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Results for “Visna-maedi virus”

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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Immunologic aspects of preparation of antiserum to the reverse transcriptase from avian myeloblastosis virus].

After immunization of rabbits the antiserum was prepared against purified reverse transcriptase (revertase) from avian myeloblastosis virus (AMV). The antiserum demonstrated enzymeneutralizing antibody activity that was associated with ummunoglobulin G fraction but not with IgM. The high antigenicity of AMV revertase for rabbits was shown. The active antiserum was obtained after 4 immunizations of rabbit with approximately 20 microgram of the enzyme. Non-specific revertase inhibitors were found in normal rabbit serum, which were absent in IgG fraction from this serum. The revertase activity of Rauscher leukemia virus (RLV) and Visna virus was not neutralized by antisera against AMV polymerase. This work was supported by the project "Revertase".

Avian Leukosis Virus↗
PubMed1977

Ovine cells: their long-term cultivation and susceptibility to visna virus.

Sheep choroid plexus (SCP) cells have been subcultured more than 120 times and have undergone over 300 cell generations. These fibroblastic-appearing SCP II-B cells contain ovine-specific antigens, have an absolute plating efficiency of 23 to 28% and are as susceptible to visna virus infection and virus-induced cytopathology as their low passage level counterparts. Cultures of low, relatively high and high passage level SCP cells produced equivalent amounts of visna virus at similar rates when infected with equal amounts of visna virus. The passage level of the SCP II-B cells, their elapsed number of cell generations, their possession of ovine-specific antigens and their full susceptibility to visna virus allow these cells to be considered an established line of sheep cells.

Animals↗
PubMed1975

RNA-instructed DNA polymerase activity in a cytoplasmic particulate fraction in brains from Guamanian patients.

Nervous system tissues from a number of patients with idiopathic neurological disorders were examined for biochemical evidence of RNA tumor virus infection. RNase-sensitive DNA polymerase activity was found in a cytoplasmic particulate fraction from two patients with Guamanian amyotrophic lateral sclerosis (ALS) but not in brains from two normal U.S. individuals. The buoyant density of the enzyme-containing fraction was 1.16-1.18 g/ml and could be converted to a denser region of the gradient (1.24 g/ml) by treatment with the nonionic surfactant, Sterox. The cation and detergent requirements for the endogenous RNase-sensitive DNA polymerase reaction were determined. The early (5 min) endogenous reverse transcriptase product was analyzed by cesium sulfate gradient centrifugation. RNase- and heat-sensitive RNA-DNA hybrids were detected in the product analysis of two ALS, one Parkinsonism-dementia (PD) brain, and two brains from asymptomatic Chamorros but not in brains from normal U.S. individuals and a number of patients with neuro-psychiatric disorders. The DNA product was a 4.5S heteropolymer that hybridized more extensively to RNA extracted from the enzyme-containing pellet from PD brain as compared to a similar fraction from normal U.S. brain. The DNA product appeared to be unrelated to Rausvher or visna virus 70S RNA as determined by RNA-[-3H]DNA hybridization.

Amyotrophic Lateral Sclerosis↗
PubMed1975

Long-term Visna virus infection of sheep choroid plexus cells: initiation and preliminary characterization of the carrier cultures.

Two sheep choroid plexus cell cultures were maintained and propagated for 413 days since being infected with strain K796 visna virus. The majority of the cells in these cultures contained visna virus-specific antigen on days 93 and 105 after infection. Reverse transcriptase-like activity similar to that present in visna virus preparations was obtained from these cultures when very little plaque-forming virus was being synthesized. The persistently infected cultures are resistant to the cytopathic effect which occurs in uninfected cultures upon exposure to visna virus. Persistently infected cells require more time than uninfected cells to become confluent. Less than 0.02 percent of the persistently infected sheep choroid plexus cells form macroscopic colonies within 14 days, whereas 20 to 30 percent of the cells from uninfected cultures form macroscopic colonies within this time.

Animals↗
PubMed1979

Phosphonoformate inhibition of visna virus replication.

