Our Research

Over 90% of the world’s population harbors latent varicella zoster virus (VZV), the causative agent of chickenpox and shingles. Despite the availability of a vaccine, over 1/3 of individuals will reactivate and get shingles in their lifetime significantly increasing the risk of stroke, dementia, macular degeneration, diabetes, and other debilitating diseases.

VZV induced exosomes - a major contributor to vasculitis, stroke, and CNS pathogenesis

VZV is a known risk factor for stroke and other vasculitides, such as giant cell arteritis (GCA), however the underlying mechanism(s) is unknown. Moreover, the risk of stroke is elevated for up to a year following the clearance of virus suggesting a long-lasting, non-infectious factor as a major contributor. We have recently found that VZV-induced exosomes may be a critical component in this pathology. Specifically, we found that exosomes isolated from human plasma samples from individuals with zoster, compared to controls, contained factors known to induce platelet activation and thrombosis. When we exposed naive human platelets from healthy donors to these exosomes we observed an increase in platelet activation and an increase in leukocyte aggregation (Fig. 1). These exosomes also induced proinflammatory cytokine release from brain vascular cells compared to controls. Finally, these exosomes were non-infectious and did not contain viral proteins or nucleic acids rendering them essentially undetectable from standard clinical evaluations. Overall, these findings are significant as it changes the paradigm of VZV pathogenesis which focuses on direct infection of diseased tissues and/or presence of virus to assign a causative role in disease. Understanding the immune evasive mechanisms in which VZV can contribute to stroke and other neurological diseases has the ability to change clinical practice with either longer anti-viral treatment and/or novel targets focusing on exosome transmission.

We are currently characterizing the exosome contents and studying the effects of these exosomes in the context of other diseases such as cancer, diabetes, and neuropathies.

A select publication list

  • Bubak, A.N., Como, C.N., Blackmon, A.M., Frietze, S., Mescher, T., Jones, D., Cohrs, R.J., Paucek, P., Baird, N.L., Nagel, M.A.: Varicella zoster virus induces nuclear translocation of the neurokinin-1 receptor, promoting lamellipodia formation and viral spread in spinal astrocytes. J. Infect. Dis. 218:1324-1335, 2018.

  • Nagel, M.A., Bubak, A.N.: Varicella zoster virus vasculopathy. J. Infect. Dis. 218:S107-S112, 2018.

  • Bubak, A.N., Como, C.N., Blackmon, A.M., Jones, D., Nagel, M.A.: Varicella zoster virus differentially alters morphology and suppressed proinflammatory cytokines in primary human spinal cord and hippocampal astrocytes. J. Neuroinflammation 15:318; doi: 10.1186/s12974-018-1360-9, 2018.

  •  Como, C.N., Bubak, A.N., Blackmon, A.M., Jones, D., Mueller, N.H., Davidson, R., Nagel, M.A.: Varicella zoster virus induces differential cell-type specific responses in human corneal epithelial cells and keratocytes. Invest. Ophthalmol. Vis. Sci. 60:704-711, 2019.

  •  Jones, D., Como, C.N., Jing, L., Blackmon, A., Neff, C.P., Krueger, O., Bubak, A.N., Palmer, B.E., Koelle, D.M. Nagel, M.A.: Varicella zoster virus productively infects human peripheral blood mononuclear cells to modulate expression of immunoinhibitory proteins and blocking PD-L1 enhances virus-specific CD8+ T cell effector function. PLoS Pathog. 15:e1007650, 2019.

  •  Blackmon, A.M., Como, C.N., Bubak, A.N., Mescher, T., Jones, D., Nagel, M.A.: Varicella zoster virus alters expression of cell adhesion proteins in human perineurial cells via interleukin 6. J. Infect. Dis. 220:1453-1461, 2019.

  •  Nagel, M.A., Bubak, A.N.: (Editorial) Herpes zoster, a rash of cerebrovascular events.  Mayo Clin. Proc. 94:742-744, 2019.

