bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and antigenic analysis of the nucleic acid-binding proteins of bovine and feline leukemia viruses
Authors: Morgan M A , Copeland T D , Oroszlan S
Published: January 2020

The nucleic acid-binding proteins of bovine leukemia virus (BLV) and feline leukemia virus (FeLV) were isolated in a high state of purity with chloroform-methanol extraction followed by reversed-phase liquid chromatography. Selective solubilization and purity of BLV p12 and FeLV p10 was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The compositions and molecular weights were determined by amino acid analysis. An abundance of lysine and arginine residues along with their size identifies both BLV p12 and FeLV p10 as small basic proteins similar to well-defined type C viral nucleoproteins. NH2-terminal degradation by the semiautomated Edman method provided the sequence of the first 40 amino acids for both proteins. The putative nucleic acid binding site found in several type C viral nucleoproteins was contained within this sequence, with the most homology centered around an eight-amino acid region involving seven identical residues and one substitution. Antisera were developed in rabbits, and specificity and titers were determined by electroblotting and immunoautoradiography. By this technique, an immunological cross-reaction was found between BLV p12 and FeLV p10. The shared antigenic determinant most likely exists in the highly conserved eight-amino acid region. Although this sequence is also highly conserved in the nucleic acid-binding proteins of murine leukemia viruses, the shared antigenic determinant is not found in these or any other type C viruses tested. It is suggested that substitution of arginine (BLV p12/FeLV p10) to lysine (murine leukemia virus p10) is sufficient to elicit a change in antibody specificity.
Effect of arabinofuranosylthymine on the replication of Epstein-Barr virus and relationship with a new induced thymidine kinase activity
Authors: Ooka T , Calender A , de Turenne M , Daillie J
Published: January 2020

1-beta-D-Arabinofuranosylthymine (araT) is a selective inhibitor of Epstein-Barr virus replication induced in both thymidine kinase (TK)-negative (TK-) and TK+ variants of the lymphoid cell line P3HR-I. This analog has no effect on the growth of noninduced cells (T. Ooka and A. Calender, Virology 104:219-223, 1980). The synthesis of early antigens is not affected by the analog, whereas that of late viral capsid antigens is completely inhibited, as demonstrated by the indirect immunofluorescence technique; kinetic reassociation experiments have also shown that araT strongly inhibits replication of viral DNA. Phosphorylation of the tritiated form of the analog ([3H]araT) was analyzed by thin-layer chromatography in cultures of control and induced cells, and the results demonstrated that only induced cells can convert the analog to the triphosphate form. These results indicate that the selective effect of araT in induced cells is probably related to a new virally induced TK activity. Preliminary characterization of this new activity has shown that it is able to phosphorylate the analog specifically, whereas cellular TKs cannot. araTTP, a final phosphorylation product of araT, is a potent inhibitor of Epstein-Barr virus-specific DNA polymerase, suggesting a possible inhibitory action of this product on Epstein-Barr virus replication.
Identification of a spleen focus-forming virus in erythroleukemic mice infected with a wild-mouse ecotropic murine leukemia virus
Authors: Langdon W Y , Hoffman P M , Silver J E , Buckler C E , Hartley J W , Ruscetti S K , Morse H C
Published: January 2020

An NFS/N mouse inoculated at birth with an ecotropic murine leukemia virus (MuLV) obtained from wild mice (Cas-Br-M MuLV) developed a lymphoma after 18 weeks. An extract prepared from the lymphomatous spleen was inoculated into newborn NFS/N mice, and these mice developed erythroleukemia within 9 weeks. Spleens from the erythroleukemic mice contained ecotropic and mink cell focus-inducing (MCF) MuLVs; however, when these viruses were biologically cloned and reinoculated into newborn NFS/N mice, no erythroleukemia was induced. In contrast, cell-free extracts prepared from the erythroleukemic spleens induced erythroleukemia within 5 weeks. Analysis of cell-free extracts prepared from the erythroleukemic spleens showed that they contained a viral species that induced splenomegaly and spleen focus formation in adult mice, with susceptibility controlled by alleles at the Fv-2 locus. The spleen focus-forming virus coded for a 50,000-dalton protein precipitated by antibodies specific to MCF virus gp70. RNA blot hybridization studies showed the genomic viral RNA to be 7.5 kilobases and to hybridize strongly to a xenotropic or MCF envelope-specific probe but not to hybridize with an ecotropic virus envelope-specific probe. The virus described here appears to be the fourth independent isolate of a MuLV with spleen focus-forming activity.
Protein Kinase Activity Associated with the Extracellular and Occluded Forms of the Baculovirus
Autographa californica
Nuclear Polyhedrosis Virus
Authors: Miller Lois K. , Adang Michael J. , Browne David
Published: January 2020

Protein kinase activity is associated with both the extracellular and the occluded forms of
Autographa californica
nuclear polyhedrosis virus, a baculovirus. Serine and threonine are the predominant amino acids phosphorylated by the kinase activity associated with both viral forms; no phosphotyrosine was detected. The addition of calcium, cAMP, or cGMP has no apparent effect on the amount of phosphorylation or the substrates phosphorylated.
Deletion mapping of a short polyoma virus middle T antigen segment important for transformation
Authors: Nilsson S V , Tyndall C , Magnusson G
Published: January 2020

