Cargando…

Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein

BACKGROUND: Lentiviral genomes encode multiple structural and regulatory proteins. Expression of the full complement of viral proteins is accomplished in part by alternative splicing of the genomic RNA. Caprine arthritis encephalitis virus (CAEV) and maedi-visna virus (MVV) are two highly related sm...

Descripción completa

Detalles Bibliográficos
Autores principales: Valas, Stephen, Rolland, Morgane, Perrin, Cécile, Perrin, Gérard, Mamoun, Robert Z
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2291067/
https://www.ncbi.nlm.nih.gov/pubmed/18312636
http://dx.doi.org/10.1186/1742-4690-5-22
_version_ 1782152430196097024
author Valas, Stephen
Rolland, Morgane
Perrin, Cécile
Perrin, Gérard
Mamoun, Robert Z
author_facet Valas, Stephen
Rolland, Morgane
Perrin, Cécile
Perrin, Gérard
Mamoun, Robert Z
author_sort Valas, Stephen
collection PubMed
description BACKGROUND: Lentiviral genomes encode multiple structural and regulatory proteins. Expression of the full complement of viral proteins is accomplished in part by alternative splicing of the genomic RNA. Caprine arthritis encephalitis virus (CAEV) and maedi-visna virus (MVV) are two highly related small-ruminant lentiviruses (SRLVs) that infect goats and sheep. Their genome seems to be less complex than those of primate lentiviruses since SRLVs encode only three auxiliary proteins, namely, Tat, Rev, and Vif, in addition to the products of gag, pol, and env genes common to all retroviruses. Here, we investigated the central part of the SRLV genome to identify new splice elements and their relevance in viral mRNA and protein expression. RESULTS: We demonstrated the existence of a new 5' splice (SD) site located within the central part of CAEV genome, 17 nucleotides downstream from the SD site used for the rev mRNA synthesis, and perfectly conserved among SRLV strains. This new SD site was found to be functional in both transfected and infected cells, leading to the production of a transcript containing an open reading frame generated by the splice junction with the 3' splice site used for the rev mRNA synthesis. This open reading frame encodes two major protein isoforms of 18- and 17-kDa, named Rtm, in which the N-terminal domain shared by the Env precursor and Rev proteins is fused to the entire cytoplasmic tail of the transmembrane glycoprotein. Immunoprecipitations using monospecific antibodies provided evidence for the expression of the Rtm isoforms in infected cells. The Rtm protein interacts specifically with the cytoplasmic domain of the transmembrane glycoprotein in vitro, and its expression impairs the fusion activity of the Env protein. CONCLUSION: The characterization of a novel CAEV protein, named Rtm, which is produced by an additional multiply-spliced mRNA, indicated that the splicing pattern of CAEV genome is more complex than previously reported, generating greater protein diversity. The high conservation of the SD site used for the rtm mRNA synthesis among CAEV and MVV strains strongly suggests that the Rtm protein plays a role in SRLV propagation in vivo, likely by competing with Env protein functions.
format Text
id pubmed-2291067
institution National Center for Biotechnology Information
language English
publishDate 2008
publisher BioMed Central
record_format MEDLINE/PubMed
spelling pubmed-22910672008-04-09 Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein Valas, Stephen Rolland, Morgane Perrin, Cécile Perrin, Gérard Mamoun, Robert Z Retrovirology Research BACKGROUND: Lentiviral genomes encode multiple structural and regulatory proteins. Expression of the full complement of viral proteins is accomplished in part by alternative splicing of the genomic RNA. Caprine arthritis encephalitis virus (CAEV) and maedi-visna virus (MVV) are two highly related small-ruminant lentiviruses (SRLVs) that infect goats and sheep. Their genome seems to be less complex than those of primate lentiviruses since SRLVs encode only three auxiliary proteins, namely, Tat, Rev, and Vif, in addition to the products of gag, pol, and env genes common to all retroviruses. Here, we investigated the central part of the SRLV genome to identify new splice elements and their relevance in viral mRNA and protein expression. RESULTS: We demonstrated the existence of a new 5' splice (SD) site located within the central part of CAEV genome, 17 nucleotides downstream from the SD site used for the rev mRNA synthesis, and perfectly conserved among SRLV strains. This new SD site was found to be functional in both transfected and infected cells, leading to the production of a transcript containing an open reading frame generated by the splice junction with the 3' splice site used for the rev mRNA synthesis. This open reading frame encodes two major protein isoforms of 18- and 17-kDa, named Rtm, in which the N-terminal domain shared by the Env precursor and Rev proteins is fused to the entire cytoplasmic tail of the transmembrane glycoprotein. Immunoprecipitations using monospecific antibodies provided evidence for the expression of the Rtm isoforms in infected cells. The Rtm protein interacts specifically with the cytoplasmic domain of the transmembrane glycoprotein in vitro, and its expression impairs the fusion activity of the Env protein. CONCLUSION: The characterization of a novel CAEV protein, named Rtm, which is produced by an additional multiply-spliced mRNA, indicated that the splicing pattern of CAEV genome is more complex than previously reported, generating greater protein diversity. The high conservation of the SD site used for the rtm mRNA synthesis among CAEV and MVV strains strongly suggests that the Rtm protein plays a role in SRLV propagation in vivo, likely by competing with Env protein functions. BioMed Central 2008-02-29 /pmc/articles/PMC2291067/ /pubmed/18312636 http://dx.doi.org/10.1186/1742-4690-5-22 Text en Copyright © 2008 Valas et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Valas, Stephen
Rolland, Morgane
Perrin, Cécile
Perrin, Gérard
Mamoun, Robert Z
Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
title Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
title_full Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
title_fullStr Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
title_full_unstemmed Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
title_short Characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
title_sort characterization of a new 5' splice site within the caprine arthritis encephalitis virus genome: evidence for a novel auxiliary protein
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2291067/
https://www.ncbi.nlm.nih.gov/pubmed/18312636
http://dx.doi.org/10.1186/1742-4690-5-22
work_keys_str_mv AT valasstephen characterizationofanew5splicesitewithinthecaprinearthritisencephalitisvirusgenomeevidenceforanovelauxiliaryprotein
AT rollandmorgane characterizationofanew5splicesitewithinthecaprinearthritisencephalitisvirusgenomeevidenceforanovelauxiliaryprotein
AT perrincecile characterizationofanew5splicesitewithinthecaprinearthritisencephalitisvirusgenomeevidenceforanovelauxiliaryprotein
AT perringerard characterizationofanew5splicesitewithinthecaprinearthritisencephalitisvirusgenomeevidenceforanovelauxiliaryprotein
AT mamounrobertz characterizationofanew5splicesitewithinthecaprinearthritisencephalitisvirusgenomeevidenceforanovelauxiliaryprotein