Structural relationship between the 100,000- and 17,000- molecular-weight T antigens of simian virus 40 (SV40) as deduced by comparison with the SV40-specific proteins coded by the nondefective adenovirus type 2-SV40 hybrid viruses

The two-dimensional peptide maps of the methionine-containing tryptic peptides of the 100,000-molecular-weight (100K) and 17K T antigens of simian virus 40 (SV40) have been compared. The two proteins share nine methionine-containing tryptic peptides in common. The 17K T antigen has two peptides not found in the 100K T antigen, and the 100K T antigen has 14 unique peptides. The peptide maps of the 100 K and 17K T antigens were also compared with those of the SV40-specific proteins found in cells infected by the nondefective adenovirus type 2-SV40 hybrid viruses, which we have previously shown are encoded by defined sequences within the early region of SV40 (K. Mann, T. Hunter, G. Walter, and H.K. Linke, J. Virol. 24:151-169, 1977). This comparison shows that the 100K and 17K T antigens share common N-terminal sequences coded for between 0.65 and 0.59 map units on the SV40 genome. Furthermore, none of the sequences in the 17K T antigen arises from the region between 0.54 and 0.18 map units. We deduce that the sequences unique to the 17K T antigen originate between 0.59 and 0.54 map units. This type of structural relationship between the 100K and 17K T antigens fits well with the proposed model (L.V. Crawford, C.N. Cole, A. E. Smith, E. Paucha, P. Tegtmeyer, K. Rundell, and P. Berg, Proc. Natl. Acad. Sci. U.S.A. 75:117-121, 1978) for the expression of the early region of SV40.

Association of simian virus 40 T antigen with simian virus 40 nucleoprotein complexes

Viral nucleoprotein complexes were extracted from the nuclei of simian virus 40 (SV40)-infected TC7 cells by low-salt treatment in the absence of detergent, followed by sedimentation on neutral sucrose gradients. Two forms of SV40 nucleoprotein complexes, those containing SV40 replicative intermediate DNA and those containing SV40 (I) DNA, were separated from one another and were found to have sedimentation values of 125 and 93S, respectively. [(35)S]methioninelabeled proteins in the nucleoprotein complexes were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In addition to VP1, VP3, and histones, a protein with a molecular weight of 100,000 (100K) is present in the nucleoprotein complexes containing SV40 (I) DNA. The 100K protein was confirmed as SV40 100K T antigen, both by immunoprecipitation with SV40 anti-T serum and by tryptic peptide mapping. The 100K T antigen is predominantly associated with the SV40 (I) DNA-containing complexes. The 17K T antigen, however, is not associated with the SV40 (I) DNA-containing nucleoprotein complexes. The functional significance of the SV40 100K T antigen in the SV40 (I) DNA-containing nucleoprotein complexes was examined by immunoprecipitation of complexes from tsA58-infected TC7 cells. The 100K T antigen is present in nucleoprotein complexes extracted from cells grown at the permissive temperature but is clearly absent from complexes extracted from cells grown at the permissive temperature and shifted up to the nonpermissive temperature for 1 h before extraction, suggesting that the association of the 100K T antigen with the SV40 nucleoprotein complexes is involved in the initiation of SV40 DNA synthesis.

Histocompatibility antigens in paraplegic or quadriplegic patients with sacroiliac joint changes

HLA typing for the A and B loci and radiographic examination of the sacroiliac joints were performed in 54 randomly selected patients with paraplegia or quadriplegia of more than 3 years' duration. The sacroiliac joints were abnormal in 24 patients. No association was found between any of the HLA antigens of the A and B loci and the sacroiliac joint changes. There was, however, an increased incidnece of sacroiliac joint changes in quadriplegic as compared to paraplegic patients.

