Biomedical subjects

A Yaniv

Publications and source records attributed to A Yaniv.

At least 55 records · Page 3Linked to original sources

PubMed1989

Development of an enzyme-linked immunosorbent assay for equine infectious anemia virus detection using recombinant Pr55gag.

To provide more sensitive and convenient methods for the detection of equine infectious anemia virus (EIAV), we developed an enzyme-linked immunosorbent assay (ELISA) employing the EIAV gag precursor (Pr55gag) produced by using recombinant DNA techniques. The antigenic reactivity of the recombinant EIAV Pr55gag was found to be equivalent to that of the virion p24gag and elicited high-titered antiserum in rabbits. When a large number of horse sera were analyzed for the presence of antibodies to EIAV by this ELISA, a radioimmunoassay for EIAV p15gag, or the standard agar gel immunodiffusion test, there was 98.7% concordance among the assays. By using the ELISA it was possible to specifically detect antibodies earlier after experimental infection of horses with EIAV than with the other two tests. A competition ELISA developed in order to detect EIAV gag antigens was found to be approximately 15 times more sensitive than the radioimmunoassay for EIAV p15gag. Antigens of other animal lentiviruses as well as those of the prototype oncovirus failed to compete in this assay.

Animals↗

PubMed1989

Analysis of regulatory elements of the equine infectious anemia virus and caprine arthritis-encephalitis virus long terminal repeats.

We analyzed the equine infectious anemia virus (EIAV) long terminal repeat (LTR) for sequences that influence its promoter activity and ability to be trans-activated by the EIAV tat gene product. A series of LTR deletion mutants and recombinants between LTR and simian virus 40 (SV40) regulatory sequences were used for these studies. We were able to identify the EIAV promoter region and showed that sequences within the U3 region significantly inhibited LTR-directed transcription. However, when placed in a heterologous context (SV40 promoter) these U3 sequences functioned as an enhancer. trans-activation of the EIAV LTR was found to depend upon sequences downstream of the transcription initiation site and also within U3. Deletion mutagenesis experiments showed that the major downstream element was present in a 46-nucleotide stretch (+4 to +50). An SV40 promoter construct containing these sequences could be trans-activated in cells expressing the EIAV tat gene product. For comparative purposes we also examined the LTR of another animal lentivirus, caprine arthritis-encephalitis virus (CAEV), for positive and negative transcriptional regulatory elements and demonstrated the presence of an enhancer within its U3 sequence. There is evidence that trans-activation of the CAEV LTR requires U3 sequences. When the EIAV U3 region was replaced by the CAEV U3 sequence, the promoter activity of the EIAV LTR was markedly elevated, but the responsiveness to the EIAV trans-activator could not be restored.

Animals↗

PubMed1989

Molecular cloning of an oncogenic replication-competent virus that causes lymphoproliferative disease in turkeys.

The lymphoproliferative disease virus of turkeys was molecularly cloned, structurally mapped, and shown to represent a distinct class of retroviruses evolutionarily related to the avian leukemia-sarcoma virus group. The cloned provirus did not contain any known oncogene or other cellularly derived sequences and was established as a replication-competent oncogenic entity capable of inducing the disease in the absence of any associated transforming counterpart.

Animals↗

PubMed1989

Effect of running versus isometric training programs on healthy elderly at rest.

Left ventricular function and hemodynamic alterations at rest were measured echocardiographically following running or isometric training in 40 healthy elderly. They were randomly assigned into two groups. Twenty (67 +/- 4 years) were engaged in running and 20 (67.8 +/- 3.8 years) in isometric training programs. All subjects underwent a 12-week program, 3 times a week 30 min each session. The running exercise (REX) group had an aerobic exercise conditioning program at 70% of their VO2max. The program for the isometric exercise (IEX) group included weight lifting utilizing large muscle mass at 30% of their maximal voluntary contraction. After training, the REX group increased significantly (p less than 0.05) their VO2max from 2.08 +/- 0.37 to 2.36 +/- 0.41 liter/min and ejection fraction 56 +/- 5.9 to 62 +/- 6.1%. They decreased significantly their heart rate, from 73 +/- 7 to 65 +/- 7 beats/min. No change occurred in the IEX group in left ventricular function and hemodynamic parameters. These data suggest that left ventricular responses at rest differ between the two groups following a short-term training with a favorable response after REX training. In addition, this study demonstrated that a controlled aerobic training program is a better way to improve physical capacity than is a weight lifting program for trained healthy elderly.

