RESUMO
To dissect mechanisms of caprine arthritis-encephalitis lentivirus-induced arthritis, an undefined immunodominant viral glycoprotein, gp90 (G. C. Johnson, A. F. Barbet, P. Klevjer-Anderson, and T. C. McGuire, Infect. Immun. 41:657-665, 1983), was characterized. Monoclonal antibody to gp90 and specific antiserum to env gene products demonstrated that gp90 was a transmembrane protein (TM) dimer. Goats with progressive arthritis had high antibody titers to oligomeric and monomeric (38-kDa) TM.
Assuntos
Vírus da Artrite-Encefalite Caprina/imunologia , Produtos do Gene env/imunologia , Glicoproteínas/imunologia , Infecções por Lentivirus/imunologia , Proteínas Virais/imunologia , Animais , Anticorpos Monoclonais , Artrite/etiologia , Artrite/imunologia , Artrite/veterinária , Glicosilação , Doenças das Cabras , Cabras , Epitopos ImunodominantesRESUMO
To define the structure of the caprine arthritis-encephalitis virus (CAEV) env gene and characterize genetic changes which occur during antigenic variation, we sequenced the env genes of CAEV-63 and CAEV-Co, two antigenic variants of CAEV defined by serum neutralization. The deduced primary translation product of the CAEV env gene consists of a 60- to 80-amino-acid signal peptide followed by an amino-terminal surface protein (SU) and a carboxy-terminal transmembrane protein (TM) separated by an Arg-Lys-Lys-Arg cleavage site. The signal peptide cleavage site was verified by amino-terminal amino acid sequencing of native CAEV-63 SU. In addition, immunoprecipitation of [35S]methionine-labeled CAEV-63 proteins by sera from goats immunized with recombinant vaccinia virus expressing the CAEV-63 env gene confirmed that antibodies induced by env-encoded recombinant proteins react specifically with native virion SU and TM. The env genes of CAEV-63 and CAEV-Co encode 28 conserved cysteines and 25 conserved potential N-linked glycosylation sites. Nucleotide sequence variability results in 62 amino acid changes and one deletion within the SU and 34 amino acid changes within the TM.
Assuntos
Variação Antigênica , Vírus da Artrite-Encefalite Caprina/genética , Produtos do Gene env/genética , Genes env , Genoma Viral , Sequência de Aminoácidos , Animais , Vírus da Artrite-Encefalite Caprina/imunologia , Sequência de Bases , Células Cultivadas , Clonagem Molecular , Códon/genética , DNA Viral/genética , Feminino , Produtos do Gene env/imunologia , Cabras , Dados de Sequência Molecular , RNA Viral/genética , RNA Viral/isolamento & purificação , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
The nucleotide sequence of the pol-env intergenic region of two isolates of caprine arthritis-encephalitis virus (CAEV) was determined. Two open reading frames (orfs) were identified, designated Q and S by homology with visna virus. CAEV orf S is a single exon encoding a deduced 87-amino acid gene product sharing 36 amino acid identities with the visna trans-acting transcriptional activator (Tat). Ten of these identities comprise a conserved CGCRLCNPGW sequence similar to a cysteine-rich domain essential for trans-activation by human immunodeficiency virus Tat. To determine if transcription promoted by the CAEV long terminal repeat (LTR) could be stimulated in CAEV-infected goat synovial membrane cells, a plasmid (pCAE-CAT) expressing bacterial chloramphenicol acetyltransferase (CAT) under control of the CAEV LTR was transfected into uninfected and infected cells. Sixfold enhancement of CAT activity was observed in infected cells using 100 ng of transfected plasmid. To determine if the pol-env region encodes a gene product which trans-activates the CAEV LTR, goat synovial membrane cells were cotransfected with pCAE-CAT and pRSV-1.9, a plasmid expressing the pol-env region under control of the Rous sarcoma virus LTR. Results indicated that the CAEV genome encodes a tat gene product attributable to orf S.
Assuntos
Vírus da Artrite-Encefalite Caprina/genética , Genes env/genética , Genes pol/genética , Transativadores/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Cloranfenicol O-Acetiltransferase/genética , Produtos do Gene tat/genética , Cabras , Dados de Sequência Molecular , Fases de Leitura Aberta , Plasmídeos , Sequências Repetitivas de Ácido Nucleico , Homologia de Sequência do Ácido Nucleico , Transfecção/genética , Vírus Visna-Maedi/genéticaRESUMO
The synthesis of caprine arthritis-encephalitis virus structural proteins was analysed in infected cells labelled with [35S]methionine and [3H]glucosamine and by translation of virion RNA in vitro. Viral polypeptides were isolated from infected cell lysates or from in vitro translation products by immunoprecipitation with specific antisera and resolved by SDS-PAGE. Results indicated that the gag gene-encoded p28, p19 and p16 virion core proteins were formed by cleavage processing of a 55K Mr precursor with several intermediate polypeptides. The gp135 virion surface glycoprotein, encoded by the env gene, was formed by post-translational modification of a glycosylated precursor of 150K apparent Mr. This precursor was formed by glycosylation of a 90K primary env gene product.
