title: Phylogenetic characteristics of three new HIV-1 N strains and implications for the origin of group N.
abstract: BACKGROUND
  The three divergent HIV-1 groups M, N and O were very probably introduced into the human population by independent cross-species transmissions of SIVcpz from the chimpanzee subspecies Pan troglodytes troglodytes in central Africa.
  
  
  OBJECTIVE
  To characterize HIV-1 group N strains and to elucidate the group's epidemiology and relationship to HIV-1 strains O and M, and SIVcpz.
  
  
  METHODS
  DNA amplification, sequencing and phylogenetic analyses were performed to characterize viruses from three group N-infected individuals (YBF106, YBF115 and YBF116) together with YBF30 and YBF105 previously described.
  
  
  RESULTS
  Full-length genome sequence was determined for virus YBF106; gag, pol and env sequences were obtained for YBF116; pol (integrase) and env (gp41) fragments were obtained for YBF115. The gag, pol, 5'-vif and nef sequences were phylogenetically more closely related to HIV-1 M while 3'-vif, vpr, tat, vpu and env clustered with SIVcpz from P. t. troglodytes. Sequence analysis revealed no mutations potentially responsible for drug resistance.
  
  
  CONCLUSIONS
  The finding that all group N viruses displayed the same recombinant structure and were monophyletic indicates that a single transfer event of SIVcpz to humans can account for the origin of this group. Despite the pathogenic outcome of the known group N infections, the extremely low prevalence of this divergent HIV-1 suggests that this group is not an emerging threat to human health at the present time. However, continuous monitoring of HIV-1 diversity will be important to survey the potential of unusual HIV infections, such as group N, to contribute to the HIV/AIDS pandemic.
authors.affiliation: International Centre for Medical Research, Franceville, Gabon, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Roques
authors.forename: David L
authors.initials: DL
authors.lastname: Robertson
authors.forename: Sandrine
authors.initials: S
authors.lastname: Souquière
authors.forename: Cristian
authors.initials: C
authors.lastname: Apetrei
authors.forename: Eric
authors.initials: E
authors.lastname: Nerrienet
authors.forename: Françoise
authors.initials: F
authors.lastname: Barré-Sinoussi
authors.forename: Michaela
authors.initials: M
authors.lastname: Müller-Trutwin
authors.forename: François
authors.initials: F
authors.lastname: Simon
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002648:Child; D005260:Female; D015658:HIV Infections / Q000145:classification / Q000235:genetics*; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D010802:Phylogeny