Treatment with indinavir, zidovudine, and lamivudine in adults with human immunodeficiency virus infection and prior antiretroviral therapy

Tat-dependent conditionally replicating adenoviruses expressing diphtheria toxin A for specifically killing HIV-1-infected cells

HIV-1 infection remains a public health problem with no cure. Although antiretroviral therapy (ART) is effective for suppressing HIV-1 replication, it requires lifelong drug administration due to a stable reservoir of latent proviruses and may cause serious side effects and drive the emergence of drug-resistant HIV-1 variants. Gene therapy represents an alternative approach to overcome the limitations of conventional treatments against HIV-1 infection. In this study, we constructed and investigated the antiviral effects of an HIV-1 Tat-dependent conditionally replicating adenovirus, which selectively replicates and expresses the diphtheria toxin A chain (Tat-CRAds-DTA) in HIV-1-infected cells both in vitro and in vivo. We found that Tat-CRAds-DTA could specifically induce cell death and inhibit virus replication in HIV-1-infected cells mediated by adenovirus proliferation and DTA expression. A low titer of progeny Tat-CRAds-DTA was also detected in HIV-1-infected cells. In addition, Tat-CRAds-DTA showed no apparent cytotoxicity to HIV-1-negative cells and demonstrated significant therapeutic efficacy against HIV-1 infection in a humanized mouse model. The findings in this study highlight the potential of Tat-CRAds-DTA as a new gene therapy for the treatment of HIV-1 infection.

A simultaneous knockout knockin genome editing strategy in HSPCs potently inhibits CCR5- and CXCR4-tropic HIV-1 infection

Allogeneic hematopoietic stem and progenitor cell transplant (HSCT) of CCR5 null (CCR5Δ32) cells can be curative for HIV-1-infected patients. However, because allogeneic HSCT poses significant risk, CCR5Δ32 matched bone marrow donors are rare, and CCR5Δ32 transplant does not confer resistance to the CXCR4-tropic virus, it is not a viable option for most patients. We describe a targeted Cas9/AAV6-based genome editing strategy for autologous HSCT resulting in both CCR5- and CXCR4-tropic HIV-1 resistance. Edited human hematopoietic stem and progenitor cells (HSPCs) maintain multi-lineage repopulation capacity in vivo, and edited primary human T cells potently inhibit infection by both CCR5-tropic and CXCR4-tropic HIV-1. Modification rates facilitated complete loss of CCR5-tropic replication and up to a 2,000-fold decrease in CXCR4-tropic replication without CXCR4 locus disruption. This multi-factor editing strategy in HSPCs could provide a broad approach for autologous HSCT as a functional cure for both CCR5-tropic and CXCR4-tropic HIV-1 infections.

HIV-1 mRNA knockdown with CRISPR/CAS9 enhances neurocognitive function

Mixed glia are infiltrated with HIV-1 virus early in the course of infection leading to the development of a persistent viral reservoir in the central nervous system. Modification of the HIV-1 genome using gene editing techniques, including CRISPR/Cas9, has shown great promise towards eliminating HIV-1 viral reservoirs; whether these techniques are capable of removing HIV-1 viral proteins from mixed glia, however, has not been systematically evaluated. Herein, the efficacy of adeno-associated virus 9 (AAV9)-CRISPR/Cas9 gene editing for eliminating HIV-1 messenger RNA (mRNA) from cortical mixed glia was evaluated in vitro and in vivo. In vitro, a within-subjects experimental design was utilized to treat mixed glia isolated from neonatal HIV-1 transgenic (Tg) rats with varying doses (0, 0.9, 1.8, 2.7, 3.6, 4.5, or 5.4 µL corresponding to a physical titer of 0, 4.23 × 109, 8.46 × 109, 1.269 × 1010, 1.692 × 1010, 2.115 × 1010, and 2.538 × 1010 gc/µL) of CRISPR/Cas9 for 72 h. Dose-dependent decreases in the number of HIV-1 mRNA, quantified using an innovative in situ hybridization technique, were observed in a subset (i.e., n = 5 out of 8) of primary mixed glia. In vivo, HIV-1 Tg rats were retro-orbitally inoculated with CRISPR/Cas9 for two weeks, whereby treatment resulted in profound excision (i.e., approximately 53.2%) of HIV-1 mRNA from the medial prefrontal cortex. Given incomplete excision of the HIV-1 viral genome, the clinical relevance of HIV-1 mRNA knockdown for eliminating neurocognitive impairments was evaluated via examination of temporal processing, a putative neurobehavioral mechanism underlying HIV-1-associated neurocognitive disorders (HAND). Indeed, treatment with CRISPR/Cas9 protractedly, albeit not permanently, restored the developmental trajectory of temporal processing. Proof-of-concept studies, therefore, support the susceptibility of mixed glia to gene editing and the potential of CRISPR/Cas9 to serve as a novel therapeutic strategy for HAND, even in the absence of full viral eradication.

Next-generation bNAbs for HIV-1 cure strategies

Despite the ability to suppress viral replication using anti-retroviral therapy (ART), HIV-1 remains a global public health problem. Curative strategies for HIV-1 have to target and eradicate latently infected cells across the body, i.e. the viral reservoir. Broadly neutralizing antibodies (bNAbs) targeting the HIV-1 envelope glycoprotein (Env) have the capacity to neutralize virions and bind to infected cells to initiate elimination of these cells. To improve the efficacy of bNAbs in terms of viral suppression and viral reservoir eradication, next generation antibodies (Abs) are being developed that address the current limitations of Ab treatment efficacy; (1) low antigen (Env) density on (reactivated) HIV-1 infected cells, (2) high viral genetic diversity, (3) exhaustion of immune cells and (4) short half-life of Abs. In this review we summarize and discuss preclinical and clinical studies in which anti-HIV-1 Abs demonstrated potent viral control, and describe the development of engineered Abs that could address the limitations described above. Next generation Abs with optimized effector function, avidity, effector cell recruitment and immune cell activation have the potential to contribute to an HIV-1 cure or durable control.

HIV Expression in Infected T Cell Clones

The principal barrier to an HIV-1 cure is the persistence of infected cells harboring replication-competent proviruses despite antiretroviral therapy (ART). HIV-1 transcriptional suppression, referred to as viral latency, is foremost among persistence determinants, as it allows infected cells to evade the cytopathic effects of virion production and killing by cytotoxic T lymphocytes (CTL) and other immune factors. HIV-1 persistence is also governed by cellular proliferation, an innate and essential capacity of CD4+ T cells that both sustains cell populations over time and enables a robust directed response to immunological threats. However, when HIV-1 infects CD4+ T cells, this capacity for proliferation can enable surreptitious HIV-1 propagation without the deleterious effects of viral gene expression in latently infected cells. Over time on ART, the HIV-1 reservoir is shaped by both persistence determinants, with selective forces most often favoring clonally expanded infected cell populations harboring transcriptionally quiescent proviruses. Moreover, if HIV latency is incomplete or sporadically reversed in clonal infected cell populations that are replenished faster than they are depleted, such populations could both persist indefinitely and contribute to low-level persistent viremia during ART and viremic rebound if treatment is withdrawn. In this review, select genetic, epigenetic, cellular, and immunological determinants of viral transcriptional suppression and clonal expansion of HIV-1 reservoir T cells, interdependencies among these determinants, and implications for HIV-1 persistence will be presented and discussed.

Advancements in Cell-Based Therapies for HIV Cure

The treatment of human immunodeficiency virus (HIV-1) has evolved since the establishment of combination antiretroviral therapy (ART) in the 1990s, providing HIV-infected individuals with approaches that suppress viral replication, prevent acquired immunodeficiency syndrome (AIDS) throughout their lifetime with continuous therapy, and halt HIV transmission. However, despite the success of these regimens, the global HIV epidemic persists, prompting a comprehensive exploration of potential strategies for an HIV cure. Here, we offer a consolidated overview of cell-based therapies for HIV-1, focusing on CAR-T cell approaches, gene editing, and immune modulation. Persistent challenges, including CAR-T cell susceptibility to HIV infection, stability, and viral reservoir control, underscore the need for continued research. This review synthesizes current knowledge, highlighting the potential of cellular therapies to address persistent challenges in the pursuit of an HIV cure.

