Genetic relationship of a primate RNA tumour virus genome to genes in normal mice

Radioimmunoassay for infectious primate retrovirus reverse transcriptase: characterization, comparison with conventional immunologic assays and applicability to cellular extracts

SSV reverse transcriptase (RT) was purified to homogeneity and used in a radioimmunoassay. Following iodination, the homogeneity of the protein and its identity with RT were confirmed by several criteria: (1) its molecular weight on an SDS-polyacrylamide gel; (2) its precipitation by anti-SSV RT but not by antisera to other SSV proteins; (3) its cross-reactivity in RIA with antisera to other retroviral polymerases; (4) its competition in RIA by active homogeneous SSV RT but not by other purified SSV proteins; and (5) its competition in RIA by only those fractions from a poly(U)-Sepharose column possessing SSV RT activity. Competition of the labelled probe with disrupted retroviruses of the infectious primate group showed that, while a homologous RIA detected only type-specific enzyme determinants, it did not distinguish the various woolly-gibbon retroviral DNA polymerases. A more broadly reactive heterologous assay utilizing an antiserum to R-MuLV RT detected group- but not interspecies-specific enzyme determinants. A comparison of immunologic assays for RT showed that: (1) highly purified RT is not essential for reliable results in enzyme neutralization or enzyme binding assays; (2) the greater sensitivity of enzyme binding compared to enzyme neutralization assays is a function of the antibody, not of the antigen. Competition RIAs using extracts of virus-infected cells showed that infectious primate retrovirus RT could be measured in a crude system and that cellular DNA polymerases alpha, beta and gamma did not compete with the labelled probe.

Molecular cloning and comparative analyses of the genomes of simian sarcoma virus and its associated helper virus

Closed circular viral DNA of simian sarcoma virus (SSV) and simian sarcoma-associated virus (SSAV) obtained from acutely infected dog cells was purified on preparative agarose gels, cleaved with EcoRI, and cloned in the phage lambda vector Charon 21A. The cloned 9-kilobase SSAV genome (B11) has the same restriction map as the bulk of the unintegrated linear SSAV DNA intermediate. Heteroduplex analysis between an SSV clone (lambda-C60) and an SSAV clone (lambda-B11) showed two substitution loops and one deletion loop. By using detailed restriction enzyme mapping and electron microscopic analysis, we showed that one of the substitution loops corresponds to an inversion of one of the two long terminal repeat units and adjacent cellular sequences in C60. The other substitution loop mapped close to the 3' long terminal repeat. At least part of this region was shown to contain SSV-specific sequences not shared by SSAV. The 1.9-kilobase deletion mapped at 3.5-5.5 kilobases of the linear SSAV genome, corresponding to most, if not all, of the pol gene.

Characterization of a type-C virus produced by co-cultures of human leukemic bone-marrow and fetal canine thymus cells

The putative human helper virus SKA-21/A204V, isolated by Nooter et al. in 1977 from human leukemic bone-marrow cells following co-culture with normal fetal canine thymus cells, Cf2th, has been characterized with respect to its major viral core protein, reverse transcriptase, and nucleic acid sequences. The results of these analyses show that this virus is not distinguishable from the woolly monkey type-C virus, SSAV-1, by the techniques employed.

Cellular and virological studies directed to the pathogenesis of the human myelogenous leukemias

1. Work over the past years and especially results of the past few years indicate that type-C viral or viral related genetic information exists in humans. 2. We do not know how this information entered humans or whether it causes disease, but it is of interest that the probes from the viruses used to detect this information are from the very same viruses which we find can affect growth and differentiation of some human hematopoietic cells. 3. The status of actual virus isolates from humans, though encouraging because of similarities of isolates from five different laboratories, remain very perplexing and so far have not been especially informative to human leukemogenesis. 4. In the near future we hope to clone in bacteria the viral related sequences detected in human DNA in order to more precisely determine their chemical and biological properties. The HL-60 system may also afford an opportunity to purify receptors for CSF. When CSF and other, perhaps more important, regulatory factors are purified, we would like to determine if they bind differently to leukemic and normal cells.