Translation of polyoma virus T antigens in vitro

Polyoma virus-specific RNA isolated from the cytoplasm of lytically infected cells can be translated in vitro to yield three T antigens, of Mrs approximately 90,000, 60,000, and 22,000. The tryptic peptide patterns of the T antigens synthesized in vitro are similar or identical to the patterns of the corresponding proteins in polyoma-infected cells. All three proteins incorporate methionine donated from initiator tRNA in vitro. Polyoma cRNA codes for a protein that is slightly larger than the 22,000 T antigen and that, by other criteria, is similar to the 22,000 T antigen. Translation of cRNA does not yield the 90,000 and 60,000 T antigens, suggesting that the generation of the mRNAs for these T antigens requires the removal of intervening sequences. The mRNA for the 90,000 T antigen is smaller than the mRNAs for the 22,000 and 60,000 proteins. All three proteins share common NH2-terminal sequences, and the 60,000 T antigen may be translated partially in a different reading frame from sequences also coding for the 90,000 T antigen. The demonstration that polyoma virus codes for three different T antigens raises the possibility that all three proteins may be involved in cell transformation.

Comparison of the expression of the src gene of Rous sarcoma virus in vitro and in vivo

We have compared the polypeptide products of the src gene of several strains of Rous sarcoma virus produced by in vitro translation of heat-denatured 70S virion RNA in the nuclease-treated reticulocyte lysate with those present in chick cells transformed by these viruses. We have done this by immunoprecipitation, using sera from rabbits injected at birth with Schmidt-Ruppin Rous sarcoma virus. In vitro translation results in the synthesis of at least nine polypeptides which appear to be encoded by the src gene. These range in size from 17,000 to 60,000 daltons. The sera from tumor-bearing rabbits precipitated these polypeptides arising from the in vitro translation of RNA from Schmidt-Ruppin Rous sarcoma virus of both subgroup A and subgroup D and from one stock of Prague Rous sarcoma virus of subgroup C. In each case, all of this family of related polypeptides could be precipitated except the smallest, the 17,000-dalton polypeptide. No precipitation of analogous polypeptides resulting from the translation of RNA from other strains of Rous sarcoma virus was observed. Cells transformed by these three strains of Rous sarcoma virus contain easily detectable amounts of a polypeptide, p60src, essentially identical to the 60,000-dalton in vitro product. With one exception, they do not contain significant amounts of polypeptides analogous to the smaller in vitro products which can be precipitated by these sera. Cells transformed by one stock of Schmidt-Ruppin Rous sarcoma virus of subgroup A did contain a 39,000-dalton polypeptide, which was related, by peptide mapping, to the 60,000-dalton polypeptide and was similar in size to a precipitable in vitro product. The 60,000-dalton polypeptide present in transformed cells appeared to be phosphorylated 10 to 25 min after its synthesis, metabolically very stable, and not derived from a precursor polypeptide. All immunoprecipitates from transformed cells which contained p60src also contained an 80,000-dalton phosphoprotein. This polypeptide is unrelated to p60src, as determined by peptide mapping, and may well be a host cell polypeptide which is specifically associated with p60src.

Characterization of Rous sarcoma virus src gene products synthesized in vitro

The cell-free synthesis of three major proteins from virion RNA of nondefective Rous sarcoma virus (RSV), but not from RNA of transformation-defective deletion mutants, has been observed. The apparent molecular weights of these transformation-specific proteins are approximately 60,000 (60K), 25K, and 17K. Tryptic maps of methionine-containing peptides revealed the 17K, 25K, and 60K proteins to be overlapping in sequence. However, only partial homology was observed between the 17K, 25K and 60K proteins synthesized from Schmidt-Ruppin strain, subgroup D, RSV RNA and those synthesized from Prague strain, subgroup B, RSV, RNA. About half of the methionine peptides in the Schmidt-Ruppin strain, subgroup D, 60K protein were shared with the Prague strain, subgroup D, 60K protein, and the rest were distinct to each. The virion RNAs coding for the 60K, 25K, and 17K proteins were found to be polyadenylated and to sediment with maximal mRNA activity at about 23, 19 to 20, and 18S, respectively. In addition, transformation-specific proteins with molecular weights of 39K and 33K were observed by in vitro synthesis. These proteins are also related to the 60K, 25K, and 17K proteins and were synthesized from polyadenylated RSV RNA of approximately 21 to 22S. RNase T1-resistant oligonucleotides were analyzed in parallel, and the src-specific oligonucleotides were found to be first present in equimolar amounts in those gradient fractions sedimenting at 21 to 22S. Our data suggest that synthesis of the 60K protein is initiated near the 5' terminus of the src gene, whereas the 39K, 33K, 25K, and 17K proteins are initiated internally in the src gene. All of these proteins appear to be initiated independently, but they may have a common termination site.

