# HCMV infection of terminally differentiated neurons disrupts microtubule organization, resulting in neurite retraction

## TL;DR

This study shows how HCMV infection harms neurons by disrupting microtubules, and suggests that stabilizing microtubules could help protect against neurological damage.

## Contribution

The novel finding is that HCMV disrupts microtubules in human neurons, and that microtubule stabilization partially mitigates this damage.

## Key findings

- HCMV infection causes neurite retraction and syncytia formation in human iPSC-derived neurons.
- HCMV downregulates microtubule-associated proteins but spares other cytoskeletal elements.
- Paclitaxel improves neurite outgrowth but does not affect viral replication.

## Abstract

Human cytomegalovirus (HCMV) is a prolific human herpesvirus that infects most individuals by adulthood. While typically asymptomatic in adults, congenital infection can induce serious neurological symptoms, including hearing loss, visual deficits, cognitive impairment, and microcephaly in 10%–15% of cases. HCMV has been shown to infect most neural cells, with our group recently demonstrating this capacity in stem cell-derived forebrain neurons. Infection of neurons induces deleterious effects on calcium dynamics and electrophysiological function paired with gross restructuring of neuronal morphology. Here, we utilize an induced pluripotent stem cell-derived model of the human forebrain to demonstrate how HCMV infection induces syncytia, drives neurite retraction, and remodels microtubule networks to promote viral production and release. We establish that HCMV downregulates microtubule-associated proteins while largely sparing other cytoskeletal elements. Furthermore, we pharmacologically modulate microtubule dynamics using paclitaxel (stabilize) and colchicine (destabilize) to examine the effects on neurite structure, syncytial morphology, and viral release. With paclitaxel, we found improvement of neurite outgrowth, but neither paclitaxel nor colchicine impacted viral titers. Together, these data suggest that HCMV infection-induced disruption of microtubules in human cortical neurons can be partially mitigated with microtubule stabilization, suggesting a potential avenue for future neuroprotective strategies.

Infection by human cytomegalovirus (HCMV) continues to cause significant damage to human health. In the absence of a vaccine, vertical transmission from mother to fetus can result in profound neurological damage impacting quality of life. These studies focus on understanding the impact of HCMV infection on forebrain cortical neurons derived from induced pluripotent stem cells (iPSCs). We show that infection results in loss of neurite extension accompanied by cell-to-cell fusion. These pathogenic changes involve HCMV infection-mediated disruption of the microtubule network in iPSCs from different patient backgrounds. The microtubule stabilization agent paclitaxel partially protected neurite length and altered syncytia morphology without impacting viral replication. This work is part of our continued efforts to define putative strategies to limit HCMV-induced neurological damage.