  •   Bubak, A.N., Como, C.N., Coughlan, C.M., Johnson, N.R., Hassell, J.E. Jr., Mescher, T., Niemeyer, C.S., Mahalingam, R., Cohrs, R.J., Boyd, T.D., Potter, H., Russ, H.A., Nagel, M.A.: Varicella-zoster virus infection of primary human spinal astrocytes produces intracellular amylin, amyloid-β, and an amyloidogenic extracellular environment. J. Infect. Dis. 221:1088-1097, 2020.

  •  Nagel, M.A., Niemeyer, C.S., Bubak, A.N.: Central nervous system infections produced by varicella zoster virus. Curr. Opin. Infect. Dis. 33:273-278, 2020.

  •  Bubak, A.N., Beseler, C., Como, C.N., Tyring, S.K., Haley, C., Mescher, T., Hassell, J.E. Jr., Cohrs, R.J., Potter, H., Nagel, M.A.:  Acute zoster plasma contains elevated amyloid, correlating with Aβ42 and amylin levels, and is amyloidogenic. J. NeuroVirol. 26:422-428, 2020. 

  •  Hudish. L., Bubak, A.N., Triolo, T., Niemeyer, C.S., Sussel, L., Nagel, M.A., Taliaferro, M.J., Russ, H.A.: Modeling hypoxia induced neuropathies using a fast and scalable human motor neuron differentiation system. Stem Cell Reports 14:1033-1043, 2020.

  •  Bubak, A.N., Traina-Dorge, V., Como, C.N., Feia, B., Pearce, C.M., Doyle-Meyers, L., Das, A., Looper, J., Mahalingam, R., Nagel, M.A.: Elevated serum substance P during simian varicella virus infection in rhesus macaques; implications for chronic inflammation and adverse cerebrovascular events. J. NeuroVirol. 26:945-951, 2020.

  •  Bubak, A.N., Beseler, C., Como, C.N., Coughlan, C.M., Johnson, N.R., Hassell, J.E. Jr., Burnet, A.M., Mescher, T., Schmid, D.S., Coleman, C., Mahalingam, R., Cohrs, R.J., Boyd, T.D., Potter, H., Shilleh, A.H., Russ, H.A., Nagel, M.A.: Amylin, Aβ42, and amyloid in VZV vasculopathy cerebrospinal fluid and infected vascular cells. J. Infect. Dis. 223:1284-1295, 2020.

  •  Mescher, T., Boyer, P.J., Bubak, A.N., Hassell, J.E. Jr., Nagel, M.A.: Detection of varicella zoster virus antigen and DNA in two cases of cerebral amyloid angiopathy. J. Neurol. Sci. 422:117315, 2021.

  •   Baxter, B.D., Larson, E.D., Merle, L., Feinstein, P., Polese, A.G., Bubak, A.N., Niemeyer, C.S., Hassell, J. Jr., Shepherd, D., Ramakrishnan, V.R., Nagel, M.A., Restrepo, D.: Transcriptional profiling reveals potential involvement of microvillous TRPM5-expressing cells in viral infection of the olfactory epithelium. BMC Genomics 22;224, 2021.

  •  Niemeyer, C.S., Mescher, T., Griggs, R., Orlicky, D.J., Wilkerson, G.K., Bubak, A.N., Hassell,  J.E. Jr., Feia, B., Mahalingam, R., Traina-Dorge, V., Nagel, M.A.: Histopathological analysis of adrenal glands after simian varicella virus infection. Viruses 13:1245; doi: 10.3390/v13071245, 2021.

  •  Bubak, A.N., Mescher, T., Mariani, M., Frietze, S.E., Hassell, J.E. Jr., Niemeyer, C.S., Como, C.N., Burnet, A.M., Subramnian, P.S., Cohrs, R.J., Mahalingam, R., Nagel, M.A.: Targeted RNA sequencing of formalin-fixed, paraffin-embedded temporal arteries from giant cell arteritis cases reveals viral signatures. Neurol. Neuroimmunol. Neuroinflamm. 8:e1078; doi: 10.1212/NXI.0000000000001078, 2021.

