Rectal Challenge Research Articles

PET/CT Targeted Tissue Sampling Reveals Intravenously Administered HGN194 IgG1 Affects HIV Distribution after Rectal Exposure.

Neutralizing monoclonal antibodies hold great potential for prevention of human immunodeficiency virus (HIV) acquisition. IgG is the most abundant antibody in human serum, has a long half-life, and potent effector functions, making it a prime candidate for an HIV prevention therapeutic. We combined Positron Emission Tomography imaging and fluorescent microscopy of 64Cu-labeled, photoactivatable-green fluorescent protein HIV (PA-GFP-BaL) and fluorescently labeled HGN194 IgG1 to determine whether intravenously instilled IgG influences viral interaction with mucosal barriers and viral penetration in colorectal tissue 2 h after rectal viral challenge. Our results show that IgG1 did not alter the number of virions found throughout the colon or viral penetration into the epithelium of the rectum or descending colon. A minor increase in virions was observed in the transverse colon of IgG1 treated animals. Overall, the number of viral particles found in the mesenteric lymph nodes was low. However, IgG1 administration resulted in a significant reduction of virions found in mesenteric lymph nodes. Taken together, our results show that HGN194 IgG1 does not prevent virions from penetrating into the colorectal mucosa but may perturb HIV virion access to the lymphatic system.

Combined application of inflammation-related biomarkers to predict postoperative complications of rectal cancer patients: a retrospective study by machine learning analysis.

Postoperative complications in patients of rectal cancer pose challenges to postoperative recovery. Accurately predicting these complications is crucial for developing effective treatment plans for patients. In this retrospective study, 493 patients with rectal cancer who underwent radical resection between January 2020 and December 2021 were examined. We evaluated logistic regression, support vector machines, regression trees, and random forests to predict the incidence of postoperative complications in patients and evaluate the performance of the model. The results will be analyzed to make recommendations for reducing complications. Among the four machine learning models, random forest demonstrated the highest results. The performance of this model was showed with an AUC of 0.880 (95% CI 0.807-0.949), an accuracy of 88.0% (95% CI 0.815-0.929), a sensitivity of 96.6%, and a specificity of 45.8%. Notably, factors such as inflammation related prognostic index, prognostic nutritional index, tumor location, and T stage were found to significantly increase the probability of postoperative complications. Our study provided evidence that machine learning models can effectively evaluate early postoperative complications of the patients after surgery.

Long-acting lenacapavir acts as an effective preexposure prophylaxis in a rectal SHIV challenge macaque model.

Long-acting antiretroviral agents for preexposure prophylaxis (PrEP) represent a promising new alternative to daily oral regimens for HIV prevention. Lenacapavir (LEN) is a first-in-class long-acting capsid inhibitor approved for the treatment of HIV-1 infection. Here, we assessed the efficacy of LEN for PrEP using a single high-dose simian-human immunodeficiency virus (SHIV) rectal challenge macaque model. In vitro, LEN showed potent antiviral activity against SHIV, as it did for HIV-1. In macaques, a single subcutaneous administration of LEN demonstrated dose proportional increases in and durability of drug plasma levels. A high-dose SHIV inoculum for the PrEP efficacy evaluation was identified via virus titration in untreated macaques. LEN-treated macaques were challenged with high-dose SHIV 7 weeks after drug administration, and the majority remained protected from infection, as confirmed by plasma PCR, cell-associated proviral DNA, and serology testing. Complete protection and superiority to the untreated group was observed among animals whose LEN plasma exposure exceeded its model-adjusted clinical efficacy target at the time of challenge. All infected animals had subprotective LEN concentrations and showed no emergent resistance. These data demonstrate effective SHIV prophylaxis in a stringent macaque model at clinically relevant LEN exposures and support the clinical evaluation of LEN for HIV PrEP in humans.

Long-acting refillable nanofluidic implant confers protection against SHIV infection in nonhuman primates.

