Showing papers in "Journal of General Virology in 1982"

Location and characterization of the antigenic portion of the FMDV immunizing protein

Abstract: Purified foot-and-mouth disease virus (FMDV) to type O1K was treated with several endopeptidases of differing specificity. The immunizing protein VPThr was cleaved into two detectable fragments by all enzymes except for glutamic acid-specific Staphylococcus aureus V8 protease. The longest fragments were generated by mouse submaxillary gland protease and the shortest by trypsin treatment of the intact virion. Several fragments, including the peptides resulting from the cyanogen bromide (CNBr) cleavage of the isolated protein VPThr were characterized in terms of their molecular weights N- and C-terminal amino acids, and ability to induce virus-specific antibodies. The order of the fragments along the protein was determined, and then located on the amino acid sequence of the protein. Two enzyme-sensitive areas of the protein were found on the surface of the virion: between sequence positions 138 and 154 and between portion 200 and the C terminus. Peptides containing these sections were able to induce neutralizing antibodies against the homologous FMDV. When the virus was treated with trypsin or with chymotrypsin, several amino acids between the detectable fragments were lost and the infectivity of the virus was reduced. The infectivity was retained, however, when the enzyme treatment resulted in cleavage of protein with no loss of amino acids or only the cutting away of the C-terminal section. These results suggest that the property of cell attachment is restricted to small regions of the surface of the virus particle.

Slow virus replication: the role of macrophages in the persistence and expression of visna viruses of sheep and goats.

Abstract: Lentiviruses of sheep and goats cause slowly progressive diseases of the central nervous system (visna), lungs (maedi) and joints (arthritis) in their natural hosts. However, the virus target cell(s) in these diseases are still unknown. In this report, using laboratory-adapted Icelandic visna virus and several field strains recently obtained from sheep and goats with natural disease in the U.S.A., we show that macrophages became persistently infected when inoculated in culture. Furthermore, macrophages were an invariable source of virus from experimentally and naturally infected animals. Virus-producing macrophages developed minimal cytopathic changes and virus assembly occurred mainly intracellularly, accumulating in cytoplasmic vacuoles. In contrast to macrophages, sheep choroid plexus fibroblasts developed syncytial cytopathic changes after inoculation and virus maturation occurred at the cell surfaces. Replication of the Icelandic virus was highly productive in this system but that of the field viruses was very inefficient. In some cases these agents failed to replicate in the fibroblasts and no cytopathic effect occurred. This block in the field virus replication was, however, overcome when infected nonproducer fibroblasts were co-cultivated with macrophages. In these cases, virus production with attendant cytopathic effect in the fibroblasts required the continuous presence of macrophages because the cells reverted to a non-productive state when separated from macrophages and became productive again when subcultures were added to new macrophages. The roles of the macrophage as a virus target cell and virus inducer in the virus-macrophage-fibroblast interactions are discussed with inferences to the well-known phenomenon of restricted virus replication in infected animals and the immunopathological aspects of the diseases.

Inhibition of Semliki forest virus penetration by lysosomotropic weak bases.

Abstract: The effect of five lysosomotropic weak bases (chloroquine, amantadine, tributylamine, methylamine and NH4C1) on Semliki Forest virus (SFV) infection has been studied in BHK-21 cells. When present at concentrations equal to or greater than 0.1, 0.5, 2, 15 and 15 mM respectively, the agents inhibited SFV infection by more than 90%. The effect was reversible and involved a process occurring within the first 60 min of virus-cell contact. The agents did not have a direct virucidal effect nor did they affect virus binding to the cells, receptor-mediated endocytosis of prebound virus, intracellular distribution of virus after endocytosis, or the low pH-induced membrane fusion activity of the virus spike glycoproteins. The step blocked by chloroquine and NH4C1 occurred intracellularly and was identified as the release of the virus nucleocapsid into the cytoplasm or the uncoating process. On the basis of these results, our previous studies on SFV entry, and the known effects of lipophilic amines on lysosomes, we conclude that the agents affect entry by a common mechanism: they prevent the transfer of the virus nucleocapsid into the cytoplasm by increasing the lysosomal pH above the critical value needed to trigger a low pH-dependent fusion reaction between the membranes of the lysosome and the virus.

