title: Importance of the N-distal AP-2 binding element in Nef for simian immunodeficiency virus replication and pathogenicity in rhesus macaques.
abstract: Point mutations in SIVmac239 Nef disrupting CD4 downmodulation and enhancement of virion infectivity attenuate viral replication in acutely infected rhesus macaques, but changes selected later in infection fully restore Nef function (A. J. Iafrate et al., J. Virol. 74:9836-9844, 2000). To further evaluate the relevance of these Nef functions for viral persistence and disease progression, we analyzed an SIVmac239 Nef mutant containing a deletion of amino acids Q64 to N67 (delta64-67Nef). This mutation inactivates the N-distal AP-2 clathrin adaptor binding element and disrupts the abilities of Nef to downregulate CD4, CD28 and CXCR4 and to stimulate viral replication in vitro. However, it does not impair the downmodulation of CD3 and class I major histocompatibility complex (MHC-I) or MHC-II and the upregulation of the MHC-II-associated invariant chain, and it has only a moderate effect on the enhancement of virion infectivity. Replication of the delta64-67Nef variant in acutely infected macaques was intermediate between grossly nef-deleted and wild-type SIVmac239. Subsequently, three of six macaques developed moderate to high viral loads and developed disease, whereas the remaining animals efficiently controlled SIV replication and showed a more attenuated clinical course of infection. Sequence analysis revealed that the deletion in nef was not repaired in any of these animals. However, some changes that slightly enhanced the ability of Nef to downmodulate CD4 and moderately increased Nef-mediated enhancement of viral replication and infectivity in vitro were observed in macaques developing high viral loads. Our results imply that both the Nef functions that were disrupted by the delta64-67 mutation and the activities that remained intact contribute to viral pathogenicity.
authors.affiliation: Department of Virology, Universitätsklinikum, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Brenner
authors.forename: Jan
authors.initials: J
authors.lastname: Münch
authors.forename: Michael
authors.initials: M
authors.lastname: Schindler
authors.forename: Steffen
authors.initials: S
authors.lastname: Wildum
authors.forename: Nicole
authors.initials: N
authors.lastname: Stolte
authors.forename: Christiane
authors.initials: C
authors.lastname: Stahl-Hennig
authors.forename: Dietmar
authors.initials: D
authors.lastname: Fuchs
authors.forename: Kerstin
authors.initials: K
authors.lastname: Mätz-Rensing
authors.forename: Monika
authors.initials: M
authors.lastname: Franz
authors.forename: Jonathan
authors.initials: J
authors.lastname: Heeney
authors.forename: Peter
authors.initials: P
authors.lastname: Ten Haaft
authors.forename: Tomek
authors.initials: T
authors.lastname: Swigut
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Hrecka
authors.forename: Jacek
authors.initials: J
authors.lastname: Skowronski
authors.forename: Frank
authors.initials: F
authors.lastname: Kirchhoff
mesh_terms: D000208:Acute Disease; D033962:Adaptor Protein Complex 2 / Q000378:metabolism*; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D015693:Gene Products, nef / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014644:Genetic Variation / Q000235:genetics; D006801:Humans; D016180:Lentivirus Infections / Q000235:genetics / Q000378:metabolism / Q000821:virology; D008253:Macaca mulatta / Q000235:genetics / Q000821:virology*; D008969:Molecular Sequence Data; D011485:Protein Binding; D016415:Sequence Alignment; D015302:Simian Immunodeficiency Virus / Q000472:pathogenicity* / Q000502:physiology*; D013997:Time Factors; D014779:Virus Replication
chemical_list: D033962:Adaptor Protein Complex 2; D015693:Gene Products, nef