Assistant Professor, Microbiology & Molecular Genetics
School of Medicine

virus-host interactions, alpha herpesviruses, neurovirology, latency/reactivation, local translation

Princeton University, Molecular Biology, Prof. Lynn Enquist

Alpha herpesviruses (a-HV) are common pathogens of mammals affecting more than 70% of the adult human population. After initial infection of their hosts, viral genomes reside life-long in the PNS, a state often referred to as latency. PNS neurons have specialized signaling and gene expression patterns that maintain the highly polarized morphology for optimal function. a-HV enter their hosts from mucosal surfaces (e.g. lips, eyes, genital organs) and efficiently maintain fast transport in the axons of peripheral neurons to establish successful infections in the PNS. The immediate virus-host interactions in axons define the efficiency of infection in the nervous system. Once the herpesvirus latency is established in the target tissue, these viruses become a part of the host`s microbiome and stay life-long. Several times during the life of the infected host, some of the silent viral genomes reactivate and produce infectious particles that move to peripheral tissues where they can spread to other hosts. This latency-reactivation cycle is remarkable because peripheral tissue pathogenesis is usually mild in an individual with a healthy immune system. However, in some cases reactivation is not well controlled and might lead to dermatomal rash with pain and itching, central nervous system infections (i.e. encephalitis) or neuropathic pain that can persist even long after the replicating virus is cleared from the peripheral sites of infection. The finely-tuned balance between a-HV quiescence, reactivation, and pathogenesis is not well understood. One of the major challenges is the difficulty of recapitulating the highly differentiated architecture of neurons in a culture dish to study molecular mechanisms. As a result, these immediate interactions have been largely unknown and a robust tissue culture model to study the molecular mechanisms of a-HV genome silencing and reactivation was lacking. Development of new therapies targeting multiple stages of viral life cycle demands characterization of virus-host interactions in neurons, and this requires efficient model systems.
I use primary rodent neurons cultured in compartmented dishes that physically isolate axons from the neuronal cell bodies. By infecting isolated axons, the long distance retrograde trafficking of virus particles to the neuronal cell bodies is mimicked. This system allows the investigation of the early infection events locally in axons. One of my major findings was that, virus particles induce local synthesis of several proteins in axons minutes after infection. I have also showed that there are several infection bottlenecks (e.g. long-distance transport and rate-limiting factors in axons) and thresholds (e.g. enough virus particles to induce injury signaling, protein synthesis and to engage retrograde transport machinery in axons) to initiate infection in the neuronal soma. We further identified two different modes of local interferon responses in axons. Interestingly, axonal interferon treatment limited but did not completely block a-HV capsid transport to the neuronal nucleus. Since the productive infection of neurons requires that a high number of capsids reach the cell body, the local cytokine response in axons may contribute to the establishment of a latent infection in the ganglionic cell bodies by interfering with particle transport resulting in a lower number of capsids reaching the nuclei. These findings led me to establish a reactivateable a-HV latency in vitro by using compartmented primary neurons.
My goal is to have a comprehensive understanding of the molecular details of virus induced local and global changes in neuronal biology. These studies will also contribute to better understanding of specialized neuronal pathways by addressing a fundamental question in neurovirology which is the knowledge gap regarding the temporal dynamics, signaling between axons and cell bodies, and effects of long-distance transport of HSV-1 nucleocapsids and tegument proteins in axons. The findings may reveal new pathways for preventing the significant morbidity associated with HSV-1 infection in humans and may redirect therapeutic efforts toward axonal responses in addition to the global cellular responses.

Heinrich-Pette-Institute Ph.D. Student Grant, Hamburg, Germany
Deutscher Akademischer Austausch Dienst- DAAD-Ph.D. Grant, Germany

I study virus infections of the nervous system with a focus on local and global changes in neuronal biology during infection. I have always been interested in understanding how cells respond to various stimuli, and particularly fascinated by the interplay between viral gene products and host cell machineries. My interest in virus-host interactions led me to join Prof. Dr. Thomas Dobner`s laboratory in Germany where I learned the essentials of molecular virology by studying adenoviruses and virus induced cell transformation. I started studying neurotropic virus infections in Prof. Dr. Lynn Enquist`s laboratory in Princeton University, where I learned the fundamentals of alpha herpesvirus biology and neurobiology, particularly the growth and assays of peripheral nervous system (PNS) neurons. My goal is to find a mechanistic understanding of virus induced changes in neuronal biology leading to these pathologies.

Van Cleemput J, Koyuncu OO, Laval K, Engel EA, Enquist LW. CRISPR/Cas9-constructed pseudorabies virus mutants reveal the importance of UL13 in alphaherpesvirus escape from genome silencing. J Virol. 2020 Dec 23;. doi: 10.1128/JVI.02286-20. [Epub ahead of print] PubMed PMID: 33361431.

Huang H, Koyuncu OO, Enquist LW. Pseudorabies Virus Infection Accelerates Degradation of the Kinesin-3 Motor KIF1A. J Virol. 2020 Apr 16;94(9). doi: 10.1128/JVI.01934-19. Print 2020 Apr 16. PubMed PMID: 32075931; PubMed Central PMCID: PMC7163149.

Koyuncu OO, Enquist LW, Engel EA. Invasion of the Nervous System. Curr Issues Mol Biol. 2020 Jul 29;41:1-62. doi: 10.21775/cimb.041.001. [Epub ahead of print] PubMed PMID: 32723924.