A simple indirect ELISA using F(ab')2 fragments of immunoglobulin.

Abstract: An indirect ELISA is described in which (i) virus is trapped by F(ab')2 fragments of specific IgG immobilized on a solid phase support, (ii) trapped virus is detected by intact IgG (from the same or a different antiserum) and (iii) positive reactions are identified using an enzyme conjugate specific for the Fc portion of IgG. Pepsin digestion of the Fc portion of the trapping antibody permits the use of a general purpose enzyme conjugate to discriminate between trapping and detecting antibody. Consequently, the assay requires only a single virus-specific antiserum which is often all that is available to the plant virologist. The assay was at least as sensitive for detecting small amounts of antigen as the standard double-antibody sandwich procedure and, for some viruses, two- to fourfold more sensitive. The improvement in performance resulted largely from lower and more consistent background reactions. Both assays were equally effective in revealing heterologous reactions when optimized for detecting homologous antigen. However, increased cross-reactions were obtained in the F(ab')2 procedure by the use of higher concentrations of detecting antibody. The assay is considered particularly suited for comparing antisera from different sources or of different bleeds from the same source, and for investigations involving so few tests that the effort or expense of preparing individual virus-specific conjugates is not justified.

Review article initial stages in infection with animal viruses.

Abstract: Introduction. Study of the initial stages of the interaction between animal viruses and their host cells has been overshadowed by interest in virus-directed macromolecular syntheses. However, increasing understanding of these processes has shown the difficulty of inhibiting them in vivo. The result is a resurgence of interest in the initial stages of infection, defined here as those virus-cell interactions which precede virus-directed synthetic processes. Despite incomplete data, hypotheses are taking shape and an appraisal of the situation seemed timely. This review will avoid the historical approach and focus on areas of particular interest or controversy. Early work, particularly morphological studies, has been thoroughly covered by others and will only be mentioned selectively (for details, consult Dales, 1965, 1973; Burrows, 1972; Lonberg-Holm & Philipson, 1974, 1980; Bachi et al., 1977; Howe et al., 1980; Kohn, 1979).

Monoclonal antibodies to Sindbis virus glycoprotein E1 can neutralize, enhance infectivity, and independently inhibit haemagglutination or haemolysis

Abstract: Two monoclonal antibodies raised against Sindbis virus were shown to be specific for the envelope glycoprotein E1 by radioimmunoprecipitation (RIP). They had a number of contrasting biological properties. One of them was capable of neutralizing virus infectivity and inhibiting haemagglutination, while the other had no significant neutralizing or haemagglutination-inhibiting capability, but did inhibit virus-mediated haemolysis. Both monoclonal antibodies could enhance virus infectivity of Fc receptor-bearing macrophage-like cells when present at suitable dilutions.

The Pseudotypic Paradox

Abstract: Summary The assembly of virion surface glycoproteins by enveloped viruses appears to be both specific and non-specific. It is non-specific in the sense that, during a dual infection by various unrelated viruses, there is very common (if not universal) and efficient mixing of envelope glycoproteins from both genotypes in the progeny virions. However, it seems to be specific in the sense that non-viral, cell surface proteins are, in the main, recognized as alien and are excluded from incorporation into virions during budding. These findings suggest that all enveloped viruses may share an essentially common molecular mechanism for the specific assembly and budding of virus glycoproteins while at the same time incorporating a mechanism for the exclusion of glycoproteins of cellular origin. One of the simplest explanations for this phenomenon may be that virus envelope surface structures all evolved from a single ancestral virus.

Replication of lactate dehydrogenase-elevating virus in macrophages. 1. Evidence for cytocidal replication.

Abstract: Summary A primary infection of peritoneal macrophage cultures with the lactate dehydrogenase-elevating virus (LDV) results in productive infection of 3 to 20% of the cells. When cultures were incubated in the absence of macrophage growth factor (MGF), LDV production ceased after a single cycle, but in cultures in which macrophage replication was stimulated by the presence of MGF LDV production continued for several weeks at a low level, representing not more than 1% of that observed during the acute phase. Significant amounts of interferon were not present in either acutely or persistently infected cultures, and treatment of persistently infected cultures with anti-interferon globulin or superinfection with LDV did not significantly stimulate LDV replication. Macrophage cultures established with peritoneal macrophages from LDV-infected mice also showed only a low level of LDV replication and were resistant to superinfection by LDV. Mouse hepatitis virus, Semliki Forest virus and vesicular stomatitis virus, on the other hand, replicated normally in LDV-persistently infected macrophage cultures. LDV replication was relatively resistant to interferon whether added to the cultures or generated endogenously by infection with Newcastle disease virus or defective-interfering (DI) particles of vesicular stomatitis virus. Temperature-sensitive mutants or DI particles of LDV were not detected in LDV-persistently infected cultures or chronically infected mice. The results support our hypothesis that the decrease in LDV production in mice or macrophage cultures at the end of the acute phase results from the destruction of the subpopulation of macrophages that is permissive for LDV, and that the low level persistent infection involves the passage of the virus to new permissive cells that are generated continuously, although at a low rate, from non-permissive precursor cells.

Influenza virus uncoating in infected cells and effect of rimantadine.

Abstract: Uncoating of influenza virus (strain WSN) in MDCK cells was studied by following the fate of the virus labelled with radioactive precursors. The accumulation of subviral components of input virus was observed in nuclear-associated cytoplasm (NAC) obtained by treatment of the nuclei with citric acid. Two types of subviral components were found there, ribonucleoproteins (RNPs) and larger subviral particles (SVP) containing RNPs in association with M protein. SVP, with different relative amounts of M protein, were revealed in NAC, suggesting that M protein was gradually released from RNPs. The released RNPs entered the nuclei while M protein accumulated within perinuclear membranes. Thus, SVP could be regarded as probable intermediates in virus uncoating. Rimantadine prevented the release of M protein from RNPs and their penetration into the nuclei provoking the accumulation of subviral components in NAC.

Use of Recombinant Plasmids to Investigate the Structure of the Human Cytomegalovirus Genome

Abstract: Summary Human cytomegalovirus (HCMV) DNA was digested with restriction endonucleases and the fragments characterized with respect to molecular weight and relative mole proportions. The terminal fragments were identified by digesting HCMV DNA with exonucleases before restriction endonuclease treatment and subsequent gel analysis. The HindIII fragments of HCMV DNA were cloned in Escherichia coli and recombinant plasmids were characterized by digestion with restriction endonucleases and by molecular hybridization with HindIII, BglII and XbaI fragments of the virus genome. Data from these experiments were used to construct physical maps of HCMV DNA for the HindIII, BglII and XbaI restriction endonucleases. The terminal regions of the genome and the region containing fragment HindIII M were shown to be heterogeneous.

Mapping of antigenic changes in the haemagglutinin of Hong Kong influenza (H3N2) strains using a large panel of monoclonal antibodies

Abstract: A panel of 125 monoclonal antibodies (IgG) was raised against the haemagglutinin of an early representative of the Hong Kong (H3N2) subtype of influenza. They were classified into groups based on their cross-reactions with 16 other virus strains from the same subtype. This classification was performed using methods of numerical taxonomy. Statistical tests supported the validity of the grouping. Ten such groups were identified. Nine antibodies remained unclassified. The locations on the haemagglutinin molecule of amino acid residues influencing the binding of each antibody group were estimated. This was achieved by a study of antibody cross-reactive profiles, coupled with previously published locations of amino acid changes in the primary sequence of different haemagglutinins, and their positions in the tertiary structure of the molecule. The locations of the amino acids affecting antibody binding overlapped between the different antibody groups forming a continuous ring surrounding the probable cell-receptor pocket. The amino acids affecting the binding of each antibody group may or may not represent the actual antibody binding sites. The importance of the different sites of amino acid variation in the haemagglutinin during evolution of the virus is discussed.

