Molecular biology of human immunodeficiency virus type-1

Let It Go: HIV-1 cis-Acting Repressive Sequences

After human immunodeficiency virus type 1 (HIV-1) was identified in the early 1980s, intensive work began to understand the molecular basis of HIV-1 gene expression. Subgenomic HIV-1 RNA regions, spread throughout the viral genome, were described to have a negative impact on the nuclear export of some viral transcripts. Those studies revealed an intrinsic RNA code as a new form of nuclear export regulation. Since such regulatory regions were later also identified in other viruses, as well as in cellular genes, it can be assumed that, during evolution, viruses took advantage of them to achieve more sophisticated replication mechanisms. Here, we review HIV-1 cis-acting repressive sequences that have been identified, and we discuss their possible underlying mechanisms and importance. Additionally, we show how current bioinformatic tools might allow more predictive approaches to identify and investigate them.

Pseudotyped lentiviral vectors for tract-targeting and application for the functional control of selective neural circuits

A lentiviral vector strategy for efficient gene transfer through retrograde axonal transport provides a powerful approach for studying the neural circuit mechanisms that mediate higher level functions of the central nervous system. Pseudotyping of human immunodeficiency virus type-1 with different types of fusion glycoproteins (FuGs), which are composed of segments of rabies virus glycoprotein (RV-G) and vesicular stomatitis virus glycoprotein (VSV-G), enhances the efficiency of retrograde gene transfer in both rodent and non-human primate brains. These pseudotyped lentiviral vectors are classified into two groups, highly efficient retrograde gene transfer (HiRet) and neuron-specific retrograde gene transfer (NeuRet) vectors, based on their properties of gene transduction. Combinatorial use of the pseudotyped vectors with various molecular tools for manipulating neural circuit functions (such as the cell targeting, synaptic silencing, and optogenetic or chemogenetic approaches) enables us to control the function of specific neural circuits, thus leading to a deeper understanding of the mechanism underlying various nervous system functions.

Lentiviral vectors: their molecular design, safety, and use in laboratory and preclinical research

Lentiviral vectors have been successfully used in the clinic and they are increasingly being used for nonclinical applications. They are capable of stably transducing a broad range of mammalian cell types, including nondividing cells, with high efficiency. This review summarizes the evolving molecular design of lentiviral vectors, describing how they have improved since their first description. Lentiviral vector safety and issues surrounding genotoxicity are discussed. Examples of successful application of lentiviral vectors in laboratory and preclinical research are described. These include functional genomics, target validation, protein manufacturing, in vivo imaging, transgenic animals, and stem cell research.