title: Detection of recent HIV infections in African individuals infected by HIV-1 non-B subtypes using HIV antibody avidity.
abstract: BACKGROUND
  To estimate HIV incidence several methods have been used to discriminate recent HIV infections from long-standing infections using a single serum sample.
  
  
  OBJECTIVE
  To evaluate the performance of the anti-HIV avidity index (AI) for identifying recent HIV infections in individuals with a known date of seroconversion from Uganda, where the predominant HIV subtypes are A and D.
  
  
  METHODS
  We selected 149 repository serum samples from Ugandan HIV-positive individuals and evaluated the AI. Specimens collected < or =6 months after seroconversion were considered as recent infections, and those collected >6 months as long-standing infections. All specimens were serotyped using a V3 peptide enzyme immunoassay.
  
  
  RESULTS
  The mean AI was 0.55+/-0.21 among the 108 patients with recent infections and 0.93+/-0.14 among the 41 samples from long-standing infections (p<0.0001). The AI test showed a sensitivity of 85.2% and a specificity of 85.4% at a cutoff of 0.80. No significant association was observed between serotype and the misclassification of samples by AI.
  
  
  CONCLUSIONS
  The AI, which is inexpensive and easy-to-perform, can be useful in identifying recent HIV infections in countries where HIV-1 non-B subtypes are prevalent.
authors.affiliation: Dipartimento di Malattie Infettive, Parassitarie e Immunomediate, Istituto Superiore di Sanità, Rome, Italy. barbara.suligoi@iss.it
authors.forename: Barbara
authors.initials: B
authors.lastname: Suligoi
authors.forename: Stefano
authors.initials: S
authors.lastname: Buttò
authors.forename: Claudio
authors.initials: C
authors.lastname: Galli
authors.forename: Daniela
authors.initials: D
authors.lastname: Bernasconi
authors.forename: Robert A
authors.initials: RA
authors.lastname: Salata
authors.forename: Lara
authors.initials: L
authors.lastname: Tavoschi
authors.forename: Michele
authors.initials: M
authors.lastname: Chiappi
authors.forename: Peter
authors.initials: P
authors.lastname: Mugyenyi
authors.forename: Fulvia
authors.initials: F
authors.lastname: Pimpinelli
authors.forename: Cissy
authors.initials: C
authors.lastname: Kityo
authors.forename: Vincenza
authors.initials: V
authors.lastname: Regine
authors.forename: Giovanni
authors.initials: G
authors.lastname: Rezza
mesh_terms: D000915:Antibody Affinity; D005260:Female; D005838:Genotype; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis* / Q000276:immunology; D015497:HIV-1 / Q000145:classification / Q000235:genetics / Q000276:immunology*; D006801:Humans; D015994:Incidence; D008297:Male; D012680:Sensitivity and Specificity; D012703:Serotyping; D013997:Time Factors; D014454:Uganda
chemical_list: D015483:HIV Antibodies