Spread of virus and distribution of latent infection following ocular herpes simplex in the non-immune and immune mouse.

Abstract: In both non-immune and immune mice infected with herpes simplex virus the incidence of latent infection of the trigeminal ganglion was related to the severity of ocular virus infection. During primary infection, virus was shown to travel via the ophthalmic part of the ganglion to reach the brainstem, from where centrifugal spread resulted in latent infection of neurones in the trigeminal ganglion which did not serve the site of inoculation. Primary infection also resulted in latent infection of the superior cervical ganglion. Shedding of virus occurred rarely in the tears of animals which had recovered from primary disease. In immune mice, spread of virus resulted in a much lower incidence of latent infection and that occurred only in ophthalmic neurones.

Thymidine kinase deletion mutants of herpes simplex virus type 1.

Abstract: Deletions in the cloned thymidine kinase (TK) gene of herpes simplex virus type 1 (HSV-1), strain 17 syn+, were produced by two methods. Removal of a 506 base pair fragment from between the unique SstI and Bg/II restriction endonuclease sites of pTK1 (HSV-1 BamHI p cloned in pAT153) and subsequent transformation of Escherichia coli resulted in the isolation of 50 deleted plasmids. Sequential digestion of pTK1 with Bg/II and nuclease BAL 31 followed by ligation and recleavage with Bg/II resulted in the isolation of 31 deleted plasmids. Three clones, pTK2, pTK3 and pTK4, obtained following Bg/II and SstI treatment of pTK1 were recombined with wild-type (wt) HSV-1 (17) syn+ DNA in baby hamster kidney (BHK) cells to produce TK- deletion mutants HSV-1 (17) TK 1301, HSV-1 (17) TK 1302 and HSV-1 (17) TK 1303 respectively. 5-Bromo-2'-deoxyuridine, 5-bromo-2'-deoxycytidine and 9-(2-hydroxyethoxymethyl)guanine were used to reduce the background of TK+ virus in heterogeneous recombinant stocks analysed for the presence of TK- recombinants. All recombinant clones isolated produced a small syncytial plaque morphology in BHK cells. The mutants HSV-1 (17) TK 1301 and HSV-1 (17) TK 1302 were TK-, failed to produce polypeptides of molecular weights 43000 and 19000 found in wt-infected cells and demonstrated one-step growth curves different from wt virus and the TK- mutant HSV-1 (17) dPyk-7. Superinfection studies with HSV-1 (17) TK 1301, HSV-1 (17) TK 1302, HSV-1 (MDK) and HSV-1 (17) dPyk-7 indicated that all TK- mutants except dPyK-7 produce a trans-acting gene product which can switch on the transforming HSV-1 TK gene.

DNA sequence analysis of an immediate-early gene region of the herpes simplex virus type 1 genome (map coordinates 0.950 to 0.978).

Abstract: The nucleotide sequence of 4 kilobases of DNA from within the short region of the genome of herpes simplex virus type 1 has been determined. This portion of DNA contains the junctions of the terminal and inverted repeat sequence components with the unique sequence component and the 5'-regions of the genes which encode the Vmw 12, Vmw 68 and Vmw 175 immediate-early polypeptides. The transcription and translation initiation sites of all three genes and the 5' and 3' boundaries of the Vmw 12 and Vmw 68 gene introns have been localized on the DNA sequence and shown to be flanked by sequences which resemble those found in similar positions in other eukaryotic genes. For the Vmw 12 and Vmw 68 genes the promoters, the 5'-non-coding regions of the mRNAs, and the introns lie within the terminal and internal inverted repeats respectively while the polypeptide-coding regions lie in the short unique component. The introns consist largely of tandemly reiterated copies of a 22-nucleotide sequence: the Vmw 12 gene intron contains seven of these and the Vmw 68 gene intron five. The Vmw 175 gene is located entirely within the short repeats, of which those regions sequenced here have the extremely high G + C content of 78%, in marked contrast to the value of 66% obtained for the adjacent region of the unique sequence component. Prediction of the complete amino acid sequence of the Vmw 12 polypeptide, accounting for a mol. wt. of 9830, and of the first 523 amino-terminal amino acids of the Vmw 175 polypeptide has been made from the DNA sequence. The polypeptide-coding region of the Vmw 175 gene has an average G + C content of 80% but nevertheless specifies a wide range of amino acid types because of the maximal assignment of G and C residues to colon third base positions.