The impact of pre-exposure prophylaxis (PrEP) on slowing the global HIV epidemic hinges on effective drugs and delivery platforms. Oral drug regimens are the pillar of HIV PrEP, but variable adherence has spurred development of long-acting delivery systems with the aim of increasing PrEP access, uptake, and persistence. We have developed a long-acting subcutaneous nanofluidic implant that can be refilled transcutaneously for sustained release of the HIV drug islatravir, a nucleoside reverse transcriptase translocation inhibitor that is used for HIV PrEP. In rhesus macaques, the islatravir-eluting implants achieved constant concentrations of islatravir in plasma (median 3.14 nM) and islatravir triphosphate in peripheral blood mononuclear cells (median 0.16 picomole per 106 cells) for more than 20 months. These drug concentrations were above the established PrEP protection threshold. In two unblinded, placebo-controlled studies, islatravir-eluting implants conferred 100% protection against infection with SHIVSF162P3 after repeated low-dose rectal or vaginal challenge in male or female rhesus macaques, respectively, compared to placebo control groups. The islatravir-eluting implants were well tolerated with mild local tissue inflammation and no signs of systemic toxicity over the 20-month study period. This refillable islatravir-eluting implant has potential as a long-acting drug delivery system for HIV PrEP.

HIV, asymptomatic STI, and the rectal mucosal immune environment among young men who have sex with men.

Young men who have sex with men (YMSM) are disproportionately affected by HIV and bacterial sexually transmitted infections (STI) including gonorrhea, chlamydia, and syphilis; yet research into the immunologic effects of these infections is typically pursued in siloes. Here, we employed a syndemic approach to understand potential interactions of these infections on the rectal mucosal immune environment among YMSM. We enrolled YMSM aged 18-29 years with and without HIV and/or asymptomatic bacterial STI and collected blood, rectal secretions, and rectal tissue biopsies. YMSM with HIV were on suppressive antiretroviral therapy (ART) with preserved blood CD4 cell counts. We defined 7 innate and 19 adaptive immune cell subsets by flow cytometry, the rectal mucosal transcriptome by RNAseq, and the rectal mucosal microbiome by 16S rRNA sequencing and examined the effects of HIV and STI and their interactions. We measured tissue HIV RNA viral loads among YMSM with HIV and HIV replication in rectal explant challenge experiments among YMSM without HIV. HIV, but not asymptomatic STI, was associated with profound alterations in the cellular composition of the rectal mucosa. We did not detect a difference in the microbiome composition associated with HIV, but asymptomatic bacterial STI was associated with a higher probability of presence of potentially pathogenic taxa. When examining the rectal mucosal transcriptome, there was evidence of statistical interaction; asymptomatic bacterial STI was associated with upregulation of numerous inflammatory genes and enrichment for immune response pathways among YMSM with HIV, but not YMSM without HIV. Asymptomatic bacterial STI was not associated with differences in tissue HIV RNA viral loads or in HIV replication in explant challenge experiments. Our results suggest that asymptomatic bacterial STI may contribute to inflammation particularly among YMSM with HIV, and that future research should examine potential harms and interventions to reduce the health impact of these syndemic infections.

Dose-Ranging Plasma and Genital Tissue Pharmacokinetics and Biodegradation of Ultra-Long-Acting Cabotegravir In Situ Forming Implant.

