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Biomedical subjects

C Patience

Publications and source records attributed to C Patience.

24 records · Page 2Linked to original sources
PubMed1996

Endogenous D-type (HERV-K) related sequences are packaged into retroviral particles in the placenta and possess open reading frames for reverse transcriptase.

All primates studied to date produce retroviral-like particles in their placentae. We have purified these particles from two primate species, one Old World (human) and one New World (marmoset), and have identified the retroviral sequences which are packaged into these particles. Three families of sequences have been detected in these particles in human, all of which have the highest homology to B- and D-type retroviruses and to the human endogenous retrovirus HERV-K10. Previous studies have reported that the New World monkeys do not possess sequences with homology to HERV-K10. We have identified a new family of low-copy-number sequences which are present in New World monkeys and which possess 70% homology to the HERV-K family. Particles from both species possess reverse transcriptase activity and we have found that some of these retroviral particles package sequences which encode long open reading frames in pol, as revealed by expression cloning in Escherichia coli. These open reading frames could encode the reverse transcriptase enzyme activity found in the particles.

Animals↗
PubMed1996

Human endogenous retrovirus expression and reverse transcriptase activity in the T47D mammary carcinoma cell line.

We have examined the human mammary tumor cell line T47D and have found that these cells produce virus-like particles which band at the typical density for retroviral particles on a sucrose gradient, possess reverse transcriptase activity, and package HERV-K10-like sequences. Using this information and a bacterial expression system to identify long open reading frames, we have identified individual clones which have full-length open reading frames for reverse transcriptase and RNase H and which could encode the reverse transcriptase activity detected in these cells.

Base Sequence↗
PubMed1995

Peripheral blood mononuclear cells produce normal amounts of defective Vif- human immunodeficiency virus type 1 particles which are restricted for the preretrotranscription steps.

Previous studies have demonstrated the absence of viral replication of Vif- mutants in stimulated primary blood mononuclear cells (PBMC). Human immunodeficiency virus type 1 strain NDK Vif- mutants were propagated on the semipermissive CEM cell line, and the viral stock obtained was compared with the wild-type virus during a single cycle in PBMC. The Vif- virus was able to enter PBMC with the same efficiency as the wild type, as demonstrated by quantification of the strong-stop cDNA, and retrotranscription was observed for both viruses within 4 h postinfection. Using a PCR assay with an Alu-long terminal repeat pair of primers, we detected integration for both the wild-type and Vif- viruses. We then used qualitative and quantitative reverse transcription-mediated PCR techniques to study the steady-state level of intracellular and extracellular viral RNAs. All mRNA species were detected in PBMC infected with the wild-type virus or with the Vif- virus 36 h postinfection. Furthermore, quantification of viral RNA released from infected cells demonstrated similar levels of virus produced after a unique cycle of replication. However, the Vif- virus obtained after one replication cycle in PBMC was unable to initiate retrotranscription in permissive target cells. These data strongly suggest that the failure to infect target cells is due to a defect in the formation of the viral particle in PBMC.

Base Sequence↗
PubMed1994

In vitro assessment of compounds for anti-HIV activity.

Human immunodeficiency virus types 1 and 2 (HIV-1, -2), the etiological agents of AIDS, are retroviruses that replicate in CD4+ T lymphocytes, monocytes, and macrophages. Early anti-HIV therapies were directed at the step in the virus life cycle that was considered the most readily blocked: the transcription of viral RNA into its DNA copy by the viral enzyme reverse transcriptase (RT). Unfortunately, to date, patient therapies have been relatively unsuccessful and hampered by toxicological problems. This has promoted further research into inhibitors of HIV replication, which may act at alternative stages in the viral replicative cycle as well as more effective RT inhibitors. In order to facilitate such research, simple and accurate in vitro assays are highly desirable. Here we describe such assays that measure components of the HIV replicative cycle and are suitable for use within antiviral experiments.

Amino Acid Sequence↗
PubMed1993

Transcomplementation of VIF- HIV-1 mutants in CEM cells suggests that VIF affects late steps of the viral life cycle.

The vif gene of HIV-1 has previously been claimed to be essential for the ability of cell-free virus preparations to infect cells. Here we report that the CEM T-cell-line, stably transfected with and expressing vif, supports the replication of vif- HIV-1 viruses to the same extent as wild-type HIV1. Cell entry and early replication stages are the same for vif- and vif+ HIV-1 passaged in CEM, as measured both by a PCR-based cell entry assay and by fusogenic potential. These findings indicate that vif does not affect viral infectivity on CEM cells, but seems to act at a later stage of virus replication/maturation. We also show that the VIF proteins of two different HIV-1 strains can transcomplement different vif- HIV-1 mutants.

Cell Line↗