Generation of a replication-competent simian–human immunodeficiency virus, the neutralization sensitivity of which can be enhanced in the presence of a small-molecule CD4 mimic

Simian-human immunodeficiency virus (SHIV) carrying the envelope from the clade B clinical human immunodeficiency virus type 1 (HIV-1) isolate MNA, designated SHIV MNA, was generated through intracellular homologous recombination. SHIV MNA inherited biological properties from the parental HIV-1, including CCR5 co-receptor preference, resistance to neutralization by the anti-V3 loop mAb KD-247 and loss of resistance in the presence of the CD4-mimic small-molecule YYA-021. SHIV MNA showed productive replication in rhesus macaque PBMCs. Experimental infection of a rhesus macaque with SHIV MNA caused a transient but high titre of plasma viral RNA and a moderate antibody response. Immunoglobulin in the plasma at 24 weeks post-infection was capable of neutralizing SHIV MNA in the presence but not in the absence of YYA-021. SHIV MNA could serve a model for development of novel therapeutic interventions based on CD4-mimic-mediated conversion of envelope protein susceptible to antibody neutralization.