SIV/HIV nef Recombinant Virus (SHIVnef) Produces Simian AIDS in Rhesus Macaques

Abstract

The simian immunodeficiency virus (SIV) nef gene is an important determinant of viral load and acquired immunodeficiency syndrome (AIDS) in macaques. A role(s) for the HIV-1 nef gene in infection and pathogenesis was investigated by constructing recombinant viruses in which the nef gene of the pathogenic molecular clone SIVmac239 nef was replaced with either HIV-1sf2nef or HIV-1sf33nef. These chimeras, designated SHIV-2nef and SHIV-33nef, expressed HIV-1 Nef protein and replicated efficiently in cultures of rhesus macaque lymphoid cells. In two SHIV-2nef-infected juvenile rhesus macaques and in one of two SHIV-33nef-infected juvenile macaques, virus loads remained at low levels in both peripheral blood and lymph nodes in acute and chronic phases of infection (for >83 weeks). In striking contrast, the second SHIV-33nef-infected macaque showed high virus loads during the chronic stage of infection (after 24 weeks). CD4+ T-cell numbers declined dramatically in this latter animal, which developed simian AIDS (SAIDS) at 47-53 weeks after inoculation; virus was recovered at necropsy at 53 weeks and designated SHIV-33Anef. Sequence analysis of the HIV-1sf33 nef gene in SHIV-33Anef revealed four consistent amino acid changes acquired during passage in vivo. Interestingly, one of these consensus mutations generated a tyr-x-x-leu (Y-X-X-L) motif in the HIV-1sf33 Nef protein. This motif is characteristic of certain endocytic targeting sequences and also resembles a src-homology region-2 (SH-2) motif found in many cellular signaling proteins. Four additional macaques infected with SHIV-33Anef contained high virus loads, and three of these animals progressed to fatal SAIDS. Several of the consensus amino acid changes in Nef, including Y-X-X-L motif, were retained in these recipient animals exhibiting high virus load and disease. In summary, these findings indicate that the SHIV-33Anef chimera is pathogenic in rhesus macaques and that this approach, i.e., construction of chimeric viruses, will be important for analyzing the function(s) of HIV-1 nef genes in immunodeficiency in vivo, testing antiviral therapies aimed at inhibiting AIDS, and investigating adaptation of this HIV-1 accessory gene to the macaque host.

Nef Binds p6* in GagPol during Replication of Human Immunodeficiency Virus Type 1

“…This finding suggests genetically a link between Nef and p6* in GagPol. Second, when Nef from HIV-1 is introduced into the simian immunodeficiency virus SIVmac239, the resulting chimeric virus replicates poorly in rhesus macaques until mutations in Nef are observed (30). One study describes the accumulation of such compensatory changes in the C-terminal flexible loop of Nef.…”

Human Immunodeficiency VirusnefSignature Sequences Are Associated with Pulmonary Hypertension

“…18 These substitutions (including H 40 Y and A 53 P) became the predominant residues in close to 100% of the molecular clones recovered 53 weeks postinfection, suggesting positive selection pressures.…”

“…The full-length HIV-nef from the subject samples was cloned and nucleotide sequences were aligned and translated using Geneious. 20 We also compared the HIV-nef alleles recovered from subjects in this study to nef sequences in SHIV-nef-infected macaques 18 with PH-like pulmonary vascular remodeling. 17 …”

“…Furthermore, Nef is associated with significant pulmonary vascular remodeling including obliterative vascular lesions indistinguishable from those in end-stage human PH. 17,18 Recent studies from Sehgal's group revealed remarkable Golgi fragmentation in endothelial and smooth muscle cells in the PHlike vascular lesions in macaques and, strikingly, the same cells displayed endosomes bearing HIV-nef.…”

Interactions of HIV-1 NEF with cellular signal transducing proteins

“…• CD4 (17,19,72,157) • p35 thioesterase (160) • β-COP (161) • Actin (162) • Adaptins (22)(23)(24)26,163) • V-ATPase (25) immediate cellular partners that it interacts with. A large number of cellular proteins have already been reported to bind to Nef (Table 2).…”