HIV continues to affect millions of men and women worldwide. The development of long-acting injectables for HIV prevention can overcome adherence challenges with daily oral prevention regimens by reducing dosing frequency and stigma. We previously developed an ultra-long-acting injectable, biodegradable, and removeable in situ forming implant (ISFI) with cabotegravir (CAB) that demonstrated protection after multiple rectal SHIV challenges in female macaques. Here, we sought to further characterize CAB ISFI pharmacokinetics (PK) in mice by assessing the effect of dose and number of injections on CAB PK, time to completion of CAB release and polymer degradation, long-term genital tissue PK, and CAB PK tail after implant removal. CAB concentrations in plasma were above the benchmark for protection for 11-12 months with proportionality between dose and drug exposure. CAB ISFI exhibited high concentrations in vaginal, cervical, and rectal tissues for up to 180 days. Furthermore, depots were easily retrievable up to 180 days post-administration with up to 34% residual CAB and near complete (85%) polymer degradation quantified in depots ex vivo. After depot removal, results demonstrated a median 11-fold decline in CAB plasma concentrations across all doses. Ultimately, this study provided critical PK information for the CAB ISFI formulation that could aid in its future translation to clinical studies.

Ultra-long-acting in-situ forming implants with cabotegravir protect female macaques against rectal SHIV infection

Ultra-long-acting delivery platforms for HIV pre-exposure prophylaxis (PrEP) may increase adherence and maximize public health benefit. We report on an injectable, biodegradable, and removable in-situ forming implant (ISFI) that is administered subcutaneously and can release the integrase inhibitor cabotegravir (CAB) above protective benchmarks for more than 6 months. CAB ISFIs are well-tolerated in female mice and female macaques showing no signs of toxicity or chronic inflammation. In macaques, median plasma CAB concentrations exceed established PrEP protection benchmarks within 3 weeks and confer complete protection against repeated rectal SHIV challenges. Implant removal via a small incision in 2 macaques at week 12 results in a 7- to 48-fold decrease in plasma CAB levels within 72 hours. Modeling to translate CAB ISFI dosing suggests that a 3 mL injection would exceed protective benchmarks in humans for over 5 months post administration. Our results support the clinical advancement of CAB ISFIs for ultra-long-acting PrEP in humans.

Pharmacokinetics and efficacy of topical inserts containing tenofovir alafenamide fumarate and elvitegravir administered rectally in macaques.

Topical on-demand forms for HIV pre-exposure prophylaxis (PrEP) may be a desirable alternative for people that prefer not to use daily PrEP. CONRAD has developed inserts containing tenofovir alafenamide (TAF) and elvitegravir (EVG) for on-demand vaginal or rectal pericoital use. We assessed the pharmacokinetics (PK) and pre-exposure efficacy of rectally applied TAF/EVG inserts in macaques. PK was assessed in 12 pigtailed macaques. Tenofovir (TFV) and EVG levels were assayed in rectal biopsies and secretions, and tenofovir-diphosphate (TFV-DP) levels in biopsies and peripheral blood mononuclear cells (PBMC). Drug biodistribution was evaluated in 10 animals at necropsy 4 h post-dosing. For efficacy assessments, one or two TAF/EVG inserts were administered to macaques (n=6) 4 h before repeated rectal SHIV162p3 challenges. One TAF/EVG insert resulted in rapid and high EVG and TFV-DP in rectal tissue 4 h after application. Adding a second insert led to a 10-fold increase in EVG and TFV-DP in rectal tissue. Efficacy of one and two TAF/EVG inserts were 72.6% (CI 24.5%-92.6%) and 93.1% (CI 73.3%-99.2%), respectively. Although high TFV-DP and EVG levels were observed with one rectal TAF/EVG insert, it only conferred partial protection from rectal SHIV challenges. Adding a second insert led to an increase in TFV and EVG in rectal tissues resulting in higher (>90%) efficacy. These results highlight the high efficacy of TAF/EVG inserts as topical on-demand rectal PrEP, as well as the need for appropriate drug coverage in the deep rectum and colon to achieve high protection. The work related to animal studies was funded by CDC intramural funds and an interagency agreement between CDC and USAID (USAID/CDC IAA AID-GH-T-15-00002). The work related to the insert formulation was funded by U.S. PEPFAR through USAID under a Cooperative Agreement (AID-OAA-A-14-00010) with CONRAD/Eastern Virginia Medical School. The findings and conclusions of this manuscript are those of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention (CDC), USAID, President's Emergency Plan for AIDS Relief (PEPFAR), Eastern Virginia Medical School (EVMS), or the US government.