Evolution Driven By A Varying Host Environment Selects For Distinct HIV-1 Entry Phenotypes and Other Informative Variants

HIV-1 generates remarkable intra- and inter-host viral diversity during infection. In response to dynamic selective pressures of the host environment, HIV-1 will evolve distinct phenotypes - biological features that provide fitness advantages. The transmitted form of HIV-1 has been shown to require a high density of CD4 on the target cell surface (as found on CD4+ T cells) and typically uses CCR5 as a co-receptor during entry. This phenotype is referred to as R5 T cell-tropic (or R5 T-tropic); however, HIV-1 can switch to a secondary co-receptor, CXCR4, resulting in a X4 T cell-tropic phenotype. Macrophage-tropic (or M-tropic) HIV-1 can evolve to efficiently enter cells expressing low densities of CD4 on their surface (such as macrophages/microglia). So far only CCR5-using M-tropic viruses have been found. M-tropic HIV-1 is most frequently found within the central nervous system, and infection of the CNS has been associated with neurological impairment. It has been shown that interferon resistance phenotypes have a selective advantage during transmission, but the underlying mechanism of this is still unclear. During untreated infection, HIV-1 evolves under selective pressure from both the humoral/antibody response and CD8+ T cell killing. Sufficiently potent antiviral therapy will suppress viral replication, but if the antiviral drugs are not sufficiently potent to stop replication then the replicating virus will evolve drug resistance. HIV-1 phenotypes are highly relevant to treatment efforts, clinical outcomes, vaccine studies, and cure strategies. Therefore, it is critical to understand the dynamics of the host environment that drive these phenotypes and how they affect HIV-1 pathogenesis. This review will provide a comprehensive discussion of HIV-1 entry, transmission, and drug resistance phenotypes. Finally, we will assess the methods used in previous and current research to characterize these phenotypes.

Biphasic decay of intact SHIV genomes following initiation of antiretroviral therapy complicates analysis of interventions targeting the reservoir

The latent reservoir for HIV-1 in resting CD4+ T cells persists despite antiretroviral therapy (ART) and precludes cure. Reservoir-targeting interventions are evaluated in ART-treated macaques infected with simian immunodeficiency virus (SIV) or simian-human immunodeficiency virus (SHIV). Efficacy is determined by reservoir measurements before and after the intervention. However, most proviruses persisting in the setting of ART are defective. In addition, intact HIV-1 and SIV genomes undergo complex, multiphasic decay observable when new infection events are blocked by ART. Intervention-induced elimination of latently infected cells must be distinguished from natural decay. Here, we address these issues for SHIV. We describe an intact proviral DNA assay that allows digital counting of SHIV genomes lacking common fatal defects. We show that intact SHIV genomes in circulating CD4+ T cells undergo biphasic decay during the first year of ART, with a rapid first phase (t1/2 = 30.1 d) and a slower second phase (t1/2 = 8.1 mo) that is still more rapid that the slow decay observed in people with HIV-1 on long-term ART (t1/2 = 3.7 y). In SHIV models, most interventions are tested during 2nd phase decay. Natural 2nd phase decay must be considered in evaluating interventions as most infected cells present at this time do not become part of the stable reservoir. In addition, for interventions tested during 2nd phase decay, a caveat is that the intervention may not be equally effective in people with HIV on long-term ART whose reservoirs are dominated by latently infected cells with a slower decay rate.

HIV-1 mRNA Knockdown with CRISPR/Cas9 Enhances Neurocognitive Function

Mixed glia are infiltrated with HIV-1 virus early in the course of infection leading to the development of a persistent viral reservoir in the central nervous system. Modification of the HIV-1 genome using gene editing techniques, including CRISPR/Cas9, has shown great promise towards eliminating HIV-1 viral reservoirs; whether these techniques are capable of removing HIV-1 viral proteins from mixed glia, however, has not been systematically evaluated. Herein, the efficacy of adeno-associated virus 9 (AAV9)-CRISPR/Cas9 gene editing for eliminating HIV-1 mRNA from cortical mixed glia was evaluated in vitro and in vivo. In vitro, a within-subjects experimental design was utilized to treat mixed glia isolated from neonatal HIV-1 transgenic (Tg) rats with varying doses (0, 0.9, 1.8, 2.7, 3.6, 4.5, or 5.4 μL) of CRISPR/Cas9 for 72 hours. Dose-dependent decreases in the number of HIV-1 mRNA, quantified using an innovative in situ hybridization technique, were observed in a subset (i.e., n=5 out of 8) of primary mixed glia. In vivo, HIV-1 Tg rats were retro-orbitally inoculated with CRISPR/Cas9 for two weeks, whereby treatment resulted in profound excision (i.e., approximately 53.2%) of HIV-1 mRNA from the mPFC. Given incomplete excision of the HIV-1 viral genome, the clinical relevance of HIV-1 mRNA knockdown for eliminating neurocognitive impairments was evaluated via examination of temporal processing, a putative neurobehavioral mechanism underlying HIV-1 associated neurocognitive disorders (HAND). Indeed, treatment with CRISPR/Cas9 partially restored the developmental trajectory of temporal processing. Proof-of-concept studies, therefore, support the susceptibility of mixed glia to gene editing and the potential of CRISPR/Cas9 to serve as a novel therapeutic strategy for HAND, even in the absence of full viral eradication.

Development of lipophilic ester prodrugs of dolutegravir for intestinal lymphatic transport

The establishment of latent cellular and anatomical viral reservoirs is a major obstacle to achieving a cure for people infected by HIV. Mesenteric lymph nodes (MLNs) are one of the most important anatomical reservoirs of HIV. Suboptimal levels of antiretroviral (ARVs) drugs in these difficult-to-penetrate viral reservoirs is one of the limitations of current antiretroviral therapy (ART) regimens. This study aimed to design and assess highly lipophilic ester prodrugs of dolutegravir (DTG) formulated with long-chain triglyceride (LCT) for delivery of DTG to the viral reservoir in mesenteric lymph and MLNs. A number of alkyl ester prodrugs of DTG were designed based on the predicted affinity to chylomicrons (CM), and the six most promising prodrugs were selected and synthesised. The synthesised prodrugs were further assessed for their intestinal lymphatic transport potential and biotransformation in biorelevant media in vitro and ex vivo. DTG and the most promising prodrug (prodrug 5) were then assessed in pharmacokinetic and biodistribution studies in rats. Although oral administration of 5 mg/kg of unmodified DTG (an allometrically scaled dose from humans) with or without lipids achieved concentrations above protein binding-adjusted IC90 (PA-IC90) (64 ng/mL) in most tissues, the drug was not selectively targeted to MLNs. The combination of lipophilic ester prodrug and LCT-based formulation approach improved the targeting selectivity of DTG to MLNs 4.8-fold compared to unmodified DTG. However, systemic exposure to DTG was limited, most likely due to poor intestinal absorption of the prodrug following oral administration. In vitro lipolysis showed a good correlation between micellar solubilisation of the prodrug and systemic exposure to DTG in rats in vivo. Thus, it is prudent to include in vitro lipolysis in the early assessment of orally administered drugs and prodrugs in lipidic formulations, even when intestinal lymphatic transport is involved in the absorption pathway. Further studies are needed to clarify the underlying mechanisms of low systemic bioavailability of DTG following oral administration of the prodrug and potential ways to overcome this limitation.

Prevention, treatment and cure of HIV infection

The development of antiretroviral therapy for the prevention and treatment of HIV infection has been marked by a series of remarkable successes. However, the efforts to develop a vaccine have largely failed, and efforts to discover a cure are only now beginning to gain traction. In this Review, we describe recent progress on all fronts - pre-exposure prophylaxis, vaccines, treatment and cure - and we discuss the unmet needs, both current and in the coming years. We describe the emerging arsenal of drugs, biologics and strategies that will hopefully address these needs. Although HIV research has largely been siloed in the past, this is changing, as the emerging research agenda is marked by multiple cross-discipline synergies and collaborations. As the limitations of antiretroviral drugs as a means to truly end the epidemic are becoming more apparent, there is a great need for continued efforts to develop an effective preventative vaccine and a scalable cure, both of which remain formidable challenges.

