title: Low avidity antibody: a reliable method to diagnose a recent HIV-1 infection.
abstract: Standard serological tests (both EIA and Immunoblotting) have reached high levels of sensitivity and reproducibility, but do not indicate whether infection is recent or longstanding. Since many patients with HIV-1 infection are not usually diagnosed until symptom presentation, the possibility to distinguish between acute and chronic infection has become increasingly important for the purposes of therapeutic decision-making, partner notification and epidemiological surveillance. We evaluated a guanidine-based-antibody-avidity assay in a selected group of recent (within six months from seroconversion) and chronic (more than forty eight months) HIV-1 infections in an attempt to shed more light on the significance of the avidity index in establishing the time of infection. Sera from newly infected individuals showed a low mean avidity index (ranging from 0.35 to 0.60 with a standard deviation 0.09) at baseline and a clear increasing value at the following times of observation. Our data showed that an avidity index <0.70 might be presumptive of infection occurring within 9 months. Avidity index levels might distinguish between acute and chronic infection. The method is semi-automated, inexpensive and easy to perform, and estimates the time elapsed from seroconversion, thereby identifying a recent infection.
authors.affiliation: Section of Microbiology and Section of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Bologna, Bologna, Italy. mariacarla.re@unibo.it
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Re
authors.forename: Pasqua
authors.initials: P
authors.lastname: Schiavone
authors.forename: Francesca
authors.initials: F
authors.lastname: Vitone
authors.forename: Isabella
authors.initials: I
authors.lastname: Bon
authors.forename: Elisa
authors.initials: E
authors.lastname: De Crignis
authors.forename: Carlo
authors.initials: C
authors.lastname: Biagetti
authors.forename: Federica
authors.initials: F
authors.lastname: Alessandrini
authors.forename: Davide
authors.initials: D
authors.lastname: Gibellini
mesh_terms: D000208:Acute Disease; D000328:Adult; D000915:Antibody Affinity; D005260:Female; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology; D006679:HIV Seropositivity; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D015483:HIV Antibodies