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nsP4 Is a Major Determinant of Alphavirus Replicase Activity and Template Selectivity
- Source :
- Journal of Virology, Journal of virology
- Publication Year :
- 2021
- Publisher :
- American Society for Microbiology, 2021.
-
Abstract
- Alphaviruses have positive-strand RNA genomes containing two open reading frames (ORFs). The first ORF encodes the nonstructural (ns) polyproteins P123 and P1234 that act as precursors for the subunits of the viral RNA replicase (nsP1 to nsP4). Processing of P1234 leads to the formation of a negative-strand replicase consisting of nsP4 (RNA polymerase) and P123 components. Subsequent processing of P123 results in a positive-strand replicase. The second ORF encoding the structural proteins is expressed via the synthesis of a subgenomic RNA. Alphavirus replicase is capable of using template RNAs that contain essential cis-active sequences. Here, we demonstrate that the replicases of nine alphaviruses, expressed in the form of separate P123 and nsP4 components, are active. Their activity depends on the abundance of nsP4. The match of nsP4 to its template strongly influences efficient subgenomic RNA synthesis. nsP4 of Barmah Forest virus (BFV) formed a functional replicase only with matching P123, while nsP4s of other alphaviruses were compatible also with several heterologous P123s. The P123 components of Venezuelan equine encephalitis virus and Sindbis virus (SINV) required matching nsP4s, while P123 of other viruses could form active replicases with different nsP4s. Chimeras of Semliki Forest virus, harboring the nsP4 of chikungunya virus, Ross River virus, BFV, or SINV were viable. In contrast, chimeras of SINV, harboring an nsP4 from different alphaviruses, exhibited a temperature-sensitive phenotype. These findings highlight the possibility for formation of new alphaviruses via recombination events and provide a novel approach for the development of attenuated chimeric viruses for vaccination strategies. IMPORTANCE A key element of every virus with an RNA genome is the RNA replicase. Understanding the principles of RNA replicase formation and functioning is therefore crucial for understanding and responding to the emergence of new viruses. Reconstruction of the replicases of nine alphaviruses from nsP4 and P123 polyproteins revealed that the nsP4 of the majority of alphaviruses, including the mosquito-specific Eilat virus, could form a functional replicase with P123 originating from a different virus, and the corresponding chimeric viruses were replication-competent. nsP4 also had an evident role in determining the template RNA preference and the efficiency of RNA synthesis. The revealed broad picture of the compatibility of the replicase components of alphaviruses is important for understanding the formation and functioning of the alphavirus RNA replicase and highlights the possibilities for recombination between different alphavirus species.
- Subjects :
- Sindbis virus
animal structures
viruses
Immunology
RNA-dependent RNA polymerase
Alphavirus
Viral Nonstructural Proteins
Semliki Forest virus
Virus Replication
Microbiology
Cell Line
03 medical and health sciences
chemistry.chemical_compound
Virology
RNA polymerase
Animals
Humans
Viral Replicase Complex Proteins
replicase
030304 developmental biology
Subgenomic mRNA
Polyproteins
0303 health sciences
genetic recombination
biology
Base Sequence
030306 microbiology
Alphavirus Infections
RNA polymerases
RNA
virus diseases
DNA-Directed RNA Polymerases
biochemical phenomena, metabolism, and nutrition
biology.organism_classification
RNA-Dependent RNA Polymerase
3. Good health
Genome Replication and Regulation of Viral Gene Expression
chemistry
Eilat virus
Insect Science
RNA, Viral
RNA replication
Human medicine
Subjects
Details
- Language :
- English
- ISSN :
- 10985514 and 0022538X
- Volume :
- 95
- Issue :
- 20
- Database :
- OpenAIRE
- Journal :
- Journal of Virology
- Accession number :
- edsair.doi.dedup.....5c22f00787b2a803f6b625ec4ebe11ab