Viable polyoma virus mutants were constructed that had small deletions in the early region of the genome. The deletions together removed most of the segment missing from the genome of the nontransforming mutant dl23 (N. Smolar and B. E. Griffin, J. Virol. 38:958-967, 1981). The transformation properties, as measured by colony formation in soft agar, of mutants with overlapping or contiguous deletions showed that part or all of the middle T antigen segment, consisting of the short amino acid sequence Glu4-Tyr-Met-Pro-Met, was essential for the activity of the protein in transformation. However, the segment could be deleted without significant effect on the in vitro protein kinase activity associated with the middle T antigen.
Intracisternal A particles: RNA expression and DNA methylation in murine teratocarcinoma cell lines
Authors: Hojman-Montes de Oca F , Dianoux L , Peries J , Emanoil-Ravicovitch R
Published: January 2020

Two main intracisternal-A-particle-specific RNA species (29 to 30S and 35 to 36S) are variably expressed in particle-producing and particle-nonproducing murine teratocarcinoma cell lines. An analysis of DNA methylation patterns after hybridization with an intracisternal-A-particle-specific probe showed an apparent direct correlation between DNA methylation and RNA expression. However, when the methylation assay was performed on the excised intracisternal A particle genes in one of the particle-rich cell lines (PCC6), some undermethylated sequences were detectable. These results are consistent with the concept that only few of the genes are transcriptionally active.
Transcription of mouse mammary tumor virus: identification of a candidate mRNA for the long terminal repeat gene product
Authors: Wheeler D A , Butel J S , Medina D , Cardiff R D , Hager G L
Published: January 2020

We have examined an assortment of preneoplastic and neoplastic mouse mammary tissues for the presence of an mRNA which could encode the putative long terminal repeat gene product of mouse mammary tumor virus. We report here the detection of a novel mouse mammary tumor virus-specific, polyadenylic acid-containing transcript in certain preneoplastic and neoplastic mammary tissue of BALB/c mice. The molecule is 1.6 kilobases in length and contains sequences from the transcriptional leader and the U3 region of the proviral DNA. The upstream terminus of the 3' information lies 75 to 80 nucleotides from the beginning of the long terminal repeat open reading frame, in close proximity to a consensus splice acceptor in the DNA. The transcript was detected in hormonally or chemically induced neoplastic, preneoplastic, and lactating mammary tissue of BALB/c mice, but not in preneoplastic or tumor tissue induced by exogenous viruses in any strain of mice examined. This implies that the RNA we observed is transcribed from an endogenous provirus template.
Herpes simplex virus mutants defective in the virion-associated shutoff of host polypeptide synthesis and exhibiting abnormal synthesis of alpha (immediate early) viral polypeptides
Authors: Read G S , Frenkel N
Published: January 2020

Six mutants isolated from herpes simplex virus type 1 were judged to be defective with respect to the virion-associated function acting to rapidly shut off host polypeptide synthesis in herpes simplex virus-infected cells. The mutants were capable of proper entry into the cells, but, unlike the parent wild-type virus, they failed to shut off host polypeptide syntehsis in the presence of actinomycin D. They were consequently designated as virion-associated host shutoff (vhs) mutants. In the presence of actinomycin D, three of the mutants, vhs1, -2, and -3, failed to shut off the host at both 34 and 39 degrees C, whereas vhs4, -5, and -6 exhibited a temperature-dependent vhs phenotype. Since the mutants were capable of growth at 34 degrees C, it appeared that the vhs function was not essential for virus replication in cultured cells. Temperature-shift experiments performed with the vhs4 mutant showed that an active vhs function was required throughout the shutoff process and that, once established, the translational shutoff could not be reversed. In the absence of actinomycin D, the mutants induced a generalized, secondary shutoff of host translation, which required the synthesis of beta (early) or gamma (late) viral polypeptide(s). The vhs mutants appeared to be defective also with respect to post-transcriptional shutoff of alpha (immediate early) viral gene expression, since (i) cells infected with mutant viruses overproduced alpha viral polypeptides, (ii) there was an increased functional stability of alpha mRNA in the vhs1 mutant virus-infected cells, and (iii) superinfection of vhs1-infected cells with wild-type virus, in the presence of actinomycin D, resulted in a more pronounced shutoff of alpha polypeptide synthesis from preformed alpha mRNA than equivalent superinfection with vhs1 virus. The data suggest that the synthesis of alpha polypeptides in wild-type virus infections is subject to a negative post-transcriptional control involving viral gene product(s) present in infected cell lysates constituting virus stocks. The vhs1 mutant and possibly other vhs mutants contain a mutation in the gene encoding this function.
Deletion mutants of Moloney murine leukemia virus which lack glycosylated gag protein are replication competent
Authors: Schwartzberg P , Colicelli J , Goff S P
Published: January 2020

A series of deletion mutations localized near the 5' end of the Moloney murine leukemia virus genome was generated by site-specific mutagenesis of cloned viral DNA. The mutants recovered from such deleted DNAs failed to synthesize the normal glycosylated gag protein gPr80gag. Two of the mutants made no detectable protein, and a third mutant, containing a 66-base pair deletion, synthesized an altered gag protein which was not glycosylated. All the mutants made normal amounts of the internal Pr65gag protein. The viruses were XC positive and replicated normally in NIH/3T3 cells as well as in lymphoid cell lines. These results indicate that the additional peptides of the glycosylated gag protein are encoded near the 5' end, that the glycosylated and internal gag proteins are synthesized independently, and that the glycosylated gag protein is not required during the normal replication cycle. In addition, the region deleted in these mutants apparently encodes no cis-acting function needed for replication. Thus, all essential sequences, including those for packaging viral RNA, must lie outside this area.
Synthesis and processing of the three major envelope glycoproteins of Epstein-Barr virus
Authors: Edson C M , Thorley-Lawson D A
Published: January 2020