Early and Delayed Shut-off of Host Protein Synthesis in Cells Infected with Herpes Simplex Virus

Abstract: A mutant of herpes simplex virus type 1 [HSV-1(HFEM)], tsB7, appears to have two temperature-sensitive functions. One is required during the first hour of infecting a cell (suggesting that it is performed by a virion protein) and the other is the non-essential function of "early shut-off" of cellular protein synthesis, which is mediated by a virion protein. The latter function remained temperature-sensitive in a revertant virus (RC2) grown at the non-permissive temperature (39 degrees C). However, under these conditions RC2 did cause inhibition of host synthesis, showing that "delayed shut-off", requiring virus protein synthesis, can occur independently of early shut-off, which is mediated by a virion protein. Early shut-off by u.v.-irradiated tsB7 was reversed when the temperature was raised, whereas delayed shut-off by intact tsB7 was not. Of two wild-type strains of virus examined, HSV-1(F) also exhibited temperature-sensitive early shut-off, but HSV-2(G) did not.

Pathogenesis of herpes simplex virus in congenitally athymic mice: the relative roles of cell-mediated and humoral immunity.

Abstract: Summary Athymic nude (nu/nu) mice were inoculated in the ear pinna with 104 p.f.u. herpes simplex virus type 1 (strain SC 16). Initially, the virus was observed to replicate in the pinna, spreading via a neurological route to the dorsal root ganglia, spinal cord, brain and adrenal glands. Following the transfer of lymphoid cells from day 7 herpesvirus-infected hairy immunocompetent donors into infected nude mice, virus was not isolated from the pinna and nervous system of the majority of the mice. The passive transfer of neutralizing polyclonal anti-herpesvirus serum or neutralizing monoclonal anti-gp D serum did not reduce infectivity in the pinna, but markedly reduced the amount of virus in the ganglia and spinal cord. These data suggest that neutralizing antibodies play an important role in restricting the movement of virus to the nervous system, whereas cell-mediated immune (CMI) mechanisms are essential for eliminating virus from the pinna.

Are ‘Pathogenesis-related’ Proteins Involved in Acquired Systemic Resistance of Tobacco Plants to Tobacco Mosaic Virus?

Abstract: Summary Four host-coded ‘pathogenesis-related’ proteins accumulate systemically in local-lesion-forming varieties of tobacco after infection with tobacco mosaic virus. It has been suggested that they are involved in the acquired systemic resistance of plants to a second inoculation. Pathogenesis-related protein concentration and amount of resistance (reduction in size and number of lesions formed in the second inoculation) were measured at various times after the first inoculation. The results showed no quantitative or temporal relationship between amounts of resistance and pathogenesis-related proteins. In particular, resistance could be demonstrated in leaves before detectable accumulation of pathogenesis-related protein. Abscisic acid sprayed on plants induced an apparent resistance without inducing pathogenesis-related proteins. Low doses of methyl benzimidazol-2yl-carbamate caused accumulation of pathogenesis-related protein but not resistance. Nicotiana glutinosa plants accumulated large amounts of a similar protein after infection, but became more susceptible to a second inoculation. All these results suggest that the pathogenesis-related proteins do not play a central role in the mechanism of acquired systemic resistance.

