title: Neutralization of primary HIV-1 isolates by anti-envelope monoclonal antibodies.
abstract: OBJECTIVE
  To evaluate human monoclonal antibodies (MAb) for neutralizing activity against primary HIV-1 isolates in peripheral blood mononuclear cells.
  
  
  METHODS
  Neutralization activity data were obtained from 11 laboratories on a coded panel consisting of six human MAb to HIV envelope V3, CD4-binding region or gp41. Hyperimmune globulin against HIV-1 and normal human immunoglobulin G were supplied as controls. Each laboratory received pre-titered virus for use in the studies.
  
  
  METHODS
  Each laboratory measured neutralization of the MAb against laboratory strain HIVMN, genomic clone HIVJR-CSF, two subtype B and one subtype D primary isolates.
  
  
  RESULTS
  The titers of the centrally supplied virus stocks as determined by re-titration or back-titration varied among laboratories and were generally 10-100-fold less than provided. The neutralizing activity of each MAb varied by as much as a 1000-fold among laboratories. These differences may result from varying sensitivity in neutralization assay protocols and the differing susceptibility of primary cells to infection with HIV-1.
  
  
  CONCLUSIONS
  To consolidate the data from multiple laboratories, the neutralization titers were compared by classifying antibodies as neutralizing if the antibody concentration for 50% virus inhibition was < or = 10 micrograms/ml. By this criterion, the CD4-binding region and gp41 MAb neutralized all four subtype B viruses and the subtype D isolate in a few of the laboratories. The V3 MAb neutralized only HIVMN and the closely related HIVJR-CSF viruses.
authors.affiliation: Division of AIDS, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: D'Souza
authors.forename: G
authors.initials: G
authors.lastname: Milman
authors.forename: J A
authors.initials: JA
authors.lastname: Bradac
authors.forename: D
authors.initials: D
authors.lastname: McPhee
authors.forename: C V
authors.initials: CV
authors.lastname: Hanson
authors.forename: R M
authors.initials: RM
authors.lastname: Hendry
mesh_terms: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens / Q000276:immunology; D015686:Gene Products, env / Q000276:immunology*; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120 / Q000276:immunology; D015700:HIV Envelope Protein gp41 / Q000276:immunology; D015497:HIV-1 / Q000145:classification / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D066298:In Vitro Techniques; D007963:Leukocytes, Mononuclear / Q000821:virology; D009500:Neutralization Tests; D010446:Peptide Fragments / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D015686:Gene Products, env; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments