Search PubMed⌕ Search

Biomedical subjects

R Renne

Publications and source records attributed to R Renne.

26 records · Page 2Linked to original sources
PubMed1993

Simian foamy virus type 3 (SFV-3) in latently infected Vero cells: reactivation by demethylation of proviral DNA.

Cell cultures latently infected with simian foamy virus type 3 (SFV-3) were established by suppressing lytic infection in Vero cells with 3'-azido-3'-deoxythymidine (AZT) and homologous antibodies (African green monkey serum immune to SFV-3). The resulting cell line, designated Vero-L, was shown to contain at least one copy per cell of SFV-3 DNA stably integrated at a defined site of the host cell genome. Sequencing of 669 bp at the integration site did not identify a coding region and revealed a 4-bp imperfect repeat in host cell DNA due to SFV-3 integration. Over 2 years of subcultivation, no spontaneous expression of proviral genes could be detected. However, the demethylating agent 5'-azacytidine reactivated lytic infection, proving conservation of the complete viral genome. Comparison of proviral DNA from latently and lytically infected cells supports the notion that methylation is instrumental in keeping SFV-3 infection in latency.

Animals↗
PubMed1993

Functional domains of the simian foamy virus type 1 transcriptional transactivator (Taf).

The genome of simian foamy virus type 1 encodes a transcriptional transactivator (Taf) that dramatically elevates gene expression directed by the viral long terminal repeat. In this report, we describe the functional domains of simian foamy virus type 1 Taf. Several taf mutants and fusion proteins of Taf and the DNA-binding domain of the Saccharomyces cerevisiae transcriptional transactivator GAL4 were used in this study. Taf contains two potent activation domains. One of the activation domains is located at the amino terminus (positions 1 to 48, with position 1 representing the initiator amino acid methionine) and contains several acidic amino acids. The second activation domain was mapped to a region at the carboxy terminus (positions 277 to 300). These two domains activate gene expression directed by the viral long terminal repeat independently of each other. No significant amino acid sequence homology between the activation domains is noted. Thus, Taf belongs in part to the family of acidic transcriptional transactivators. The activation domain at the carboxy terminus is conserved among foamy virus transactivators but is not related to other known transcriptional activators. Therefore, the mechanism of gene activation by the carboxy terminus of Taf may be novel. In addition, a potential binding domain rich in basic amino acids (positions 179 to 222) and a highly conserved sequence among foamy virus transactivators (positions 93 to 109) were found to be critical for Taf activity.

Amino Acid Sequence↗
PubMed1993

Foamy viruses.

Foamy viruses share complex genome organization with lentiviruses and certain oncoviruses. The open reading frame 3' of env encodes a transcriptional transactivator. Distinct responsive sequences were identified in the long terminal repeats (LTRs) of simian (SFV-1 and SFV-3) and human foamy viruses (HFV). Transactivation of heterologous LTRs was described including those of simian and human immunodeficiency viruses. Foamy viruses persist for the whole lifetime in infected hosts (primates, cats, hamsters, cattle, and probably other mammals). The virus may be orally shed and transmitted, while being latent in various internal organs. Selective viral gene expression in the brains of mice transgenic for HFV has suggested a particular relationship to neural tissue. In latently SFV-3-infected cultured cells, methylation of proviral DNA is apparently involved in the control of latency. Demethylation as well as transfection with the transactivator were shown to be instrumental in viral reactivation. Natural infections with foamy viruses are common, elicit strong immune responses, and seem to be asymptomatic in nonhuman primates. Detection of such infections, however, may not be a triviality in man. While accidental transmission of foamy viruses to man is well documented, reported seroprevalence in human populations and the association of HFV with specific pathology (e.g. thyroiditis de Quervain, amyotrophic lateral sclerosis, and Graves' disease) are controversial and remain to be proven.

Animals↗
PubMed1992

Genomic organization and expression of simian foamy virus type 3 (SFV-3).

