and neuraminidase, and was greatly reduced by treatment with reducing agent. These data suggest that the stability of the a determinant is due to the structure of the antibody binding site itself, rather than to involvement in the quaternary structure of the particle, and that intact disulphide bonds and carbohydrate, closely related to the antibody binding site, are necessary for the full expression of serological activity.

Serial high multiplicity passage of a cloned stock of vesicular stomatitis virus was found to generate defective interfering particles containing three size classes of RNA, with sedimentation coefficients of 31S, 23S and 19S. The 31S and 23S RNA species were found to be complementary to both the 12 to 18S and 31S size classes of VSV mRNAs. The 19S class of RNA was found to be partially base-paired. All three RNA species were found to contain ppAp at their 5′ termini.

A comparison was made of the T antigens induced in transformed cells or infected permissive cells by representatives of three categories of human papovavirus. The transformed hamster cell lines employed contained T antigen induced by either the BK or RF strains of papovavirus associated with human renal allografts; the JC strain of papovavirus from progressive multifocal leukoencephalopathy (PML), or a variant of SV40 virus isolated from PML. The human papovavirus T antigens were also compared with that of a human cell line transformed by SV40 of simian origin. Anti-T antibody prepared in hamsters against each of the hamster cell lines was absorbed with crude T antigen from each cell line, and the unabsorbed and absorbed antisera were tested for residual T antibody against each cell line, or against infected permissive cells by immunoperoxidase (IP) staining and complement-fixation (CF) tests.

In unabsorbed antisera, T antibodies from each cell line cross-reacted with all T antigens in IP tests, and CF tests showed that T antisera reacted preferentially with T antigen induced by homologous virus.

Absorption studies showed that T antigens from each subdivision had unique antigenic determinants. T antigens of the two urine-derived strains, BK and RF, were identical or nearly so, but were clearly separable from T antigens of JC virus, PML-derived SV40 or simian-derived SV40. JC T antigen was intermediate, being more closely related to T antigens both of BK virus and SV40 virus than the latter were to each other. The T antigen of PML-derived SV40 could be distinguished from the T antigen of simian-derived SV40 and the T antigen of the SV40 variant from human brain was more closely related to those of the other human-derived papovaviruses than was the T antigen of SV40 from monkey kidney.

The RNA genome segments of thirty-three isolates of cytoplasmic polyhedrosis viruses (CPVs) were examined by polyacrylamide gel electrophoresis. Major differences were observed in the gel profiles of the RNA segments from many of the viruses; differences which were reinforced by polyacrylamide gel electrophoresis of the virus structural proteins. As a result of these studies, a provisional classification scheme for CPVs is proposed, where viruses with similar RNA gel profiles are included within the same ‘type’, while isolates differing in the molecular weights of most, or all of the RNA segments are assigned to different types. Using this system, eleven distinct CPV types were recognized. All eleven CPV types, like reoviruses, probably contain ten segments of RNA with a total mol. wt. of approx. 15 × 106.

Formation of cowpox virus-specific cell surface antigen (CPV S-ag) was enhanced in HVJ (Sendai virus) carrier cells compared to that in parent cells. Temperature shifts from 32 to 35 to 37 °C for these carrier cultures reduced this enhancing activity, making them equivalent to parent cells. The eclipse phase and one-step growth of CPV in the carrier cells were shorter than in normal cells. Extracts of carrier cells exhibited a stimulating activity causing the temporary rise and subsequent lowering of CPV infectivity in their reactions with CPV in vitro, suggesting a cellular acceleration of CPV uncoating. The S-ag forming ability of these carrier cells did not decrease as much as that of parent cells in the presence of actinomycin D or puromycin. The results indicate that persistent infection with HVJ, especially the temperature-sensitive variant, promotes the first step of intracellular growth of CPV, resulting in enhanced formation of S-ag.

