ABSTRACT
Two types of endogenous retroviral-like sequences related to type C or Intracisternal A Particle (IAP) genes respectively were detected in the Chinese hamster (CH) genome. Their structure and expression were analysed by virological and molecular approaches in different CH cell lines. Several clones were isolated from a CHO genomic library by screening--in stringent conditions--with type C (Gross-MuLV) or IAP (pMIA1) specific probes. These clones were further characterized by restriction mapping and sequencing. Transcripts of type C and IAP-like retroviral sequences were revealed either by PCR or by Northern blot analysis and hybridization with the respective specific probes. However only a few retroviral-like type C particles and no IA particles were detectable by electron microscopy. Only weak activation of type C viral production by halogenated pyrimidines or other classical viral activation agents was observed. No replication of this virus could be obtained in rodent, canine, simian or human cell lines.
Subject(s)
CHO Cells/microbiology , Genes, Viral , Retroviridae/genetics , Animals , Cloning, Molecular , Cricetinae , DNA, Viral/genetics , DNA, Viral/isolation & purification , Genes, Intracisternal A-Particle , RNA, Viral/genetics , Retroviridae/isolation & purification , Transcription, GeneticABSTRACT
Retrovirus like sequences homologous to mouse IAP are present in Chinese hamster genome (Lueders K.K. and Kuff, E.L., 1981, 1983, Servenay et al., 1990). Murine IAP long terminal repeats (LTRs) can function as effective promoters in different cell types (Horowitz M. et al., 1984, Howe, C.C. et al., 1986). Thus CHO IAP sequences could act as retrotransposons in the cellular genome, and in this way affect the expression of other genes at the target sites. We had sequenced previously a Chinese hamster IAP genomic region corresponding mainly to the gag gene and including 57 nucleotides of U5 5' LTR (Servenay et al., 1988). In this paper, we present the 5' LTR complete nucleotide sequence of the Chinese hamster IAP element and its comparison with those of mouse and Syrian hamster.
Subject(s)
Genes, Intracisternal A-Particle , Repetitive Sequences, Nucleic Acid , Animals , Base Sequence , Cricetinae , Cricetulus , DNA , Molecular Sequence Data , Sequence Homology, Nucleic AcidABSTRACT
Endogenous retrovirus-like sequences that are homologous to the multigenic murine and Syrian hamster intracisternal type A particle (IAP) genes can be detected in very few copies in the Chinese hamster (CH) genome. They were cloned from a CHO gene library and two recombinants, harboring the major IAP-like DNA genes characterized by Southern blot hybridization after DNA digestion with several restriction enzymes. The IAP DNA inserts of the two clones analyzed were 4.70 and 8.04 kb respectively, allowing us to construct a physical map of our Chinese hamster clone that represents an almost complete IAP element.