In pulse-chase experiments, the three major Epstein-Barr virus envelope glycoproteins, gp350/300, gp250/200, and gp85, were shown to be synthesized from separate precursors of 190,000, 160,000, and 83,000 daltons, respectively. These three pulse-labeled species were chased into the mature forms of the glycoproteins between 1 and 3 h after transfer to nonradioactive medium. Digestion of precursor forms with endo-beta-N-acetylglucosaminidase H (endo H) yielded polypeptides of 160,000, 120,000, and 75,000 daltons. Comparison of these results with those from experiments with tunicamycin, which specifically blocks N-linked glycosylation, indicated that some other post-translational modification(s), probably O-linked glycosylation, contributes about 100,000 and 60,000 daltons of apparent molecular mass to gp350/300 and gp250/200, respectively. Experiments with endo H showed that mature gp350/300 and gp250/200 contain complex-type (endo H-resistant) N-linked glycosyl chains, whereas gp85 contains both high-mannose (endo H-sensitive)- and complex-type oligosaccharides. In contrast to the results obtained with the three envelope glycoproteins, no precursor forms of the two unglycosylated protein, p160 (the major Epstein-Barr virus capsid antigen) and p140 (an envelope protein), were detected. The partial proteolytic maps of gp350/300 and gp250/200 were quite similar, suggesting that polypeptide sequence homology could account for at least part of the observed serological cross-reactivity of the two proteins. Taken together, these results demonstrate that the polypeptide portions of gp350/300 and gp250/200 are closely related but not derived from a common precursor. Furthermore, the polypeptide portions comprise half or less of the apparent molecular weight of the mature glycoproteins on sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Comparative analysis of the human type 1a and bovine type 1 papillomavirus genomes
Authors: Danos O , Engel L W , Chen E Y , Yaniv M , Howley P M
Published: January 2020

The DNA sequences of the genomes of the bovine type 1 and human type 1a papillomaviruses were compared. The overall organization of both genomes is very similar. Three areas of maximal homology were found in the L1 and E1/E2 genes, and at the beginning of L2. The conservation of homologous amino acid sequences encoded in the open reading frames argues that these segments represent real genes or exons. Within these segments, however, only certain domains of the putative proteins are preferentially conserved. Two polypeptide chains show homologous arrangement of the cysteine residue clusters Cys-X-X-Cys, despite a lack of conservation of the rest of the amino acid sequence. A significant sequence divergence in a region where the three reading frames are open suggests that papillomavirus genomes have evolved not solely by accumulation of point mutations. Conserved sequences were also found in the noncoding region, and their possible involvement in regulation of viral gene expression is discussed.
94,000- and 100,000-molecular-weight simian virus 40 T-antigens are associated with the nuclear matrix in transformed and revertant mouse cells
Authors: Verderame M F , Kohtz D S , Pollack R E
Published: January 2020

A small fraction of the 94,000-molecular-weight multifunctional large T-antigen of simian virus 40 was associated with the nuclear protein matrix derived from simian virus 40-transformed mouse cells. The interaction between this fraction of T-antigen and the matrix was largely or entirely independent of nuclear DNA. Similar amounts of T-antigen were retained by the nuclei of transformed and revertant cell lines. A 100,000-molecular-weight variant of T-antigen, which has been found to correlate specifically with anchorage-independent growth, was present in the nuclear protein matrix of a transformed cell line. A T-antigen-containing revertant selected for the reacquisition of a high serum requirement and an anchorage requirement for growth retained T-antigen in association with its matrix.
Evidence that bacteriophage T4 eph1 is a missense hoc mutation
Authors: Childs J D , Pilon R
Published: January 2020

An electrophoretic mutation of bacteriophage T4, eph1, appears to code for a missense hoc (highly antigenic outer capsid) protein. This is based on the observation that particles lacking hoc protein (hoc- particles), after incubation in a crude extract of Escherichia coli infected with phage carrying the eph1 mutation acquired the electrophoretic mobility of the eph1 strain (the electrophoretic mobility of the eph1 strain itself is slower than that of hoc- particles). Thus, it is likely that during infection of E. coli with the eph1 strain, a hoc protein is made that has a lower negative charge than normal hoc protein but can nevertheless bind to particles lacking hoc protein. These results confirm that eph1 is a hoc mutation.
Gene mapping in Pichinde virus: assignment of viral polypeptides to genomic L and S RNAs
Authors: Harnish D G , Dimock K , Bishop D H , Rawls W E
Published: January 2020

Previous studies have demonstrated that Pichinde virus encodes at least three primary translation products. Using wild-type Pichinde and Munchique viruses and a reassortant between the two, designated RE-2, we were able to assign polypeptides L, GPC, and NP to viral L and S RNAs. The RE-2 virus contains the L RNA of Pichinde virus and the S RNA of Munchique virus. Two-dimensional tryptic peptide mapping of L-[35S]methionine-containing peptides demonstrated that NP and GPC were identical in Munchique and RE-2 viruses, and both differed from the corresponding Pichinde virus tryptic profiles. On the basis of this, NP and GPC must be encoded by viral S RNA. Similar comparisons for L polypeptide demonstrated that L is a virus-specific polypeptide encoded by L RNA.
Physical mapping of the mutation in an antigenic variant of herpes simplex virus type 1 by use of an immunoreactive plaque assay
Authors: Holland T C , Sandri-Goldin R M , Holland L E , Marlin S D , Levine M , Glorioso J C
Published: January 2020