Aged↗

PubMed1988

Localization of sequences responsible for trans-activation of the equine infectious anemia virus long terminal repeat.

We used the Escherichia coli chloramphenicol acetyltransferase gene (cat) to study sequences that influence expression of the equine infectious anemia virus (EIAV) genome. The EIAV long terminal repeat (LTR) directed CAT activity in a canine cell line, but at levels much lower than those achieved with other eucaryotic viral promoters. In the same cells infected with EIAV or cotransfected with molecularly cloned EIAV genomic DNA, LTR-directed activity was markedly enhanced. Comparison of cat mRNA and protein levels in these cells indicated that this trans-activating effect could be accounted for by a bimodal mechanism in which both transcriptional and posttranscriptional events are enhanced. trans-Activation but not promoter activity was abolished by deletion of the R-U5 region of the EIAV LTR. EIAV sequences responsible for the trans-activating function could be localized to a region encompassing the 3' and 5' termini of the pol and env genes, respectively (nucleotides 4474 to 5775). Interestingly, this stretch harbors a short open reading frame with some amino acid sequence similarity to the human immunodeficiency virus type I tat gene product.

DNA Mutational Analysis↗

PubMed1987

Nucleotide sequence analysis of equine infectious anemia virus proviral DNA.

The nucleotide sequence of the integrated form of the genome of the equine infectious anemia virus was determined. By comparison with LTR sequences of other retroviruses, signals for the control of viral gene transcription and translation could be identified in the EIAV LTR. Open reading frames for gag and pol genes were identified and their sequences matched very closely to those determined previously by others. However, in the present study, the pol gene reading frame was open throughout its entire length. The open reading frame for the env gene product was constructed from the sequences of two independent EIAV clones. Thus, a noninfectious genomic-length clone was shown to contain a frameshift mutation approximately in the middle of the presumed env gene coding sequence, whereas the sequence of another clone was open in this region. The deduced amino acid sequences of the EIAV gag and pol products showed closer evolutionary relationships to those of known lentiviruses than to other retroviruses. There was also partial sequence homology between predicted env gene products of EIAV, visna virus, and HTLV-III/LAV. Sequences analogous to the sor region of other lentiviruses could not be identified in our EIAV clone. A short open reading frame at the 3' end of the genome that overlapped env but not the 3' LTR was present but lacked significant sequence similarity to the 3' open reading frames of other lentiviruses. Thus, the sequence and general structure of EIAV most closely resemble those of known lentiviruses.

Amino Acid Sequence↗

PubMed1986

Molecular cloning and physical characterization of integrated equine infectious anemia virus: molecular and immunologic evidence of its close relationship to ovine and caprine lentiviruses.

Molecular clones of the integrated form of the genome of equine infectious anemia virus (EIAV), the etiologic agent of a naturally occurring, worldwide disease of horses, were obtained. The restriction map of a full-length genome was determined. Additional evidence for the close evolutionary relationship between EIAV and a prototype lentivirus (caprine arthritis encephalitis virus) was acquired by Southern blotting and immunological analyses. An interspecies radioimmunoassay was developed in which EIAV and ovine and caprine lentiviruses could be detected equally well. These studies make available precisely defined reagents to pursue the study of the mechanisms of pathogenesis of lentiviral induced diseases.

Animals↗

PubMed1986

Analysis of structural polypeptides of the lymphoproliferative disease virus (LPDV) of turkeys.

The polypeptide composition of the lymphoproliferative disease virus (LPDV) of turkeys was shown to comprise several polypeptides with apparent molecular weights of 76, 31, 28, 20 and 15 kDa. This polypeptide pattern is distinctly different from the protein profiles of avian leukosis viruses, reticuloendotheliosis virus, or murine leukemia viruses. Moreover, LPD virions contain 2 major structural proteins (p31 and p28), in contrast to only one major internal protein present in most other retroviruses. The 76 kDa protein was established as the major viral envelope glycoprotein. The uniqueness of the LPDV polypeptide pattern is consistent with the lack of genetic relatedness of LPDV genome to other retroviruses, establishing LPDV as a representative of a distinct group of retroviridae.

Animals↗

PubMed1986

Nucleotide sequence analysis of the long terminal repeat of integrated caprine arthritis encephalitis virus.