The latent reservoir of inducible, infectious HIV-1 does not decrease despite decades of antiretroviral therapy

HIV-1 persists in a latent reservoir in resting CD4+ T cells despite antiretroviral therapy (ART). The reservoir decays slowly over the first 7 years of ART (t1/2 = 44 months). However, whether decay continues with long-term ART is unclear. Recent integration site studies indicate gradual selection against inducible, intact proviruses, raising speculation that decades of ART might allow treatment interruption without viral rebound. Therefore, we measured the reservoir in 42 people on long-term ART (mean 22 years) using a quantitative viral outgrowth assay. After 7 years of ART, there was no long-term decrease in the frequency of inducible, replication-competent proviruses but rather an increase with an estimated doubling time of 23 years. Another reservoir assay, the intact proviral DNA assay, confirmed that reservoir decay with t1/2 of 44 months did not continue with long-term ART. The lack of decay reflected proliferation of infected cells. Most inducible, replication-competent viruses (79.8%) had env sequences identical to those of other isolates from the same sample. Thus, although integration site analysis indicates changes in reservoir composition, the proliferation of CD4+ T cells counteracts decay, maintaining the frequency of inducible, replication-competent proviruses at roughly constant levels over the long term. These results reinforce the need for lifelong ART.

Opioid abuse and SIV infection in non-human primates

Human immunodeficiency virus (HIV) and drug abuse are intertwined epidemics, leading to compromised adherence to combined antiretroviral therapy (cART) and exacerbation of NeuroHIV. As opioid abuse causes increased viral replication and load, leading to a further compromised immune system in people living with HIV (PLWH), it is paramount to address this comorbidity to reduce the NeuroHIV pathogenesis. Non-human primates are well-suited models to study mechanisms involved in HIV neuropathogenesis and provide a better understanding of the underlying mechanisms involved in the comorbidity of HIV and drug abuse, leading to the development of more effective treatments for PLWH. Additionally, using broader behavioral tests in these models can mimic mild NeuroHIV and aid in studying other neurocognitive diseases without encephalitis. The simian immunodeficiency virus (SIV)-infected rhesus macaque model is instrumental in studying the effects of opioid abuse on PLWH due to its similarity to HIV infection. The review highlights the importance of using non-human primate models to study the comorbidity of opioid abuse and HIV infection. It also emphasizes the need to consider modifiable risk factors such as gut homeostasis and pulmonary pathogenesis associated with SIV infection and opioid abuse in this model. Moreover, the review suggests that these non-human primate models can also be used in developing effective treatment strategies for NeuroHIV and opioid addiction. Therefore, non-human primate models can significantly contribute to understanding the complex interplay between HIV infection, opioid abuse, and associated comorbidities.

Long-term Outcomes of Patients With HIV and Pneumocystis jirovecii Pneumonia in the Antiretroviral Therapy Era

Background

Pneumocystis jirovecii pneumonia (PCP) is one of the most frequent opportunistic infections in people with HIV (PWH). However, there are limited data on long-term outcomes of PCP in the antiretroviral therapy (ART) era.

Methods

We conducted a secondary analysis of 2 prospective studies on 307 PWH, 81 with prior PCP, with a median follow-up of 96 weeks. Laboratory data were measured at protocol-defined intervals. We reviewed clinically indicated chest computerized tomography imaging in 63 patients with prior PCP at a median of 58 weeks after PCP diagnosis and pulmonary function tests (PFTs) of patients with (n = 10) and without (n = 14) prior PCP at a median of 18 weeks after ART initiation.

Results

After 96 weeks of ART, PWH with prior PCP showed no significant differences in laboratory measurements, including CD4 count, when compared with those without prior PCP. Survival rates following ART initiation were similar. However, PWH with prior PCP had increased evidence of restrictive lung pathology and diffusion impairment in PFTs. Furthermore, on chest imaging, 13% of patients had bronchiectasis and 11% had subpleural cysts. Treatment with corticosteroids was associated with an increased incidence of cytomegalovirus disease (odds ratio, 2.62; P = .014).

Conclusions

PCP remains an important opportunistic infection in the ART era. While it did not negatively affect CD4 reconstitution, it could pose an increased risk for incident cytomegalovirus disease with corticosteroid treatment and may cause residual pulmonary sequelae. These findings suggest that PCP and its treatment may contribute to long-term morbidity in PWH, even in the ART era.

HIV and hypertension epidemiology

PURPOSE OF REVIEW

The aim of this study was to provide an overview of the burden, pathogenesis, and recent recommendations for treating hypertension among people living with HIV (PLWH). This review is relevant because of the increase in the prevalence of HIV as a chronic disease and the intersection of the increasing prevalence of hypertension.

RECENT FINDINGS

The contribution of HIV to the pathogenesis of hypertension is complex and still incompletely understood. Evidence suggests that chronic inflammation from HIV, antiretroviral treatment (ART), and comorbidities such as renal disease and insulin resistance contribute to developing hypertension in PLWH. Treatment is not distinct from guidelines for HIV-noninfected people. Nonpharmacological guidelines such as decreasing blood pressure by promoting a healthy lifestyle emphasizing exercise, weight loss, and smoking cessation are still recommended in the literature. The pharmacological management of hypertension in PLWH is similar, but special attention must be given to specific drugs with potential interaction with ART regimens. Further research is needed to investigate the pathways and effects of hypertension on HIV.

SUMMARY

There are different pathways to the pathogenesis of hypertension in PLWH. Clinicians should take it into consideration to provide more precise management of hypertension in PLWH. Further research into the subject is still required.

Targeting and eradicating latent CNS reservoirs of HIV-1: original strategies and new models

Nowadays, combination antiretroviral therapy (cART) is the standard treatment for all people with human immunodeficiency virus (HIV-1). Although cART is effective in treating productive infection, it does not eliminate latent reservoirs of the virus. This leads to lifelong treatment associated with the occurrence of side effects and the development of drug-resistant HIV-1. Suppression of viral latency is therefore the major hurdle to HIV-1 eradication. Multiple mechanisms exist to regulate viral gene expression and drive the transcriptional and post-transcriptional establishment of latency. Epigenetic processes are amongst the most studied mechanisms influencing both productive and latent infection states. The central nervous system (CNS) represents a key anatomical sanctuary for HIV and is the focal point of considerable research efforts. However, limited and difficult access to CNS compartments makes understanding the HIV-1 infection state in latent brain cells such as microglial cells, astrocytes, and perivascular macrophages challenging. This review examines the latest advances on epigenetic transformations involved in CNS viral latency and targeting of brain reservoirs. Evidence from clinical studies as well as in vivo and in vitro models of HIV-1 persistence in the CNS will be discussed, with a special focus on recent 3D in vitro models such as human brain organoids. Finally, the review will address therapeutic considerations for targeting latent CNS reservoirs.

Modeling Drug Resistance Emergence and Transmission in HIV-1 in the UK

A deeper understanding of HIV-1 transmission and drug resistance mechanisms can lead to improvements in current treatment policies. However, the rates at which HIV-1 drug resistance mutations (DRMs) are acquired and which transmitted DRMs persist are multi-factorial and vary considerably between different mutations. We develop a method for the estimation of drug resistance acquisition and transmission patterns. The method uses maximum likelihood ancestral character reconstruction informed by treatment roll-out dates and allows for the analysis of very large datasets. We apply our method to transmission trees reconstructed on the data obtained from the UK HIV Drug Resistance Database to make predictions for known DRMs. Our results show important differences between DRMs, in particular between polymorphic and non-polymorphic DRMs and between the B and C subtypes. Our estimates of reversion times, based on a very large number of sequences, are compatible but more accurate than those already available in the literature, with narrower confidence intervals. We consistently find that large resistance clusters are associated with polymorphic DRMs and DRMs with long loss times, which require special surveillance. As in other high-income countries (e.g., Switzerland), the prevalence of sequences with DRMs is decreasing, but among these, the fraction of transmitted resistance is clearly increasing compared to the fraction of acquired resistance mutations. All this indicates that efforts to monitor these mutations and the emergence of resistance clusters in the population must be maintained in the long term.