Phosphonoformate (PFA) inhibits multiplication of visna virus in sheep choroid plexus cells; a 50% reduction of virus yield was obtained by 20 to 80 microM PFA. Morphological changes, such as syncytial formation and cell degeneration, could be reversibly prevented by PFA. Cell growth was not significantly affected at 500 microM PFA, although prolonged treatment with 2 mM PFA did arrest cell growth. Cell-free reverse transcriptase activity primed with various synthetic template-primers was inhibited about 90% in the presence of 100 microM PFA. The results from kinetic experiments suggested that reverse transcriptase was utilized early but not late in the infection cycle. A structurally related substance, phosphonoacetate, did not inhibit visna virus multiplication and had no inhibitory effect on reverse transcriptase activity at a concentration of 500 microM.

Animals↗
PubMed1975

Zwoegerziekte virus, the causative agent for progressive interstitial pneumonia (maedi) and meningo-leucoencephalitis (visna) in sheep.

The final results of experimental infections with virus recovered from the lungs of sheep suffering from progressive interstitial pneumonia (=zwoegerziekte=maedi) are reported. The virus could be reisolated from blood samples of all experimentally infected sheep. Every animal produced antibodies against the virus. The neutralising, complement-fixing and precipitating antibodies remained present in the blood for six years. Fourteen out of 21 intrapulmonarily infected sheep developed clinical and/or histopathological lung lesions and in three a meningo-leucoencephalitis was detected in addition. One of these three developed the clinical and pathological signs of 'visna' 14 months after inoculation. Signs of visna were seen in eight of 10 sheep that had been inoculated intracerebrally. Furthermore, nine of these sheep suffered from progressive interstitial pneumonia. Hence the name maedi-visna virus is proposed for the agent which causes both disease entities. Three sheep that yielded virus after infection and in which antibodies were detected, did not develop histopathological lesions.

Animals↗
PubMed1975

Persistent or slow viral infections and related diseases.

The discovery of persistent transmissible agents by veterinarians has led to striking advances in the infectious cause of neuropathies of human beings. There is evidence for persisting infection in congenital rubella and the herpes group of viruses including cytomegalovirus infections. Hepatitis types A and B are candidates for inclusion in the category of persisting viral infections. The rubeola or measles virus is established as a persistent virus which causes elevated antibodies in the serum and cerebrospinal fluid of many patients with severe demyelinating disease such as subacute sclerosing panencephalitis and multiple sclerosis. Elevated antibodies against vaccinia virus have been found in the cerebrospinal fluid of some patients with multiple sclerosis and neuromyelitis optica, a rare form of multiple sclerosis.

Adolescent↗
PubMed1975

Comparative studies of Visna and Maedi viruses as antigens.

Rabbits were immunized with purified visna and maedi viruses, using complete Freund adjuvant, in footpad and intramuscular sites. The resulting antisera and their isolated immunoglobulin G (IgG) and M (IgM) classes were evaluated by tanned-cell passive hemagglutination (PHA), complement fixation, gel diffusion, and virus neutralization tests. Early, intermediate, and late bleedings showed increasingly high antibody activities by the PHA, complement fixation, and gel diffusion tests. The activities were associated mainly with the IgG class, although low, but significant activities were also found in the IgM class, as detected by PHA and complement fixation tests. Both antibody classes appeared at the same time during the course of immunization. The viruses, when tested against specific rabbit anti-visna and anti-maedi sera in gel diffusion tests, showed the presence of one to two precipitin lines depending upon the antibody concentration of the sera. A low amount of neutralizing activity was demonstrated in late bleedings but was not seen in earlier bleedings. The neutralizing activity against visna virus in immunized rabbit sera was found to be associated only with the IgG class. Visna and maedi viruses appeared to be immunologically identical when examined in gel diffusion tests and showed the same degree of inhibition when compared in passive hemagglutination inhibition test using antisera made specific for each virus.

Animals↗
PubMed1979

Serological definition of the lentivirus group of retroviruses.

The major polypeptides of visna viruses and other lentiviruses have been isolated and shown to be closely related if not identical in radioimmunoassays. By this criterion the lentiviruses form a distinct group of retroviruses unrelated to spuma viruses, mammalian and avian retroviruses that cause tumors, and unclassified retroviruses of cattle and horses. Two sera obtained from goats immunized with Mason-Pfizer monkey virus or squirrel monkey virus reacted with visna p30. Additional data suggest that this reaction represents infection of goats with a lentivirus or a new retrovirus closely related to the lentiviruses.

Animals↗
PubMed1979

Phosphonoformate inhibits reverse transcriptase.