A clade C HIV-1 vaccine protects against heterologous SHIV infection by modulating IgG glycosylation and T helper response in macaques.

The rising global HIV-1 burden urgently requires vaccines capable of providing heterologous protection. Here, we developed a clade C HIV-1 vaccine consisting of priming with modified vaccinia Ankara (MVA) and boosting with cyclically permuted trimeric gp120 (CycP-gp120) protein, delivered either orally using a needle-free injector or through parenteral injection. We tested protective efficacy of the vaccine against intrarectal challenges with a pathogenic heterologous clade C SHIV infection in rhesus macaques. Both routes of vaccination induced a strong envelope-specific IgG in serum and rectal secretions directed against V1V2 scaffolds from a global panel of viruses with polyfunctional activities. Envelope-specific IgG showed lower fucosylation compared with total IgG at baseline, and most of the vaccine-induced proliferating blood CD4+ T cells did not express CCR5 and α4β7, markers associated with HIV target cells. After SHIV challenge, both routes of vaccination conferred significant and equivalent protection, with 40% of animals remaining uninfected at the end of six weekly repeated challenges with an estimated efficacy of 68% per exposure. Induction of envelope-specific IgG correlated positively with G1FB glycosylation, and G2S2F glycosylation correlated negatively with protection. Vaccine-induced TNF-α+ IFN-γ+ CD8+ T cells and TNF-α+ CD4+ T cells expressing low levels of CCR5 in the rectum at prechallenge were associated with decreased risk of SHIV acquisition. These results demonstrate that the clade C MVA/CycP-gp120 vaccine provides heterologous protection against a tier2 SHIV rectal challenge by inducing a polyfunctional antibody response with distinct Fc glycosylation profile, as well as cytotoxic CD8 T cell response and CCR5-negative T helper response in the rectum.

Identification of CX3CR1+ mononuclear phagocyte subsets involved in HIV-1 and SIV colorectal transmission

SummaryThe difficulty to unambiguously identify the various subsets of mononuclear phagocytes (MNPs) of the intestinal lamina propria has hindered our understanding of the initial events occurring after mucosal exposure to HIV-1.Here, we compared the composition and function of MNP subsets at steady-state and following ex vivo and in vivo viral exposure in human and macaque colorectal tissues.Combined evaluation of CD11c, CD64, CD103, and CX3CR1 expression allowed to differentiate lamina propria MNPs subsets common to both species. Among them, CD11c+ CX3CR1+ cells expressing CCR5 migrated inside the epithelium following ex vivo and in vivo exposure of colonic tissue to HIV-1 or SIV. In addition, the predominant population of CX3CR1high macrophages present at steady-state partially shifted to CX3CR1low macrophages as early as three days following in vivo SIV rectal challenge of macaques.Our analysis identifies CX3CR1+ MNPs as novel players in the early events of HIV-1 and SIV colorectal transmission.

Protective efficacy of the anti-HIV broadly neutralizing antibody PGT121 in the context of semen exposure.