Two mutations affecting herpes simplex virus type 1 glycoprotein B were mapped by marker rescue using cloned sequences of wild-type herpes simplex virus type 1 strain KOS DNA. One mutant, tsB5, is a temperature-sensitive mutant which does not express mature, functional glycoprotein B at the nonpermissive temperature. The other mutant, marB1.1, expresses an antigenic variant of glycoprotein B and was selected for resistance to neutralization by a monoclonal antibody. The mutation in tsB5 mapped to a 1.2-kilobase segment of the herpes simplex virus type 1 genome between coordinates 0.361 and 0.368, whereas the mutation in marB1.1 mapped to a 1.6-kilobase segment between coordinates 0.350 and 0.361. An in situ enzyme immunoassay was used to detect plaques of recombinant wild-type virus among the progeny of transfections with mutant marB1.1 DNA and wild-type DNA fragments.
Respiratory syncytial virus mRNA coding assignments
Authors: Huang Y T , Wertz G W
Published: January 2020

The polypeptide coding assignments for six of the respiratory syncytial virus-specific mRNAs were determined by translation of the individual mRNAs in vitro. The coding assignments of the RNAs are as follows. RNA band 1 is complex and can be separated into at least two components on the basis of electrophoretic mobility (molecular weights [MWs] approximately equal to 0.21 X 10(6) and 0.31 X 10(6), respectively) that code for three polypeptides of 9.5, 11, and 14 kilodaltons (K). RNA 2 (MW, 0.39 X 10(6)) codes for a 34K polypeptide; RNA 3 (MW, 0.40 X 10(6)) codes for a 26K polypeptide; RNA 4 (MW, 0.47 X 10(6)) codes for a 42K polypeptide; and RNA 5 (MW, 0.74 X 10(6)) codes for a 59K polypeptide. By limited-digest peptide mapping, the 34, 26, and 42K polypeptides synthesized in vitro appeared to be unique. Additionally, peptide mapping showed that the 34, 26, and 42K polypeptides synthesized in vitro were indistinguishable from their counterparts synthesized in infected cells. Thus, the 34, 26, and 42K polypeptides coded for by mRNAs 2, 3, and 4, respectively, were identified as the respiratory syncytial virus phosphoprotein (34K), matrix protein (26K), and nucleocapsid protein (42K), respectively. RNA 5 was shown to code for a 59K polypeptide. The 59K polypeptide synthesized in vitro did not comigrate with any polypeptide specific to infected cells, suggesting that it is a candidate for co- or post-translational modification.
Transformation of rodent cells by DNA extracted from transformation-defective adenovirus mutants
Authors: Rowe D T , Graham F L
Published: January 2020

Complementation group II host range mutants of adenovirus type 5 which map in early region 1B (E1B, 4.5 to 11.0 map units) have been shown to be defective for the synthesis of the E1B 58,000-dalton (58K) antigen in infections of HeLa or KB cells (Lassam et al., Cell 18:781-791, 1979) and unable to transform cultured rodent cells (Graham et al., Virology 86:10-21, 1978). In this report we show that DNA extracted from group II mutants hr6 and hr50 can transform rat cells with the same efficiency as wild-type DNA. Furthermore, group II mutant-transformed hamster cells were shown to contain no detectable E1B 58K tumor antigen but were capable of inducing tumors in newborn hamsters. Hamster cell lines 1019-3 and 1019-C3, transformed by hr50 DNA, produced no detectable quantities of either the E1B 58K or 19K antigen but nonetheless exhibited a fully transformed oncogenic phenotype. Our results show that the E1B 58K antigen is not absolutely required for oncogenic transformation and suggest that even cells lacking the 19K protein can be oncogenic.
In vitro synthesis of late bacteriophage phi 29 RNA
Authors: Holder R D , Whiteley H R
Published: January 2020

A crude P-100 fraction prepared from Bacillus subtilis 21 min after infection with wild-type phage phi 29 supported the in vitro synthesis of late phi 29 RNA by added RNA polymerase. Synthesis of late RNA was also detected when purified phi 29 DNA was transcribed by RNA polymerase in the presence of an S-150 fraction obtained by lysis of phi 29-infected cells in the presence of 1 M NaCl. Late phi 29 RNA was not synthesized when either the P-100 or the S-150 fraction was prepared from cultures infected with phi 29 having a mutation in gene 4.
Identification of adenovirus genes that require template replication for expression
Authors: Crossland L D , Raskas H J
Published: January 2020

The relationship between adenovirus type 2 DNA replication and expression of intermediate stage viral genes was investigated. The 1.03-kilobase mRNA from early region 1b (E1b) and the mRNAs coding for proteins IX and IVa2 were first detected between 6 and 8 h postinfection. Inhibition of viral DNA replication with hydroxyurea prevented expression of the IX and IVa2 mRNAs, but not of the E1b mRNA. Pulse-labeling experiments demonstrated that the block of IX and IVa2 expression in hydroxyurea-treated cells was at the level of transcription. By a series of superinfection experiments, it was determined that the viral and cellular factors present during the late stage of adenovirus infection are insufficient to activate IX gene expression. The viral DNA template must first replicate before IX transcription can begin.
Vesicular stomatitis virus mutant with altered polyadenylic acid polymerase activity in vitro
Authors: Hunt D M
Published: January 2020

