Contents


PART 1

DNA TUMOR VIRUSES

Symposium Participants    v

Foreword    xvii

Viral Oncogenes H. M. Temin    1



Synopses

Transforming Genes of DNA Tumor Viruses L. V. Crawford    9

Transforming Genes of Retroviruses P. H. Duesberg    13



DNA Tumor Viruses: Early RNAs and Early Proteins

Transcription of the SV40 Genome in Virus-transformed Cells and Early Lytic Infection P. K. Ghosh, M. Piatak, V. B. Reddy, J. Swinscoe, P. Lebowitz, and S. M. Weissman    31

Regulation of 5V40 Gene Expression through RNA Splicing G. Khoury, J. C. Aiwine, R. Dhar, P. Gruss, C.-J. Lai, S. Segal, and L Seif    41

A Third Splice Site in SV40 Early mRNA D. F. Mark and P. Berg    55

Comparison of Polyoma Virus Transcription in Productively Infected Mouse Cells and Transformed Rodent Cell Lines R. Kamen, J. Favaloro, J. Parker, R. Treisman, L. Lania, M. Fried, and A. Mellor    63

Transcription of SV40 DNA in Transformed Rat Cells M. Grigoryan, P. Chumakov, and E. Lukanidin    77

Expression of Transforming Viral Genes in Semipermissive Cells Transformed by SV40 or Adenovirus Type 2 or Type 5 S. J. Flint and G. A. Beltz    89

Catalytic Properties of the SV40 Large T Antigen R. Tjian, A. Robbins, and R. Clark    103

Enzymatic Activities Associated with the SV40 Large T Antigen J. D. Griffin, G. Spangler, and D. M. Livingston    113

DNA Binding and Sedimentation Properties of SV40 T Antigens Synthesized In Vivo and In Vitro C. Prives, Y. Beck, D. Gidoni, M. Oren, and H. Shure    123

Organization of T Antigens in the Polyoma Virus Genome T. Hunter, M. A. Hutchinson, W. Eckhart, T. Friedmann, A. Esty, P. La Porte, and P. Deininger    131

Is Polyoma Virus Middle T Antigen a Protein Kinase? A. E. Smith, M. Fried, Y. Ito, N. Spurr, and R. Smith    141



T Antigens

Polyoma Virus T Antigens Expressed in Transformed Cells: Significance of Middle T Antigen in Transformation Y. Ito and N. Spurr    149

Purification and Characterization of the SV40 F-gene Protein P. Tegtmeyer, T. Spillman, and F. R. Schuetz    159

Phosphorylation of SV40 Large T Antigen G. Walter and P. J. Flory, Jr    165

T Antigens of SV40-transformed Cells F. McCormick, F. Chaudry, R. Harvey, R. Smith, P. W. J. Rigby, E. Paucha, and A. F. Smith    171

Characterization of the Complex between SV40 Large T Antigen and the 53K Host Protein in Transformed Mouse Cells L. V. Crawford, D. P. Lane, D. T. Denhardt, E. F. Harlow, P. M. Nicklin, K. Osborn, and D. C. Pim    179

New Genetic Information Expressed in SV40-transformed Cells: Characterization of the 55K Proteins and Evidence for Unusual SV40 mRNAs P. May, M. Kress, M. Lange, and F. May    189

T-antigen-associated Proteins Induced by SV40 Transformation J. A. Melero, D. S. Greenspan, and R. B. Carroll    201

SV40 17K Protein Is Associated with Two Cellular Proteins K. Rundell, P. Hearing, and Y. C. Yang    211

Characterization of a Murine Cellular SV40 Antigen in SV40-transformed Cells and in Uninfected Embryonal Carcinoma Cells D. I. H. Linzer, W. Maltzman, and A. J. Levine    215

SV40 T-antigen-related Molecules on the Surfaces of HeLa Cells Infected with Adenovirus-2-SV40 Hybrids and on SV40-transformed Cells W. Deppert and R. Henning    225

