The central nervous system (CNS) orchestrates complex processes enabling organisms to control their movements and behavior. These functions and others are controlled by collections of neurons that are intricately wired into circuits through synaptic connections (Shepherd, 2004). Understanding the structure and function of these neural circuits is essential for neuroscience research. The use of genetic tools for visualizing and perturbing circuits together with the development of methodologies to deliver genes to the CNS have recently made it much easier to map these neuronal networks.

Background on neuronal tracing

A key aspect to understanding the brain’s function is knowing its architecture, in particular the connections between different brain regions. For example, communication between the hippocampus and the prefrontal cortex brain regions is involved in the formation of episodic memory, a special type of memory which includes autobiographical events (see Jin & Maren, 2015). Directional flow of information between different parts of the brain is mediated via individual neurons. Neurons are composed of a cell body, with dendrites receiving incoming information, and a projecting axon sending information onwards to other neuronal cells. Synapses at the terminals of axons form connections to dendrites of proximal neuronal cells. In the specific example of episodic memory, a subset of hippocampal neurons projects axons directly to the prefrontal cortex, but also indirectly via synapses to neurons in other brain regions. Further, the connections between regions are often reciprocal, forming a neuronal loop which is activated and strengthened during memory formation and memory retrieval.

While lentiviral vectors are popular gene delivery tools, producing lentivirus, can pose certain challenges. Whether choosing a system that is the best fit for the experiment, trying to produce virus of a usable titer, or fine-tuning selection and expression in your target cell line, researchers often find themselves faced with a roadblock. In this post, we will provide an overview of some of the common challenges associated with producing and using lentivirus and offer some tips and tricks for overcoming these hurdles.

It was by serendipity that I got into the field of gene therapy, more specifically AAV-based retinal gene therapy. The year was 2001 and I started a job as a technician in a lab using adeno-associated viral vectors (AAVs) to treat an inherited retinal degenerative disease called Retinitis Pigmentosa. I quickly became fascinated by this emerging technology and its potential for the treatment of some genetic diseases.

Viruses are intracellular parasites and natural vehicles for genetic information. Therefore they make excellent tools for genetic engineering. There are several different viral vectors to choose from, for example gamma-retrovirus, lentivirus, Adenovirus, and Adeno-associated virus (AAV). If you are wondering which virus fits you experiments best have a look at this viral vector overview.