I n the span of a few months, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as the aetiological agent of coronavirus disease 2019 (COVID-19). Weeks later, viral diagnostic measures were deployed 1. This served to supplement the common disease signs and symptoms of COVID-19 of cough, fever and dyspnoea. As all are seen during seasonal upper respiratory tract infections 2 , precise diagnostic tests detect viral nucleic acids, viral antigens or serological tests are required to affirm SARS-CoV-2 infection 3. Chest computed tomography (CT) or magnetic resonance imaging (MRI) confirm disease manifestations 2,3. The signature of COVID-19 is the life-threatening acute respiratory distress syndrome (ARDS) 4. While the lung is the primary viral target, the cardiovascular, brain, kidney, liver and immune systems are commonly compromised by infection 5. Thus, due to significant COVID-19 morbidity and mortality, containment of viral transmission through contact tracing, clinical assessment and virus detection was implemented through social distancing, face masks, contact isolation and hand hygiene to limit SARS-CoV-2 transmission 6 .

Elimination of HIV-1 requires clearance and removal of integrated proviral DNA from infected cells and tissues. Here, sequential long-acting slow-effective release antiviral therapy (LASER ART) and CRISPR-Cas9 demonstrate viral clearance in latent infectious reservoirs in HIV-1 infected humanized mice. HIV-1 subgenomic DNA fragments, spanning the long terminal repeats and the Gag gene, are excised in vivo, resulting in elimination of integrated proviral DNA; virus is not detected in blood, lymphoid tissue, bone marrow and brain by nested and digital-droplet PCR as well as RNAscope tests. No CRISPR-Cas9 mediated off-target effects are detected. Adoptive transfer of human immunocytes from dual treated, virus-free animals to uninfected humanized mice fails to produce infectious progeny virus. In contrast, HIV-1 is readily detected following sole LASER ART or CRISPR-Cas9 treatment. These data provide proof-of-concept that permanent viral elimination is possible.

Potent antiretroviral activities and a barrier to viral resistance characterize the human immunodeficiency virus type one (HIV-1) integrase strand transfer inhibitor dolutegravir (DTG). Herein, a long-acting parenteral DTG was created through chemical modification to improve treatment outcomes. A hydrophobic and lipophilic modified DTG prodrug is encapsulated into poloxamer nanoformulations (NMDTG) and characterized by size, shape, polydispersity, and stability. Retained intracytoplasmic NMDTG particles release drug from macrophages and attenuate viral replication and spread of virus to CD4+ T cells. Pharmacokinetic tests in Balb/cJ mice show blood DTG levels at, or above, its inhibitory concentration90 of 64 ng/mL for 56 days, and tissue DTG levels for 28 days. NMDTG protects humanized mice from parenteral challenge of the HIV-1ADA strain for two weeks. These results are a first step towards producing a long-acting DTG for human use by affecting drug apparent half-life, cell and tissue drug penetration, and antiretroviral potency.

Suppression of HIV replication by antiretroviral therapy (ART) or host immunity can prevent AIDS but not other HIV-associated conditions including neurocognitive impairment (HIV-NCI). Pathogenesis in HIV-suppressed individuals has been attributed to reservoirs of latent-inducible virus in resting CD4+ T cells. Macrophages are persistently infected with HIV but their role as HIV reservoirs in vivo has not been fully explored. Here we show that infection of conventional mice with chimeric HIV, EcoHIV, reproduces physiological conditions for development of disease in people on ART including immunocompetence, stable suppression of HIV replication, persistence of integrated, replication-competent HIV in T cells and macrophages, and manifestation of learning and memory deficits in behavioral tests, termed here murine HIV-NCI. EcoHIV established latent reservoirs in CD4+ T lymphocytes in chronically-infected mice but could be induced by epigenetic modulators ex vivo and in mice. In contrast, macrophages expressed EcoHIV constitutively in mice for up to 16 months; murine leukemia virus (MLV), the donor of gp80 envelope in EcoHIV, did not infect macrophages. Both EcoHIV and MLV were found in brain tissue of infected mice but only EcoHIV induced NCI. Murine HIV-NCI was prevented by antiretroviral prophylaxis but once established neither persistent EcoHIV infection in mice nor NCI could be reversed by long-acting antiretroviral therapy. EcoHIV-infected, athymic mice were more permissive to virus replication in macrophages than were wild-type mice, suffered cognitive dysfunction, as well as increased numbers of monocytes and macrophages infiltrating the brain. Our results suggest an important role of HIV expressing macrophages in HIV neuropathogenesis in hosts with suppressed HIV replication.

Macrophages serve as vehicles for the carriage and delivery of polymer-coated nanoformulated antiretroviral therapy (nanoART). Although superior to native drug, high drug concentrations are required for viral inhibition. Herein, folate-modified atazanavir/ritonavir (ATV/r)-encased polymers facilitated macrophage receptor targeting for optimizing drug dosing. Folate coating of nanoART ATV/r significantly enhanced cell uptake, retention and antiretroviral activities without altering cell viability. Enhanced retentions of folate-coated nanoART within recycling endosomes provided a stable subcellular drug depot. Importantly, five-fold enhanced plasma and tissue drug levels followed folate-coated formulation injection in mice. Folate polymer encased ATV/r improves nanoART pharmacokinetics bringing the technology one step closer to human use.