SV40 Transplantation Antigen: Relationship to SV40-specific Proteins S. S. Tevethia, R. S. Greenfield, D. C. Flyer, and M. J. Tevethia    235

Host Antigens in the Centriolar Region Are Induced in SV40-infected TC7 Cells: SV40 Small-T-function Requirement H. Kasamatsu, M. Shyamala, and W. Lin    243

Transformation Induced by Epstein-Barr Virus and the Role of the Nuclear Antigen G. Klein, J. Luka, and J. Zeuthen    253



The Genetics of Transformation by DNA Tumor Viruses

The hr-t Gene of Polyoma Virus T. L. Benjamin, G. G. Carmichael, and B. S. Schaffhausen    263

Early Mutants of Polyoma Virus (dl8 and dl23) with Altered Transformation Proper- ties: Is Polyoma Virus Middle T Antigen a Transforming Gene Product? B. E. Griffin, Y. Ito, U. Novak, N. Spurr, S. Dilworth, N. Smolar, R. Pollack, K. Smith, and D. Rifkin    271

Deletion Mutants of SV4O That Affect the Structure of Viral Tumor Antigens J. M. Pipas, S. P. Adler, K. W. C. Peden, and D. Nathans    285

Origin-defective Mutants of SV40 Y. Gluzman, R. J. Frisque, and 1. Sambrook    293

Lytic Infection of Teratocarcinoma Cells by Polyoma Virus Mutants M. Vasseur, C. Kress, N. Montreau, and D. Blangy    301

SV40 Mutant tsA 1499 Is Heat-sensitive for Lytic Growth but Generates Cold-sensitive Rat-cell Transformants D. Pintel, N. Bouck, G. di Mayorca, B. Thimmappaya, B. Swerdlow, and T. Shenk    305

Roles of the T Antigens in Transformation by SV40 R. G. Martin, V. P. Setlow, A. B. Chepelinsky, R. Seif, A. M. Lewis, Jr., C. D. Scher, C. D. Stiles, and J. Avila    311

Requirement for the Large T and Small T Proteins of 5V40 in the Maintenance of the Transformed State R. J. Frisque, D. B. Rifkin, and W. C. Topp    325

Host-virus Interactions Critical for Cellular Transformation by Polyoma Virus and SV40 M. Rassoulzadegan, E. Mougneau, B. Perbal, P. Gaudray, F. Birg, and F. Cuzin    333

Viral and Cellular Control of the SV40-transformed Phenotype J. B. Hiscott and V. Defendi    343

Location of Additional Early Regions within the Left Quarter of the Adenoviral Genome J. Williams, R. S. Galos, M. H. Binger, and S. J. Flint    353

Functional Analysis of Adenovirus-5 Host-range Deletion Mutants Defective for Transformation of Rat Embryo Cells T. Shenk, N. Jones, W. Colby, and D. Fowlkes    367

SV-induced Somatic Mutations: Possible Relevance to Viral Transformation M. Theile, M. Strauss, L. Luebbe, S. Scherneck, H. Krause, and F. Geissler    377



The Transforming Genes of Adenoviruses and Their Expression

Structure and Function of the Transforming Genes of Human Adenoviruses and SV40 AJ. van der Eb, H. van Ormondt, P. I. Schrier, J. H. Lupker, H. Jochemsen, P. J. van den Elsen, R. J. DeLeys, J. Maat, C. P. van Beveren, R. Dijkema, and A. de Waard    383

RNA Transcription and Splicing at Early and Intermediate Times after Adenovirus-2 Infection L. T. Chow, J. B. Lewis, and T. R. Broker    401

Biogenesis, Structures, and Sites of Encoding of the 5¢ Termini of Adenovirus-2 mRNAs C. C. Baker and F. B. Ziff    415

Phenotypes of Adenovirus-5 Host-range Mutants for Early mRNA Synthesis A. J. Berk, F. Lee, T. Harrison, J. Williams, and P. A. Sharp    429

Expression of Genes from the Transforming Region of Adenovirus D. J. Spector, D. N. Halbert, L. D. Crossland, and H. J. Raskas    437