The isolation and some properties of a lipopolysaccharide (LPS)-specific phage isolated against Pseudomonas aeruginosa is reported. The phage, designated ϕPLS-1, is a Bradley A type phage with a head diameter of 70 nm and a contractile tail 120 nm long. The average adsorption rate constant for ϕPLS-1 is 4.48 × 10−9 ml/min. ϕPLS-1 is inactivated by purified LPS from P. aeruginosa strain 1-1A, showing a PhI50 value of 1.25 µg/ml.

Several strains of measles virus which did not agglutinate monkey erythrocytes in phosphate-buffered saline did so in buffer containing 0.8 m-ammonium sulphate. Haemadsorption to cells infected with these viruses was also salt-dependent. In a series of tests salt-dependent agglutinin was shown to be a stable structural component of the infectious virion.

The relevance of these findings is discussed in the light of previous reports that many measles virus preparations do not agglutinate erythrocytes.

The ‘18S’ RNA population from Sendai virus-infected cells efficiently directed the synthesis of three virus-specific polypeptides P, NP and M, in wheat germ cell-free extracts. In agreement with previous results obtained with a reticulocyte extract, there was little or no production of virus glycopolypeptides. Analyses of tryptic peptides revealed close correspondence between the primary structures of NP and M made in vitro and the authentic virus polypeptides.

Partial denaturation maps of 30 HSV-1 DNA molecules have been obtained using a procedure designed to avoid possible hydrolysis of the DNA at alkalilabile bonds. From the denaturation pattern of the long unique DNA region these molecules were divided into two groups comprised of 16 and 14 molecules. Histogram plots relating the percentage denaturation to position on the DNA for these two groups were aligned in a manner appropriate to the HSV-1 genome model. It was apparent that these groups had the orientation of the long region inverted with respect to each other. Similarly, from the denaturation maps of the short unique region, the molecules were divided into two groups each comprising 15 molecules. Alignment of the histogram plots of these groups indicated that the orientation of the short region was inverted in one group relative to the other. These partial denaturation data confirm the presence of four HSV-1 genome arrangements resulting from the possible combinations of inversions of the two unique DNA regions.

Bacteriophage φW-14 is sensitive to osmotic shock. It contains sufficient free putrescine, 2-hydroxyputrescine and spermidine to neutralize about 15% of the DNA phosphates. The α-putrescinylthymine residues of the DNA could neutralize a further 25% of the phosphates. Label is transferred from ornithine to the α-putrescinyl residues of φW-14 DNA. The rates of polyamine synthesis in Pseudomonas acidovorans are increased by φW-14 infection.

Two strains of S.S.P.E. virus show both haemagglutinin and salt-dependent haemagglutinin. These properties are associated with distinct plaque forms within each strain. The existence of salt-dependent strains in wild-type measles virus suggests that they should be found in the early isolates of all strains of S.S.P.E.

Infectious influenza and parainfluenza viruses were produced as plaque-forming units (p.f.u.) in dog kidney cells (MDCK) after several passages of egg-grown viruses in MDCK monolayers. Virus titres of 106 to 1011 p.f.u./ml were obtained for several A and B strains of influenza and parainfluenza viruses.

Pig rotavirus was purified from faeces. The RNA from this virus was resistant to pancreatic ribonuclease, indicating that it is double-stranded. When electrophoresed on polyacrylamide-agarose gels, pig rotavirus RNA migrated as 9 bands comprised of 11 or 12 RNA segments with a total mol. wt. of approx. 11 × 106. Co-electrophoresis experiments revealed that the RNAs from the pig virus and two isolates of the calf rotavirus were indistinguishable.

Virus-like particles were found in nine different bovine sera for tissue culture from commercial suppliers. These particles were spherical with an overall diam. between 70 and 95 nm. After negative staining, surface projections of about 11 to 12 nm were clearly seen. One of the nine sera was positive in an Ouchterlony test with antisera against bovine viral diarrhoea virus.

A hysteresis has been noted between the adsorption and desorption isotherms of TMV nucleoprotein. By comparison with hydrations of RNA and protein separately, the hysteresis can be attributed to TMV capillary water. Following the inactivation by ultraviolet irradiation of nucleic acid in solution, some photorecovery on bean leaves can be observed; this does not seem to occur if the RNA is irradiated dry.