Stepping toward a macaque model of HIV-1 induced AIDS

Phagocytosis-shielded lentiviral vectors improve liver gene therapy in nonhuman primates

Liver-directed gene therapy for the coagulation disorder hemophilia showed safe and effective results in clinical trials using adeno-associated viral vectors to replace a functional coagulation factor, although some unmet needs remain. Lentiviral vectors (LVs) may address some of these hurdles because of their potential for stable expression and the low prevalence of preexisting viral immunity in humans. However, systemic LV administration to hemophilic dogs was associated to mild acute toxicity and low efficacy at the administered doses. Here, exploiting intravital microscopy and LV surface engineering, we report a major role of the human phagocytosis inhibitor CD47, incorporated into LV cell membrane, in protecting LVs from uptake by professional phagocytes and innate immune sensing, thus favoring biodistribution to hepatocytes after systemic administration. By enforcing high CD47 surface content, we generated phagocytosis-shielded LVs which, upon intravenous administration to nonhuman primates, showed selective liver and spleen targeting and enhanced hepatocyte gene transfer compared to parental LV, reaching supraphysiological activity of human coagulation factor IX, the protein encoded by the transgene, without signs of toxicity or clonal expansion of transduced cells.

Toward a Macaque Model of HIV-1 Infection: Roadblocks, Progress, and Future Strategies

The human-specific tropism of Human Immunodeficiency Virus Type 1 (HIV-1) has complicated the development of a macaque model of HIV-1 infection/AIDS that is suitable for preclinical evaluation of vaccines and novel treatment strategies. Several innate retroviral restriction factors, such as APOBEC3 family of proteins, TRIM5α, BST2, and SAMHD1, that prevent HIV-1 replication have been identified in macaque cells. Accessory proteins expressed by Simian Immunodeficiency virus (SIV) such as viral infectivity factor (Vif), viral protein X (Vpx), viral protein R (Vpr), and negative factor (Nef) have been shown to play key roles in overcoming these restriction factors in macaque cells. Thus, substituting HIV-1 accessory genes with those from SIV may enable HIV-1 replication in macaques. We and others have constructed macaque-tropic HIV-1 derivatives [also called simian-tropic HIV-1 (stHIV-1) or Human-Simian Immunodeficiency Virus (HSIV)] carrying SIV vif to overcome APOBEC3 family proteins. Additional modifications to HIV-1 gag in some of the macaque-tropic HIV-1 have also been done to overcome TRIM5α restriction in rhesus and cynomolgus macaques. Although these viruses replicate persistently in macaque species, they do not result in CD4 depletion. Thus, these studies suggest that additional blocks to HIV-1 replication exist in macaques that prevent high-level viral replication. Furthermore, serial animal-to-animal passaging of macaque-tropic HIV-1 in vivo has not resulted in pathogenic variants that cause AIDS in immunocompetent macaques. In this review, we discuss recent developments made toward developing macaque model of HIV-1 infection.

The current state of animal models and genomic approaches towards identifying and validating molecular determinants of Mycobacterium tuberculosis infection and tuberculosis disease

Animal models are important in understanding both the pathogenesis of and immunity to tuberculosis (TB). Unfortunately, we are beginning to understand that no animal model perfectly recapitulates the human TB syndrome, which encompasses numerous different stages. Furthermore, Mycobacterium tuberculosis infection is a very heterogeneous event at both the levels of pathogenesis and immunity. This review seeks to establish the current understanding of TB pathogenesis and immunity, as validated in the animal models of TB in active use today. We especially focus on the use of modern genomic approaches in these models to determine the mechanism and the role of specific molecular pathways. Animal models have significantly enhanced our understanding of TB. Incorporation of contemporary technologies such as single cell transcriptomics, high-parameter flow cytometric immune profiling, proteomics, proteomic flow cytometry and immunocytometry into the animal models in use will further enhance our understanding of TB and facilitate the development of treatment and vaccination strategies.

Identification of the major histocompatibility complex class-II DM and DO alleles in a cohort of northern pig-tailed macaques (Macaca leonina)

The northern pig-tailed macaque (Macaca leonina) has been considered as an independent species from the pig-tailed macaque group. We have previously reported that this species macaque has the potential to be a useful animal model in HIV/AIDS pathogenesis and vaccine studies due to its susceptibility to HIV-1. To develop this animal into a potential HIV/AIDS model, we have studied the classical MHC genes of this animal. In this study, the non-classical MHC genes Malo-DM and Malo-DO alleles were first characterized by sequencing and cloning in 12 unrelated northern pig-tailed macaques. A total of 20 full-length sequences identified include 4 Malo-DMA, 5 Malo-DMB, 7 Malo-DOA, and 4 Malo-DOB alleles. Most of these allele sequences were shared between northern pig-tailed macaque and other macaque species in exon 2. The full-length MHC-DM and MHC-DO sequences provide more comprehensive analysis of immunogenetics of northern pig-tailed macaques and increase the value of the macaques in further biomedical studies.