Primary Virus Envelope Cross-Reactivity of the Broadening Neutralizing Antibody Response during Early Chronic Human Immunodeficiency Virus Type 1 Infection

To test the hypothesis that changing neutralizing antibody responses against human immunodeficiency virus type 1 (HIV-1) during chronic infection were a response to emergence of neutralization escape mutants, we cloned expressed and characterized envelope clones from patients in the Multicenter AIDS Cohort Study (MACS). Pseudotyped HIV-1 envelope clones obtained from differing time points were assessed for sensitivity to neutralization by using sera from different times from the same and different patients. Clones from early and late time points during chronic infection had similar neutralization sensitivity, and neutralizing antibody responses cross-reacted with early, late, and heterologous envelopes. The potential for broadly effective HIV-1 immunization is supported.