Neurological Complications of Oncogenic Viruses: Mechanisms, Clinical Manifestations, and Emerging Insights

Oncogenic viruses are widely recognized for their pivotal role in malignant transformation; however, their capacity to induce neurological disorders has received comparatively less attention. Increasing evidence indicates that several oncogenic viruses, including human T-cell leukemia virus type 1 (HTLV-1), human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), and Kaposi's sarcoma-associated herpesvirus (KSHV), are associated with a broad spectrum of neurological complications involving both the central and peripheral nervous systems. These manifestations arise through diverse mechanisms, including direct viral neuroinvasion, persistent infection, immune-mediated tissue injury, chronic neuroinflammation, and disruption of neurovascular integrity. Moreover, virus-induced molecular alterations, such as oxidative stress, mitochondrial dysfunction, epigenetic remodelling, and aberrant cytokine signalling, contribute t neuronal dysfunction and disease progression. In this review, we critically examine the current understanding of the neurological complications associated with major oncogenic viruses by integrating evidence from molecular, experimental, and clinical studies. We first discuss the general mechanisms by which viral infections induce neurological injury, highlighting pathways shared among neurotropic and non-neurotropic viruses. We then summarise the neurological manifestations and virus-specific pathogenic mechanisms associated with each oncogenic virus, emphasising both common and distinct molecular pathways underlying neuropathogenesis. Finally, we address current diagnostic challenges, emerging biomarkers, and therapeutic strategies while identifying critical knowledge gaps that limit causal interpretation and clinical translation. A comprehensive understanding of the complex interactions between oncogenic viruses, the immune system, and the nervous system will facilitate earlier diagnosis, improve patient management, and support the development of targeted therapeutic approaches for virus-associated neurological disorders.