Micromonas pusilla Virus: the Virus Growth Cycle and Associated Physiological Events Within the Host Cells; Host Range Mutation

Abstract: Summary The photosynthetic marine flagellate Micromonas pusilla (Butch.) Manton et Parke (Prasinophyceae) and its cytoplasmic virus, M. pusilla virus (MPV), were cloned. Host cells were maintained in liquid culture. Infectivity titration was by endpoint dilution, using loss of host chlorophyll as an indicator of the presence of infective virus. The virus growth cycle was characterized by an eclipse period of 3 h, a latent period of 7 h and a total lytic cycle of 14 h. The average burst size was 72 infective particles per cell. Inhibition of CO2 photoassimilation began 2 h after inoculation with virus. An almost immediate decrease in in vivo chlorophyll a fluorescence in infected cells was light-dependent. M. pusilla cells can mutate to virus resistance at the cell surface. Host range mutants of MPV exhibited variable infectivity in different strains of M. pusilla.

Murine Coronaviruses: Isolation and Characterization of Two Plaque Morphology Variants of the JHM Neurotropic Strain

Abstract: Summary Two plaque-size variants of the neurotropic JHM strain of mouse hepatitis virus have been isolated from the virus stock after eight serial passages in suckling mouse brain. One variant, JHM-DL, produces large plaques, while the other, JHM-DS, produces small plaques in tissue culture. DS replicates more slowly, has a lower virus yield in vitro, and is less virulent for mice than DL. They also differ in their pathogenicity for mice: JHM-DL infection results in acute encephalomyelitis while JHM-DS infection results in demyelination. Oligonucleotide fingerprint analysis of the RNA genomes of these two variants revealed that they had almost identical genetic sequences. Each variant, however, had a unique oligonucleotide spot not found in the other. The unique spot of the large plaque variant, JHM-DL, was localized at approximately 3 to 5 kb from the 3′ end, while the JHM-DS unique spot was mapped at 14 to 15 kb from the 3′ end of the genome. We have further shown that these oligonucleotide changes are not correlated with the plaque morphology. These two viruses may be useful for studying the molecular basis of virus-induced demyelination.

Monoclonal antibodies against the flavivirus West Nile.

Abstract: SUMMARY Monoclonal antibodies having three different specificities have been prepared against the Egypt 101 strain of West Nile virus (WNV). All were reactive against the envelope glycoprotein in radioimmune precipitation tests, and all enhanced WNV replication in the mouse macrophage line P388D 1. One antibody, which is of IgG2a subclass, had strong neutralizing activity against the homologous virus, although it failed to neutralize a different WNV strain. The other two antibodies, both of IgG1 subclass, had little neutralizing activity, but one had strong reactivity with the haemagglutinin of the inducing virus and other flavivirus haemagglutinins.

Evidence that Potato Leafroll Virus RNA is Positive-stranded, is Linked to a Small Protein and Does Not Contain Polyadenylate

Abstract: Summary RNA extracted from particles of potato leafroll virus (PLRV) infected tobacco mesophyll protoplasts. Treating the RNA with proteinase K did not abolish its infectivity. In messenger-dependent rabbit reticulocyte lysate, PLRV RNA induced the synthesis of specific polypeptides: a major product of mol. wt. 71000 but no product the size of coat protein. PLRV RNA is therefore positive-stranded. A genome-linked protein (apparent mol. wt. 7000) was detected in preparations of PLRV RNA but no polyadenylate sequence was found. These features may prove to be characteristic of luteoviruses.

Genetic Studies on the Mechanism of Chemical and Physical Inactivation of Reovirus

Abstract: Summary The three serotypes of reovirus differ markedly in their response to a variety of chemical inactivating agents. We used intertypic recombinants containing various combinations of genes derived from the parental serotypes to study the basis of these differences. In addition to recombinants derived from types 1 and 3, and 2 and 3, we were able to isolate recombinants derived from types 1 and 2, suggesting that these two serotypes also undergo unrestricted reassortment. The intertypic recombinants behaved like one parent or the other in the presence of the inactivating agents and allowed us to determine the genes responsible for each difference. Recombinants derived from crosses between wild-type parental serotypes produced straightforward results, while recombinants derived from mutagenized, temperature-sensitive parents often did not. Sensitivity to 2.5 m-guanidine-HCl and pH 11 was determined by the S1 gene, sensitivity to 55 °C and 1% SDS was determined by the S4 gene, and sensitivity to 33% ethanol and to 1% phenol was determined by the M2 gene. Thus, relatively nonspecific chemical agents appear to have their predominant effect on specific proteins of the reovirus virion.

