Rabies Virus Target Cell Specificity and Tropism

Abstract

Rabies virus (RABV), the causative agent of rabies, is an extremely neurotropic pathogen known to cause fatal encephalitis in humans and animals. The virus shows a high degree of cellular specificity for neurons and spreads efficiently along neural networks to access the central nervous system. It is important to elucidate the mechanisms that govern viral tropism, receptor interactions, and neuronal targeting. In this article, we provide a broad overview of the current literature on rabies virus target cell specificity and tropism. Illustration A total of published studies about viral structure, receptor-mediated entry, neuron- and non-neuron cell interactions, axon transport mechanisms and viral strain differences were reviewed to summarize current knowledge regarding host virus interactions and infection dynamics. The infection of the rabies virus is initiated by viral replication in peripheral tissues such as skeletal muscle cells followed by receptor-mediated entry into peripheral neurons at the neuromuscular junctions. The attachment and internalization of the virus are mediated by multiple host receptors, including nicotinic acetylcholine receptors (nAChRs), p75 neurotrophin receptor (NTR), neural cell adhesion molecule (NCAM) and metabotropic glutamate receptor (mGluR). Hosts Virus Glycoprotein Host Cell Entry Membrane Fusion Immune Evasion Upon entry, the virus hijacks dynein-mediated retrograde axonal transport to access the central nervous system in an immune privileged environment2. Additional data indicate that non-neuronal cells like astrocytes can also become infected by the virus and contribute to immune responses. Furthermore, vesicular stomatitis virus infection interferes with neuronal function by disrupting neurotransmitter signaling and axonal structure. Differences also emerge in neural circuit usage, as viral strain variance and host receptor distributions can shape the 

viruses: host organism interface and drive differences in infection spread through neural circuits. Rabies virus is a neurotropic pathogen that causes fatal encephalitic disease in humans and mammals. This tropism for neural tissues and its spread through neuronal networks underpins the mechanisms of pathogenesis. This review discusses the host range and target cell requirements of rabies virus, with an emphasis on elucidating the molecular mechanisms that determine viral entry into cells, intracellular trafficking and host–virus interplay. The virus first replicates in peripheral tissues, mainly skeletal muscle cells, and subsequently spreads to peripheral neurons by receptor-mediated entry at neuromuscular junctions. Attachment and internalization of viral particles is facilitated by a number of neuronal receptors including nicotinic acetylcholine receptors, p75 neurotrophin receptors, neural cell adhesion molecules, and metabotropic glutamate receptors.  The viral glycoprotein is involved in crucial processes like receptor binding, membrane fusion, and immune avoidance–all of which also directly influence the infectivity and pathogenicity of the virus. After entering, the rabies virus hijacks dynein-driven retrograde axonal transport to access the central nervous system while evading immune detection. Besides neurons, accumulating evidence indicates that non-neuronal cells including astrocytes may play a role in viral persistence and innate immune modulation. In addition, the infection causes considerable changes in neuronal function: disruptions to neurotransmitter signaling and axonal integrity. Specificity and efficiency of viral spread within neural circuits is additionally influenced by viral strain variation and host receptor distribution. Molecular determinants of rabies virus tropism need to be established, as they not only further our understanding of viral neuro-pathogenesis, but also pave the way for optimised human health therapeutic approaches and enhanced safety in synaptic tracing with rabies-based eukaryotic viruses. The tropism of rabies virus is determined by a complex interplay of viral structural proteins, host receptor availability, and neuronal transport processes. Collectively, these processes facilitate effective neuroinvasion and throughout the nervous system dispersal. These findings provide insights into the molecular and cellular processes underlying rabies viruses; such knowledge will support improv ed antiviral strategies, as well as vaccine design, or safer rabies-based viral tools for neural circuit mapping in neuroscience studies.