Characterization of the mRNA's for the polyoma virus capsid proteins VP1, VP2, and VP3

Polyadenylated cytoplasmic RNA from polyoma virus-infected cells can be translated in the wheat germ system to yield all there polyoma virus capsid proteins, VP1, VP2, and VP3. The translation products of RNA selected from total cytoplasmic RNA of infected cells by hybridization to polyoma virus DNA showed a high degree of enrichment for VP1, VP2, and VP3. The identity of the in vitro products with authentic virion proteins was established in two ways. First, tryptic peptide maps of the in vitro products were found to be essentially identical to those of their in vivo counterparts. Second, the mobilities of the in vitro products on two-dimensional gels were the same as those of viral proteins labeled in vivo. VP1, VP2, and vp3 were all labeled with [35S] formylmethionine when they were synthesized in the presence of [35S] formylmethionyl-tRNAfmet. We determined the sizes of the polyadenylated mRNA's for VP1, VP2, and VP3 by fractionation on gels. The sizes of the major mRNA species for the capsid proteins are as follows: VP2, 8.5 X 10(5) daltons; VP3, 7.4 X 10(5) daltons; and VP1, 4.6 X 10(5) daltons. We conclude that all three viral capsid proteins are synthesized independently in vitro, that all three viral capsid proteins are virally coded, and that each of the capsid proteins has a discrete mRNA.

Characterization of T antigens in polyoma-infected and transformed cells

Polyoma-infected 3T6 cells contain a number of proteins precipitable by serum from rats carrying polyoma-induced tumors. The virus codes for three species having apparent molecular weights of 90,000, 60,000 and 22,000 daltons, as determined by polyacrylamide gel electrophoresis (90K, 60K and 22k). The 90K and 22K species produced by a large plaque and a small plaque wild-type polyoma have similar mobilities, but the 60K species produced by the large plaque wild-type. In cells infected by each of seven polyoma tsA mutants, the 90K species is unstable at the nonpermissive temperature, while the 60K and 22K species are stable. In cells infected by a mutant carrying a deletion between roughly 98 and 3 map units in the early region of the viral genome, the 22K species is present, but the 90K and 60K species are absent. Tryptic peptide analysis of the isolated 90K, 60K and 22K species shows that the three species have common N terminal regions. The 60K and 22K species contain amino acid sequences not found in the 90K species , and the 60K species has several unique, methionine-containing peptides not found in either the 22K or 90K species. Two polyoma-transformed BHK cell lines do not have detectable amounts of the 90K protein.

Spinal fractures complicating ankylosing spondylitis

The ankylosed osteoporotic spines of patients with long-standing ankylosing spondylitis are prone to fracture. The spinal trauma is of a trivial nature in many patients and the diagnosis may be overlooked, unless neurologic damage occurs. The fractures most commonly occur in the cervical region and may be multiple. Because of spinal osteoporosis and deformity, radiographic visualization of the fracture site may be difficult. Tomography may be helpful in some patients. Management may be conservative or surgical and is complicated by increased instability of the fracture site, spinal osteoporosis, and deformity. Conservative management of cervical fractures is probably best accomplished by halo traction and body cast. Progression of the neurologic deficit is an indication for surgical intervention.

Evidence for simian virus 40 (SV40) coding of SV40 T-antigen and the SV40-specific proteins in HeLa cells infected with nondefective adenovirus type 2-SV40 hybrid viruses