Metabolism of mRNA from the Transforming Region of Adenovirus 2 M. C. Wilson, J. R. Nevins, J.-M. Blanchard, H. S. Ginsberg, and J. E. Darnell, Jr    447

Studies on Early Proteins and Transformation Proteins of Human Adenoviruses M. Green, W. S. M. Wold, K. Brackmann, and M. A. Cartas    457 Analysis of Cloned mRNA Sequences from the Transforming Region of Adenovirus

2 M. Perricaudet, G. Akusjärvi, A. Virtanen, and U. Pettersson    471

Transforming Proteins of Human Adenovirus 5: Studies with Infected and Trans- formed Cells N. J. Lassam, S. T. Bayley, and F. L. Graham    477

Organization and Expression of the Left Third of the Genome of Adenovirus J. B. Lewis, H. Esche, J. E. Smart, B. W. Stillman, M. L. Harter, and M. B. Mathews    493

Adenoviral Early Glycoprotein E3-19K and Its Association with Transplantation Antigens H. Persson, S. Kvist, L. Östberg, P. A. Peterson, and L. Philipson    509

Nucleotide Sequences, Integration, and Transcription of the Adenovirus-12 Trans- forming Genes K. Fujinaga, Y. Sawada, Y. Uemizu, T. Yamashita, H. Shimojo, K. Shiroki, H. Sugisaki, K. Sugimoto, and M. Takanami    519

Products of the Adenovirus-12 Transforming Genes and Their Functions K. Shiroki, K. Segawa, I. Saito, H. Shimojo, and K. Fujinaga    533



Transforming Genes of DNA Tumor Viruses and Their Arrangement in Transformed Cells

Viral DNA Sequences in Adenovirus-transformed Cells L. Visser, M. W. van Maar- schalkerweerd, T. H. Rozijn, A. D. C. Wassenaar, A. M. C. B. Reemst, and J. S. Sussenbach    541

Selectivity in Integration Sites of Adenoviral DNA W. Doerfier, S. Stabel, H. Ibelgaufts, D. Sutter, R. Neumann, J. Groneberg, K. H. Scheidtmann, R. Deuring, and U. Winterhoff    551

Methylation of Integrated Viral DNA Sequences in Hamster Cells Transformed by Adenovirus 12 D. Sutter and W. Doerlier    565 Analysis of the Sites of Integration of Viral DNA Sequences in Rat Cells Transformed by Adenovirus 2 or SV40 J. Sambrook, R. Greene, J. Stringer, T. Mitchison, S.-L. Hu, and M. Botchan    569

Mechanism for Circularization of MVM DNA by "Noose" Sliding in a Lassolike Structure: Implication for Integration Y. Aloni, S. Bratosin, O. Laub, and J. Tal    585

Tumorigenicity of Polyoma Virus in Hamsters M. A. Israel, K. Chowdhury, J. Ramseur, K. Chandrasekaran, D. F. Vanderryn, and M. A. Martin    591

Organization and Expression of Integrated Polyoma Virus DNA Sequences in Trans- formed Rodent Cells L. Lania, A. Hayday, G. Biursell, D. Gandini-Attardi, and M. Fried    597

Monkey Cells Transformed by SV40 DNA Fragments: Flat Revertants Synthesize Large and Small T Antigens M. Graessmann, A. Graessmann, and C. Mueller    605

Integration and Excision of Polyoma Virus Genomes C. Basilico, D. Zouzias, G. Della-Valle, S. Gattoni, V. Colantouni, R. Fenton, and L. Dailey Rapid Detection, Isolation, and Amplification of Host-substituted SV40 Variants F. Winocour, M. Singer, and E. Kuff    621

Morphological Transformation by DNA Fragments of Human Herpesviruses: Evi- dence for Two Distinct Transforming Regions in Herpes Simplex Virus Types 1 and 2 and Lack of Correlation with Biochemical Transfer of the Thymidine Kinase Gene G. R. Reyes, R. LaFemina, S. D. Hayward, and G. S. Hayward    629



