Long-term persistence of cytomegalovirus genome in cultured human cells of prostatic origin

Cells from prostatic tissue obtained from a 3-year-old male donor exhibited scattered foci of cytopathology on primary culture. A virus was isolated and shown by serological analysis to be cytomegalovirus (CMV). After a number of cell culture passages, a cell line (disignated CMV-Mj-P) was obtained in which foci of infection could no longer be demonstrated, nor could virus be rescued. On continued passage the doubling time of the cells decreased markedly, and the fibroblastoid cells ceased to demonstrate contact inhibition. CMV-specific antigen(s) was detected on the surface of the cells by indirect immunofluorescence techniques after exposure of the cultures to iododeoxyuridine. Microcytotoxocity tests established that CMV-Mj-P cells, but not control human prostate cells or human embryonic lung cells, share a membrane antigen with hamster cells transformed by CMV. Nucleic acid hybridization studies revealed that virus genetic information was carried by the human prostate cells and that the cells contained an average of about 10 to 15 genome equivalents of CMV DNA. Karyotypic analysis confirmed that the CMV-Mj-P cells were of human male origin. These results indicate that the cells either have been transformed by CMV or are chronically infected with CMV and releasing virus at levels below detection.

Antitumor agents. 16. Steroidal alpha-methylene-gamma-lactones

Several novel steroidal alpha-methylene-gamma-lactones and related derivatives have been synthesized as potential steroid alkylating antitumor agents. The synthesis of these compounds involved the convenient Reformatsky-type reaction between ethyl-alpha-(bromomethyl)acrylate and the proper steroidal ketones. In vitro assay for the cytotoxicity of these compounds against the growth of tissue culture cells originating from human epidermoid carcinoma of the larynx (H.Ep.-2) has shown significant activity. Cytotoxicity was improved at least sixfold with the introduction of lipophilic steroidal character. Preliminary in vivo tumor assay also indicated that these compounds were active against Walker 256 carcinosarcoma in rats and were inactive against both L1210 lymphoid leukemia and Ehrlich ascites carcinoma in mice. However, the simple alpha-methylene-beta,beta-dicarbethoxy-gamma-butyrolactone significantly inhibited Ehrlich ascites tumor growth.

Human cytomegalovirus. III. Virus-induced DNA polymerase

Infection of WI-38 human fibroblasts with human cytomegalovirus (CMV) led to the stimulation of host cell DNA polymerase synthesis and induction of a novel virus-specific DNA polymerase. This cytomegalovirus-induced DNA polymerase was purified and separated from host cell enzymes by DEAE-cellulose and phosphocellulose column chromatographies. It can be distinguished from host cell enzymes by chromatographic behavior, template primer specificity, sedimentation property, and the requirement of salt for maximal activity. This virus-induced enzyme has a sedimentation coefficient of 9.2S and is found in both the nuclei and cytoplasm of virus-infected cells, but not in uninfected cells. This enzyme could efficiently use activated calf-thymus DNA, oly(dA)-oligo(dT)12-18, and poly(dC)-oligo(dG)12-18 as template primers, especially poly(dA)-oligo(dT)12-18, but it could not use poly(rA)-oligo(dT)12-18, poly(rC)-oligo(dG)12-18, or oligo(dT)12-18. The enzyme requires Mg2+ for maximal activity, is sensitive to p-hydroxymercuribenzoate, and is not a zinc metalloenzyme. In addition, the cytomegalovirus-induced DNA polymerase activity can be enhanced by adding 0.06 to 0.12 M NaCl or 0.03 to 0.06 M (NH4)2SO4 to the reaction mixture.

Iodination of herpesvirus nucleic acids

A simple method is described for the iodination of herpes simplex virus (HSV) DNA. The procedure involved synthesis of 125-I-labeled 5-iodo-dCTP which was subsequently used as a precursor for the in vitro repair synthesis of HSV DNA. Synthesis of 5-iodo-dCTP and purification from oxidation and reduction reagents, buffer salts, unreacted dCTP and Na125-I was accomplished in a single chromatographic step. It was possible to prepare 125-I-labeled HSV DNA in vitro with specific activities exceeding 10-8 counts/min/mu-g. The DNA prepared by this method reassociated with DNA extracted from HSV-infected HEp-2 cells but not with HEp-2 cell DNA. Iodinated HSV DNA was susceptible to S-1-endonuclease digestion once denatured but was resistant to digestion in the native form. This method was used to synthesize 125-I-labeled ribo-CTP (5-iodo-CTP) which was used to prepare cytomegalovirus-specific complementary RNA. The method should be of value in the preparation of viral probes and for use in autoradiography of viral nucleic acids.

Human cytomegalovirus. II. Lack of relatedness to DNA of herpes simples I and II, Epstein-Barr virus, and nonhuman strains of cytomegalovirus

The purified DNA of human cytomegalovirus, radiolabeled in vitro, was examined for homology to Epstein-Barr virus, herpes simplex type I and II, and simian and murine cytomegalovirus DNA by DNA-DNA reassociation kinetics analyses with the S1 enzyme differential digestion technique. Cross-matching of the DNAs showed no relatedness or less than 5% detectable homology.