Comprehending the Structure, Dynamics, and Mechanism of Action of Drug-Resistant HIV Protease

Since the emergence of the Human Immunodeficiency Virus (HIV) in the 1980s, strategies to combat HIV-AIDS are continuously evolving. Among the many tested targets to tackle this virus, its protease enzyme (PR) was proven to be an attractive option that brought about numerous research publications and ten FDA-approved drugs to inhibit the PR activity. However, the drug-induced mutations in the enzyme made these small molecule inhibitors ineffective with prolonged usage. The research on HIV PR, therefore, remains a thrust area even today. Through this review, we reiterate the importance of understanding the various structural and functional components of HIV PR in redesigning the structure-based small molecule inhibitors. We also discuss at length the currently available FDA-approved drugs and how these drug molecules induced mutations in the enzyme structure. We then recapitulate the reported mechanisms on how these drug-resistant variants remain sufficiently active to cleave the natural substrates. We end with the future scope covering the recently proposed strategies that show promise to deal with the mutations.

Years Since Diagnosis Among People Living With Diagnosed HIV in New York City

Antiretroviral treatment has greatly improved the survival of people living with diagnosed HIV (PLWDH), but little information is available on the time since diagnosis among them. Using New York City HIV surveillance data, we described the trend in the number of years since diagnosis among PLWDH during 2010-2019 and reported the mean, median, and interquartile range (IQR) of years since diagnosis among PLWDH in New York City in 2019, overall and by gender, race and ethnicity, and transmission risk. The median number of years since diagnosis among PLWDH in New York City increased from 10.5 years (IQR, 6.3-15.6) in 2010 to 16.3 years (IQR, 8.9-22.1) in 2019. By gender, transgender people had the shortest time since diagnosis, with a median of 11.4 years (IQR, 5.6-17.9), compared with men (median = 15.2 years; IQR, 8.1-21.6) and women (median, 18.5 years; IQR, 12.0-23.0). By race and ethnicity, non-Hispanic White people had been living with the diagnosis for the longest time (median = 17.4 years; IQR, 9.5-23.5), and Asian/Pacific Islander people had been living with the diagnosis for the shortest time (median = 10.1 years; IQR, 4.7-17.0). With an expected and continuing increase in the number of years since HIV diagnosis among PLWDH, programs that provide treatment and support services will need to be expanded, updated, and improved.

Undetectable proviral DNA and viral RNA levels after raltegravir administration in two cats with natural feline leukemia virus infection

Feline leukemia virus (FeLV) infection was discovered over 50 years ago; however, the serious clinical changes associated with FeLV infection still have great importance in the diagnosis, prevention, and clinical management of symptomatic patients. Progressive infection with FeLV leads to a reduction in the patient's life expectancy and quality of life. This report describes the use of an antiretroviral integrase inhibitor, raltegravir, in two cats with natural FeLV infection. Raltegravir was administered orally at a dose of 40 mg/cat every 12 h in both cases. In case one, 13 weeks after starting raltegravir, RNA loads were undetectable, while proviral DNA loads were still detectable. In case two, proviral DNA loads were undetectable after 32 weeks of medication, while RNA loads were undetectable throughout the treatment. No adverse effects or laboratory test abnormalities were detected with the use of raltegravir in either patient. The patients are currently clinically healthy, still receiving the drug, and are under close observation. To our knowledge, this is the first report describing the use of raltegravir in naturally infected FeLV-positive cats and its effects on circulating viral load. Moreover, the patients described here were followed-up for a longer period than those in previously reported cases.

Highly Potent and Oral Macrocyclic Peptides as a HIV-1 Protease Inhibitor: mRNA Display-Derived Hit-to-Lead Optimization

Human immunodeficiency virus type-1 (HIV-1) protease is essential for viral propagation, and its inhibitors are key anti-HIV-1 drug candidates. In this study, we discovered a novel HIV-1 protease inhibitor (compound 16) with potent antiviral activity and oral bioavailability using a structure-based drug design approach via X-ray crystal structure analysis and improved metabolic stability, starting from hit macrocyclic peptides identified by mRNA display against HIV-1 protease. We found that the improvement of the proteolytic stability of macrocyclic peptides by introducing a methyl group to the α-position of amino acid is crucial to exhibit strong antiviral activity. In addition, macrocyclic peptides, which have moderate metabolic stability and solubility in solutions containing taurocholic acid, exhibited desirable plasma total clearance and oral bioavailability. These approaches may contribute to the successful discovery and development of orally bioavailable peptide drugs.

HLA-II-Associated HIV-1 Adaptation Decreases CD4+ T-Cell Responses in HIV-1 Vaccine Recipients

Epitopes with evidence of HLA-II-associated adaptation induce poorly immunogenic CD4+ T-cell responses in HIV-positive (HIV+) individuals. Many such escaped CD4+ T-cell epitopes are encoded by HIV-1 vaccines being evaluated in clinical trials. Here, we assessed whether this viral adaptation adversely impacts CD4+ T-cell responses following HIV-1 vaccination, thereby representing escaped epitopes. When evaluated in separate peptide pools, vaccine-encoded adapted epitopes (AE) induced CD4+ T-cell responses less frequently than nonadapted epitopes (NAE). We also demonstrated that in a polyvalent vaccine, where both forms of the same epitope were encoded, AE were less immunogenic. NAE-specific CD4+ T cells had increased, albeit low, levels of interferon gamma (IFN-γ) cytokine production. Single-cell transcriptomic analyses showed that NAE-specific CD4+ T cells expressed interferon-related genes, while AE-specific CD4+ T cells resembled a Th2 phenotype. Importantly, the magnitude of NAE-specific CD4+ T-cell responses, but not that of AE-specific responses, was found to positively correlate with Env-specific antibodies in a vaccine efficacy trial. Together, these findings show that HLA-II-associated viral adaptation reduces CD4+ T-cell responses in HIV-1 vaccine recipients and suggest that vaccines encoding a significant number of AE may not provide optimal B-cell help for HIV-specific antibody production. IMPORTANCE Despite decades of research, an effective HIV-1 vaccine remains elusive. Vaccine strategies leading to the generation of broadly neutralizing antibodies are likely needed to provide the best opportunity of generating a protective immune response against HIV-1. Numerous studies have demonstrated that T-cell help is necessary for effective antibody generation. However, immunogen sequences from recent HIV-1 vaccine efficacy trials include CD4+ T-cell epitopes that have evidence of immune escape. Our study shows that these epitopes, termed adapted epitopes, elicit lower frequencies of CD4+ T-cell responses in recipients from multiple HIV-1 vaccine trials. Additionally, the counterparts to these epitopes, termed nonadapted epitopes, elicited CD4+ T-cell responses that correlated with Env-specific antibodies in one efficacy trial. These results suggest that vaccine-encoded adapted epitopes dampen CD4+ T-cell responses, potentially impacting both HIV-specific antibody production and efficacious vaccine efforts.

A Historical Review of Military Medical Strategies for Fighting Infectious Diseases: From Battlefields to Global Health

The environmental conditions generated by war and characterized by poverty, undernutrition, stress, difficult access to safe water and food as well as lack of environmental and personal hygiene favor the spread of many infectious diseases. Epidemic typhus, plague, malaria, cholera, typhoid fever, hepatitis, tetanus, and smallpox have nearly constantly accompanied wars, frequently deeply conditioning the outcome of battles/wars more than weapons and military strategy. At the end of the nineteenth century, with the birth of bacteriology, military medical researchers in Germany, the United Kingdom, and France were active in discovering the etiological agents of some diseases and in developing preventive vaccines. Emil von Behring, Ronald Ross and Charles Laveran, who were or served as military physicians, won the first, the second, and the seventh Nobel Prize for Physiology or Medicine for discovering passive anti-diphtheria/tetanus immunotherapy and for identifying mosquito Anopheline as a malaria vector and plasmodium as its etiological agent, respectively. Meanwhile, Major Walter Reed in the United States of America discovered the mosquito vector of yellow fever, thus paving the way for its prevention by vector control. In this work, the military relevance of some vaccine-preventable and non-vaccine-preventable infectious diseases, as well as of biological weapons, and the military contributions to their control will be described. Currently, the civil-military medical collaboration is getting closer and becoming interdependent, from research and development for the prevention of infectious diseases to disasters and emergencies management, as recently demonstrated in Ebola and Zika outbreaks and the COVID-19 pandemic, even with the high biocontainment aeromedical evacuation, in a sort of global health diplomacy.