The Transformed Cell

Sarcoma Growth Factor: Specific Binding to and Elution from Membrane Receptors for Epidermal Growth Factor J. F. DeLarco and G. J. Todaro    643

Transformation-specific Secreted Proteins D. R. Senger, D. F. Wirth, C. Bryant, and R. O. Hynes    651

A Common Transformation-related Protein in Murine Sarcomas and Leukemias G. Jay, A. B. DeLeo, E. Appella, G. C. Dubois, L. W. Law, G. Khoury, and L. J. Old    659

Regulation of Plasminogen Activator Synthesis in Chick Embryo Fibroblasts Infected with Avian Retroviruses D. B. Rifkin    665

New Assay for the Plasminogen Activator Activity of Transformed Cells W. F. Mangel, D. C. Livingston, J. R. Brocklehurst, H.-Y. Liu, G. A. Peltz, J. F. Cannon, S. P. Leytus, J. A. Wehrly, B. L. Salter, and J. L. Mosher    669

SV40 and Cellular Gene Expression in the Maintenance of the Tumorigenic Syn- drome R. Pollack, A. Lo, B. Steinberg, K. Smith, H. Shure, G. Blanck, and M. Verderame    681

Expression of Transformation in Cell Hybrids: Analysis of a Revertant of SVT2 K. K. Jha, F. G. Gurney, L. A. Feldman, and H. L. Ozer    689

Tumor Formation by Transformed Cells in Nude Mice P. Kahn, R. S. Simon, A. S. Klein, and S. Shin    695

A Study to Determine the Reasons for Differences in the Tumorigenicity of Rat Cell Lines Transformed by Adenovirus 2 and Adenovirus 12 P. H. Gallimore and C. Paraskeva    703

Monoclonal Antibodies: Detection of Transformation-related Antigens S. S. Ved- Brat, U. Hammerling, W. D. Hardy, F. Borenfreund, and W. Prensky    715



PART 2

RNA TUMOR VIRUSES

The Genomes and Proteins of Retroviruses

Organization of Murine Sarcoma Virus Genomes D. J. Donoghue, M. P. Goldfarb, P. A. Sharp, and R. A. Weinberg    721

Cellular Origin of the Transforming Gene of Moloney Murine Sarcoma Virus E. Canaani, S. R. Tronick, K. C. Robbins, P. R. Andersen, C. Y. Dunn, and S. A. Aaronson    727

Characterization of Integrated Moloney Sarcoma Proviruses and Flanking Host Sequences Cloned in Bacteriophage l G. W. Vande Woude, M. Oskarsson, W. L. McClements, L. W. Enquist, D. Blair, P. J. Fischinger, J. V. Maizal, and M. Sullivan    735

Characterization of Virus-specified Proteins Present in NRK Cells Infected with a Temperature-sensitive Transformation Mutant of Moloney Murine Sarcoma Virus T. G. Wood, J. Peltier-Horn, W. G. Robey, D. G. Blair, and R. B. Arlinghaus    747

Comparative Analysis of Cellular and Viral Sequences Related to Sarcomagenic Cell Transformation L.-H. Wang, P. Snyder, T. Hanafusa, C. Moscovici, and H. Hanafusa    755

Transforming Protein Encoded by the Cellular Information of Recovered Avian Sarcoma Viruses R. E. Karess, W. S. Hayward, and H. Hanafusa    765

Correlation of Transient Accumulation of Linear Unintegrated Viral DNA and Transient Cell Killing by Avian Leukosis and Reticuloendotheliosis Vimses H. M. Temin, E. Keshet, and S. K. Weller    773

Endogenous Virogenes and Oncogenes in Rat-cell Transformation: A New Model System S. Rasheed    779

Isolation and Characterization of Proteins Carrying the Feline Oncornavirus-asso- ciated Cell-membrane Antigen H. W. Snyder, Jr., K. J. Phillips, W. D. Hardy, Jr., F. E. Zuckerman, M. Essex, A. H. Sliski, and J. Rhim    787