In vitro RNA synthesis by purified virions of a stock of tsG16(I) was aberrant compared with that of wild-type (wt) vesicular stomatitis virus. RNA made in vitro by tsG16(I) contained a larger proportion of A residues in polyadenylic acid [poly(A)] tracts than did RNA synthesized by wt virus, tsG13(I), tsG21(II) or tsG41(IV). Experiments to determine whether the aberrant polyadenylation was correlated with the known thermolability of the tsG16(I) L protein were inconclusive. Total product RNA made by tsG16(I) was methylated to almost the same extent as wt RNA, contained the same major methylated 5' cap structure as wt RNA, and was translated as well in a reticulocyte cell-free system, yielding the same molecular weight proteins in similar ratios. Most polyadenylated [poly(A)+] RNA made by tsG16(I) was considerably larger than wt poly(A)+ RNA and richer in AMP:UMP residues; however, the protein-coding capacities of mutant and wt poly(A)+ RNAs were similar. This suggested that most mRNAs made in vitro by tsG16(I) might possess very long poly(A)+ tracts, and digestion of RNA by T1 RNase supported this. It appeared, therefore, that a virally coded component of vesicular stomatitis virus could affect polyadenylation. This could be the poly(A) polymerase itself, a protein involved in control of polyadenylation, or a protein which affects an event spatially and temporally connected with polyadenylation (such as initiation of the subsequent mRNA).
Molecular cloning and characterization of endogenous feline leukemia virus sequences from a cat genomic library
Authors: Soe L H , Devi B G , Mullins J I , Roy-Burman P
Published: January 2020

Recombinant bacteriophage lambda clones from a cat genomic library derived from placental DNA of a specific pathogen-free cat were screened to identify endogenous feline leukemia virus (FeLV) sequences. Restriction endonuclease mapping of four different clones indicates that there are a number of similarities among them, notably the presence of a 6.0- to 6.4-kilobase pair (kbp) EcoRI hybridizing fragment containing portions of sequences homologous to the gag, pol, env, and long terminal repeat-like elements of the infectious FeLV. The endogenous FeLV sequences isolated are approximately 4 kbp in length and are significantly shorter than the cloned infectious FeLV isolates, which are 8.5 to 8.7 kbp in length. The endogenous elements have 3.3- to 3.6-kbp deletions in the gag-pol region and approximately 0.7- to 1.0-kbp deletions in the env region. These deletions would render them incapable of encoding an infectious virus and may therefore be related to the non-inducibility of FeLV from uninfected cat cells and the subgenomic expression of these endogenous sequences in placental tissue. It appears that there is conservation in the ordering of restriction sites previously reported in the proviruses of the infectious FeLVs in sequences corresponding to the pol and env boundary as well as the region spanning the env gene of the endogenous clones, whereas a greater divergence occurs among restriction sites mapped to the gag and part of the pol regions of the infectious FeLV. Such deleted, FeLV-related subsets of DNA sequences could have originated either by germ-line integration of a complete ecotropic virus followed by deletion, or by integration of a preexisting, defective, deleted variant of the infectious virus.
Capped and conserved terminal structures in human rotavirus genome double-stranded RNA segments
Authors: Imai M , Akatani K , Ikegami N , Furuichi Y
Published: January 2020

Both 3'- and 5'-terminal structures of human rotavirus genome double-stranded RNA segments were determined. RNAs were labeled at the 3'-termini with [32P]pCp by incubation with RNA ligase and at the 5'-termini with [32P]phosphate by polynucleotide kinase or, in the case of 5' caps, with 3H by chemical modification with [3H]NaBH4. Examination of radiolabeled termini released by digestion with several base-specific RNases revealed that rotavirus RNA segments are base paired end-to-end and contain the same terminal structures: (formula; see text)
Nonoverlapping antigenic sites of woodchuck hepatitis virus surface antigen and their cross-reactivity with ground squirrel hepatitis virus and hepatitis B virus surface antigens
Authors: Cote P J , Gerin J L
Published: January 2020

Five nonoverlapping antigenic sites (sites I through V) of woodchuck hepatitis virus surface antigen were identified with competitive binding assays involving monoclonal antibodies. Site I contributed to cross-reactions among surface antigens of hepatitis B-like viruses infecting woodchucks, ground squirrels, and humans. At least three distinct sites (sites I, II, and III) are responsible for cross-reactions between woodchuck and ground squirrel hepatitis virus surface antigens. Sites IV and V of woodchuck hepatitis virus surface antigen are not major cross-reactive sites, suggesting that these elicit virus-specific antibodies. There were no cross-reactions with duck hepatitis B virus surface antigen.
Posttranslational modification and intracellular transport of mumps virus glycoproteins
Authors: Herrler G , Compans R W
Published: January 2020

