Faculty & Research
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Molecular Biology Faculty

Lynn W. Enquist

Henry L. Hillman Professor in Molecular Biology
Professor of Molecular Biology and the Princeton Neuroscience Institute
 

Lynn Enquist

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Phone (609) 258-2415
locationSchultz Laboratory, 314
Phone Lab (609) 258-4990


Faculty Assistant
Matt Montondo
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Phone (609) 258-2664

 

Research Focus

Neurovirology

My research focuses on mechanisms of herpesvirus pathogenesis. Most alpha-herpesviruses (e.g., herpes simplex virus HSV; varicella-zoster virus, VZV; and pseudorabies virus, PRV) are parasites of the peripheral nervous system (PNS) in their natural hosts. This life style is remarkable because of all the neurotropic viruses that also enter the PNS (e.g., rabies), only the alpha-herpesviruses routinely STOP in the PNS of their natural hosts and establish a reactivatable, latent infection. Normally, this PNS infection is relatively benign, promoting survival of both virus and host. However, aberrations in this pathway give rise to the set of common diseases caused by these viruses. For example, invasion of the CNS is a rare, but exceedingly serious possibility. The directional spread of a herpes infection from epithelial surfaces to PNS neurons (where latency is established), and then, upon reactivation, spread back to epithelial surfaces constitutes the virus survival strategy. Research in my laboratory is directed toward answering several basic questions: What are the virus- and cell-encoded mechanisms that direct virus into and back out of the PNS? Why does the virus only occasionally enter the CNS in its natural host? What are the molecular roadblocks that make CNS infection rare in the natural host and frequent in the non-natural host? What are the viral gene products that promote disease and how do they work? How do the PNS and CNS respond to viral infection? These basic questions continue to lead us into exciting (and sometimes unexpected) areas. Two major areas of work are outlined below.

Pseudorabies Virus (PRV) as a Model System

PRV is a broad host range herpesvirus that causes fatal encephalitis in a wide variety of animal species except its natural host, the adult pig. PRV is not a human pathogen and grows well in the lab. Using rodent and chick embryo models and defined mutations in specific PRV genes, we are studying mechanisms of spread from site of primary infection, evasion of innate and acquired immune defense, and cell/tissue damage. We have identified several PRV gene products that affect the extent of PRV pathogenesis in both model systems affecting cell to cell spread, direction of spread, and host response to infection. We have constructed infectious bacterial artificial chromosomes carrying the entire PRV genome and are using E. coli mutagenesis and recombination techniques for genetic analysis of PRV. cDNA analyses coupled with gene array technology are being developed to understand the role of virus and host genes in virus replications in various cell types and tissues of infected animals.

Genetics of Directional Spread of Virus In and Between Neurons

Our work with PRV infections in rats, mice, and chicken embryos demonstrates that directional spread of virus in the nervous system is regulated, in part, by several viral genes. We have developed technology to culture primary embryonic sensory and autonomic PNS neurons from mice, rats, and chickens. Based on these systems, we have defined two distinct processes involved in directional spread: (1) movement of virion components into axons and long distance movement of these components to axon terminals; and (2) interactions between the infected axon terminals and connected cells that promote assembly, virus release, or both. The small type II membrane protein called Us9 affects the first process: it promotes the movement of virion envelope (but not tegument or capsid) components into axons. The type I viral membrane proteins gE and gI also are required for directional spread in the nervous system, but the mechanism for their action is distinct from that of Us9. gE and gI affect the entry of all viral components into axons. gE expression also exacerbates symptoms and speeds time to death in vivo, but this phenotype is not correlated with virus spread. Green and red fluorescent protein fusions to Us9, gE, gI, and other membrane proteins, as well as capsid and tegument proteins enable us to follow synthesis, transport, and assembly of virions in cultured neurons as well as in tissue. The genetics and biochemistry of these proteins and others that affect endocytosis, targeting, virus assembly, egress, spread, and virulence are a major focus of our work.