Genetic Structure of Avian Acute Leukemia Viruses K. Bister and P. H. Duesberg    801

RNAs of Defective and Nondefective Components of Friend Anemia and Poly- cythemia Virus Strains Identified and Compared L. Evans, M. Nunn, P. Dues- berg, D. Troxler, and F. Scolnick    823

Analysis of RNA Specific for the Transforming Agent of R-strain Avian Eryth- roblastosis Viruses K. Toyoshima, T. Kamahora, H. Sugiyama, M. Owada, A. Nomoto, and M. Yoshida    837

Characterization of the src Gene of a Rous Sarcoma Virus Mutant Temperature- sensitive for Cell Transformation J.-L. Darlix, P. A. Bromley, and P.-F. Spahr    843

Structure and Expression of the Abelson Murine Leukemia Virus Genome and Its Relationship to a Normal Cell Gene D. Baltimore, A. Shields, G. Otto, S. Goff, P. Besmer, O. Witte, and N. Rosenberg    849

A Trans-acting Protein Kinase Identified in Cells Transformed by Abelson Murine Leukemia Virus O. N. Witte, L. Sun, N. Rosenberg, and D. Baltimore    855

Characterization of Abelson Murine Leukemia Virus Isolates Differing in P120 Expression N. Rosenberg ,O. N. Witte, and D. Baltimore    859

Mammalian RNA Type-C Transforming Viruses: Characterization of Virus-coded Polyproteins Containing Phosphorylated Components with Possible Transforming Functions J. R. Stephenson, W. J. M. Van de Ven, A. S. Khan, and F. H. Reynolds, Jr    865

RNA Sequences and Proteins Specific to Friend Strain of Spleen Focus-forming Virus Y. Ikawa, Y. Kobayashi, M. Obinata, F. Harada, S. Hino, and H. Yoshikura    875

Progressive Shutdown of Viral Gene Expression in Friend-virus-induced Eryth- roleukemia Cells A. S. Berkower, F. Plata, R. Anand, F. Lilly, R. Soeiro, and R. A. Steeves    887

Host Control of Sequences Specific to Friend Erythroleukemia Virus in Normal and Leukemic Mice T. W. Mak, C. L. Gamble, M. E. MacDonald, and A. Bernstein    893

Moloney Murine Sarcoma Virions Contain Subgenomic-length mRNA-like Molecules That Direct the Synthesis of 'Sarcoma-specific' Polypeptides In Vitro D. Dina and B. Nadal-Ginard    901



src

Protein Phosphorylation Mediated by Partially Purified Avian Sarcoma Virus Transforming-gene Product R. L. Erikson, M. S. Collett, E. Erikson, A. F. Purchio, and J. S. Brugge    907

Origin and Function of Avian Retrovirus Transforming Genes J. M. Bishop, S. A. Courtneidge, A. D. Levinson, H. Oppermann, N. Quintrell, D. K. Sheiness, S. R. Weiss, and H. E. Varmus    919

Studies on the Structure and Function of the Avian Sarcoma Virus Transforming-gene Product T. Hunter, B. M. Sefton, and K. Beemon    931

In Vitro Synthesis and Processing of Rous Sarcoma Virus src-gene Products J.

Kamine, J. G. Burr, and J. M. Buchanan    943 Activities of the src -gene Product of Avian Sarcoma Virus P. F. Maness, H. Engeser, M. F. Greenberg, M. O'Farrell, W. E. Gall, and G. M. Edelman    949

Comparison of Protein Kinase Activities in Normal Cells and Cells Transformed by a Temperature-sensitive Mutant of Avian Sarcoma Virus to Those of Cell-free Viral Translational Products M. Owada, P. Donner, K. E. J. Dittmar, and K. Moelling    959

F-actin Inhibits Protein Kinase Activity Associated with the src-gene Product S. D. Tsen, R. Lee, B. Damiani, P. Hsieh, and L. B. Chen    967

Transformation by Rous Sarcoma Virus: Effects of src-gene Expression on the Synthesis and Phosphorylation of Cellular Polypeptides K. Radke and G. S. Martin    975