Laval K, Vernejoul JB, Van Cleemput J, Koyuncu OO, Enquist LW. Virulent Pseudorabies Virus Infection Induces a Specific and Lethal Systemic Inflammatory Response in Mice. J Virol. 2018 Dec 15;92(24). doi: 10.1128/JVI.01614-18. Print 2018 Dec 15. PubMed PMID: 30258005; PubMed Central PMCID: PMC6258956.

MacGibeny MA, Koyuncu OO, Wirblich C, Schnell MJ, Enquist LW. Retrograde axonal transport of rabies virus is unaffected by interferon treatment but blocked by emetine locally in axons. PLoS Pathog. 2018 Jul;14(7):e1007188. doi: 10.1371/journal.ppat.1007188. eCollection 2018 Jul. PubMed PMID: 30028873; PubMed Central PMCID: PMC6070286.

Koyuncu OO, MacGibeny MA, Enquist LW. Latent versus productive infection: the alpha herpesvirus switch. Future Virol. 2018 May;13(6):431-443. doi: 10.2217/fvl-2018-0023. Epub 2018 May 22. Review. PubMed PMID: 29967651; PubMed Central PMCID: PMC6021814.

Koyuncu OO, MacGibeny MA, Hogue IB, Enquist LW. Compartmented neuronal cultures reveal two distinct mechanisms for alpha herpesvirus escape from genome silencing. PLoS Pathog. 2017 Oct;13(10):e1006608. doi: 10.1371/journal.ppat.1006608. eCollection 2017 Oct. PubMed PMID: 29073268; PubMed Central PMCID: PMC5658187.

Song R, Koyuncu OO, Greco TM, Diner BA, Cristea IM, Enquist LW. Two Modes of the Axonal Interferon Response Limit Alphaherpesvirus Neuroinvasion. mBio. 2016 Feb 2;7(1):e02145-15. doi: 10.1128/mBio.02145-15. PubMed PMID: 26838720; PubMed Central PMCID: PMC4742712.

Engel EA, Song R, Koyuncu OO, Enquist LW. Investigating the biology of alpha herpesviruses with MS-based proteomics. Proteomics. 2015 Jun;15(12):1943-56. doi: 10.1002/pmic.201400604. Epub 2015 May 15. Review. PubMed PMID: 25764121; PubMed Central PMCID: PMC4482226.

Koyuncu OO, Song R, Greco TM, Cristea IM, Enquist LW. The number of alphaherpesvirus particles infecting axons and the axonal protein repertoire determines the outcome of neuronal infection. mBio. 2015 Mar 24;6(2). doi: 10.1128/mBio.00276-15. PubMed PMID: 25805728; PubMed Central PMCID: PMC4453538.

Koyuncu OO, Hogue IB, Enquist LW. Virus infections in the nervous system. Cell Host Microbe. 2013 Apr 17;13(4):379-93. doi: 10.1016/j.chom.2013.03.010. Review. PubMed PMID: 23601101; PubMed Central PMCID: PMC3647473.

Koyuncu OO, Speiseder T, Dobner T, Schmid M. Amino acid exchanges in the putative nuclear export signal of adenovirus type 5 L4-100K severely reduce viral progeny due to effects on hexon biogenesis. J Virol. 2013 Feb;87(3):1893-8. doi: 10.1128/JVI.02061-12. Epub 2012 Nov 21. PubMed PMID: 23175361; PubMed Central PMCID: PMC3554178.

Koyuncu OO, Perlman DH, Enquist LW. Efficient retrograde transport of pseudorabies virus within neurons requires local protein synthesis in axons. Cell Host Microbe. 2013 Jan 16;13(1):54-66. doi: 10.1016/j.chom.2012.10.021. Epub 2013 Jan 16. PubMed PMID: 23332155; PubMed Central PMCID: PMC3552305.

Taylor MP, Koyuncu OO, Enquist LW. Subversion of the actin cytoskeleton during viral infection. Nat Rev Microbiol. 2011 Jun;9(6):427-39. doi: 10.1038/nrmicro2574. Epub 2011 Apr 27. Review. PubMed PMID: 21522191; PubMed Central PMCID: PMC3229036.

Koyuncu OO, Dobner T. Arginine methylation of human adenovirus type 5 L4 100-kilodalton protein is required for efficient virus production. J Virol. 2009 May;83(10):4778-90. doi: 10.1128/JVI.02493-08. Epub 2009 Mar 4. PubMed PMID: 19264777; PubMed Central PMCID: PMC2682095.

Blackford AN, Bruton RK, Dirlik O, Stewart GS, Taylor AM, Dobner T, Grand RJ, Turnell AS. A role for E1B-AP5 in ATR signaling pathways during adenovirus infection. J Virol. 2008 Aug;82(15):7640-52. doi: 10.1128/JVI.00170-08. Epub 2008 May 14. PubMed PMID: 18480432; PubMed Central PMCID: PMC2493339.

Demirezen S, Dirlik OO, Beksaç MS. The association of Candida infection with intrauterine contraceptive device. Cent Eur J Public Health. 2005 Mar;13(1):32-4. PubMed PMID: 15859178.

“Establishing a Laboratory Model of Herpes simplex virus (HSV) Latency Using Compartmented Neuron Cultures” (R21)

American Society of Microbiology

American Society of Virology

Postdoctoral researcher
Princeton University 2009—2020

Cellular and Molecular Biosciences

Link to this profile
https://faculty.uci.edu/profile/?facultyId=6903

Last updated
02/17/2021