Tracing the Hardwiring of the Nervous System with a Virus

Unlike infections of the natural host (the adult pig), PRV infections of all other permissive species (e.g., baby pigs, chicken embryos, rodents, dogs, cats, and cows, to name a few) are lethal and quickly transmitted through peripheral nerves to the brain and spinal cord. These infections enable us to study not only mechanisms of virulence and how the nervous system responds to infection, but also how the virus spreads in the nervous system. Amazingly enough, in all permissive species, the virus spreads only in chains of synaptically connected neurons (trans-neuronal spread). Therefore, PRV can be used as a self-amplifying tracer of neuronal circuits. The ability to reveal a neural circuit (neuron A is wired to neuron B is wired to neuron C etc) is powerful technology, but demands attention to many details. Tracing studies are rewarding because they require close collaboration between neurobiologists and virologists. For example, circuit tracing requires use of mutant viruses that are much less virulent than wild type PRV. Understanding why these mutants are good tracing strains has led us to a better understanding of virulence and mechanisms by which virus spreads between neurons. In addition, we capitalize on our ability to manipulate PRV to construct less virulent, innovative tracing viruses: e.g., viruses expressing beta-galactosidase and variants of green fluorescent protein, as well as viruses that replicate only in certain neurons and not others. These viruses provide powerful tools to study neural circuits and how the nervous system responds to infection.


Selected Publications

 

Wojaczynski GJ, Engel EA, Steren KE, Enquist LW, Card JP. (2014) The neuroinvasive profiles of H129 (herpes simplex virus type 1) recombinants with putative anterograde-only transneuronal spread properties. Brain Struct Funct. Mar 2. [Epub ahead of print]

Szpara ML, Gatherer D, Ochoa A,...Enquist LW,...Davison AJ. (2014) Evolution and diversity in human herpes simplex virus genomes. J Virol. 88: 1209-27. Pubmed

Granstedt AE, Bosse JB, Thiberge SY, Enquist LW. (2013) In vivo imaging of alphaherpesvirus infection reveals synchronized activity dependent on axonal sorting of viral proteins. Proc Natl Acad Sci. 110: E3516-25.  Pubmed

Sun XR, Badura A, Pacheco DA,...Enquist LW,...Wang SS. (2013) Fast GCaMPs for improved tracking of neuronal activity. Nat Commun. 4: 2170. Pubmed

Granstedt AE, Brunton BW, Enquist LW. (2013) Imaging the transport dynamics of single alphaherpesvirus particles in intact peripheral nervous system explants from infected mice. MBio. 4: e00358-13. Pubmed

Koyuncu OO, Hogue IB, Enquist LW. (2013) Virus infections in the nervous system. Cell Host Microbe. 13: 379-93. Pubmed

Kratchmarov R, Kramer T, Greco TM,...Enquist LW. (2013) Glycoproteins gE and gI are required for efficient KIF1A-dependent anterograde axonal transport of alphaherpesvirus particles in neurons. J Virol. 87: 9431-40. Pubmed

Kratchmarov R, Taylor MP, Enquist LW. (2013) Role of us9 phosphorylation in axonal sorting and anterograde transport of pseudorabies virus. PLoS One. 8: e58776. Pubmed

Kramer T, Enquist LW. (2013) Directional spread of alphaherpesviruses in the nervous system. Viruses. 5: 678-707. Pubmed

Koyuncu OO, Perlman DH, Enquist LW. (2013) Efficient retrograde transport of pseudorabies virus within neurons requires local protein synthesis in axons. Cell Host Microbe. 13: 54-66. Pubmed

Kramer T, Greco TM, Taylor MP, Ambrosini AE, Cristea IM, Enquist LW. (2012) Kinesin-3 mediates axonal sorting and directional transport of alphaherpesvirus particles in neurons. Cell Host Microbe. 12: 806-14. Pubmed

Taylor MP, Kobiler O, Enquist LW. (2012) Alphaherpesvirus axon-to-cell spread involves limited virion transmission. Proc Natl Acad Sci. 109: 17046-51. Pubmed

Card JP, Enquist LW. (2012) Use and visualization of neuroanatomical viral transneuronal tracers. Visualization Techniques: From Immunohistochemistry to Magnetic Resonance Imaging. Neuromethods 70: 225-68.

Kratchmarov R, Taylor MP, Enquist LW. (2012) Making the case: married versus separate models of alphaherpes virus anterograde transport in axons. Rev Med Virol. 22: 378-91. Pubmed

Enquist LW. (2012) Ten years under the JVI flag. J. Virol. 86: 7025-26.