The complete nucleotide sequence of simian foamy virus type 3 (SFV-3) strain LK-3, isolated from an African green monkey, was determined. In addition to translation frames representing the gag, pol, and env genes, two open reading frames are located in the region between the env gene and the 3' long terminal repeat (LTR). Both SFV-3 and SFV-1 encode two open reading frames between env and the 3' LTR, whereas HFV encodes three open reading frames in this region. Northern blot analysis of cell cultures infected with SFV-3 revealed subgenomic RNAs for these open reading frames. The protease of SFV-3 is encoded by the pol gene in contrast to HFV which encodes the protease in the gag gene. Notably, the pol gene of SFV-3 in the +1 translational frame relative to the gag gene; this observation is in agreement with SFV-1, but differs for HFV and all other retrovirus genomes reported. Thus, gag-pol precursors of the SFVs appear to be expressed by a +1 frameshift. Nucleotide and deduced amino acid alignments of SFV-3, SFV-1, and HFV revealed an unexpected homology pattern; highest homologies are observed in the pol and env genes but low homologies are noted in the gag genes and the additional open reading frames. Analysis of phylogenetic trees confirms the classification of foamy viruses as a subfamily of retroviruses, distinct from the lentiviruses and oncoviruses.

Amino Acid Sequence↗
PubMed1990

Inhalation toxicity studies of cobalt sulfate in F344/N rats and B6C3F1 mice.

Groups of 10 F344/N rats and B6C3F1 mice of each sex were exposed to cobalt sulfate heptahydrate aerosols of 0, 0.3, 1.0, 3.0, 10, or 30 mg/m3, 6 hr per day, 5 days per week, for 13 weeks. All rats and female mice and all but 2/10 male mice exposed at the top concentration survived to the end of the studies. Polycythemia was observed in exposed rats but not in mice. Sperm motility was decreased in mice exposed at 3 mg/m3 (the lowest concentration evaluated) and at higher concentrations, and increased numbers of abnormal sperm and decreased testis and epididymal weights occurred in mice exposed to 30 mg/m3. Cobalt content in the urine of rats increased with increasing atmospheric cobalt exposure. Primary histopathologic effects were limited to the respiratory tract. Lesions in rats and mice included degeneration of the olfactory epithelium, squamous metaplasia of the respiratory epithelium, and inflammation in the nose; inflammation, necrosis, squamous metaplasia, ulcers (rats), and inflammatory polyps (rats) of the larynx; metaplasia of the trachea (mice); and fibrosis, histiocytic infiltrates, bronchiolar epithelial regeneration, and epithelial hyperplasia in the alveoli of the lung. The most sensitive tissue was the larynx, with squamous metaplasia observed in rats and mice at the lowest exposure concentration of 0.3 mg/m3. Thus, a no-observed-adverse-effect level was not reached in these studies.

Administration, Inhalation↗
PubMed1989

Structural analysis of proviral DNA in simian foamy virus (LK-3)-infected cells.

Proviral DNA of the T-cell lymphotropic simian foamy virus strain LK-3 was characterized. In infected cells, multiple copies of unintegrated linear duplex viral DNA of about 13 kbp length are present. Nuclease S1 treatment of the DNA generated two fragments of 6.5 and 6.0 kbp length that were cloned in phage and plasmid vectors. The proviral DNA contains a single-stranded gap of 109 nucleotides. A DNA fragment spanning the gap was cloned after completing the double strand by DNA synthesis in vitro. At the 3' end, the gap contains a polypurine tract (PPT) similar to the putative initiation site of retroviral plus strand DNA synthesis, suggesting discontinuous DNA synthesis. Further analysis of the genome architecture revealed LTRs of 1.7 kbp length. An additional 1.7 kbp DNA fragment was detected after nuclease S1 digestion of proviral DNA and probably represents trimmed intermediates of "strong-stop" DNA.

Animals↗