Mutation in the Disordered Linker Region of Capsid Disrupts Viral Kinetics of a Neuropathogenic SIV in Rhesus
Cheri A Lee1, Vanessa M Hirsch1
1Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Abstract:
TRIM5α polymorphism in rhesus macaques (RM) limits the genetic pool of animals in which we can perform simian immunodeficiency virus (SIV) studies without first screening animals for permissive TRIM5α genotypes. We have previously shown that polymorphisms in the TRIM5α B30.2/SPRY domain impact the level of SIVsmm viremia in RM and that amino acid substitutions (P37S/R98S) in the capsid N-terminal domain (CA-NTD) enables the virus to overcome restriction in RMs with the restrictive homozygous TRIM5αTFP/TFP genotype. Since this genotype also negatively impacted the development of central nervous system (CNS) lesions in animals infected with the parental source of CL757, we sought to generate a TRIM5αTFP/TFP-resistant clone, SIV-804E-CL757-P37S/R98S (CL757-SS), using a similar strategy. Unexpectedly, viral replication of CL757-SS was impaired in RMs with either the permissive TRIM5αTFP/Q or the restrictive TRIM5αTFP/TFP genotype. Analysis of the virus which emerged in the latter animals led to the discovery of a preexisting mutation relative to other SIVs. This P146T substitution in a conserved disordered linker region in the C-terminal domain of capsid (CA-CTD) has been shown to inhibit proper formation of HIV-1 capsid particles. Restoration of this residue to proline in the context of the TRIM5α-SS escape mutations not only restored viral replication, but also enhanced the infectivity of our previously reported neurotropic clone, even in RMs with permissive TRIM5α genotypes. IMPORTANCE SIV infection of rhesus macaques has become a valuable model for the development of AIDS vaccines and antiretroviral therapies. Polymorphisms in the rhesus macaque TRIM5α gene can affect SIV replication, making it necessary to genetically screen macaques for TRIM5α alleles that are permissive for SIV replication. This limits the pool of animals that can be used in a study, thereby making the acquisition of animals needed to fulfill study parameters difficult. We have constructed a viral clone that induces neuroAIDS in rhesus macaques regardless of their TRIM5α genotype, while also highlighting the important role the disordered linker domain plays in viral infectivity.
Insights
Researchers developed a simian immunodeficiency virus (SIV) clone that causes neuroAIDS in rhesus macaques irrespective of their TRIM5α genotype. This breakthrough overcomes limitations in SIV studies and enhances understanding of viral infectivity.
Area of Science:
- Virology
- Immunology
- Genetics
Background:
- Simian immunodeficiency virus (SIV) infection in rhesus macaques (RM) is a key model for AIDS research.
- TRIM5α gene polymorphisms in RM restrict SIV replication, necessitating genetic screening and limiting available animal models.
- Previous work identified TRIM5α B30.2/SPRY domain polymorphisms affecting SIVsmm viremia and capsid N-terminal domain (CA-NTD) substitutions enabling SIV to overcome TRIM5α restriction.
Purpose of the Study:
- To create a TRIM5α-resistant SIV clone that overcomes TRIM5α restriction in RM.
- To investigate viral replication and neuroAIDS development in RM with different TRIM5α genotypes.
- To identify viral factors influencing infectivity and host restriction.
Main Methods:
- Generation of a TRIM5α-resistant SIV clone (CL757-SS) with specific capsid N-terminal domain (CA-NTD) substitutions.
- Infection of rhesus macaques with different TRIM5α genotypes (TFP/Q and TFP/TFP) using the parental and engineered SIV clones.
- Analysis of viral replication, emergence of mutations, and central nervous system (CNS) lesion development.
Main Results:
- The engineered CL757-SS clone showed impaired replication in both permissive (TFP/Q) and restrictive (TFP/TFP) TRIM5α genotypes.
- A pre-existing P146T substitution in the capsid C-terminal domain (CA-CTD) disordered linker region was discovered in emerging viruses.
- Restoring the P146 residue to proline in the context of TRIM5α-SS escape mutations restored viral replication and enhanced neurotropic clone infectivity across TRIM5α genotypes.
Conclusions:
- A novel SIV clone induces neuroAIDS in rhesus macaques irrespective of TRIM5α genotype, expanding the utility of this animal model.
- The study highlights the critical role of the CA-CTD disordered linker region in viral infectivity and host restriction.
- This work provides a valuable tool for AIDS vaccine and antiretroviral therapy development by overcoming TRIM5α-mediated restriction.
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