The mapping of connections among central nervous system (CNS) neurons is a longstanding goal of neuroscientists. Knowledge of the connections will inform our understanding of the function of the nervous system, in both health and disease. Dye labeling, physiological recordings, anatomy at the level of electron microscopy, and the transfer of proteins have all been used to track synaptic connections. Neurotropic viruses have also been used, taking advantage of their ability to spread among neurons. Viral tracers offer the promise of higher throughput, and can expand the repertoire of assays beyond mapping connections, via their gene transfer capabilities. We have recently developed vesicular stomatitis virus (VSV) as a transsynaptic tracer. This virus has several advantages over the previously developed transsynaptic viruses, rabies virus (RABV) and pseudorabies virus (PRV). RABV is a lethal virus, which limits its use in the laboratory. PRV has a large and complex genome, making it difficult to engineer in a straightforward manner. VSV has a relatively simple genome, very similar to that of RABV. It is very well characterized as it rapidly grows to high titr and has a long track record for safety in the laboratory. We found that VSV can transmit transsynaptically in mice, monkeys, and multiple other species, including birds, amphibians, and fish. Moreover, we found that we could create VSV vectors that could transmit specifically retrogradely or specifically anterogradely. The directionality was entirely dependent upon the viral envelope glycoprotein, encoded by a viral G gene. We propose to create a series of transsynaptic viral tracers that will be useful to neuroscientists working in different organisms and different areas of the nervous system. We will first explore the use of VSV with different viral G proteins, applying what we learn to the design of specific anterograde and retrograde tracers. We hope to expand the repertoire of G proteins that can be used not only with VSV, but with other tracers as well. We also propose to develop an alternative non-toxic virus for use as a tracer, using some of the tools that we have already developed for VSV. Finally, we propose to develop a tracer that, although based upon a virus, is actually not a virus, but a vehicle to move Cre recombinase across synapses to map connected neurons. These alternative strategies offer the promise of reduced toxicity, relative to VSV, RABV, or PRV, as well as other features that can be combined with engineered lines of mice, or other model organisms.

Public Health Relevance

The function of the nervous system is dependent upon communication among neurons via synaptic connections. In order to define these connections, we propose to develop viral vectors, and virus-like particles, that move from one neuron to another across synapses. This will allow a faster method to define such connections in normal and diseased nervous systems.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Molecular Neurogenetics Study Section (MNG)
Program Officer
Gnadt, James W
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Harvard Medical School
Schools of Medicine
United States
Zip Code
Drokhlyansky, Eugene; Göz Aytürk, Didem; Soh, Timothy K et al. (2017) The brain parenchyma has a type I interferon response that can limit virus spread. Proc Natl Acad Sci U S A 114:E95-E104
Beier, Kevin T; Mundell, Nathan A; Pan, Y Albert et al. (2016) Anterograde or Retrograde Transsynaptic Circuit Tracing in Vertebrates with Vesicular Stomatitis Virus Vectors. Curr Protoc Neurosci 74:1.26.1-27
Mundell, Nathan A; Beier, Kevin T; Pan, Y Albert et al. (2015) Vesicular stomatitis virus enables gene transfer and transsynaptic tracing in a wide range of organisms. J Comp Neurol 523:1639-63
Drokhlyansky, Eugene; Soh, Timothy K; Cepko, Constance L (2015) Preferential Budding of Vesicular Stomatitis Virus from the Basolateral Surface of Polarized Epithelial Cells Is Not Solely Directed by Matrix Protein or Glycoprotein. J Virol 89:11718-22
Wollmann, Guido; Drokhlyansky, Eugene; Davis, John N et al. (2015) Lassa-vesicular stomatitis chimeric virus safely destroys brain tumors. J Virol 89:6711-24