In Vitro Selection and Characterization of HIV-1 Variants with Increased Resistance to LP-40, Enfuvirtide-Based Lipopeptide Inhibitor

In our previous work, we replaced the TRM (tryptophan-rich motif) of T20 (Enfuvirtide) with fatty acid (C16) to obtain the novel lipopeptide LP-40, and LP-40 displayed enhanced antiviral activity. In this study, we investigated whether the C16 modification could enhance the high-resistance barrier of the inhibitor LP-40. To address this question, we performed an in vitro simultaneous screening of HIV-1_NL4-3 resistance to T20 and LP-40. The mechanism of drug resistance for HIV-1 Env was further studied using the expression and processing of the Env glycoprotein, the effect of the Env mutation on the entry and fusion ability of the virus, and an analysis of changes to the gp41 core structure. The results indicate that the LP-40 activity is enhanced and that it has a high resistance barrier. In a detailed analysis of the resistance sites, we found that mutations in L33S conferred a stronger resistance, except for the well-recognized mutations in amino acids 36–45 of gp41 NHR, which reduced the inhibitory activity of the CHR-derived peptides. The compensatory mutation of eight amino acids in the CHR region (NDQEEDYN) plays an important role in drug resistance. LP-40 and T20 have similar resistance mutation sites, and we speculate that the same resistance profile may arise if LP-40 is used in a clinical setting.

Beyond Inhibition: A Novel Strategy of Targeting HIV-1 Protease to Eliminate Viral Reservoirs

HIV-1 protease (PR) is a viral enzyme that cleaves the Gag and Gag-Pol polyprotein precursors to convert them into their functional forms, a process which is essential to generate infectious viral particles. Due to its broad substrate specificity, HIV-1 PR can also cleave certain host cell proteins. Several studies have identified host cell substrates of HIV-1 PR and described the potential impact of their cleavage on HIV-1-infected cells. Of particular interest is the interaction between PR and the caspase recruitment domain-containing protein 8 (CARD8) inflammasome. A recent study demonstrated that CARD8 can sense HIV-1 PR activity and induce cell death. While PR typically has low levels of intracellular activity prior to viral budding, premature PR activation can be achieved using certain non-nucleoside reverse transcriptase inhibitors (NNRTIs), resulting in CARD8 cleavage and downstream pyroptosis. Used together with latency reversal agents, the induction of premature PR activation to trigger CARD8-mediated cell killing may help eliminate latent reservoirs in people living with HIV. This represents a novel strategy of utilizing PR as an antiviral target through premature activation rather than inhibition. In this review, we discuss the viral and host substrates of HIV-1 protease and highlight potential applications and advantages of targeting CARD8 sensing of HIV-1 PR.

The transformation of HIV therapy: One pill once a day

A co-formulated, one pill once a day antiretroviral regimen (single-tablet regimen), containing efavirenz, emtricitabine, and tenofovir disoproxyl fumarate ( Atripla), revolutionized the antiretroviral therapy landscape. Single-tablet regimens provide not only dosing convenience but help optimize adherence and persistence with antiretroviral therapy to achieve durably suppressed viremia with both individual and societal benefits. Given the many excellent options available now, single-tablet regimens are the preferred choice for initiating antiretroviral therapy in almost all patients with rare exceptions for drug interactions and pregnancy, and for simplification of more complex antiretroviral therapy to a single-tablet regimen. In this special commemorative article, we celebrate this astounding advancement in antiretroviral therapy, championed by John C. Martin while CEO of Gilead Sciences, and its transformative impact on HIV care nationally and globally.

Complex decay dynamics of HIV virions, intact and defective proviruses, and 2LTR circles following initiation of antiretroviral therapy

In persons living with HIV-1 (PLWH) who start antiretroviral therapy (ART), plasma virus decays in a biphasic fashion to below the detection limit. The first phase reflects the short half-life (<1 d) of cells that produce most of the plasma virus. The second phase represents the slower turnover (t1/2 = 14 d) of another infected cell population, whose identity is unclear. Using the intact proviral DNA assay (IPDA) to distinguish intact and defective proviruses, we analyzed viral decay in 17 PLWH initiating ART. Circulating CD4+ T cells with intact proviruses include few of the rapidly decaying first-phase cells. Instead, this population initially decays more slowly (t1/2 = 12.9 d) in a process that largely represents death or exit from the circulation rather than transition to latency. This more protracted decay potentially allows for immune selection. After ∼3 mo, the decay slope changes, and CD4+ T cells with intact proviruses decay with a half-life of 19 mo, which is still shorter than that of the latently infected cells that persist on long-term ART. Two-long-terminal repeat (2LTR) circles decay with fast and slow phases paralleling intact proviruses, a finding that precludes their use as a simple marker of ongoing viral replication. Proviruses with defects at the 5' or 3' end of the genome show equivalent monophasic decay at rates that vary among individuals. Understanding these complex early decay processes is important for correct use of reservoir assays and may provide insights into properties of surviving cells that can constitute the stable latent reservoir.

Uptake Success and Cost Savings from Switching to a Two-Drug Antiretroviral Regimen

The emergence of dual therapy for antiretroviral (ARV)-experienced persons living with HIV (PWH) offers the opportunity to reduce lifetime exposure to unnecessary ARV drugs while maintaining viral suppression and reducing the cost of care. Our objective, using retrospective analysis of a quality care initiative, was to examine in routine clinical practice the clinical impact of switching PWH stable on a three-drug to a two-drug single-tablet formulation (STF) ARV regimen. We also examined the cost implications of this STF adjustment. Between January 1, 2020 and January 1, 2021 eligible patients (i.e., virally suppressed, no active hepatitis B infection, no documented nucleoside reverse transcriptase inhibitors/integrase strand transfer inhibitor resistance) were offered, on a convenience basis and as part of routine care, the opportunity to adjust their current three-drug STF to a two-drug STF (dolutegarvair/lamivudine). The acceptance, clinical efficacy, safety, tolerability, and cost of treatment were measured for patients who switched in 2020. Of 989 eligible PWH, 408 were approached and 391 (39.5%) switched to two-drug regimen; 99% remained on the two-drug STF at year's end (median 240 days follow-up). Only 2/391 patients who switched lost viral control. The total ARV drug cost for all 989 patients decreased by 10.3% generating an actual savings of $1,596,666 among patients approached and switched in 2020. Patient interest and uptake in switching to two-drug STF was substantial and resulted in few discontinuations for any reason. It provided significant and immediate cost savings within the first year. Our results bring clarity to discussions on whether using two-drug regimens would be practical and acceptable in nonclinical trial settings.