Analysis of the pronase-derived glycopeptides of isolated mumps virus glycoproteins revealed the presence of both complex and high-mannose-type oligosaccharides on the HN and F1 glycoproteins, whereas only high-mannose-type glycopeptides were detected on F2. Endoglycosidase F, a newly described glycosidase that cleaves N-linked high mannose as well as complex oligosaccharides, appeared to completely cleave the oligosaccharides linked to HN and F2, whereas F1 was resistant to the enzyme. Two distinct cleavage products of F2 were observed, suggesting the presence of two oligosaccharide side chains. Tunicamycin was found to reduce the infectious virus yield and inhibit mumps virus particle formation. The two glycoproteins, HN and F, were not found in the presence of the glycosylation inhibitor. However, two new polypeptides were detected, with molecular weights of 63,000 (HNT) and 53,000 (FT), respectively, which may represent nonglycosylated forms of the glycoproteins. Synthesis of the nonglycosylated virus-coded proteins (L, NP, P, M, pI, and pII) was not affected by tunicamycin. The formation of HN oligomers and the proteolytic cleavage of the F protein were found to occur with the same kinetics. Analysis of the time course of appearance of mumps virus glycoproteins on the cell surface suggested that dimerization of HN and cleavage of F occur immediately after their exposure on the plasma membrane.
Ionic and nonionic interactions in adenoviral nucleoprotein complexes
Authors: Fedor M J , Daniell E
Published: January 2020

Ionic and nonionic interactions between the adenoviral histone-like proteins and DNA were examined by determining effects of ionic strength and urea concentration on disruption of viral nucleoprotein. The viral proteins were as susceptible to dissociation by salt in the presence of urea as histones. Nonionic interactions between viral proteins appeared more extensive than those between histones.
Involvement of Directly Repeated Sequences in the Generation of Deletions of the Avian Sarcoma Virus
src
Gene
Authors: Omer Charles A. , Pogue-Geile Katherine , Guntaka Ramareddy , Staskus Katherine A. , Faras Anthony J.
Published: January 2020

Nucleotide sequence analysis of two molecular clones of transformation-defective avian sarcoma virus indicate that direct repeated sequences of 6 and 20 nucleotides are involved in the formation of the
src
deletions in these clones.
In vitro activation of bacteriophage P2 late gene expression by extracts from phage P4-infected cells
Authors: Gibbs W , Eisen H , Calendar R
Published: January 2020

We have used a cell-free, DNA-dependent protein-synthesizing system to study the stimulation of phage P2 late gene expression by satellite phage P4. An activity is present in extracts prepared from P4-infected cells, which, when added to the in vitro system with P2 DNA template, stimulates the synthesis of a number of P2 proteins. These stimulated proteins include the major P2 capsid protein (N gene product) and a major component of the P2 phage tail (FII gene product). Extracts prepared from P4-infected cells are also able to stimulate the synthesis from P4 DNA of two low-molecular-weight proteins (18,500 and 17,000 Mr). The stimulating activity has no effect on the synthesis of proteins from lambda plac5 template. Extracts prepared from cells infected with P4 alpha amber mutants lack this stimulating activity.
Molecular cloning of the unintegrated squirrel monkey retrovirus genome: organization and distribution of related sequences in primate DNAs
Authors: Chiu I M , Andersen P R , Aaronson S A , Tronick S R
Published: January 2020

The closed circular form of the endogenous squirrel monkey type D retrovirus (SMRV) was molecularly cloned in a bacteriophage vector. The restriction map of the biologically active clone was determined and found to be identical to that of the parental SMRV linear DNA except for the deletion of one long terminal repeat. Restriction enzyme analysis and Southern blotting indicated that the SMRV long terminal repeat was approximately 300 base pairs long. The SMRV restriction map was oriented to the viral RNA by using a gene-specific probe from baboon endogenous virus. Restriction enzyme digests of a variety of vertebrate DNAs were analyzed for DNA sequence homology with SMRV by using the cloned SMRV genome as a probe. Consistent with earlier studies, multiple copies of SMRV were detected in squirrel monkey DNA. Related fragments were also detected in the DNAs from other primate species, including humans.
Stabilization of the large T protein in temperature-independent (type A) FR 3T3 rat cells transformed with the simian virus 40 tsA30 mutant
Authors: Imbert J , Clertant P , de Bovis B , Planche J , Birg F
Published: January 2020

The stabilities of in vivo [35S]methionine-labeled large T and small t proteins, synthesized in temperature-sensitive (type N) and temperature-insensitive (type A) FR 3T3 rat cells transformed by an early temperature-sensitive mutant of simian virus 40 (SV40), tsA30, were analyzed at the permissive and restrictive temperatures. The two polypeptides, detected in greatly reduced amounts in cells of the N type at the restrictive temperature, were also unstable at the permissive temperature. However, both were made in similar amounts and were apparently stable in cells of the A type, irrespective of the temperature. The structures of the viral RNAs present at the permissive temperature were analyzed for transformants representative of each type, and containing a single integration of viral DNA. The two cell lines synthesized transcripts identical to the large T and small t mRNAs identified in SV40-infected monkey cells. Similar amounts of viral RNA were found in A and N transformants in active growth at the permissive and restrictive temperatures, which argued against a control at a transcriptional level. Assay of a defined function of the protein, namely, the binding of nucleotide detected by affinity labeling with periodate-oxidized [alpha-32P]ATP, clearly showed that the large T proteins from both types of transformants exhibited, at least for that particular biochemical function, the same in vitro temperature sensitivity. In transformants of the A type only could a reduced binding activity be detected in extracts from cells grown at the restrictive temperature. Thus, the temperature-independent behavior of the A transformants may result from an in vivo partial stabilization of the newly synthesized large T protein, probably through interaction with a cellular component(s).
Genetic and phenotypic analysis of herpes simplex virus type 1 mutants conditionally resistant to immune cytolysis
Authors: Pancake B A , Aschman D P , Schaffer P A
Published: January 2020