Canine Parvovirus: Relationship to Wild-type and Vaccine Strains of Feline Panleukopenia Virus and Mink Enteritis Virus

Abstract: Canine parvovirus (CPV), feline panleukopenia virus (FPLV) and mink enteritis virus (MEV) were compared serologically, by determination of their host range in cell cultures, as well as by restriction enzyme analysis. Maps of the virus genomes were established using seven different restriction enzymes cutting at a total of 56 sites. MEV and FPLV gave maps which were identical except for one restriction site. The map of CPV is closely related to those of FPLV/MEV since their DNAs share about 80% of the restriction sites tested. However, CPV is clearly distinct from FPLV/MEV since either eight (German isolate) or nine (Belgian, Swiss and American isolates) restriction sites are different. The DNAs of six vaccine strains of FPLV and MEV were also analysed. They gave maps which closely resembled those of the respective wild-type strains. CPV and FPLV/MEV also differed with respect to antigenicity, as well as to host range in cell cultures.

Monoclonal Antibodies to Three Non-glycosylated Antigens of Herpes Simplex Virus Type 2

Abstract: Summary The production and properties of three monoclonal antibodies, designated LP1, LP4 and AP2, directed against non-glycosylated polypeptides of herpes simplex virus type 2 are described. LP1 is specific for polypeptide VP16 and cross-reacts with HSV-1; LP4 reacts with the major DNA-binding protein and is type-specific. AP2 is directed against the major capsid antigen of HSV-1 and HSV-2.

The presence of alpha-interferon in human amniotic fluid.

Abstract: Summary Almost all the samples of amniotic fluid from 62 pregnant women from the 16th week to the end of the pregnancy contained detectable amounts of α-type interferon The presence of this substance in amniotic fluid during pregnancy raises the question of the physiological significance of this finding It is postulated that the amniotic type of α-interferon might be a product of a constitutive gene, rather than induced by latent virus infection

Replication of lactate dehydrogenase-elevating virus in macrophages. 2. Mechanism of persistent infection in mice and cell culture.

Abstract: SUMMARY A primary infection of peritoneal macrophage cultures with the lactate dehydrogenase-elevating virus (LDV) results in productive infection of 3 to 20% of the cells. When cultures were incubated in the absence of macrophage growth factor (MGF), LDV production ceased after a single cycle, but in cultures in which macrophage replication was stimulated by the presence of MGF LDV production continued for several weeks at a low level, representing not more than 1% of that observed during the acute phase. Significant amounts of interferon were not present in either acutely or persistently infected cultures, and treatment of persistently infected cultures with anti-interferon globulin or superinfection with LDV did not significantly stimulate LDV replication. Macrophage cultures established with peritoneal macrophages from LDV-infected mice also showed only a low level of LDV replication and were resistant to superinfection by LDV. Mouse hepatitis virus, Semliki Forest virus and vesicular stomatitis virus, on the other hand, replicated normally in LDV-persistently infected macrophage cultures. LDV replication was relatively resistant to interferon whether added to the cultures or generated endogenously by infection with Newcastle disease virus or defective-interfering (DI) particles of vesicular stomatitis virus. Temperature-sensitive mutants or DI particles of LDV were not detected in LDV-persistently infected cultures or chronically infected mice. The results support our hypothesis that the decrease in LDV production in mice or macrophage cultures at the end of the acute phase results from the destruction of the subpopulation of macrophages that is permissive for LDV, and that the low level persistent infection involves the passage of the virus to new permissive cells that are generated continuously, although at a low rate, from non-permissive precursor cells.

Molecular basis of rabies virus virulence. I. Selection of avirulent mutants of the CVS strain with anti-G monoclonal antibodies.

Abstract: Summary Two avirulent mutants of the CVS strain of rabies virus were isolated from clones resistant to one neutralizing monoclonal antibody. The virulence of clones resistant to three other anti-glycoprotein monoclonal antibodies was similar to that of the wild-type.

