Abstract
RNA-dependent RNA polymerases (RdRps) play a key role in the life cycle of RNA viruses and impact their immunobiology. The arenavirus lymphocytic choriomeningitis virus (LCMV) strain Clone 13 provides a benchmark model for studying chronic infection. A major genetic determinant for its ability to persist maps to a single amino acid exchange in the viral L protein, which exhibits RdRp activity, yet its functional consequences remain elusive. To unravel the L protein interactions with the host proteome, we engineered infectious L protein-tagged LCMV virions by reverse genetics. A subsequent mass-spectrometric analysis of L protein pulldowns from infected human cells revealed a comprehensive network of interacting host proteins. The obtained LCMV L protein interactome was bioinformatically integrated with known host protein interactors of RdRps from other RNA viruses, emphasizing interconnected modules of human proteins. Functional characterization of selected interactors highlighted proviral (DDX3X) as well as antiviral (NKRF, TRIM21) host factors. To corroborate these findings, we infected Trim21-/- mice with LCMV and found impaired virus control in chronic infection. These results provide insights into the complex interactions of the arenavirus LCMV and other viral RdRps with the host proteome and contribute to a better molecular understanding of how chronic viruses interact with their host.
Highlights
RNA viruses hijack and utilize host factors at all steps of their life cycle
Integration of the L protein interactomes with known RNA-dependent RNA polymerases (RdRps) interactomes from other RNA viruses highlighted common and virus-specific strategies to interact with the host proteome, which may indicate novel avenues for antiviral interventions
We developed infectious lymphocytic choriomeningitis virus (LCMV) virions with a protein tag fused to the L protein, enabling us to identify interacting host proteins by immunoprecipitation followed by mass spectrometry
Summary
RNA viruses hijack and utilize host factors at all steps of their life cycle. The viral RNA-dependent RNA polymerase (RdRp) is a key enzyme responsible for transcription and replication of viral genomes. Lymphocytic choriomeningitis virus (LCMV) is a (-) RNA virus of the Arenaviridae and represents a well-established model system that led to seminal findings in immunology and host-pathogen research [9,10,11,12]. It serves as a benchmark model of chronic viral infections [9, 13] whereby the strain Clone 13 (Cl13) causes immunosuppression and persists in mice for several months [14, 15]. A better molecular understanding of the L protein and its role in the viral biology is hampered by lack of complete protein structure and unknown host protein interactors
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