Expression of Viral Oncogenes in Differentiating Chick Embryo Neuroretinal Cells Infected with Avian Tumor Viruses G. Calothy, F. Poirier, G. Dambrine, P. Mignatti, P. Combes, and B. Pessac    983

Localization and Characterization of the src -gene Product of Rous Sarcoma Virus A. R. Goldberg, J. G. Krueger, and E. Wang    991

Transformation-defective, Temperature-sensitive Mutants of Rous Sarcoma Virus Have a Reversibly Defective src-gene Product R. R. Friis, B. M. Jockusch, C. B. Boschek, A. Ziemiecki, H. Rübsamen, and H. Bauer    1007

Localization of pp60src within Normal Rat Kidney Cells Infected with Temperature- sensitive Mutants (T-class) of Rous Sarcoma Vims L. R. Rohrschneider    1013

Nature and Intracellular Location of the Product of the src Gene of Avian Sarcoma Virus I. Pastan, G. Jay, N. Richert, P. J. A. Davies, and M. Willingham    1023

Genetic and Biochemical Approaches to Analyzing Transformation by Rous Sarcoma Virus D. D. Anderson, D. W. Salter, L. R. Rohrschneider, and M. J. Weber    1031

Isolation of a Glucose Transport System from Normal Chicken Fibroblasts and from Chicken Fibroblasts Transformed by Rous Sarcoma Virus F. Lipmann and S. G. Lee    1043

Growth-Related Alterations Induced in Chick Embryo Fibroblasts by src-gene Deletion Mutants of the Schmidt-Ruppin Strain of Rous Sarcoma Virus M. L. Breitman, R. Vigne, and P. K. Vogt    1047

Expression of the src-gene Product, pp60src, in Transformed and Reverted Mammalian Cells Infected with Avian Sarcoma Virus A. F. Lau, R. A. Krzyzek, J. S. Brugge, M. S. Collett, R. L. Erikson, and A. J. Faras    1057

Factors Affecting Phenotypic Reversion of Rat Cells Transformed by Avian Sarcoma Virus J. A. Wyke, J. A. Beamand, and H. E. Varmus    1065



Proviruses and Their Expression

Organization of Endogenous and Exogenous Viral and Linked Nonviral Sequences S. H. Hughes, P. K. Vogt, E. Stubblefield, H. Robinson, J. M. Bishop, and H. E. Varmus    1077

Synthesis and Integration of Avian Sarcoma Virus DNA J. M. Taylor, T. W. Hsu, C. Yeater, and W. S. Mason    1091

Avian Endogenous Proviral DNA: Analysis of Integrated ev 1 and a Related gs¯chf¯ Provirus Purified by Molecular Cloning A. Skalka, P. DeBona, F. Hishinuma, and W. McClements    1097

Ten Genetic Loci in the Chicken That Contain Structural Genes for Endogenous Avian Leukosis Viruses S. M. Astrin, H. L. Robinson, L. B. Crittenden, E. G. Buss, J. Wyban, and W. S. Hayward    1105

Transcriptional Products and DNA Structure of Endogenous Avian Proviruses W. S. Hayward, S. B. Braverman, and S. M. Astrin    1111

Role of the C Region in Relative Growth Rates of Endogenous and Exogenous Avian Oncoviruses P. N. Tsichlis and J. M. Coffin    1123

Subgroup-E Avian-leukosis-virus-associated Disease in Chickens H. L. Robinson, M. N. Pearson, D. W. DeSimone, P. N. Tsichlis, and J. M. Coffin    1133

Structure and Infectivity of Integrated Murine Leukemia Virus DNA D. R. Lowy, E. Rands, S. K. Chattopadhyay, and G. L. Hager    1143

Construction and Characterization of Molecular Clones Containing Integrated Mouse Mammary Tumor Virus Sequences L. A. Donehower, J. Andre, D. S. Berard, R. G. Wolford, and G. L. Hager    1153