The nucleotide sequence of the long terminal repeat (LTR) of caprine arthritis encephalitis virus (CAEV), a prototype lentivirus was determined. 6-bp directly repeated host cell sequences flank the 376-bp proviral LTRs. By comparison with other retroviral sequences, the CAEV LTR likely contains U3, R and U5 regions 207, 86 and 83 base-pairs in length, respectively. Sequences conforming to consensus transcriptional promoter sites were identified in the U3 region upstream of a potential transcription initiation site. A consensus polyadenylation signal is present 20 bases upstream of the putative R-U5 border and a potential poly(A) addition site. Sequence comparisons of the CAEV LTR with those of other retroviruses uncovered significant similarities with that of visna virus. No other global homologies with other retrovirus LTRs could be detected. CAEV utilizes a primer binding site complementary to lysine tRNA as does visna, AIDS associated retroviruses, and mouse mammary tumor virus. The putative primer for positive-strand DNA synthesis identified in the CAEV sequence is identical to that of visna virus and very similar to those of AIDS retroviruses and MMTV. In addition, a stretch that includes the TATA box of the CAEV LTR resembles closely the corresponding region in the AIDS retrovirus. These and other findings further strengthen the classification of AIDS retrovirus as a lentivirus.

Animals↗

PubMed1985

Molecular cloning of integrated caprine arthritis-encephalitis virus.

A full-length DNA clone of the exogenous retrovirus, caprine arthritis-encephalitis virus (CAEV), was isolated from high molecular weight DNA of CAEV-infected Himalayan tahr ovary cells. Although other restriction maps of CAEV have been published, this is the first time that the proviral DNA has been cloned. The restriction enzyme map of the clone was determined and found to be identical to that of unintegrated linear CAEV DNA except for the presence of cellular flanking sequences. These findings establish that lentiviruses are able to integrate within the infected host cellular genome. The cloned CAEV genome was shown to contain terminal repeats of approximately 450 base pairs in length, and its restriction enzyme map was oriented with respect to the direction of viral RNA transcription. When the cloned CAEV DNA was used as a molecular probe, it failed to detect related proviral sequences in the genomes of a variety of vertebrate species, including the goat, sheep, horse, mouse, and man. When CAEV DNA was hybridized under relaxed conditions to a variety of cloned DNAs, representing different oncoviral genera, homology to mouse mammary tumor virus (MMTV) was observed, while no homology to avian type C or mammalian type A, C, and D retroviruses was detected. This homology was localized to a region in MMTV corresponding to the 3' end of the gag gene and the 5' end of the pol gene.

Animals↗

PubMed1985

Iron, transferrin, and acid and alkaline phosphatase in healthy turkeys and in turkeys inoculated with the lymphoproliferative disease virus.

Presented are data on iron-binding capacity determinations in the serum of turkeys infected with lymphoproliferative disease (LPD) virus and in healthy males and females (laying eggs and nonlaying) from a breeding flock. Also presented are results of serum and tissue total acid and alkaline phosphatase determinations in turkey poults infected with LPD virus and their uninfected controls and of serum enzyme levels in healthy males and females from the breeding flock. There was no significant alteration in total iron binding capacity (transferrin level) in the serum of turkeys with LPD. Turkey poults inoculated with LPD virus showed a significant decrease in serum alkaline phosphatase activity 4 and 7 weeks postinfection (pi), and a decrease in serum acid phosphatase activity 7 weeks pi. Acid and alkaline phosphatase activity determined in the spleen and pancreas (organs with pronounced tumor involvement) 7 weeks pi did not differ significantly from that of healthy controls, although there was a tendency for both enzymes to decline in the pancreas of the infected turkeys. Healthy laying female turkeys demonstrated marked elevation in serum transferrin level and in acid and alkaline phosphatase activity, as compared with males of the same age. Serum alkaline phosphatase of turkey poults was markedly higher than that of adult turkeys.

Acid Phosphatase↗

PubMed1985

Appearance of ovine progressive pneumonia virus outside the United States.

A recently isolated Israeli retrovirus from a sheep with maedi-visna was compared with other retroviruses, using cDNA-RNA hybridization in solution. The Israeli isolate was shown to have close, if not identical, genetic homologic features with the ovine progressive pneumonia virus reported in the United States, rather than with those of the maedivisna viruses of European origin.

Animals↗

PubMed1984

Isolation and characterization of a novel retrovirus from sheep affected by pulmonary carcinoma.

Sheep pulmonary carcinoma (SPC) has been shown to be associated in nature with a retrovirus, by electron microscopic, biochemical, and epidemiological criteria and by experimental transmission. In this study, a retrovirus has been isolated from SPC tumors which were experimentally induced by inoculation with a cell-free, reverse transcriptase containing fraction from a spontaneous field case of SPC, and propagated in culture. This novel virus was shown to be unrelated to murine, avian, and bovine leukemia viruses, to be exogenous to the ovine species, and to have only limited genetic relatedness to the lentiviridae (maedi-visna and caprine arthritis encephalitis virus).