Histone deacetylase inhibition reduces deleterious cytokine release induced by ingenol stimulation

Latency reversing agents (LRAs), such as protein kinase C (PKC) agonists, constitute a promising strategy for exposing and eliminating the HIV-1 latent reservoir. PKC agonists activate NF-κB and induce deleterious pro-inflammatory cytokine production. Adjuvant pharmacological agents, such as ruxolitinib, a JAK inhibitor, have previously been combined with LRAs to reduce deleterious pro-inflammatory cytokine secretion without inhibiting HIV-1 reactivation in vitro. Histone deacetylase inhibitors (HDACi) are known to dampen pro-inflammatory cytokine secretion in the context of other diseases and synergize with LRAs to reactivate latent HIV-1. This study investigates whether a panel of epigenetic modifiers, including HDACi, could dampen PKC-induced pro-inflammatory cytokine secretion during latency reversal. We screened an epigenetic modifier library for compounds that reduced intracellular IL-6 production induced by the PKC agonist Ingenol-3,20-dibenzoate. We further tested the most promising epigenetic inhibitor class, HDACi, for their ability to reduce pro-inflammatory cytokines and reactivate latent HIV-1 ex vivo. We identified nine epigenetic modulators that reduced PKC-induced intracellular IL-6. In cells from aviremic individuals living with HIV-1, the HDAC1-3 inhibitor, suberohydroxamic acid (SBHA), reduced secretion of pro-inflammatory cytokines TNF-α, IL-5, IL-2r, and IL-17 but did not significantly reactivate latent HIV-1 when combined with Ingenol-3,20-dibenzoate. Combining SBHA and Ingenol-3,20-dibenzoate reduces deleterious cytokine production during latency reversal but does not induce significant viral reactivation in aviremic donor PBMCs. The ability of SBHA to reduce PKC-induced pro-inflammatory cytokines when combined with Ingenol-3,20-dibenzoate suggests SBHA can be used to reduced PKC induced pro-inflammatory cytokines but not to achieve latency reversal in the context of HIV-1.

Suicide gene therapy in cancer and HIV-1 infection: An alternative to conventional treatments

Suicide Gene Therapy (SGT) aims to introduce a gene encoding either a toxin or an enzyme making the targeted cell more sensitive to chemotherapy. SGT represents an alternative approach to combat pathologies where conventional treatments fail such as pancreatic cancer or the high-grade glioblastoma which are still desperately lethal. We review the possibility to use SGT to treat these cancers which have shown promising results in vitro and in preclinical trials. However, SGT has so far failed in phase III clinical trials thus further improvements are awaited. We can now take advantages of the many advances made in SGT for treating cancer to combat other pathologies such as HIV-1 infection. In the review we also discuss the feasibility to add SGT to the therapeutic arsenal used to cure HIV-1-infected patients. Indeed, preliminary results suggest that both productive and latently infected cells are targeted by the SGT. In the last section, we address the limitations of this approach and how we might improve it.

Drug Combinations as a First Line of Defense against Coronaviruses and Other Emerging Viruses

The world was unprepared for coronavirus disease 2019 (COVID-19) and remains ill-equipped for future pandemics. While unprecedented strides have been made developing vaccines and treatments for COVID-19, there remains a need for highly effective and widely available regimens for ambulatory use for novel coronaviruses and other viral pathogens. We posit that a priority is to develop pan-family drug cocktails to enhance potency, limit toxicity, and avoid drug resistance. We urge cocktail development for all viruses with pandemic potential both in the short term (<1 to 2 years) and longer term with pairs of drugs in advanced clinical testing or repurposed agents approved for other indications. While significant efforts were launched against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in vitro and in the clinic, many studies employed solo drugs and had disappointing results. Here, we review drug combination studies against SARS-CoV-2 and other viruses and introduce a model-driven approach to assess drug pairs with the highest likelihood of clinical efficacy. Where component agents lack sufficient potency, we advocate for synergistic combinations to achieve therapeutic levels. We also discuss issues that stymied therapeutic progress against COVID-19, including testing of agents with low likelihood of efficacy late in clinical disease and lack of focus on developing virologic surrogate endpoints. There is a need to expedite efficient clinical trials testing drug combinations that could be taken at home by recently infected individuals and exposed contacts as early as possible during the next pandemic, whether caused by a coronavirus or another viral pathogen. The approach herein represents a proactive plan for global viral pandemic preparedness.

Fighting HIV-1 Persistence: At the Crossroads of "Shoc-K and B-Lock"

Despite the success of highly active antiretroviral therapy (HAART), integrated HIV-1 proviral DNA cannot be eradicated from an infected individual. HAART is not able to eliminate latently infected cells that remain invisible to the immune system. Viral sanctuaries in specific tissues and immune-privileged sites may cause residual viral replication that contributes to HIV-1 persistence. The “Shock or Kick, and Kill” approach uses latency reversing agents (LRAs) in the presence of HAART, followed by cell-killing due to viral cytopathic effects and immune-mediated clearance. Different LRAs may be required for the in vivo reactivation of HIV-1 in different CD4⁺ T cell reservoirs, leading to the activation of cellular transcription factors acting on the integrated proviral HIV-1 LTR. An important requirement for LRA drugs is the reactivation of viral transcription and replication without causing a generalized immune activation. Toll-like receptors, RIG-I like receptors, and STING agonists have emerged recently as a new class of LRAs that augment selective apoptosis in reactivated T lymphocytes. The challenge is to extend in vitro observations to HIV-1 positive patients. Further studies are also needed to overcome the mechanisms that protect latently infected cells from reactivation and/or elimination by the immune system. The Block and Lock alternative strategy aims at using latency promoting/inducing agents (LPAs/LIAs) to block the ability of latent proviruses to reactivate transcription in order to achieve a long term lock down of potential residual virus replication. The Shock and Kill and the Block and Lock approaches may not be only alternative to each other, but, if combined together (one after the other), or given all at once [namely “Shoc-K(kill) and B(block)-Lock”], they may represent a better approach to a functional cure.

Long term dual antiretroviral therapy: A real life retrospective countrywide Israeli study

AIM

Combined antiretroviral treatment (cART) traditionally consists of three antiretroviral medications, while two-drug regimens (2DR), historically used infrequently, recently been suggested to be non-inferior to three-drug regimens, is emerging as a potential treatment option and is currently a recommended option for treatment initiation in many guidelines.

PURPOSE

Characterize the indications and clinical efficacy of 2DR use at a real-life setting in a nation-wide survey.

METHODS

A cross-sectional survey of Israeli patients treated by 2DR until July 2019, included demographic, immunologic, virologic, genotypic and biochemical/metabolic parameters at diagnosis, ART initiation, 2DR initiation and following 24, 48, 96 and 144 weeks of 2DR treatment.

RESULTS

176 patients were included in the study. In contrast to historical data implicating ART resistance and adverse effects as the major reasons leading to 2DR switching, treatment simplification was the main reason leading to 2DR treatment in 2019. 2DR that included INSTI and PI were more commonly used in cases of drug resistance, while a combination of INSTI and NNRTI was used in all other 2DR indications. A switch to 2DR induced a mean CD4 T cell increase from 599 cells/μl at treatment initiation to 680 cells/μl at 96 weeks of treatment p<0.001 and viral suppression improvement from 73.9% at initiation to 87.0% at 48 weeks of treatment (p = 0.004). PI and INSTI 2DR was inferior in suppressing viral levels compared to other 2DRs but used for subset of more complex patients.

CONCLUSIONS

2DR in a large-scale real-life nation-wide survey proved to be safe and effective. Most 2DRs, other than PI and INSTI, were similarly effective in suppressing HIV viremia and in elevating CD4 T cell counts.

The Interplay Among HIV, LINE-1, and the Interferon Signaling System

Human immunodeficiency viruses (HIVs) are retroviruses that replicate effectively in human CD4⁺ cells and cause the development of acquired immune deficiency syndrome (AIDS). On the other hand, type 1 long interspersed elements (LINE-1s or L1s) are the only active retroelements that can replicate autonomously in human cells. They, along with other active yet nonautonomous retroelements, have been associated with autoimmune diseases. There are many similarities between HIV and LINE-1. Being derived (or evolved) from ancient retroviruses, both HIV and LINE-1 replicate through a process termed reverse transcription, activate endogenous DNA and RNA sensors, trigger innate immune activation to promote interferon (IFN) expression, and are suppressed by protein products of interferon-stimulated genes (ISGs). However, these similarities make it difficult to decipher or even speculate the relationship between HIV and LINE-1, especially regarding the involvement of the IFN signaling system. In this review, we summarize previous findings on the relationships between HIV and innate immune activation as well as between LINE-1 and IFN upregulation. We also attempt to elucidate the interplay among HIV, LINE-1, and the IFN signaling system in hopes of guiding future research directions for viral suppression and immune regulation.