Kramer T, Enquist LW. (2012) Alphaherpesvirus infection disrupts mitochondrial transport in neurons. Cell Host Microbe. 11: 504-14. Pubmed

Taylor MP, Kramer T, Lyman MG, Kratchmarov R, Enquist LW. (2012) Visualization of an alphaherpesvirus membrane protein that is essential for anterograde axonal spread of infection in neurons. MBio. 3: e00063-12. Pubmed

Enquist LW. (2012) Five questions about viral trafficking in neurons. PLoS Pathog. 8: e1002472. Pubmed

Kobiler O, Brodersen P, Taylor MP, Ludmir EB, Enquist LW. (2011) Herpesvirus replication compartments originate with single incoming viral genomes. MBio. 2: e00278-11. Pubmed

Szpara ML, Tafuri YR, Parsons L,...Enquist LW. (2011) A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses. PLoS Pathog. 7: e1002282. Pubmed

Szpara ML, Tafuri YR, Enquist LW. (2011) Preparation of viral DNA from nucleocapsids. J Vis Exp. pii: 3151. Pubmed

Card JP, Kobiler O, Ludmir EB, Desai V, Sved AF, Enquist LW. (2011) A dual infection pseudorabies virus conditional reporter approach to identify projections to collateralized neurons in complex neural circuits. PLoS One. 6: e21141. Pubmed

Haugo AC, Szpara ML, Parsons L, Enquist LW, Roller RJ. (2011) Herpes simplex virus 1 pUL34 plays a critical role in cell-to-cell spread of virus in addition to its role in virus replication. J Virol. 85: 7203-15. Pubmed

Kramer T, Greco TM, Enquist LW, Cristea IM. (2011) Proteomic characterization of Pseudorabies virus extracellular virions. J Virol. 85: 6427-41. Pubmed

Taylor MP, Koyuncu OO, Enquist LW. (2011) Subversion of the actin cytoskeleton during viral infection. Nat Rev Microbiol. 9: 427-39. Pubmed

Szpara ML, Parson L, Enquist LW. (2010) Sequence variability in clinical and lab isolates of Herpes Simplex Virus 1 reveals new mutations. J Virol. 84: 5303-13. PubMed

Szpara ML, Kobiler O, Enquist LW. (2010) A common neuronal response to alphaherpesvirus infection. J Neuroimmune Pharmacol. 5: 418-27. PubMed

Granstedt AE, Kuhn B, Wang SS, Enquist LW (2010). Calcium imaging of neuronal circuits in vivo using a circuit-tracing pseudorabies virus. Cold Spring Harb Protoc. pdb.prot5410. PubMed

Curanovic D, Enquist L. (2009) Directional transneuronal spread of alpha-herpesvirus infection. Future Virol. 4: 591-603. PubMed

McCarthy KM, Tank DW, Enquist LW. (2009) Pseudorabies virus infection alters neuronal activity and connectivity in vitro. PLoS Pathog. 5: e1000640. PubMed

Granstedt AE, Szpara ML, Kuhn B, Wang SS, Enquist LW. (2009) Fluorescence-based monitoring of in vivo neural activity using a circuit-tracing pseudorabies virus. PLoS One. 4: e6923. PubMed

Ludmir EB, Enquist LW. (2009) Viral genomes are part of the phylogenetic tree of life. Nat Rev Microbiol. 7: 615. PubMed

Curanovic D, Enquist LW. (2009) Virion-incorporated glycoprotein B mediates transneuronal spread of pseudorabies virus. J Virol. 83: 7796-804. PubMed

Lyman MG, Kemp CD, Taylor MP, Enquist LW. (2009) Comparison of the pseudorabies virus Us9 protein with homologs from other veterinary and human alphaherpesviruses. J Virol. 83: 6978-86. PubMed

Enquist LW for the Editors of the Journal of Virology. (2009) Virology in the 21st century. J Virol. 83: 5296-308. PubMed

Lyman MG, Enquist LW. (2009) Herpesvirus interactions with the host cytoskeleton. J Virol. 83: 2058-66. PubMed

Curanović D, Lyman MG, Bou-Abboud C, Card JP, Enquist LW. (2009) Repair of the UL21 locus in pseudorabies virus Bartha enhances the kinetics of retrograde, transneuronal infection in vitro and in vivo. J Virol. 83: 1173-83. PubMed

Lyman MG, Curanovic D, Brideau AD, Enquist LW. (2008) Fusion of enhanced green fluorescent protein to the pseudorabies virus axonal sorting protein Us9 blocks anterograde spread of infection in mammalian neurons. J Virol. 82: 10308-11. PubMed