HeLa cells infected with the nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid viruses (Ad2(+)ND1, Ad2(+)ND2, Ad2(+)ND4, and Ad2(+)ND5) synthesize SV40-specific proteins ranging in size from 28,000 to 100,000 daltons. By analysis of their methionine-containing tryptic peptides, we demonstrated that all these proteins shared common amino acid sequences. Most methionine-containing tryptic peptides derived from proteins of smaller size were contained within the proteins of larger size. Seventeen of the 21 methionine-containing tryptic peptides of the largest SV40-specific protein (100,000 daltons) from Ad2(+)ND4-infected cells were identical to methionine-containing peptides of SV40 T-antigen immunoprecipitated from extracts of SV40-infected cells. All of the methionine-containing tryptic peptides of the Ad2(+)ND4 100,000-dalton protein were found in SV40 T-antigen immunoprecipitated from SV40-transformed cells. All SV40-specific proteins observed in vivo could be synthesized in vitro using the wheat germ cell-free system and SV40-specific RNA from hybrid virus-infected cells that was purified by hybridization to SV40 DNA. As proof of identity, the in vitro products were shown to have methionine-containing tryptic peptides identical to those of their in vivo counterparts. Based on the extensive overlap in amino acid sequence between the SV40-specific proteins from hybrid virus-infected cells and SV40 T-antigen from SV40-infected and -transformed cells, we conclude that at least the major portion of the SV40-specific proteins cannot be Ad2 coded. From the in vitro synthesis experiments with SV40-selected RNA, we further conclude that the SV40-specific proteins must be SV40 coded and not host coded. Since SV40 T-antigen is related to the SV40-specific proteins, it must also be SV40 coded.

In vitro translation yields a possible Rous sarcoma virus src gene product

In vitro translation of Rous sarcoma virus (RSV) virion RNA in the messenger-dependent reticulocyte lysate system yielded polypeptides that were not synthesized by translation of RNA from a transformation-defective deletion mutant of RSV. These RSV-specific products migrated on sodium dodecyl sulfate/polyacrylamide gels as two doublets of approximately 25,000 and 17,000 daltons. Synthesis of these proteins was not sensitive to inhibition by m7GTP; however, synthesis of the 76,000-dalton precursor of the internal structural proteins was sensitive to inhibition by m7GTP. Tryptic peptide maps showed the 25,000- and 17,000-dalton proteins to be related to one another but to be distinct from the 76,000-dalton protein. The 25,000-dalton protein was translated only from a polyadenylylated RNA of approximately 2500 nucleotides, whereas the 76,000-dalton protein was translated from 38S RNA, corresponding to the entire viral genome. A 180,000-dalton protein was also synthesized from 38S RSV virion RNA. From the absence of the 25,000- and 17,000-dalton proteins in the translation products of transformation-defective RSV RNA and the size of their RNA templates, we conclude that these proteins may be derived from coding sequences within the RSV src gene.

Azathioprine in early rheumatoid arthritis. Comparison with gold and chloroquine

This study compares the effect of azathioprine with those of gold and chloroquine in early (Class II) rheumatoid arthritis (RA). Thirty-three similar patients with classic or definite RA of less than 5 years duration were randomly entered, 11 into each drug group. Assessment of standard clinical and laboratory measures at 12 and 24 weeks showed significant improvement in all three groups. In general, all three drugs were effective antirheumatic agents with low toxicity. However, because of serious potential toxicity, azathioprine could not be recommended over gold and chloroquine in early RA therapy.