BackgroundHIV-1 infections occur following viral exposure at anogenital mucosal surfaces in the presence of semen. Semen contains immunosuppressive and pro-inflammatory factors. Semen from HIV-1-infected donors contains anti-HIV-1 antibodies. We assessed if passively infused anti-HIV-1 neutralizing antibody conferred protection from rectal SHIVSF162P3 challenge at semen exposed mucosae.MethodsWe pooled seminal plasma from HIV-1-infected donors. The pool was screened by ELISA for antibodies against HIV-1SF162 gp140. The ability of seminal plasma to inhibit macaque NK cells from responding to direct and antibody-dependent stimulation was assessed. The ability of seminal plasma to inhibit macaque granulocytes from mediating oxidative burst was also assessed. To demonstrate viral infectivity in the presence of seminal plasma, macaques (n = 4) were rectally challenged with SHIVSF162P3 following exposure to 2.5 mL of seminal plasma. To evaluate if anti-HIV-1 neutralizing antibody confers protection against rectal SHIV challenge at semen exposed mucosae, eight macaques were intravenously infused with PGT121, either wild type (n = 4) or the Fc receptor binding deficient LALA variant (n = 4), and rectally challenged with SHIVSF162P3 following exposure to 2.5 mL of seminal plasma.FindingsAnti-HIV-1SF162 gp140 antibodies were detected in seminal plasma. Seminal plasma inhibited direct and antibody-dependent NK cell activation and granulocyte oxidative burst in vitro. Rectal SHIVSF162P3 challenge of control macaques following seminal plasma exposure resulted in infection of all animals. All macaques infused with wild type or LALA PGT121 and challenged with SHIVSF162P3 following seminal plasma exposure were protected.InterpretationPGT121 conferred protection against rectal SHIVSF162P3 challenge at semen exposed mucosae. Future research should investigate if semen alters protection conferred by antibodies more dependent on non-neutralizing functions.

Th17 T Cells and Immature Dendritic Cells Are the Preferential Initial Targets after Rectal Challenge with a Simian Immunodeficiency Virus-Based Replication-Defective Dual-Reporter Vector.

Understanding the earliest events of human immunodeficiency virus (HIV) sexual transmission is critical to developing and optimizing HIV prevention strategies. To gain insights into the earliest steps of HIV rectal transmission, including cellular targets, rhesus macaques were intrarectally challenged with a single-round simian immunodeficiency virus (SIV)-based dual reporter that expresses luciferase and near-infrared fluorescent protein 670 (iRFP670) upon productive transduction. The vector was pseudotyped with the HIV-1 envelope JRFL. Regions of tissue containing foci of luminescent transduced cells were identified macroscopically using an in vivo imaging system, and individual transduced cells expressing fluorescent protein were identified and phenotyped microscopically. This system revealed that anal and rectal tissues are both susceptible to transduction 48 h after the rectal challenge. Detailed phenotypic analysis revealed that, on average, 62% of transduced cells are CCR6-positive (CCR6+) T cells-the vast majority of which express RORγT, a Th17 lineage-specific transcription factor. The second most common target cells were immature dendritic cells at 20%. These two cell types were transduced at rates that are four to five times higher than their relative abundances indicate. Our work demonstrates that Th17 T and immature dendritic cells are preferential initial targets of HIV/SIV rectal transmission. IMPORTANCE Men and women who participate in unprotected receptive anal intercourse are at high risk of acquiring HIV. While in vitro data have developed a framework for understanding HIV cell tropism, the initial target cells in the rectal mucosa have not been identified. In this study, we identify these early host cells by using an innovative rhesus macaque rectal challenge model and methodology, which we previously developed. Thus, by shedding light on these early HIV/SIV transmission events, this study provides a specific cellular target for future prevention strategies.

Oral Vaccination Approaches for Anti-SHIV Immunity.