Exosomes in HIV infection

PURPOSE OF REVIEW

The exosomes play a critical role in HIV infection, which constitute a pathway to release intracellular material and exchange material and information between cells. Exosomes have become a hotspot in the field of AIDS research. This review introduces the formation process of HIV particles and exosomes, and summarizes the role of exosomes in the progression of HIV disease from multiple aspects.

RECENT FINDINGS

Many components of the exosomes involved in HIV transfer and replication affect the occurrence, development, and outcome of AIDS, and are closely related to HIV infection. Exosomes can have a dual impact on HIV infection, and play an important role in activating the latent reservoir of HIV and affecting the chronic inflammation of HIV. The biological information carried by exosomes is also of great significance for the prediction of HIV disease.

SUMMARY

The present review summarizes the role of exosomes in HIV disease progression in various aspects in order to further understand the underlying mechanism affecting the infection and providing a new idea for the clinical diagnosis and treatment of AIDS.

Potential Utility of Natural Killer Cells for Eliminating Cells Harboring Reactivated Latent HIV-1 Following the Removal of CD8+ T Cell-Mediated Pro-Latency Effect(s)

An impediment to curing HIV-1 infection is the persistence of latently infected cells in ART-treated people living with HIV (PLWH). A key strategy for curing HIV-1 infection is to activate transcription and translation of latent virus using latency reversing agents (LRAs) and eliminate cells harboring reactivated virus via viral cytopathic effect or immune clearance. In this review, we provide an overview of available LRAs and their use in clinical trials. Furthermore, we describe recent data suggesting that CD8⁺ T cells promote HIV-1 latency in the context of ART, even in the presence of LRAs, which might at least partially explain the clinical inefficiency of previous “shock and kill” trials. Here, we propose a novel cure strategy called “unlock, shock, disarm, and kill”. The general premise of this strategy is to shut down the pro-latency function(s) of CD8⁺ T cells, use LRAs to reverse HIV-1 latency, counteract anti-apoptotic molecules, and engage natural killer (NK) cells to mediate the killing of cells harboring reactivated latent HIV-1.

Characterizing the Latent HIV-1 Reservoir in Patients with Viremia Suppressed on cART: Progress, Challenges, and Opportunities

Modern combination antiretroviral therapy (cART) can bring HIV-1 in blood plasma to level undetectable by standard tests, prevent the onset of acquired immune deficiency syndrome (AIDS), and allow a near-normal life expectancy for HIV-infected individuals. Unfortunately, cART is not curative, as within a few weeks of treatment cessation, HIV viremia in most patients rebounds to pre-cART levels. The primary source of this rebound, and the principal barrier to a cure, is the highly stable reservoir of latent yet replication-competent HIV-1 proviruses integrated into the genomic DNA of resting memory CD4+ T cells. In this review, prevailing models for how the latent reservoir is established and maintained, residual viremia and viremic rebound upon withdrawal of cART, and the types and characteristics of cells harboring latent HIV-1 will be discussed. Selected technologies currently being used to advance our understanding of HIV latency will also be presented, as will a perspective on which areas of advancement are most essential for producing the next generation of HIV-1 therapeutics.

Oral administration of tipranavir with long-chain triglyceride results in moderate intestinal lymph targeting but no efficient delivery to HIV-1 reservoir in mesenteric lymph nodes

The introduction of combination antiretroviral therapy (cART) led to substantial improvement in mortality and morbidity of HIV-1 infection. However, the poor penetration of antiretroviral agents to HIV-1 reservoirs limit the ability of the antiretroviral agents to eliminate the virus. Mesenteric lymph nodes (MLNs) are one of the main HIV-1 reservoirs in patients under suppressive cART. Intestinal lymphatic absorption pathway substantially increases the concentration of lipophilic drugs in mesenteric lymph and MLNs when they are co-administered with long-chain triglyceride (LCT). Chylomicrons (CM) play a crucial role in the intestinal lymphatic absorption as they transport drugs to the lymph lacteals rather than blood capillary by forming CM-drug complexes in the enterocytes. Thus, lipophilic antiretroviral drugs could potentially be delivered to HIV-1 reservoirs in MLNs by LCT-based formulation approach. In this study, protease inhibitors (PIs) were initially screened for their potential for intestinal lymphatic targeting using a computational model. The candidates were further assessed for their experimental affinity to CM. Tipranavir (TPV) was the only-candidate with substantial affinity to both artificial and natural CM in vitro and ex vivo. Pharmacokinetics and biodistribution studies were then performed to evaluate the oral bioavailability and intestinal lymphatic targeting of TPV in rats. The results showed similar oral bioavailability of TPV with and without co-administration of LCT vehicle. Although LCT-based formulation led to 3-fold higher concentrations of TPV in mesenteric lymph compared to plasma, the levels of the drug in MLNs were similar to plasma in both LCT-based and lipid-free formulation groups. Thus, LCT-based formulation approach alone was not sufficient for effective delivery of TPV to MLNs. Future efforts should be directed to a combined highly lipophilic prodrugs/lipid-based formulation approach to target TPV, other PIs and potentially other classes of antiretroviral agents to viral reservoirs within the mesenteric lymphatic system.

The Importance of Glycans of Viral and Host Proteins in Enveloped Virus Infection

Animal viruses are parasites of animal cells that have characteristics such as heredity and replication. Viruses can be divided into non-enveloped and enveloped viruses if a lipid bilayer membrane surrounds them or not. All the membrane proteins of enveloped viruses that function in attachment to target cells or membrane fusion are modified by glycosylation. Glycosylation is one of the most common post-translational modifications of proteins and plays an important role in many biological behaviors, such as protein folding and stabilization, virus attachment to target cell receptors and inhibition of antibody neutralization. Glycans of the host receptors can also regulate the attachment of the viruses and then influence the virus entry. With the development of glycosylation research technology, the research and development of novel virus vaccines and antiviral drugs based on glycan have received increasing attention. Here, we review the effects of host glycans and viral proteins on biological behaviors of viruses, and the opportunities for prevention and treatment of viral infectious diseases.

Direct acting anti-hepatitis C combinations as potential COVID-19 protease inhibitors

The coronavirus pandemic could be the most threatening outbreak in the twenty-first century. According to the latest records of world health organization, more than 130 millions have been infected by COVID-19, with more than 2.9 million reported deaths. Yet, there is no magic cure for treatment of COVID-19. The concept of drug repurposing has been introduced as a fast, life-saving approach for drug discovery. Drug repurposing infers investigating already approved drugs for new indications, using the available information about pathophysiology of diseases and pharmacodynamics of drugs. In a recent work, more than 3000 FDA approved drugs were tested using virtual screening as potential antiviral agents for COVID-19. In this work, the top ranked five hits from the previous docking results together with drugs of similar chemical feature and/or mechanistic destinations were further tested using AutoDock Vina. The results showed that anti-HCV combinations could be potential therapeutic regimens for COVID-19 infections.

STING and cGAS gene expressions were downregulated among HIV-1-infected persons after antiretroviral therapy

Background

The HIV-1 epidemic is still considered a global public health problem, but great advances have been made in fighting it by antiretroviral therapy (ART). ART has a considerable impact on viral replication and host immunity. The production of type I interferon (IFN) is key to the innate immune response to viral infections. The STING and cGAS proteins have proven roles in the antiviral cascade. The present study aimed to evaluate the impact of ART on innate immunity, which was represented by STING and cGAS gene expression and plasma IFN-α level.

Methods

This cohort study evaluated a group of 33 individuals who were initially naïve to therapy and who were treated at a reference center and reassessed 12 months after starting ART. Gene expression levels and viral load were evaluated by real-time PCR, CD4⁺ and CD8⁺ T lymphocyte counts by flow cytometry, and IFN-α level by enzyme-linked immunosorbent assay.

Results

From before to after ART, the CD4⁺ T cell count and the CD4⁺/CD8⁺ ratio significantly increased (p < 0.0001), the CD8⁺ T cell count slightly decreased, and viral load decreased to undetectable levels in most of the group (84.85%). The expression of STING and cGAS significantly decreased (p = 0.0034 and p = 0.0001, respectively) after the use of ART, but IFN-α did not (p = 0.1558). Among the markers evaluated, the only markers that showed a correlation with each other were STING and CD4⁺ T at the time of the first collection.

