307 – High Resistance of HIV-1CH040 Envelope Glycoproteins to bNAbs Without Loss of Efficient Viral Entry

Background

A transmitter/founder (T/F) HIV-1 strain can establish a productive infection in healthy individuals. HIV-1 envelope glycoproteins (Envs) mediate viral entry and have to maintain a delicate balance between evasion from neutralizing antibodies and entry compatibility. Escape from broadly neutralizing antibodies (bnAbs), which target highly conserved regions in HIV Envs, pose significant challenges to HIV-1 Envs. 

Methods

We evaluated the impact of the T/F HIV-1_CH040 resistance to multiple bnAbs on efficient viral entry by comparing the infectivity of recombinant luciferase-expressing viruses that display CH040 Envs with the infectivity of recombinant viruses displaying Envs from different HIV-1 strains. We also introduced rationally designed engineered changes to disrupt bnAbs epitopes using Stratagene site-directed mutagenesis and tested the effects on susceptibility. We studied the efficiency of HIV-1 entry, mediated by engineered variants of CH040 Envs, by cell-cell fusion, western blotting analysis, cell-cell transmission, and cold sensitivity. We measured sensitivity to multiple bnAbs and known Env susceptibilities by neutralizing assays. In addition, viral replication kinetics and viral-cell fusion activity were tested in the context of recombinant simian-immunodeficiency viruses (SHIVs) in macaque lymphocytes.

Results

We identified high resistance of a transmitted/founding Envs CH040 to most bnAbs without a fitness cost associated with loss of efficient entry. HIV-1_CH040, which mediates viral entry as efficiently as other primary Envs, represents a resistant viral strain of high public health concern. Unexpectedly, expression of CH040 Envs is relatively low, but HIV-1 CH040 replicates well in human T cells and HIV-1_CH040 replicates well in vitro in pig-tailed macaque lymphocytes. These results highlight the potential ability of some T/F strains to evolve high bnAb resistance and replication fitness in parallel.

Conclusions

Our findings highlight several aspects of HIV strains of public health concern and provide additional considerations for the development of HIV-1 prevention and therapeutic strategies.

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