Genomic Location of Mouse Mammary Tumor Virus Proviral DNA in Normal Mouse Tissue and in Mammary Tumors N. E. Hynes, B. Groner, H. Diggelmann, R. Van Nie, and R. Michalides    1161

Transformation of NIH-3T3 Mouse Cells by Avian Retroviral DNAs G. M. Cooper, N. G. Copeland, A. D. Zelenetz, and T. Krontiris    1169



The Transformed Phenotype and Differentiation

Control of Proliferation and Differentiation in Cells Transformed by Friend Virus D. Housman, R. Levenson, V. Volloch, A. Tsiftsoglou, J. Gusella, D. Parker, J. Kernen, A. Mitrani, V. Weeks, O. Witte, and P. Besmer    1177

Transformation by Abelson Murine Leukemia Virus: Properties of the Transformed Cells W. C. Raschke    1187

Cell-surface Antigens of Abelson and Friend Murine Leukemia Viruses and of Hematopoietic Differentiation R. Risser, D. Grunwald, C. Sinaiko, and P. Jelen    1195

Normal B-cell Activation Involves Endogenous Retroviral Antigen Expression: Im- plications for Leukemogenesis C. Moroni, J. P. Stoye, J. F. DeLamarter, P. Erb, F. A. Jay, J. Jon gstra, D. Martin, and G. Schumann    1205

In Vitro Transformation of Mouse Hematopoietic Cells by the Spleen Focus-forming Virus W. D. Hankins, S. B. Krantz, T. A. Kost, and M. J. Koury    1211

Three New Types of Viral Oncogenes in Defective Avian Leukemia Viruses. I. Specific Nucleotide Sequences of Cellular Origin Correlate with Specific Trans- formation D. Stéhelin, S. Saule, M. Roussel, A. Sergeant, C. Lagrou, C. Rom - mens, and M. B. Raes    1215

Three New Types of Viral Oncogenes in Defective Avian Leukemia Viruses. II. Biological, Genetic, and Immunochemical Evidence T. Graf, H. Beug, A. von Kirchbach, and M. J. Hayman    1225

Recombination in the Avian Oncoviruses as a Model for the Generation of Defective Transforming Viruses R. N. Eisenman, M. Linial, M. Groudine, R. Shaikh, S. Brown, and P. E. Neiman    1235

Progenitor-cell Populations Can Be Infected by RNA Tumor Viruses, but Trans- formation is Dependent on the Expression of Specific Differentiated Func- tions D. Boettiger and F. M. Durban    1249



Viruses of Thymic Leukemia

Murine-leukemia-virus-related Cell-surface Antigens as Serological Markers of AKR Ecotropic, Xenotropic, and Dualtropic Viruses P. V. O'Donnell, E. Stockert, Y. Obata, A. B. DeLeo, and L. J. Old    1255

Status of the Association of Mink Cell Focus-forming Viruses with Leukemogenesis W. P. Rowe, M. W. Cloyd, and J. W. Hartley    1265

Analysis of the Genomes of Mink Cell Focus-forming Murine Type-C Viruses: A Progress Report M. L. Lung, C. Hering, J. W. Hartley, W. P. Rowe, and N. Hopkins    1269

Nucleotide Sequence of a Cloned Murine Leukemia Vims DNA Fragment J. G. Sutcliffe, T. M. Shinnick, R. A. Lerner, P. Johnson, and I. M. Verma    1275

Murine Leukemia Virus env-gene Expression in Preleukemic Thymocytes and Leukemia Cells of AKR Strain Mice N. G. Famulari, J.-S. Tung, P. V. O'Don- nell, and E. Fleissner    1281

Evolution of Oncogenic Mouse Type-C Viruses in Cell Culture U. R. Rapp and G. J. Todaro    1289

T-lymphoma Retroviral Receptors and Control of T-lymphoma Cell Proliferation M. S. McGrath, F. Pillemer, D. A. Kooistra, S. Jacobs, L. Jerabek, and I. L. Weissman    1297



Summary

Molecular Biology of Viral Oncogenes P. A. Sharp    1305