Conclusions

ART provided immune recovery and viral suppression to the studied group and indirectly downregulated the STING and cGAS genes. In contrast, ART did not influence IFN-α. The expression of STING and cGAS was not correlated with the plasma level of IFN-α, which suggests that there is another pathway regulating this cytokine in addition to the STING–cGAS pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01548-6.

Antiretroviral Long-Term Efficacy and Resistance of Lopinavir/Ritonavir Plus Lamivudine in HIV-1-Infected Treatment-Naïve Patients (ALTERLL): 144-Week Results of a Randomized, Open-Label, Non-Inferiority Study From Guangdong, China

Dual therapy with lopinavir/ritonavir (LPV/r) plus lamivudine (3TC) has been demonstrated to be non-inferior to the triple drug regimen including LPV/r plus two nucleoside reverse transcriptase inhibitors (NRTIs) in 48-week studies. However, little is known about the long-term efficacy and drug resistance of this simplified strategy. A randomized, controlled, open-label, non-inferiority trial (ALTERLL) was conducted to assess the efficacy, drug resistance, and safety of dual therapy with LPV/r plus 3TC (DT group), compared with the first-line triple-therapy regimen containing tenofovir (TDF), 3TC plus efavirenz (EFV) (TT group) in antiretroviral therapy (ART)-naïve HIV-1-infected adults in Guangdong, China. The primary endpoint was the proportion of patients with plasma HIV-1 RNA < 50 copies/ml at week 144. Between March 1 and December 31, 2015, a total of 196 patients (from 274 patients screened) were included and randomly assigned to either the DT group (n = 99) or the TT group (n = 97). In the primary intention-to-treat (ITT) analysis at week 144, 95 patients (96%) in the DT group and 93 patients (95.9%) in the TT group achieved virological inhibition with plasma HIV-1 RNA <50 copies/ml (difference: 0.1%; 95% CI, -4.6-4.7%), meeting the criteria for non-inferiority. The DT group did not show significant differences in the mean increase in CD4+ cell count (247.0 vs. 204.5 cells/mm3; p = 0.074) or the CD4/CD8 ratio (0.47 vs. 0.49; p = 0.947) from baseline, or the inflammatory biomarker levels through week 144 compared with the TT group. For the subgroup analysis, baseline high viremia (HIV-1 RNA > 100,000 copies/ml) and genotype BC did not affect the primary endpoint or the mean increase in CD4+ cell count or CD4/CD8 ratio from baseline at week 144. However, in patients with genotype AE, the DT group showed a higher mean increase in CD4+ cell count from baseline through 144 weeks than the TT group (308.7 vs. 209.4 cells/mm3; p = 0.038). No secondary HIV resistance was observed in either group. Moreover, no severe adverse event (SAE) or death was observed in any group. Nonetheless, more patients in the TT group (6.1%) discontinued the assigned regimen than those in the DT group (1%) due to adverse events. Dual therapy with LPV/r plus 3TC manifests long-term non-inferior therapeutic efficacy, low drug resistance, good safety, and tolerability compared with the first-line triple-therapy regimen in Guangdong, China, indicating dual therapy is a viable alternative in resource-limited areas. Clinical Trial Registration: [http://www.chictr.org.cn], identifier [ChiCTR1900024611].

Formulation, Stability, Pharmacokinetic, and Modeling Studies for Tests of Synergistic Combinations of Orally Available Approved Drugs against Ebola Virus In Vivo

Outbreaks of Ebola ebolavirus (EBOV) have been associated with high morbidity and mortality. Milestones have been reached recently in the management of EBOV disease (EVD) with licensure of an EBOV vaccine and two monoclonal antibody therapies. However, neither vaccines nor therapies are available for other disease-causing filoviruses. In preparation for such outbreaks, and for more facile and cost-effective management of EVD, we seek a cocktail containing orally available and room temperature stable drugs with strong activity against multiple filoviruses. We previously showed that (bepridil + sertraline) and (sertraline + toremifene) synergistically suppress EBOV in cell cultures. Here, we describe steps towards testing these combinations in a mouse model of EVD. We identified a vehicle suitable for oral delivery of the component drugs and determined that, thus formulated the drugs are equally active against EBOV as preparations in DMSO, and they maintain activity upon storage in solution for up to seven days. Pharmacokinetic (PK) studies indicated that the drugs in the oral delivery vehicle are well tolerated in mice at the highest doses tested. Collectively the data support advancement of these combinations to tests for synergy in a mouse model of EVD. Moreover, mathematical modeling based on human oral PK projects that the combinations would be more active in humans than their component single drugs.

IFNL4 Genotype Does Not Associate with CD4 T-Cell Recovery in People Living with Human Immunodeficiency Virus

Immune non-responders (INRs) are people with HIV infection who fail to restore their CD4 T-cell counts in spite of prolonged virologic suppression, a condition associated with higher rates of all-cause mortality. The mechanisms of immune non-response are not entirely clear. We used existing clinical and genetic data from AIDS Clinical Trials Group clinical trials to ask whether an IFNL4 single-nucleotide polymorphism, shown to be associated with outcomes for other infectious diseases, correlated with immune non-response for HIV. Analysis of data from 426 participants with clearly defined CD4 T-cell recovery phenotypes, including 88 INRs with CD4 < 200 cells/mm³ after 2 years of suppressive antiretroviral therapy, did not identify an association of IFNL4 genotype with immune non-response. Thus, the IFNL4 genotype is unlikely to influence immunologic recovery.

Targeting SARS-CoV-2 M3CLpro by HCV NS3/4a Inhibitors: In Silico Modeling and In Vitro Screening

Currently the entire human population is in the midst of a global pandemic caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2). This highly pathogenic virus has to date caused >71 million infections and >1.6 million deaths in >180 countries. Several vaccines and drugs are being studied as possible treatments or prophylactics of this viral infection. M3CLpro (coronavirus main cysteine protease) is a promising drug target as it has a significant role in viral replication. Here we use the X-ray crystal structure of M3CLpro in complex with boceprevir to study the dynamic changes of the protease upon ligand binding. The binding free energy was calculated for water molecules at different locations of the binding site, and molecular dynamics (MD) simulations were carried out for the M3CLpro/boceprevir complex, to thoroughly understand the chemical environment of the binding site. Several HCV NS3/4a protease inhibitors were tested in vitro against M3CLpro. Specifically, asunaprevir, narlaprevir, paritaprevir, simeprevir, and telaprevir all showed inhibitory effects on M3CLpro. Molecular docking and MD simulations were then performed to investigate the effects of these ligands on M3CLpro and to provide insights into the chemical environment of the ligand binding site. Our findings and observations are offered to help guide the design of possible potent protease inhibitors and aid in coping with the COVID-19 pandemic.

Dual Antiretroviral Therapy-All Quiet Beneath the Surface?

Infection with the human immunodeficiency virus (HIV) is characterized by progressive depletion of CD4+ lymphocytes cells as a result of chronic immune activation. Next to the decreases in the number of CD4+ cells which leads to opportunistic infections, HIV-related immune activation is associated with several prevalent comorbidities in the HIV-positive population such as cardiovascular and bone disease. Traditionally, combination antiretroviral therapy (cART) consists of three drugs with activity against HIV and is highly effective in diminishing the degree of immune activation. Over the years, questions were raised whether virological suppression could also be achieved with fewer antiretroviral drugs, i.e., dual- or even monotherapy. This is an intriguing question considering the fact that antiretroviral drugs should be used lifelong and their use could also induce cardiovascular and bone disease. Therefore, the equilibrium between drug-induced toxicity and immune activation related comorbidity is delicate. Recently, two large clinical trials evaluating two-drug cART showed non-inferiority with respect to virological outcomes when compared to triple-drug regimens. This led to adoption of dual antiretroviral therapy in current HIV treatment guidelines. However, it is largely unknown whether dual therapy is also able to suppress immune activation to the same degree as triple therapy. This poses a risk for an imbalance in the delicate equilibrium. This mini review gives an overview of the current available evidence concerning immune activation in the setting of cART with less than three antiretroviral drugs.