Antigenic characterization of a new gibbon ape leukemia virus isolate: seroepidemiologic assessment of an outbreak of gibbon leukemia

A type-C virus recently isolated from a leukemic gibbon in a colony located on Hall's Island, Bermuda, was characterized with respect to the antigenic properties of its gag and env gene-coded proteins. This virus, designated GaLV-H, was found to be closely related immunologically to type-C viruses previously isolated from gibbons (GaLV-SF, GaLV-SEATO, GaLV-Br) and from woolly monkey (SSAV). However, GaLV-H was readily differentiated from these isolates in a radioimmunoassay for its env gene product, gp70. Seroepidemiology established that GaLV-H was horizontally transmitted among gibbons within the colony. There was no evidence of exposure leading to an immune response to the virus or viral antigenemia in humans working in association with these animals.

The use of standard and relaxed hybridization conditions to detect two classes of sequences related to type-D retroviruses in the DNAs of primates

Using standard hybridization conditions (68 degrees C and 0.4 M sodium phosphate) and assaying for RNAase-resistant RNA . DNA duplexes in the presence of 2 X SSC (1 X SSC is 0.15 M NaCl and 0.015 M sodium citrate), sequences representing approx. 20% of the Mason-Pfizer virus (MPV) genome have previously been shown to be endogenous in DNAs of all Old World monkeys examined (Drohan, W., Colcher, D., Schochetman, G. and Schlom, J. (1977) J. Virol. 23, 36--43). We now report that titration of both the temperature at which hybridizations are carried out and the Na+ concentration at which 125I-labeled MPV RNA . DNA hybrids are scored, reveals a second class of sequences related to the MPV genome in the DNAs of primates. These MPV-related sequences, which are similar to an additional 40% of the MPV genome, are detected when the temperature of hybridization is reduced to 54 degrees C and when the resulting 125I-labeled RNA . DNA duplexes are scored for RNAase resistance in 8 X SSC. These sequences are found in the DNAs of all Old World monkeys examined, and the Tm values of the hybrid duplexes are approx. 6--7 degrees C lower than those of the hybrid duplexes formed using standard conditions. These studies further demonstrate the wide distribution of type-D retrovirus sequences in primates.

A method for classification of 5' termini of retroviruses

A new method for the classification of retroviruses is presented. The scheme is based on the length and sequence of a DNA transcript of the 5' end of the genome. The method can be used to detect similarities between distantly related viruses as well as to discriminate between very closely related viruses. The method is applied to viruses isolated from mice, baboons, gibbons, a woolly monkey and chickens.

Evolutionary relationships between gag gene-coded proteins of murine and primate endogenous type C RNA viruses

Several low molecular weight proteins of endogenous type C viruses of the RD114/baboon group are compared with the gag gene translational products of endogenous type C viruses of murine origin. The p10 proteins of each virus group are shown to be immunologically and biochemically related, while the p12 proteins of RD114/baboon viruses are demonstrated to share antigenic determinants with murine viral p15. Moreover, highly type-specific phosphoproteins, p15 of RD114/baboon viruses and p12 of murine viruses, are shown to possess very similar biochemical properties. These findings, along with previous studies indicating immunologic cross-reactivity between their major internal antigens, p30, demonstrate that each of the gag gene-coded proteins of murine type C viruses has a analogue in viruses of the RD114/baboon group. The immunologic and biochemical relatedness of their gag gene translational products supports the concept of a common progenitor in the evolution of these endogenous viruses.

Proviral sequences of baboon endogenous type C RNA virus in DNA of human leukaemic tissues

Hybridisation of RNA from a baboon endogenous type C RNA virus to DNA from tissues of leukaemic patients indicates that a virus of this type is horizontally transmitted among humans. DNA from several patients with leukaemia hybridised 70% of the hybridisable RNA from baboon endogenous type C RNA virus (BaEV) and yielded hybrids of high tm, whereas DNA from normal human tissues hybridised only 23% of the BaEV RNA, and the tm of these hybrids was lower.