We modified a Sabin Oral Poliovirus Vaccine (OPV) vector to permit secretion of the antigens of interest with the goal of improving anti-HIV Env humoral responses in a SHIV mucosal immunization composed of DNA and recombinant OPVs. We evaluated stimulation of systemic and mucosal cell-mediated and humoral immunity in Rhesus macaques by two regimens, both involving a prime with a SHIVBG505 DNA construct producing non-infectious particles formulated in lipid nanoparticles, administered in the oral cavity, and two different viral vector boostings, administered in the oral cavity and intestinally. Group 1 was boosted with rMVA-SHIVBG505, expressing SIV Gag/Pol and HIVBG505 Env. Group 2 was boosted with a SHIVBG505-OPV vaccine including a non-secreting SIVmac239CA-p6-OPV, expressing Gag CA, NC and p6 proteins, and a HIVBG505C1-V2-OPV, secreting the C1-V2 fragment of HIV EnvBG505, recognized by the broadly neutralizing antibody PG16. A time course analysis of anti-SHIV Gag and Env CD4+ and CD8+ T-cell responses in PBMC and in lymph node, rectal, and vaginal MNC was carried out. Both regimens stimulated significant cell-mediated responses in all compartments, with SHIVBG505-OPV immunization stimulating more significant levels of responses than rMVA- SHIVBG505. Boolean analysis of these responses revealed predominantly monofunctional responses with multifunctional responses also present in all tissues. Stimulation of antibody responses was disappointing in both groups with negative anti-SHIV IgG in plasma, and IgA in salivary, rectal and vaginal secretions being restricted to a few animals. After repeated rectal challenge with SHIVBG505, two Group 1 animals remained uninfected at challenge termination. No significant differences were observed in post-infection viral loads between groups. After the acute phase decline, CD4+ T cell percentages returned to normal levels in vaccinated as well as control animals. However, when compared to controls, vaccinate groups had more significant preservation of PBMC and rectal MNC Th17/Treg ratios, considered the strongest surrogate marker of progression to AIDS. We conclude that the vaccine platforms used in this study are insufficient to stimulate significant humoral immunity at the tested doses and schedule but sufficient to stimulate significant mucosal and systemic cell-mediated immunity, impacting the preservation of key Th17 CD4+ T cells in blood and rectal mucosa.

Development of surgical concepts in rectal cancer resection and challenges in minimally invasive surgical proctectomy

Since the early 1900s there have been dramatic changes in the management of patients with rectal cancer. Surgical approaches initially performed for palliation, have now been adapted, modernised and undertaken as part of a multimodal approach. This has resulted in significant improvements in long-term oncological survival and patient quality of life. With the introduction of total mesorectal excision (TME) in the 1980's, and its global acceptance by the surgical community, local and distant disease-free survival in patients with rectal malignancy has significantly improved. Since the inception of minimally invasive surgery, laparoscopy has seen dramatic changes both in the evolution of technological advances and application in multiquadrant surgery for colorectal malignancy. Favorable short-term clinical benefits and long-term oncological equivalence from many multicentre randomized controlled trials in laparoscopic colonic cancer resection has led the colorectal surgical community to translate and adapt minimally invasive surgical (MIS) techniques for proctectomy in patients with rectal tumours. MIS proctectomy is technically challenging and is associated with a steep learning curve. Reported challenges in the literature continuously identify a group within three common themes which can be divided into patient/anatomical factors, tumour characteristics and the use of neoadjuvant therapies. Despite a large body of evidence highlighting efficacy of MIS in proctectomy, significant challenges exist in male patients with a narrow pelvis and distal tumors. Such patients are at increased risk of a poor surgical specimen, positive distal and circumferential resection margins (CRMs), and increased local recurrence. Despite advances in laparoscopy and robotic platforms, approaching such lesions from a “top down” approach expose the ongoing limitations to lower pelvic access. This technically challenging issue has led to the colorectal surgical community adopting previously taught MIS techniques to develop a “bottom up” transanal approach to TME, now known as transanal TME (taTME) in order to mitigate this increased margin risk.

Preventive efficacy of a tenofovir alafenamide fumarate nanofluidic implant in SHIV-challenged nonhuman primates.