Animals↗

PubMed1984

Expression of the normal human sis/PDGF-2 coding sequence induces cellular transformation.

The human sis proto-oncogene contains the coding sequence for one of two polypeptide chains present in preparations of biologically active human platelet-derived growth factor (PDGF). A human clone, c-sis clone 8, which contains all of the v-sis-related sequences present in human DNA, was transcriptionally inactive when transfected into NIH/3T3 cells. When placed under the control of a retrovirus LTR, the clone was transcribed at levels comparable to that observed in cells transformed by SSV DNA. However, c-sis clone 8 DNA did not express detectable sis/PDGF-2 proteins and lacked biologic activity. A putative upstream exon was identified by its ability to detect the 4.2 kb sis-related transcript in certain human cells. When this sequence was inserted in the proper orientation between the LTR and c-sis clone 8, the chimeric molecule acquired high titered transforming activity, comparable to that of SSV DNA. Transformants containing this construct expressed human sis/PDGF-2 translational products. Thus the normal coding sequence for a human growth factor has transforming activity when expressed in an appropriate assay cell.

Amino Acid Sequence↗

PubMed1983

Genetic control of the organ specificity of lymphoproliferative disease virus (LPDV) of turkeys.

In a previous study based on the kinetics of virus replication and tumor formation (Gazit et al., 1982), it was shown that the organotropism of lymphoproliferative disease virus (LPDV) is confined to lymphoid tissues. The present paper demonstrates that this organ specificity is controlled at the level of infection and integration, that is, the lymphoid organs, which are the only organs sustaining virus replication, and also the only organs in whose cells integrated LPDV proviruses are detectable. At the same time, the efficiency of virus replication within the various target organs is regulated both at the level of infection and integration and at the level of viral gene transcription.

Animals↗

PubMed1983

The caprine arthritis-encephalitis virus is a distinct virus within the Lentivirus group.

The genetic relatedness among viral genomes of caprine arthritis-encephalitis virus, visna virus, and progressive pneumonia virus, was determined. Whereas the genomic RNAs of two strains of visna virus are indistinguishable as reflected both by their annealing kinetics as well as by the thermal stability of the hybrids, the caprine arthritis-encephalitis virus and visna virus have only 30% of their nucleic acid sequences in common. Furthermore, within the homologous regions of the two viral genomes, there is a significant level (approximately 10%) of mismatched base pairs. This limited homology that exists between caprine arthritis-encephalitis virus and visna virus was lower than the sequence homology observed between the genomes of visna virus and progressive pneumonia virus, or between the genomes of caprine arthritis-encephalitis virus and progressive pneumonia virus. All this indicates that caprine arthritis-encephalitis virus is an additional distinct member of the Lentivirus group of the Retroviridae family.

Animals↗

PubMed1983

Hamster endogenous retrovirus (HaER) isolated from SV-40 induced tumor cells.

A hamster cell line obtained from a secondary transplanted SV-40-induced tumor was found to spontaneously release type C virus particles. The particles possessed all biochemical features characteristic of retroviruses and induced syncytium formation in XC cells but were not oncogenic for hamsters. Nucleic acid hybridization assays demonstrated that the isolated virus was an endogenous retrovirus of hamster, lacking sequence homology with mouse and other animal species.

Animals↗

PubMed1983

Hamster endogenous retrovirus (HaER)--distinct properties of structural proteins and DNA polymerase.

The structural proteins as well as some features of the RNA-dependent DNA polymerase of the hamster endogenous retrovirus (HaER) were examined. The polypeptide pattern of this virus is substantially different from that of other known retroviruses in containing major polypeptides with molecular weights of 68,000, 59,000, 27,000 and 24,000 daltons. Double antibody competitive radioimmunoassays showed that the HaER particles do not share any detectable antigenic relatedness with the murine viruses' p30, but manifest a considerable relatedness with the feline leukemia virus p27 and a slight cross-reactivity with the rat virus major protein. The RNA-dependent DNA polymerase of HaER virus has a molecular size of approximately 73,000 daltons and in contrast to other mammalian retroviruses shows no significant preference for Mn2+ over Mg2+. Apart from the lack of antigenic relatedness between the HaER virus proteins and the p30 protein of murine viruses, there is also no antigenic relatedness between HaER and murine viruses insofar as their DNA polymerase is concerned.

Animals↗