SIV Infection Is Associated with Transient Acute-Phase Steatosis in Hepatocytes In Vivo.

Metabolic-dysfunction-associated fatty liver disease (MAFLD) is a major cause of morbidity and mortality in HIV-infected individuals, even those receiving optimal antiretroviral therapy. Here, we utilized the SIV rhesus macaque model and advanced laparoscopic techniques for longitudinal collection of liver tissue to elucidate the timing of pathologic changes. The livers of both SIV-infected (N = 9) and SIV-naïve uninfected (N = 8) macaques were biopsied and evaluated at four time points (weeks -4, 2, 6, and 16-20 post-infection) and at necropsy (week 32). SIV DNA within the macaques' livers varied by over 4 logs at necropsy, and liver SIV DNA significantly correlated with SIV RNA in the plasma throughout the study. Acute phase liver pathology (2 weeks post-infection) was characterized by evidence for fat accumulation (microvesicular steatosis), a transient elevation in both AST and cholesterol levels within the serum, and increased hepatic expression of the PPARA gene associated with cholesterol metabolism and beta oxidation. By contrast, the chronic phase of the SIV infection (32 weeks post-infection) was associated with sinusoidal dilatation, while steatosis resolved and concentrations of AST and cholesterol remained similar to those in uninfected macaques. These findings suggest differential liver pathologies associated with the acute and chronic phases of infection and the possibility that therapeutic interventions targeting metabolic function may benefit liver health in people newly diagnosed with HIV.

Western-style diet in the presence of elevated circulating testosterone induces adipocyte hypertrophy without proinflammatory responses in rhesus macaques.

PROBLEM: Anovulatory infertility is commonly associated with hyperandrogenemia (elevated testosterone, T), insulin resistance, obesity, and white adipose tissue (WAT) dysfunction associated with adipocyte hypertrophy. However, whether hyperandrogenemia and adipocyte hypertrophy per se induce a proinflammatory response is unknown. METHOD OF STUDY: Young adult female rhesus macaques were exposed to an obesogenic Western-style diet (WSD) in the presence of elevated circulating testosterone (T+WSD) or a low-fat control diet with no exogenous T. Immune cells residing in visceral omental white adipose tissue (OM-WAT), corpus luteum and the contralateral ovary, endometrium, lymph nodes, bone marrow, and peripheral blood mononuclear cells were characterized by flow cytometry during the luteal phase of the reproductive cycle. RESULTS: Following one year of treatment, T+WSD animals became more insulin-resistant and exhibited increased body fat and adipocyte hypertrophy compared to controls. T+WSD treatment did not induce macrophage polarization toward a proinflammatory phenotype in the tissues examined. Additionally, T+WSD treatment did not affect TNFα production by bone marrow macrophages in response to toll-like receptor agonists. While the major lymphoid subsets were not significantly affected by T+WSD treatment, we observed a significant reduction in the frequency of effector memory CD8+ T-cells (Tem) in OM-WAT, but not in other tissues. Notably, OM-WAT Tem frequencies were negatively correlated with insulin resistance as assessed by the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). CONCLUSION: This study shows that short-term T+WSD treatment induces weight gain, insulin resistance, and adipocyte hypertrophy, but does not have a significant effect on systemic and tissue-resident proinflammatory markers, suggesting that adipocyte hypertrophy and mild hyperandrogenemia alone are not sufficient to induce a proinflammatory response.

A Multifunctional and Highly Adaptable Reporter System for CRISPR/Cas Editing.

CRISPR/Cas systems are some of the most promising tools for therapeutic genome editing. The use of these systems is contingent on the optimal designs of guides and homology-directed repair (HDR) templates. While this design can be achieved in silico, validation and further optimization are usually performed with the help of reporter systems. Here, we describe a novel reporter system, termed BETLE, that allows for the fast, sensitive, and cell-specific detection of genome editing and template-specific HDR by encoding multiple reporter proteins in different open-reading frames. Out-of-frame non-homologous end joining (NHEJ) leads to the expression of either secretable NanoLuc luciferase, enabling a highly sensitive and low-cost analysis of editing, or fluorescent mTagBFP2, allowing for the enumeration and tissue-specific localization of genome-edited cells. BETLE includes a site to validate CRISPR/Cas systems for a sequence-of-interest, making it broadly adaptable. We evaluated BETLE using a defective moxGFP with a 39-base-pair deletion and showed spCas9, saCas9, and asCas12a editing as well as sequence-specific HDR and the repair of moxGFP in cell lines with single and multiple reporter integrants. Taken together, these data show that BETLE allows for the rapid detection and optimization of CRISPR/Cas genome editing and HDR in vitro and represents a state-of the art tool for future applications in vivo.

Therapeutic neutralizing monoclonal antibody administration protects against lethal yellow fever virus infection.

Yellow fever virus (YFV) is a reemerging global health threat, driven by several factors, including increased spread of the mosquito vector and rapid urbanization. Although a prophylactic vaccine exists, vaccine hesitancy, supply deficits, and distribution difficulties leave specific populations at risk of severe YFV disease, as evidenced by recent outbreaks in South America. To establish a treatment for patients with severe YFV infection, we tested 37 YFV-specific monoclonal antibodies isolated from vaccinated humans and identified two capable of potently neutralizing multiple pathogenic primary YFV isolates. Using both hamster and nonhuman primate models of lethal YFV infection, we demonstrate that a single administration of either of these two potently neutralizing antibodies during acute infection fully controlled viremia and prevented severe disease and death in treated animals. Given the potential severity of YFV-induced disease, our results show that these antibodies could be effective in saving lives and fill a much-needed void in managing YFV cases during outbreaks.

Long-term hepatitis B virus infection of rhesus macaques requires suppression of host immunity.

Hepatitis B virus has infected a third of the world's population, and 296 million people are living with chronic infection. Chronic infection leads to progressive liver disease, including hepatocellular carcinoma and liver failure, and there remains no reliable curative therapy. These gaps in our understanding are due, in large part, to a paucity of animal models of HBV infection. Here, we show that rhesus macaques regularly clear acute HBV infection, similar to adult humans, but can develop long-term infection if immunosuppressed. Similar to patients, we longitudinally detected HBV DNA, HBV surface antigen, and HBV e antigen in the serum of experimentally infected animals. In addition, we discovered hallmarks of HBV infection in the liver, including RNA transcription, HBV core and HBV surface antigen translation, and covalently closed circular DNA biogenesis. This pre-clinical animal model will serve to accelerate emerging HBV curative therapies into the clinic.