Pre-exposure prophylaxis (PrEP) using antiretroviral oral drugs is effective at preventing HIV transmission when individuals adhere to the dosing regimen. Tenofovir alafenamide (TAF) is a potent antiretroviral drug, with numerous long-acting (LA) delivery systems under development to improve PrEP adherence. However, none has undergone preventive efficacy assessment. Here we show that LA TAF using a novel subcutaneous nanofluidic implant (nTAF) confers partial protection from HIV transmission. We demonstrate that sustained subcutaneous delivery through nTAF in rhesus macaques maintained tenofovir diphosphate concentration at a median of 390.00 fmol/106 peripheral blood mononuclear cells, 9 times above clinically protective levels. In a non-blinded, placebo-controlled rhesus macaque study with repeated low-dose rectal SHIVSF162P3 challenge, the nTAF cohort had a 62.50% reduction (95% CI: 1.72% to 85.69%; p=0.068) in risk of infection per exposure compared to the control. Our finding mirrors that of tenofovir disoproxil fumarate (TDF) monotherapy, where 60.00% protective efficacy was observed in macaques, and clinically, 67.00% reduction in risk with 86.00% preventive efficacy in individuals with detectable drug in the plasma. Overall, our nanofluidic technology shows potential as a subcutaneous delivery platform for long-term PrEP and provides insights for clinical implementation of LA TAF for HIV prevention.

Two-dose emtricitabine/tenofovir alafenamide plus bictegravir prophylaxis protects macaques against SHIV infection.

ObjectivesCurrent prophylaxis options for people at risk for HIV infection include two US FDA-approved daily pre-exposure prophylaxis (PrEP) regimens and guidelines for a 2-1-1 event-driven course specifically for men who have sex with men. Despite this, PrEP use rates remain suboptimal, and additional PrEP options may help to improve uptake among diverse populations. Here, we evaluated protective efficacy of two-dose PrEP and two-dose postexposure prophylaxis (PEP) schedules with emtricitabine (FTC)/tenofovir alafenamide (TAF) with or without bictegravir (BIC) in an SHIV macaque model.MethodsMacaques received one oral dose of 200 mg emtricitabine, 25 mg tenofovir alafenamide and 25-100 mg of bictegravir to establish pharmacokinetic profiles of each drug either in the plasma or the peripheral blood mononuclear cells. Protective efficacy of multiple two-dose PrEP and PEP schedules with FTC/TAF with or without bictegravir was then assessed in two repeat low-dose rectal SHIV challenge studies.ResultsThe data revealed over 95% per-exposure risk reduction with FTC/TAF PrEP initiated 2 h before the exposure, but a loss of significant protection with treatment initiation postexposure. In contrast, FTC/TAF plus BIC offered complete protection as PrEP and greater than 80% per-exposure risk reduction with treatment initiation up to 24 h postexposure.ConclusionsTogether, these results demonstrate that two-dose schedules can protect macaques against SHIV acquisition and highlight the protective advantage of adding the integrase inhibitor bictegravir to the reverse transcriptase inhibitors emtricitabine and tenofovir alafenamide as part of event-driven prophylaxis.

Prevention and treatment of SHIVAD8 infection in rhesus macaques by a potent d-peptide HIV entry inhibitor

Cholesterol-PIE12-trimer (CPT31) is a potent d-peptide HIV entry inhibitor that targets the highly conserved gp41 N-peptide pocket region. CPT31 exhibited strong inhibitory breadth against diverse panels of primary virus isolates. In a simian-HIV chimeric virus AD8 (SHIVAD8) macaque model, CPT31 prevented infection from a single high-dose rectal challenge. In chronically infected animals, CPT31 monotherapy rapidly reduced viral load by ∼2 logs before rebound occurred due to the emergence of drug resistance. In chronically infected animals with viremia initially controlled by combination antiretroviral therapy (cART), CPT31 monotherapy prevented viral rebound after discontinuation of cART. These data establish CPT31 as a promising candidate for HIV prevention and treatment.