  •  Bubak, A.N., Como, C.N., Hassell, J.E. Jr., Mescher, T., Frietze, S.E., Niemeyer, C.S., Cohrs, R.J., Nagel, M.A.: Targeted RNA sequencing of VZV-infected brain vascular adventitial fibroblasts indicates that amyloid may be involved in VZV vasculopathy. Neurol. Neuroimmunol. Neuroinflamm. 9:e1103; doi: 10.1212/NXI.0000000000001103, 2022.

  •  Niemeyer, C.S., Mescher, T., Bubak, A.N., Medina, E.M., Hassell, J.E. Jr., Nagel, M.A.: VZV infection of primary human adrenal cortical cells produces a proinflammatory environment without cell death. Viruses 14:674; doi: 10.3390/v14040674, 2022.

  •  Sarkar, L., Oko, L., Gupta, S., Bubak, A.N., Das, B., Gupta, P., Safiriyu, A.A., Singhal, C., Neogi, U., Bloom, D., Banerjee, A., Mahalingam, R., Cohrs, R.J., Koval, M., Shindler, K.S., Pal, D., Nagel, M., Das Sharma, J.:Azadirachta indica A. Juss bark extract and its Nimbin isomers restrict β-coronaviral infection and replication. Virology 569:13-28, 2022.

  •  Mahalingam, R., Feia, B., Coleman, C., Anupindi, K., Saravanan, P., Luthens, A., Bustilios, A., Das, A., de Haro, E., Doyle-Meyers, L., Looper, J., Bubak, A.N., Niemeyer, C.S., Palmer, B., Nagel, M.A., Traina-Dorge, V.: Simian varicella virus pathogenesis in skin during varicella and zoster. Viruses 14:1167; doi: 10.3390/v14061167, 2022. 

Please see link below for a full list of publications from our lab.

https://www.ncbi.nlm.nih.gov/myncbi/andrew.bubak.1/bibliography/public/

https://www.ncbi.nlm.nih.gov/myncbi/christy.beitzel.1/bibliography/public/

Varicella Zoster Virus

VZV contributions to amyloid-associated diseases

Our group was the first to show VZV can induce amyloid, providing a direct causative role for the the virus in diseases such as Alzheimer’s disease, macular degeneration, and diabetes that have been linked by epidemiological studies. In addition to increasing host amyloid proteins (i.e., Ab42 and amylin), VZV also contains an amyloidogenic viral protein (glycoprotein B; gB) that can self-aggregate into amyloid fibrils as well as serve as a catalyst for Ab42 and amylin fibril formation (Fig. 2).

Our recent investigations into viral contributors to amyloid-associated diseases have focused on applying Nanostring spatial transcriptomics and proteomics on very rare familial Alzheimer’s disease (FAD) olfactory bulb/tract tissues from human autopsies to probe for viral signatures (Fig. 3). We are focusing on the olfactory system for 2 reasons; 1) it provides a direct route for pathogens from the environment to enter the CNS, and 2) latent VZV and HSV-1 viruses can directly access the olfactory bulb via innervation from the trigeminal ganglia following a reactivation event. We believe that neuroinflammation and cell death in the olfactory bulb can lead to a reduction in synaptic activity in the hippocampus, thus resulting in the neurodegeneration of hippocampal neurons.

We are currently using mouse models of familial Alzheimer’s disease to test whether direct VZV infection and/or exposure to non-infectious VZV exosomes can accelerate dementia thereby providing the clinical justification for prophylactic anti-viral/vaccine uptake for at-risk individuals.

Fig. 1. Exosomes from zoster (HZ) plasma induced platelet-leukocyte aggregations compared to controls (non-HZ)

Fig. 2. Directly infected primary human astrocytes show intracellular amyloid aggregates (left). Conditioned supernatant from astrocytes incubated with human amylin showed robust fibril formation from VZV-infected cells only and not mock-infected cells.

Fig. 3. Olfactory bulb/tract from a FAD patient prepped for Nanostring spatial transcriptomics.