Sensitivity to inhibition by beta-chemokines correlates with biological phenotypes of primary HIV-1 isolates

Primary HIV-1 isolates were evaluated for their sensitivity to inhibition by beta-chemokines RANTES (regulated upon activation, normal T-cell expressed and secreted), macrophage inflammatory protein 1 alpha (MIP-1 alpha), and MIP-1 beta. Virus isolates of both nonsyncytium-inducing (NSI) and syncytium-inducing (SI) biological phenotypes recovered from patients at various stages of HIV-1 infection were assessed, and the results indicated that only the isolates with the NSI phenotype were substantially inhibited by the beta-chemokines. More important to note, these data demonstrate that resistance to inhibition by beta-chemokines RANTES, MIP-1 alpha and MIP-1 beta is not restricted to T cell line-adapted SI isolates but is also a consistent property among primary SI isolates. Analysis of isolates obtained sequentially from infected individuals in whom viruses shifted from NSI to SI phenotype during clinical progression exhibited a parallel loss of sensitivity to beta-chemokines. Loss of virus sensitivity to inhibition by beta-chemokines RANTES, MIP-1 alpha, and MIP-1 beta was furthermore associated with changes in the third variable (V3) region amino acid residues previously described to correlate with a shift of virus phenotype from NSI to SI. Of interest, an intermediate V3 genotype correlated with a partial inhibition by the beta-chemokines. In addition, we also identified viruses sensitive to RANTES, MIP-1 alpha, and MIP-1 beta of NSI phenotype that were isolated from individuals with AIDS manifestations, indicating that loss of sensitivity to beta-chemokine inhibition and shift in viral phenotype are not necessarily prerequisites for the pathogenesis of HIV-1 infection.