DOP52 The phenotype of NOD-scid IL-2Rγnull mice reconstituted with peripheral blood mononuclear cells from patients with Crohn’s disease or ulcerative colitis reflects the respective disease

Abstract Background Recently, we have developed a mouse model that relies on NOD-scid IL-2Rγnull (NSG) mice reconstituted with peripheral blood mononuclear cells (PBMC) derived from patients with ulcerative colitis (UC, NSG-UC). In this model, symptoms of UC are induced by rectal challenge with ethanol. The objective of the study was to adapt this model to Crohn’s disease and to compare the phenotypes of the NSG-UC and NSG-CD mouse models. Methods NSG mice were reconstituted with PBMC from UC (n = 4) or CD (n = 3) patients. Mice were separated into two groups: unchallenged control and ethanol challenged mice. Readout were clinical-, colon and histological scores, analysis of frequencies of subgroups of human T cells, monocytes and B cells isolated from spleen and colon by flow cytometry, and the expression levels of the inflammatory markers TGFß, CRP, MCP-3, and IL-6 in the colon or serum by Luminex analysis. Results The pathological phenotype was markedly different in NSG-UC mice as compared with NSG-CD mice. Firstly, histological analysis revealed that NSG-UC mice exhibited more of a pro-inflammatory phenotype as indicated by a severe influx of inflammatory cells, oedema, crypt loss, crypt abscesses and epithelial hyperplasia. In contrast, NSG-CD mice displayed crypt loss and goblet cell atrophy and pronounced fibrosis indicating ongoing wound healing processes. These observations were corroborated by frequencies of splenic and colonic leucocytes. Antigen experienced CD4+ T (CD45RO+) cells and switched B cells (CD19+ CD27+ IgD-) were significantly increased in NSG-UC mice, whereas significantly higher levels of experienced CD8+ T cells and M1 (CD64+), M2 (CD163+) CD14+ monocytes and unswitched B cells (CD19+ CD27+ IgD+) indicated a monocyte driven inflammation in NSG-CD mice. This observation was also reflected in the colon of mice. Inflammation in UC was characterised by increased frequencies of neutrophils, activated CD4+ T cells (CD69+) and increased levels of CRP and MCP-3, whereas NSG-CD mice were signified by increased frequencies of M2 and M1 monocytes and of TGFß levels. In contrast to NSG-CD mice, NSG-UC mice also displayed higher serum levels of IL-6. Secondly, the impact of ethanol was more pronounced in the NSG-UC mice. In NSG-CD mice, the challenge did not evoke significant differences as compared with unchallenged control mice. Conclusion The comparison of pathological phenotypes of the NSG-UC and NSG-CD mouse models revealed differences, some of which reflect the respective human disease. The NSG-UC and NSG-CD mouse models may constitute powerful tools to get a better understanding of the different inflammatory processes in UC and CD.

Islatravir for the treatment and prevention of infection with the human immunodeficiency virus type 1.

To discuss the potential role of islatravir (ISL), a novel reverse transcriptase translocation inhibitor, in the treatment and prevention of human immunodeficiency virus type 1 (HIV-1) infection. Islatravir (4'-ethynyl-2-fluoro-2'-deoxyadenosine, MK-8591) is a long-acting first-in-class nucleoside reverse transcriptase translocation inhibitor with the potential for versatile dosing routes and dosing intervals. It demonstrated robust antiviral activity when dosed once daily and once weekly in HIV-1-infected individuals and SIV-infected rhesus macaques. In clinical trials of ISL in combination with doravirine and lamivudine, daily oral administration resulted in high levels of virologic suppression in HIV-infected individuals. In preclinical studies, ISL dosed orally once-weekly as preexposure prophylaxis (PrEP), protected rhesus macaques against SHIV infection via the mucosal route in the low-dose rectal challenge model. Most recently, data in healthy HIV-1-uninfected individuals demonstrated the feasibility of formulating of ISL as an implant. In these studies, levels of intracellular ISL-triphosphate were consistent with the potential for a once-yearly implantable administration of ISL as PrEP. Islatravir is a promising new agent for both the treatment and prevention of HIV-1 infection.

Editorial introductions

Editorial introductions