Nucleic Acid-binding Properties of Adenovirus Structural Polypeptides

Abstract: The ability of adenovirus structural polypeptides to bind nucleic acids was assessed by separating the polypeptides on SDS-polyacrylamide gels, transferring them electrophoretically to nitrocellulose and probing with 32P-labelled nucleic acids. Polypeptides IVa2, V, VI and VII, as well as trace amounts of pVII and a polypeptide of apparent mol. wt. 40 X 10(3) were able to bind label under these conditions. Labelling was also detected with a smaller polypeptide, possibly related to the cleavage products of pVII and/or pVI. The binding of DNA to polypeptide VI appeared to be more sensitive to detergents than the others. No sequence specificity could be detected in the DNA binding.

Specificity and Properties of the Genome-linked Proteins of Nepoviruses

Abstract: SUMMARY The infectivity of the RNA of six nepoviruses was decreased or abolished by proteinase K treatment, whereas that of the RNA of cowpea mosaic virus (comovirus group) or tomato bushy stunt virus was unaffected. The extent of the decrease in infectivity was characteristic for each nepovirus and was independent of the plant species used as virus source or as assay host. The infectivity of raspberry ringspot virus (RRV) RNA was less affected than that of the other nepoviruses but treatment with Pronase decreased infectivity more than treatment with proteinase K. Proteinase K treatment also abolished the infectivity for tobacco mesophyll protoplasts of RNA of tobacco ringspot virus (TRSV) and tomato black ring virus (TBRV). Tests on virus RNA, labelled with ~25I by the chloramine T method, provided evidence that three nepoviruses and Echtes Ackerbohnenmosaik-Virus (EAMV; comovirus group) have genome-linked proteins (VPg). Pronase treatment rendered about half (RNA of strawberry latent ringspot virus; SLRV), or nearly all (RNA of the other nepoviruses and EAMV), of the '25I soluble in 70 % ethanol. Treatment of nepovirus RNA with ribonuclease P 1 yielded a product with an estimated mol. wt. of 4000 __+ 900. Mobilities in polyacrylamide gels of VPg from the RNA of different viruses differed slightly (SLRV > TBRV > TRSV > RRV). TRSV VPg yielded one ~25I-labelled tryptic peptide whereas the genome-linked proteins of RRV and TBRV both yielded two major products, of which one was resistant to further digestion and the other was converted, apparently via intermediates, to a second more stable product. No difference was detected between the tryptic peptides obtained from VPg of different strains of RRV, or of TBRV, or between those obtained from RNA-1, RNA-2 or RNA-3 (satellite RNA) of TBRV. Nepovirus VPg is therefore virus-specific. It seems to be coded on RNA-1 and probably has multiple functions.

Polypeptides of Varicella-Zoster Virus (VZV) and Immunological Relationship of VZV and Herpes Simplex Virus (HSV)

Abstract: Varicella-zoster virus (VZV), labelled with [35S]methionine or [14C]glucosamine, was purified by centrifugation through sucrose gradients followed by equilibrium centrifugation in CsCl, and analysed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). At least 32 polypeptides ranging in mol. wt. from approx. 280 X 10(3) to 21.5 X 10(3) (280K to 21.5K) and six glycopeptides ranging in mol. wt. from approx. 115K to 45K (gp1 to gp6) were found in the virion. The immunological relationship of VZV and herpes simplex virus (HSV) was investigated. In neutralization (NT) tests, no cross-neutralization was observed between VZV and HSV-1 or -2. In fluorescent antibody staining, however, a cross-reaction was observed between VZV- and HSV-1-infected human embryonic lung (HEL) cells and heterologous antiserum. When cross-reactions were investigated by immunoprecipitation followed by SDS-PAGE, several cross-reacting polypeptides were discovered. Cross-reacting glycopeptides of 64K (gp3) and 55K (gp5) were isolated from VZV-infected cell lysates by affinity column chromatography to immobilized HSV-1 antibodies.