Limitations and use of the Morpheus-V5 dual reporter virus in assessing interventions that target HIV latency.

HIV can persist indefinitely in latently infected CD4 + T-cells as an integrated provirus with limited or no viral transcription and expression of viral proteins. We further characterised a recently described dual reporter virus, Morpheus-V5, that expresses murine heat-stable antigen and mCherry in productively infected cells (which is HIV LTR dependent) and V5 and Nerve growth factor receptor (NGFR) in latently infected cells (which is HIV LTR independent). We demonstrated successful infection of resting and activated CD4 + T-cells using Morpheus-V5 pseudotyped with either X4, R5 or dual tropic envelope proteins. We also showed that expression of NGFR (a transmembrane protein) enriched for infected cells (that contained HIV DNA) with inducible virus, however uninfected cells also expressed NGFR as a result of NGFR incorporation into virion preparations. Following treatment of CD4 + T-cells infected with Morpheus-V5 with latency reversal agents, we demonstrated an increase in the percentage of cells expressing mCherry and a decrease in the percentage of cells expressing NGFR. In addition, using this model, we showed that latent and productively infected cells had different levels of sensitivity to pro-apoptotic compounds. The Morpheus-V5 dual reporter virus has some limitations and overestimates the number of latently infected cells, but is a useful tool to investigate interventions that disrupt HIV latency.