Nine temperature-sensitive (ts) mutants of herpes simplex virus type 1 selected for their inability to render cells susceptible to immune cytolysis after infection at the nonpermissive temperature have been characterized genetically and phenotypically. The mutations in four mutants were mapped physically by marker rescue and assigned to functional groups by complementation analysis. In an effort to determine the molecular basis for cytolysis resistance, cells infected with each of the nine mutants were monitored for the synthesis of viral glycoprotein in total cell extracts and for the presence of these glycoproteins in plasma membranes. The four mutants whose ts mutations were mapped were selected with polypeptide-specific antiserum to glycoproteins gA and gB; however, three of the four mutations mapped to DNA sequences outside the limits of the structural gene specifying these glycoproteins. Combined complementation and phenotypic analysis indicates that the fourth mutation also lies elsewhere. The ts mutations in five additional cytolysis-resistant mutants could not be rescued with single cloned DNA fragments representing the entire herpes simplex virus type 1 genome, suggesting that these mutants may possess multiple mutations. Complementation tests with the four mutants whose ts lesions had been mapped physically demonstrated that each represents a new viral gene. Examination of mutant-infected cells at the nonpermissive temperature for the presence of viral glycoproteins in total cell extracts and in membranes at the cell surface demonstrated that (i) none of the five major viral glycoproteins was detected in extracts of cells infected with one mutant, suggesting that this mutant is defective in a very early function; (ii) cells infected with six of the nine mutants exhibited greatly reduced levels of all the major viral glycoproteins at the infected cell surface, indicating that these mutants possess defects in the synthesis or processing of viral glycoproteins; and (iii) in cells infected with one mutant, all viral glycoproteins were precipitable at the surface of the infected cell, despite the resistance of these cells to cytolysis. This mutant is most likely mutated in a gene affecting a late stage in glycoprotein processing, leading to altered presentation of glycoproteins at the plasma membrane. The finding that the synthesis of both gB and gC was affected coordinately in cells infected with six of the nine mutants suggests that synthesis of these two glycoproteins, their transport to the cell surface, or their insertion into plasma membranes is coordinately regulated.
Polyomavirus large T antigen binds independently to multiple, unique regions on the viral genome
Authors: Pomerantz B J , Mueller C R , Hassell J A
Published: January 2020

To map the polyomavirus large T antigen binding sites on the viral genome we employed a quantitative immunoassay. Defined, radiolabeled fragments of the viral genome were reacted with crude nuclear extracts prepared from lytically infected mouse 3T6 cells, and the fragments bound by large T antigen were immunoprecipitated with anti-T serum and Formalin-fixed Staphylococcus aureus. The immunoprecipitated DNA was then analyzed by gel electrophoresis and autoradiography. By the use of a variety of restriction endonuclease-generated fragments of wild-type and mutant viral DNAs, the region of high-affinity binding was localized to a 153-base-pair stretch between nucleotides 5292 and 152. At least two independent binding sites lie within this region, one upstream and the other downstream of the Bg/I site at nucleotide 87. One of the binding sites is located within sequences required in cis for DNA replication; the other overlaps the TATA box and cap sites of the early transcription unit. The two sites share a common sequence, A/TGAGGC-N4/5-A/TGAGGC, which may serve as the recognition sequence for large T antigen.
Blockage of antiviral induction of interferon by homologous cell biochemical activity: effect of chicken embryo fibroblast mitotic cell cycle phases on Sindbis virus growth
Authors: Ghubril V A
Published: January 2020

The antiviral activity of interferon, measured as the reduction of viral yield, was studied as a function of the cell cycle phases. The present study shows that cells which are about to enter DNA replication phase S and cells that are in mitosis phase M are not refractive to viral infection when treated with interferon. The growth of Sindbis virus, used as the challenger, dropped considerably at the G1-S junction, at mitosis phase M, and as cells entered into a deeper quiescent state.
Nucleotide sequence analysis of the long terminal repeat of murine virus-like DNA (VL30) and its adjacent sequences: resemblance to retrovirus proviruses
Authors: Itin A , Keshet E
Published: January 2020

VL30 DNA represents a retrovirus-like multigene family of mice whose genetic origin is unknown. We have now determined the primary nucleotide sequences and the adjacent sequences of the long terminal direct repeats (LTRs) possessed by a randomly selected VL30 unit. The LTR of the VL30 unit comprised 435 nucleotide base pairs and had an inverted repeat of five bases at its 5' and 3' termini. At the joints with flanking mouse DNA was the VL30 sequence (5')TG . . . CA(3') and a tetranucleotide direct repeat of flanking sequences. At the inner boundary of the 5' LTR was an 18-base sequence that is complementary to tRNApro, and at the inner boundary of the 3' LTR was a purine-rich tract ending with AATG. These results suggested that VL30 DNA used the same integration strategy that is exercised by retrovirus proviruses and transposable elements and that the VL30 LTR is synthesized in a similar way that the LTR of retroviruses is synthesized. The data thus reinforce the retrovirus-like nature of VL30 genetic information.
Evidence for a new form of retroviral env transcript in leukemic and normal mouse lymphoid cells
Authors: Boccara M , Souyri M , Magarian C , Stavnezer E , Fleissner E
Published: January 2020