In vitro polyoma DNA synthesis: inhibition by 1-beta-d-arabinofuranosyl CTP

The effects of 1-beta-D-arabinofuranosyl CTP (ara-CTP) on DNA replication were studied in an in vitro system from polyoma-infected BALB/3T3 cells. Ara-CTP concentrations of larger than or equal to 150 muM were found to block in vitro DNA synthesis completely, and concentrations of smaller than or equal to 0.3 muM had no inhibitory effect. Intermediate concentrations resulted in a concentration-dependent reduction of the in vitro synthesis rate. Long-term labeling with [alpha-32-P]ara-CTP demonstrated the incorporation of the analogue into cellular and viral DNA concomitantly with [3-H]TTP. In pulse-labeling experiments, at noninhibitory concentrations of the analogue, ara-CTP was incorporated into short DNA fragments and long growing strands to relatively the same extent as TTP. Partial venom phosphodiesterase digestion liberated the incoporated are-CTP at essentially the same rate as incorporated TTP, excluding a predominantly terminal incorporation, and after total venom phosphodiesterase digestion greater than 80% of the incorporated ara-CTP was recovered as 5'-ara-CMP. Analysis of the long-term in vitro viral DNA product made in the presence of partially inhibiting ara-CTP concentrations demonstrated that none of the steps leading to mature viral DNA were totally inhibited at the ara-CTP concentrations used. Pulse labeling of replicating viral DNA in the presence of ara-CTP revealed two consistent differences in the pattern found in control pulses: (i) predominant labeling of short chains (5S) with reduced amounts of radioactivity in the longer growing viral DNA strands (smaller than or equal to 16S), and (ii) a one-third to one-half reduction in size for short DNA chains labeled in the presence of ara-CTP. Release of the ara-CTP inhibition with excess dCTP resulted in covalent extension of these smaller short chans to approximately the size of regular short chains labeled in the absence of the inhibitor. Isolated short chains synthesized in the presence of ara-CTP exhibited a slightly lower degree of self-complementarity than regular short chains. The predominant labeling of short chains during pulses is, therefore, not a consequence of discontinuous growth on both sides of the replication fork. Similar results were obtained with ara-ATP and N-ethylmaleimide. The experiments indicate that ara-CTP acts primarily on DNA-polymerizing activities, affecting different DNA polymerases to varying degrees. The results are discussed in terms of the possible number and identity of polymerases involved in viral (and cellular) DNA replication.

Sensitive methods for the detection and characterization of double helical ribonucleic acid

We have evaluated three methods which respond specifically to stable RNA-RNA duplexes and have compared their utility for examining several sorts of nucleic acids. We find that these methods, stepwise chromatography on Whatman CF11-cellulose; digestion with Escherichia coli RNase III; and specific inhibition of globin synthesis in vitro in rabbit reticulocyte lysates, are able to distinguish between stable double-stranded RNA and single-stranded RNA in the expected manner. The most sensitive method, inhibition of globin synthesis, responds to double-stranded RNA concentrations below 0.1 ng per ml. We have used the predominantly single-stranded RNA from several RNA bacteriophages of E. coli to test both the sensitivity and selectivity of these methods. The three viral RNAs tested contain low levels of double-stranded RNA which can be readily removed, leaving RNA which is not recognized as double-stranded RNA, despite indications from physical and sequencing studies that secondary structure is present. In particular, a potential hairpir loop of known sequence has been isolated from phage f2 RNA. Its properties were found to depart significantly from those of RNA-RNA duplexes by those two of our three methods capable of testing RNA of this size. Analysis of two eukaryotic mRNA populations by these methods was complicated by the presence of poly(A). Synthetic poly(A) chromatographs like double-stranded RNA on cellulose CF11 columns, and we could distinguish it from reovirus double-stranded RNA only at elevated temperatures.

The characteristics of inhibition of protein synthesis by double-stranded ribonucleic acid in reticulocyte lysates

All types of double-stranded RNA (DSRNA) tested inhibit protein synthesis in rabbit reticulocyte lysates. The inhibition is characterized by its strongly biphasic kinetics, and can be enhanced by preincubation of the lysate with dsRNA in the absence of protein synthesis. Only properly and extensively matched dsRNA (greater than about 50 base pairs) has this property; no form of DNA, single-stranded RNA or even RNA-DNA hybrids act as inhibitors in this way. The cause of the inhibition appears to be a failure of initiator tRNA to associate with native ribosomal subunits in the initiation process (Darnbrough, C., Hunt, T., and Jackson, R. J. (1973) Biochem. Biophys. Res. Commun. 48, 1556-1564). We have shown that this block is not accompanied by stable association of dsRNA with the ribosomes. There are several reasons to believe that the mechanism of action of dsRNA may be complex with the possible involvement of at least one catalytic step. First, the lysate is inhibited by levels of dsRNA at which ribosomes are present in 100-fold excess over base pairs of dsRNA present. Second, high concentrations of dsRNA (greater than 10 mug per ml) are not inhibitory, but can in some, but not all experiments, reverse the inhibition caused by lower levels of dsRNA. Third, a lysate which has been inhibited by dsRNA, when mixed with a fresh lysate will inhibit synthesis in the mixture much more severely than would be expected from the concentration of dsRNA now present. These results indicate that low levels of dsRNA promote the formation of an inhibitor which may exist in two forms: one that is reversible by high levels of dsRNA and one that is irreversible.