Liu WW, Goodhouse J, Jeon NL, Enquist LW. (2008) A microfluidic chamber for analysis of neuron-to-cell spread and axonal transport of an alpha-herpesvirus. PLoS One. 3: e2382. PubMed

Lyman MG, Curanovic D, Enquist LW. (2008) Targeting of pseudorabies virus structural proteins to axons requires association of the viral Us9 protein with lipid rafts. PLoS Pathog. 4: e1000065. PubMed

Ekstrand MI, Enquist LW, Pomeranz LE. (2008) The alpha-herpesviruses: molecular pathfinders in nervous system circuits. Trends Mol Med. 14: 134-40. PubMed

Lyman MG, Feierbach B, Curanovic D, Bisher M, Enquist LW. (2007) Pseudorabies virus Us9 directs axonal sorting of viral capsids. J Virol. 81: 11363-71. PubMed

Favoreel HW, Enquist LW, Feierbach B. (2007) Actin and Rho GTPases in herpesvirus biology. Trends Microbiol. 15: 426-33. PubMed

Ch'ng TH, Spear PG, Struyf F, Enquist LW. (2007) Glycoprotein D-independent spread of pseudorabies virus infection in cultured peripheral nervous system neurons in a compartmented system. J Virol. 81: 10742-57. PubMed

Feierbach B, Bisher M, Goodhouse J, Enquist LW. (2007) In vitro analysis of transneuronal spread of an alphaherpesvirus infection in peripheral nervous system neurons. J Virol. 81: 6846-57. PubMed

Viney TJ, Balint K, Hillier D,...Enquist LW,...Roska B. (2007) Local retinal circuits of melanopsin-containing ganglion cells identified by transsynaptic viral tracing. 17: 981-88. PubMed

Reynolds AE, Enquist LW. (2006) Biological interactions between herpesviruses and cyclooxygenase enzymes. Rev Med Virol. 16: 393-403. PubMed

Feierbach B, Piccinotti S, Bisher M, Denk W, Enquist LW. (2006) Alpha-herpesvirus infection induces the formation of nuclear actin filaments. PLoS Pathog. 2: e85. PubMed

Paulus C, Sollars PJ, Pickard GE, Enquist LW. (2006) Transcriptome signature of virulent and attenuated pseudorabies virus-infected rodent brain. J Virol. 80: 1773-86. PubMed

Song CK, Enquist LW, Bartness TJ. (2005) New developments in tracing neural circuits with herpesviruses. Virus Res. 111: 235-49. PubMed

del Rio T, DeCoste CJ, Enquist LW. (2005) Actin is a component of the compensation mechanism in pseudorabies virus virions lacking the major tegument protein VP22. J Virol. 79: 8614-19. PubMed

Ch'ng TH, Enquist LW. (2005) Neuron-to-cell spread of pseudorabies virus in a compartmented neuronal culture system. J Virol. 79: 10875-89. PubMed

Ch'ng TH, Enquist LW. (2005) Efficient axonal localization of alphaherpesvirus structural proteins in cultured sympathetic neurons requires viral glycoprotein E. J Virol. 79: 8835-46. PubMed

Smith GA, Pomeranz L, Gross SP, Enquist LW. (2004) Local modulation of plus-end transport targets herpesvirus entry and egress in sensory axons. Proc Natl Acad Sci. 101: 16034-39. PubMed

Smeraski CA, Sollars PJ, Ogilvie MD, Enquist LW, Pickard GE. (2004) Suprachiasmatic nucleus input to autonomic circuits identified by retrograde transsynaptic transport of pseudorabies virus from the eye. J Comp Neurol. 471: 298-313. PubMed

Ray N, Enquist LW. (2004) Transcriptional response of a common permissive cell type to infection by two diverse alphaherpesviruses. J Virol. 78: 3489-501. PubMed

Klupp BG, Hengartner CJ, Mettenleiter TC, Enquist LW. (2004) Complete, annotated sequence of the pseudorabies virus genome. J Virol 78: 424-40. PubMed

Brittle EE, Reynolds AE, Enquist LW. (2004) Two modes of pseudorabies virus neuroinvasion and lethality in mice. J Virol. 78: 12951-63. PubMed

Enquist LW, Card JP. (2003) Recent advances in the use of neurotropic viruses for circuit analysis. Curr Opin Neurobiol. 13: 603-06. PubMed


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