Murine leukemia virus-related RNA species were examined in a set of radiation-induced T-cell leukemias from BALB/c mice. No evidence was found for linkage of viral long terminal repeat-derived (U5) sequences to information of host origin. A novel class of 2-kilobase (kb) env-related transcripts, about 1kb shorter than normal viral env messenger, was found in all the leukemias. All of the 2-kb transcripts contained sequences homologous to the xenotropic virus-related env sequences in the Friend spleen focus-forming virus, representing the N-terminal portion of gp70. In two of the leukemias, these transcripts were found to contain both ecotropic p15E and U3 sequences in addition to the xenotropic gp70-related sequence. These two leukemias, but not others in which ecotropic sequences were absent from the 2-kb RNA, harbored several copies of a specific class of env recombinant proviruses. These proviruses possessed full-size env genes and were submethylated, as shown by SmaI and XmaI digests of proviral DNA. Low levels of 2-kb RNA were found in normal thymocytes from strains BALB/c, AKR, and 129 but not from congenic 129 GIX- mice. It is possible that the 2-kb RNA may originate by a novel splicing step that removes portions of the gp70 and p15E sequences from full-length env transcripts.
Persistent infection of some standard cell lines by lymphocytic choriomeningitis virus: transmission of infection by an intracellular agent
Authors: van der Zeijst B A , Noyes B E , Mirault M E , Parker B , Osterhaus A D , Swyryd E A , Bleumink N , Horzinek M C , Stark G R
Published: January 2020

Cell-free cytoplasmic extracts of the Syrian hamster cell lines C13/SV28 and BHK-21F were immunogenic in Syrian hamsters. The resulting antisera cross-reacted completely with antisera against lymphocytic choriomeningitis virus (LCMV) in an immunoradiometric assay employing BHK-21F antigen. Several other Syrian hamster cell lines not previously known to be infected with LCMV were also strongly positive when assayed for viral antigens. Also, several mouse sera and antisera raised in Syrian hamsters against cells transformed by papovaviruses had high titers of anti-LCMV activity. No cytopathic effect was evident in any of the persistently infected cell lines. Culture media from these cells were not infectious and showed no evidence of defective interfering particles. However, cell-free extracts of all the persistently infected cells contained material capable of transmitting the persistent infection to uninfected cells of Syrian hamsters, rats, mice, green monkeys, and humans. The onset of infection is much slower than when LCMV virions are used. When 2 X 10(6) uninfected BHK cells were treated with an extract from 100 persistently infected cells, the new infection was apparent within about 12 days. When an extract from 10(6) cells was used, the new infection was apparent within about 5 days, but not sooner. The intracellular infectious material was sensitive to treatment with deoxycholate, Nonidet P-40, or ether but resistant to treatment with RNase or trypsin. It was also large (5,000S) and heterodisperse on sucrose gradients. The infectious material was probably contained in large lipid vesicles and their integrity was probably essential for infection. When a few persistently infected cells were cocultivated with many uninfected cells, a few discrete colonies positive for LCMV antigens were observed after about 5 days. Since the culture media were not infectious, the infection probably spread by cell-cell contact. Several different experiments indicated that interferon did not play a major role in mediating persistence in this case. Persistent infections by LCMV can be maintained without expression of extracellular virus particles and without appearance of large amounts of viral antigens on the cell surface. Cell-cell contact could still allow transmission of intracellular infectious material. In an animal, these properties could circumvent immune surveillance.
Expression of
Campoletis sonorensis
Virus in the Parasitized Host,
Heliothis virescens
Authors: Fleming Jo-Ann G. W. , Blissard Gary W. , Summers Max D. , Vinson S. Bradleigh
Published: January 2020

Polyadenylated mRNA transcripts of the virus of
Campoletis sonorensis
were detected in
Heliothis virescens
host larvae 2 h after the larvae had been parasitized by
C. sonorensis
females and continued to be present in host larvae through 9 days postparasitization while
C. sonorensis
developed endoparasitically. cDNAs of viral transcripts present in
H. virescens
hybridized with only certain
C. sonorensis
viral DNAs.
Host range mutants of human rhinovirus in which nonstructural proteins are altered
Authors: Yin F H , Lomax N B
Published: January 2020

Human rhinovirus type 2 did not replicate in nonpermissive mouse cells; the restriction was not in adsorption but in the early events of virus replication. Mutants which had been adapted to grow in mouse cells had the following characteristics: (i) no change in the structural protein, (ii) a larger nonstructural protein and its precursor protein, and (iii) an altered viral RNA synthesis. The altered nonstructural proteins correlated with a change in host range of the virus and may be involved in viral RNA synthesis.
RNA polymerase interaction with dnaB protein and lambda P protein during lambda replication
Authors: McKinney M D , Wechsler J A
Published: January 2020

The Escherichia coli GroP- phenotype, associated with some dnaB mutants and measured as a decreased ability to plate lambda bacteriophage, was altered by some rpoB mutations. The rpoB effect showed an allele specificity. The participation both of dnaB and of lambda P alleles in the GroP- phenotype was also allele specific. It was concluded that RNA polymerase, dnaB protein, and lambda P protein form a functional complex required for lambda replication.
Monoclonal antibodies that inhibit attachment of group B coxsackieviruses
Authors: Campbell B A , Cords C E
Published: January 2020

Hybridoma cell lines that secrete monoclonal antibodies which react with HeLa cell surface antigens were produced. The monoclonal antibodies prevented cytopathic effects caused by coxsackievirus B1 and significantly reduced the amounts of coxsackieviruses B1, B5, and B6 that absorb to HeLa cells. These antibodies did not protect the cells from poliovirus cytopathic effects, and they had no effect on the attachment of other picornaviruses to HeLa cells.