ABSTRACT
Eleven in-frame vif gene mutants of HIV type 1 produced in non-permissive cells were examined for their replication potentials in various CD4-positive and -negative cell lines. Virus replication for each mutant was monitored by using several single- and multiple-cycle infectivity assays. Except for a mutant with wild-type phenotype, most mutants were severely defective for replication in all the cell lines as expected from the producer cell-dependent functioning of Vif so far reported. In contrast, two mutants, which have mutations in the hydrophilic or effector regions of Vif were found to have target cell-dependent replication potentials. These results demonstrate the presence of a novel category of the vif mutants important for elucidation of the Vif function.
Subject(s)
Gene Products, vif/metabolism , HIV-1/growth & development , Virus Replication , Amino Acid Sequence , Blotting, Western , Cloning, Molecular , DNA, Viral/biosynthesis , Gene Products, vif/chemistry , Gene Products, vif/genetics , HIV-1/genetics , HeLa Cells , Humans , Jurkat Cells , Kinetics , Molecular Sequence Data , Mutation , vif Gene Products, Human Immunodeficiency VirusABSTRACT
NM-3 is a prototype of chimeric virus between simian and human immunodeficiency viruses (SHIV). It grows in monkey lymphocytic cells in vitro and in vivo as well as in human cells. A mutant designated NM3-E65, which lacks expression of the entire vpu gene, was constructed from NM-3, and monitored for its replication property. Examination of growth properties in simian and human cells of SHIV, HIV, and their vpu mutants revealed that the vpu gene in the genome of the chimeric virus is functional, but non-essential for virus replication.
Subject(s)
HIV-1/genetics , Simian Immunodeficiency Virus/genetics , Viral Regulatory and Accessory Proteins/genetics , Animals , CD4 Antigens/analysis , Cell Line , Cells, Cultured , HIV-1/growth & development , Human Immunodeficiency Virus Proteins , Humans , Mutation , Plasmids/genetics , RNA-Directed DNA Polymerase/metabolism , Receptors, CCR5/analysis , Receptors, CXCR4/analysis , Simian Immunodeficiency Virus/growth & development , Time Factors , TransfectionABSTRACT
Hybrid viruses between human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus strain mac (SIV(MAC)) are invaluable to various fields of HIV-1 research. To date, however, no replication-competent HIV-1 strain containing the gag capsid (CA) region of SIV(MAC) has been reported. To obtain the viable gag gene chimeric virus in an HIV-1 background, seven HIV-1 strains carrying a part of SIV(MAC) CA or a small deletion in the CA region were constructed and examined for their biological and biochemical characteristics. While all the recombinants and mutants were found to express Gag and to produce progeny virions on transfection, only one chimeric virus, which has 18 bp of SIV gag CA sequence in place of the region encoding the HIV-1 CA cyclophilin A (CyPA)-binding loop, was infectious for human cell lines. Although this chimeric virus was unable to grow in monkey lymphocytic cells like wild-type (wt) HIV-1 did, it grew much better than wt virus in the presence of cyclosporin A in a human cell line which supports HIV-1 replication in a CyPA-dependent manner. These results indicate that the transfer of a small portion of the SIV(MAC) CA region to HIV-1 could confer the CyPA-independent replication potential of SIV(MAC) on the virus.
Subject(s)
Capsid/physiology , Cyclophilin A/physiology , Gene Products, gag/physiology , HIV-1/physiology , Recombinant Fusion Proteins/physiology , Simian Immunodeficiency Virus/physiology , Virus Replication , Amino Acid Sequence , Cell Line , Cyclosporine/pharmacology , Molecular Sequence DataABSTRACT
We have previously shown that some of the human immunodeficiency virus type 1 (HIV-1) gag matrix (MA), capsid (CA), and nucleocapsid (NC) mutants display host-cell-dependent replication potential, and that they are defective at the early phase of the virus replication cycle in non-permissive cells. To determine the defective replication stage of the cell-dependent mutants precisely, the processes of virus entry into cells and virus DNA synthesis were monitored by the highly sensitive enzyme-linked immunosorbent assay and polymerase chain reaction amplification analysis. The results obtained indicated that all the cell-dependent MA, CA and NC mutants are defective at the stage of uncoating/reverse transcription, and that a cellular factor(s) is involved in this process.
Subject(s)
Capsid Proteins , Capsid/physiology , Gene Products, gag/physiology , HIV Antigens/physiology , HIV Core Protein p24/physiology , HIV-1/physiology , Transcription, Genetic , Viral Proteins , Capsid/genetics , Cell Line , DNA, Viral/biosynthesis , Defective Viruses/genetics , Defective Viruses/physiology , Gene Products, gag/genetics , HIV Antigens/genetics , HIV Core Protein p24/genetics , HIV-1/genetics , HeLa Cells , Humans , Mutation , Transfection , Virion/chemistry , Virus Replication , gag Gene Products, Human Immunodeficiency VirusABSTRACT
The mature Gag proteins of human immunodeficiency virus type 1 (HIV-1) are major components of infectious virions, and thought to carry out numerous functions throughout the HIV-1 replication cycle. We have recently generated numerous gag gene mutants of HIV-1 to genetically study the functions of the Gag proteins. Through the biological and biochemical analyses, our HIV-1 gag mutants have been grouped into early (defective for uncoating/reverse transcription), late (defective for virion release/maturation), and early/late (defective for both steps) mutants. Many mutants are found to efficiently inhibit the replication of wild-type virus. Worthy of note, there are some early mutants which show host cell-dependent replication potential.
Subject(s)
DNA Mutational Analysis , Gene Products, gag/genetics , HIV-1/genetics , Defective Viruses/genetics , Gene Products, gag/biosynthesis , Gene Products, gag/therapeutic use , HIV-1/pathogenicity , Humans , Virus Replication/geneticsABSTRACT
The expression level of major histocompatibility class I (MHC-I) and the extent of down-regulation of MHC-I after an anti-MHC-I antibody treatment in numerous human T-cell leukemia virus type 1 (HTLV-1)-positive and -negative lymphocytic cell lines were examined. While there was no clear correlation between the expression level of MHC-I and the presence of HTLV-1 genome, a relatively low level of MHC-I down-regulation was generally induced in HTLV-1-positive cells by the antibody. The results may suggest the potential involvement of MHC-I in HTLV-1 leukemogenesis.