The new antiviral substance phosphonoformate (PFA) has been tested in a cell-free system for its effect on reverse transcriptases from an avian retrovirus (avian myeloblastosis virus, AMV) and from mammalian retroviruses (Rauscher leukaemia virus, RMuLV; bovine leukaemia virus; baboon endogenous virus; simian sarcoma virus; visna virus). The observed inhibitory effect of PFA has been compared with that of a structurally related substance, phosphonoacetate (PAA). Phosphonoformate, at a concentration of 100 microM, reduced the activities of all the above mentioned polymerases by 90% when (rA)n.(dT)10 was used as a template/primer. The dose-response curves for AMV and RMuLV polymerases primed with (rA)n.(dT)10 showed PFA to be a 1000-fold more active than PAA; the RMuLV polymerase activity was reduced to 50% after incubation with 0.7 microM-PFA and 0.7 mM-PAA, respectively. There was no difference in PFA inhibition of virus-associated and purified reverse transcriptase activity. Results with various synthetic templates showed that both the RNA- and the DNA-dependent polymerase activities of reverse transcriptase were inhibited by PFA. The endogenous polymerase activity of AMV was inhibited to 50% at 100 microM-PFA, while PAA had no effect. The PFA inhibition was dependent on whether Mg2+ or Mn2+ was used as divalent cation in the assay. Phosphonoformate arrested DNA synthesis immediately after being added to the assay system. The mechanism of inhibition of the AMV polymerase was non-competitive with respect to substrate and template and the apparent inhibition constants were 16 microM and 9 microM, respectively.

Animals↗
PubMedDate not supplied

["Revertase" project: results of carrying out the scientific program].

The article summarizes the data obtained within the scope of the "Revertase" project organized in 1972 under the guidance of Scientific Councel on Molecular Biology. The scientific program included four main topics: synthesis of complementary DNA via reverse transcription on the various RNA templates and their use as tools in molecular biology, enzymatic synthesis of structural genes in double DNA-polymerase system and their propagation by means of genetic engineering, enzymology of reverse transcription, problems of molecular oncornavirology. It is stressed that the success in realization of this wide and intensive research program was achieved due to cooperative efforts and division of labour between scientists of different specialities due to international cooperation within the frame of the project. Appearance of more than 80 publications between 1973 and 1977 clearly manifested that the program was fullfilled and led to creation of a new area of research absent in the given countries before functioning of the "Revertase" project.

Animals↗
PubMed1978

Infection of human cell cultures with bovine visna virus.

Fibroblastoid cell cultures derived from leukaemic bone marrow were successfully infected with BVV. After 2 months of subcultivation the cultures showed the appearance of foci of altered cells, suggestive of malignant transformation. Such foci were absent in non-inoculated cultures. Both control and inoculated cultures had a limited life span, i.e. neither of them could be developed into continuous transformed cell lines. The presence of at least some BVV genome functions in the inoculated cells was demonstrated (i) by immunofluorescence using a reference BVV serum, (ii) by detection in the supernatant culture fluid of sedimentable particles bearing RNA-dependent DNA polymerase activity with preference for Mg2+ ions, and (iii) by electron microscopic detection of scarce cell-associated virus particles in one of the infected cultures. Infectious BVV could not be rescued. In contrast to leukaemic bone marrow cultures, diploid human embryonic fibroblasts of various origin could not be infected with BVV.

Animals↗
PubMed1979

Evidence for two forms of RNA-dependent DNA polymerase in Visna virus.

The visna viral RNA-dependent DNA polymerase has been resolved into two forms by affinity chromatography. Glycerine gradient centrifugation of the two forms showed that one form sedimented at 6.9 S corresponding to an apparent molecular weight of 135 000 and the other at 6.3 S corresponding to 118 000. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of the two forms indicated that the 6.9 S enzyme is composed of 2 molecules of 68 000 mol. wt. chain and the 6.3 S is a single chain enzyme. The latter form has been identified as a glycoprotein. The 6.9 S form can be completely inactivated in 20 min at 45 degrees C, prefers poly(rC) over poly(rA) as template and has high efficiency in utilizing visna 70 S RNA as template. The 6.3 S form is stable at 45 degrees C, active with 70 S viral RNA as template, prefers poly(rA) over poly(rC), and requires higher concentration of Mn2+ (0.4 mM) for maximum activity than the 6.9 S form does (0.1 mM) with synthetic homopolymers as templates. However, both 6.9 S and 6.3 S forms prefer Mg2+ over Mn2+ regardless of the nature of the templates.

Isoenzymes↗