Human cytomegalovirus. I. Purification and characterization of viral DNA

Two human strains (AD-169 and C87) and one simian strain (GR2757) of cytomegalovirus (CMV) have been purified from the extracellular fluids of virus-infected cultures by sedimentation through a sucrose gradient followed by brief centrifugation in a preformed gradient of CsCl. Enveloped virus particles were located in the density region, 1.219 g/cm(3), and nucleocapsids at 1.263 g/cm(3). Purified viral DNA, both human and simian, sedimented in the region of 55S in neutral sucrose gradients with herpes simplex type I DNA as a marker; the molecular weight of the CMV DNA was estimated as approximately 10(8). The density of the viral DNA determined by analytical ultracentrifugation was 1.716 g/cm(3) for the human strains and 1.710 g/cm(3) for the simian strain. Tritiated viral complementary RNA synthesized in vitro with Escherichia coli transcriptase has been used for detection and localization of viral genome in membrane hybridization and in situ cytohybridization. Newly synthesized viral DNA appeared 24 h after infection and localized at two acrocentric areas; later the viral DNA distributed in a band resembling intranuclear inclusions 48 to 70 h after infection. Total DNA synthesis began to increase 24 h after infection and reached its peak at 70 h; RNA synthesis increased at 13 h, and reached its peak at 24 to 33 h. The viral DNA was also labeled with (3)H-TTP by repair-synthesis in vitro with Kornberg's enzyme in order to analyze the purity of the DNA and for detection of viral DNA by DNA-DNA reassociation kinetics.

Analysis of simian virus 40 DNA with the restriction enzyme of Haemophilus aegyptius, endonuclease Z

Limited digestion of simian virus 40 (SV40) DNA from both small- and large- plaque strains with the restriction endonuclease Z from Haemophilus aegyptius yielded 10 specific fragments. The number of nucleotide pairs for each fragment, determined by co-electrophoresis with phiX174 RF fragments produced by endonuclease Z, ranges from 2,050 to 80. The difference in the pattern between the large- and small-plaque strains is the disappearance of one fragment containing approximately 255 nucleotide pairs and the appearance of a new fragment with 145 nucleotide pairs. This finding can be explained either by deletions or insertions totaling 110 nucleotide pairs. Complementary RNA synthesized in vitro from the adeno-SV40 hybrid virus, strain ND-1, hybridized preferentially to four of the fragments of SV40 DNA.

Structure and function of the polypeptides in simian virus 40. I. Existence of subviral deoxynucleoprotein complexes

Velocity sedimentation analysis of simian virus 40 degraded in alkaline buffers, pH 10.5, yields two components: soluble protein containing the largest polypeptides, VP1 and VP2, of the virion, and a deoxynucleoprotein complex (DNP-I) containing the viral deoxyribonucleic acid (DNA) and the small polypeptides, VP4, 5, and 6, and all or part of VP3. Dissociation of DNP-I by equilibrium centrifugation in CsCl yields a complex (DNP-II) of the viral DNA and residual, tightly bound polypeptide; VP4, 5, and 6, but not VP3, are recovered after separation from DNP-II. Treatment of the virus with beta-mercaptoethanol and iodination experiments suggest that VP1 and VP2 might exist as compact structures cross-linked with disulfide bonds, perhaps forming the capsid. VP4, 5, and 6 form a relatively stable complex with the viral DNA and are supposed to be the internal proteins. The location of VP3 is not well defined; at least a portion of it is tightly bound to the viral DNA.

Structure and function of the polypeptides in simian virus 40. II. Transcription of subviral deoxynucleoprotein complexes in vitro

A deoxynucleoprotein complex (DNP-1) isolated from simian virus 40 (SV40) after disruption of the virus in an alkaline buffer contains the viral deoxyribonucleic acid (DNA) and four minor structural polypeptides. Dissociation of DNP-I by equilibrium centrifugation in CsCl yields a complex (DNP-II) that contains a small amount of polypeptide tightly bound to the viral DNA. Studies of the template activity of these deoxynucleoprotein complexes in vitro with Escherichia coli transcriptase show that the rate of transcription of DNP-I and DNP-II is 30 and 80%, respectively, compared with that of deproteinized SV40 DNA component I. In dimethyl sulfoxide gradients, the complementary ribonucleic acid (cRNA) synthesized from DNP-I is one-third to one-half the size of the cRNA species from DNA-I and DNP-II. Competition hybridization experiments show that with the E. coli transcriptase only a portion (about one-half) of the SV40 genome is transcribed with DNP-I as template, whereas most or all of the genome is transcribed with DNP-II as template. The template activity of the deoxynucleoprotein complexes with a highly active form II ribonucleic acid polymerase prepared from SV40-infected permissive cells follows similar transcription kinetics. The results indicate that structural nucleoproteins of SV40 bind nonrandomly to the viral DNA and effect the transcription of some subset of its sequences in vitro.

Structural polypeptides of simian virus 40

To determine the number and molecular weights of the structural polypeptides of simian virus 40, we have analyzed purified virus by electrophoresis on 14% polyacrylamide gels containing sodium dodecyl sulfate. Full virus purified by several different methods showed six distinct bands with molecular weights of approximately 43,000 (VP1, containing 70% of virion protein), 32,000 (VP2, 9%), 23,000 (VP3, 10%), 14,000 (VP4, 6%), 12,500 (VP5, 4%), and 11,000 (VP6, 3%) both by analysis of radioactively labeled virions and by visualization of the polypeptide bands after staining. "Empty" virions contain decreased amounts of VP4, 5, and 6. The approximate molecular ratios of the polypeptides were 6.0, 1.0, 1.5, 1.5, 1.1, and 1.0. When virus degraded in an alkaline buffer was analyzed by velocity centrifugation in sucrose gradients, the two larger polypeptides (VP1 and VP2) remained at the top of the gradient, whereas the three smallest polypeptides (VP4, 5, and 6) sedimented as a complex with the viral deoxyribonucleic acid. VP3 was found in association with either VP1 and 2 or VP4, 5, and 6, depending on the conditions of degradation. Presumably, VP1 and VP2, comprising about 80% of the protein, form the capsid of the virus. VP4, 5, and 6 may form a nucleoprotein in the virion, and VP3 may serve as an intermediate structural component.