Implication of the C terminal domain of SIVmac251 nef protein in the viral pathogenesis.
Int Conf AIDS 1998 Jun 28-Jul 3; 12:24-5 (abstract no. 11213)
La Font B, Riviere Y, Gloeckler L, Beyer C, Hurtrel B, Kirn A, Aubertin AM Unite Inserm 74-Institut de Virologie, Strasbough, France.
The inoculation of rhesus macaques with Simian immunodeficency Viruses (SIV) results in a persistent infection leading to an AIDS like disease. However several molecularly cloned SIV were reported to be highly attenuated. Among them SIVmacBK28 derived from the pathogenic SIVmac251 isolate can be used to identify virulence determinants. Given that i) the nef gene is important for the maintenance of a high viral load in macaques, ii) the SIVmacBK28 nef ORF possesses one nucleotide deletion compared to the nef gene of a pathogenic clone SIVmac239 (this results in a frameshift and the formation of a truncated Nef protein missing the 31 C terminal amino acids present in Nef SIVmac239), we analysed the evolution of the BK28 nef gene in vivo. Macaques were infected with SIVmacBK28-41, a virus with a BK28 genome in which the premature stop codon present in the transmembrane (TM) glycoprotein gene was mutated to restore a full length gp41 TM, and the infection was monitored by measuring the number of infected PBMC. At different time points, the nef gene was amplified by PCR from PBMC or lymphoid organs cells and sequenced. Different situations were observed during the follow up of 12 macaques. After the early phase of infection, some animals maintained a cell-associated viremia and progressed to AIDS whereas for others, virus isolation was intermittent or not possible. Those macaques remained asymptomatic for years and the virus carried the original BK28 nef sequence. At later time when virus replication resumed the nef ORF has a precise insertion of one nucleotide restoring a SIVmac239-like carboxyl extremity. The expression of this domain is associated with several SIVmac239-like mutations in position 19, 144, 196, 227 and 260 of the Nef protein. In macaques that maintained a high viral load the same insertion had occurred already during the first month of infection. Our analysis shows that the C terminal domain of Nef protein contributes to the full expression of its functions necessary to maintain a high level of virus replication in vivo.
Keywords: AEGIS, Gene Products, nef, SIV, Genes, nef, Simian Acquired Immunodeficiency Syndrome, Macaca mulatta, Virus Replication, Virulence, DNA Primers, Cesium, Viral Load, Polymerase Chain Reaction, Acquired Immunodeficiency Syndrome, Animal, virology, genetics, ICA12
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