Azathioprine in rheumatoid arthritis: a long-term follow-up study

In 1973 we reported the beneficial effects of azathioprine in a double blind, cross-over study in 17 patients with classic rheumatoid arthritis. During subsequent follow-up over a mean period of 40 months, 4 patients had discontinued therapy because of poor therapeutic response and 1 because of nausea. Eleven of the 12 patients still taking azathioprine had maintained their initial beneficial response or showed further improvement. Adverse side effects during the follow-up period were minor. They included nausea in 1 patient and leukopenia with thrombocytopenia in another. An increased incidence of chromosomal abnormalities was detected in those patients still receiving azathioprine.

In vitro polyoma DNA synthesis: requirement for cytoplasmic factors

Purified nuclei from polyoma-infected mouse (3T3) cells were found to be greatly reduced in their ability to synthesize viral DNA in vitro when compared with a crude system consisting of an unfractionated hypotonic lysate of the infected cells. The synthetic capacity of the nuclei could be fully reconstituted when a high-speed cytoplasmic supernatant was added back to them. Cytosols from uninfected mouse, monkey, and hamster cells were equally as effective in stimulating purified nuclei as that of virus-infected mouse cells. Optimal complementation required high concentrations of the cytosol, and most of the complementing activity was destroyed by heating to 60 C. Dialysis had no effect on the activity. Analysis of the viral DNA synthesized in purified nuclei showed an accumulation of Okazaki-type short DNA chains, which could be chased into viral progeny DNA strands if cytosol was added back to the nuclei. Kinetic analysis of the pulse-labeling pattern of viral replicative DNA showed a strong dependence of the extension of viral progeny strands and of the processing of Okazaki-type fragments on the amount of cytosol present during the reaction. It is suggested that the cytoplasmic DNA polymerase might be one of the active components in the cytosol, but most likely not the only one.

In vitro polyoma DNA synthesis: characterization of a system from infected 3T3 cells

A lysate from hypotonically swollen polyoma-infected BALB/3T3 cells incorporated labeled deoxynucleotide triphosphates into both viral and cellular DNAs. The incorporation was stimulated by the presence of ATP, deoxynucleotide triphosphates, thiols, and magnesium ions. Strong inhibition of incorporation was observed with thiol reagents and arabinosyl nucleotide triphosphates. The rate of in vitro synthesis increased with the temperature of incubation as expected. Incorporation into cellular DNA for up to 2 h was observed in lysates from virus-infected and serum-stimulated cells but not from resting cells. Synthesis in the system, therefore, appeared to reflect the physiological state of the cells before preparation of the lysate. Incorporation into viral DNA stopped far sooner than that into cellular DNA. During the initial phase of the in vitro incubation, incorporation occurred into viral replicative intermediates (RI). These RIs had identical properties to those isolated after in vivo pulse labeling and a substantial proportion of them was matured to form I DNA at later times in the incubation through all the stages known to occur in vivo. Density labeling of the in vitro product showed that practically all of the RIs pre-existing in the infected cell took part in the in vitro reaction. Analysis of DNA labeled in vitro in the presence of 5-bromodeoxyuridine triphosphate showed that synthesis occurred on RIs at all stages of replication and that the progeny strands were elongated by up to 80% of unit viral DNA length. Pre-existing RIs, pulse labeled in vivo, showed evidence of a pool at a late stage of replication which required elongation of their progeny strands by approximately 25% during conversion to form I molecules. From density-labeling experiments, we were also able to show that viral DNA synthesis in vitro was semiconservative. The major reason for cessation of viral DNA synthesis in vitro was the very limited ability of the lysate to initiate new rounds of viral DNA synthesis.

In vitro polyoma DNA synthesis: studies on an early temperature-sensitive mutant

The polyoma ts-a function was investigated by using an in vitro DNA-synthesizing system. A comparison of systems derived from ts25 (a ts-a group mutant)-and ts1260 (a late group mutant)-infected cells showed that the activation energies for DNA chain elongation and the mechanisms of discontinous growth were identical for both mutants.