Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Superinfection of Escherichia coli with amber mutants of R17 phage which produce R17 replicase inhibits production of the RNA phage Qbeta, the DNA phage fd, and the host enzyme beta-galactosidase. Inhibition required R17 replicase production and was related to the amount of replicase produced.
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PMID:R17 bacteriophage replicase: association with the inhibition of Qbeta, fd bacteriophage and beta-galactosidase production. 116 91

Vectors based on herpes simplex virus type 1 (HSV-1) show promise for gene transfer into mammalian cells because of their wide host range, efficient infection and ability to deliver genes to nondividing cells. Defective HSV-1 vectors, or amplicons, are plasmid vectors which are unable to propagate on their own but contain specific HSV-1 sequences that, in the presence of helper virus, support DNA replication and subsequent packaging into virus particles. We compared three replication-incompetent HSV-1 mutants (KOS strain 5dl1.2, strain 17 D30EBA, KOS strain d120) as the helper virus for packaging the prototype defective HSV-1 vector, pHSVlac, which uses the HSV-1 immediate-early (1E) 4/5 promoter to regulate expression of the Escherichia coli lacZ gene. Use of 5dl1.2, which contains a deletion in the IE 2 gene, consistently produced virus stocks that contained a high level of vector, undetectable levels of wild-type HSV-1 and a ratio of vector to helper greater than 1. Virus stocks prepared using 5dl1.2 were superior to those prepared using helper viruses that harbor a deletion in the IE 3 gene, either D30EBA or dl20, and supported more efficient gene transfer than possible with previously published procedures. Lactate dehydrogenase efflux assays in rat cortical cultures showed that 5dl1.2 was no more cytotoxic than either D30EBA or dl20, despite the expression of more viral genes. Rat cortical cultures infected with pHSVlac packaged with either 5dl1.2 or D30EBA were used to quantify the stability of vector expression. Our results show a decrease in the number of cells with detectable levels of beta-galactosidase to 30% of peak levels after one week, irrespective of the helper virus used. However, simultaneous superinfection with 5dl1.2, but not with either D30EBA or dl20, produced a transient increase in the number of cells expressing beta-galactosidase. Superinfection with 5dl1.2 at 9 days after gene transfer increased the number of cells expressing detectable beta-galactosidase back to peak levels, most probably because of reactivation of the IE 4/5 promoter in pHSVlac. These results thus provide the first quantitative demonstration of long-term persistence of defective HSV-1 vectors in neurons.
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PMID:Generation of high-titer defective HSV-1 vectors using an IE 2 deletion mutant and quantitative study of expression in cultured cortical cells. 867 7

Brain resistance to intracerebral superinfections develops after a peripheral inoculation of neurovirulent viruses. Superinfection resistance combines specificity, toward the virus used for the peripheral inoculum, and short-term duration after the inoculum. In order to study this unusual combination, neurovirulent superinfections were made on albino Swiss mice previously infected with a nasal inoculum. A herpesvirus strain SC16, or a homologue recombinant virus carrying the reporter lac Z gene or a vesicular stomatitis virus (VSV) (a virus taxonomically unrelated to Herpesviridae) were used. The mice underwent a neurological examination and their survival rate was recorded. The brains superinfected with the reporter virus were stained for the beta-galactosidase reaction to trace the virus spread and the inflammatory infiltrates were characterized immunocytochemically. The results confirm and extend previous observations about virus specificity and short-term duration of superinfection resistance. They show, moreover, an enhanced brain inflammation with T-cells and macrophages infiltrating the tissue around microvessels, at a time when both neurovirulence and the spread of herpesvirus in the brain are reduced. The results suggest that the immune response to superinfection in the nervous tissue is enhanced by blood-brain barrier mechanisms that promote the timely extravasation of immune cells.
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PMID:Brain resistance to HSV-1 encephalitis in a mouse model. 1205 73