Early antiretroviral therapy in SIV-infected rhesus macaques reveals a multiphasic, saturable dynamic accumulation of the rebound competent viral reservoir

The rebound competent viral reservoir (RCVR)-virus that persists during antiretroviral treatment (ART) and can reignite systemic infection when treatment is stopped-is the primary barrier to eradicating HIV. We used time to initiation of ART during primary infection of rhesus macaques (RMs) after intravenous challenge with barcoded SIVmac239 as a means to elucidate the dynamics of RCVR establishment in groups of RMs by creating a multi-log range of pre-ART viral loads and then assessed viral time-to-rebound and reactivation rates resulting from the discontinuation of ART after one year. RMs started on ART on days 3, 4, 5, 6, 7, 9 or 12 post-infection showed a nearly 10-fold difference in pre-ART viral measurements for successive ART-initiation timepoints. Only 1 of 8 RMs initiating ART on days 3 and 4 rebounded after ART interruption despite measurable pre-ART plasma viremia. Rebounding plasma from the 1 rebounding RM contained only a single barcode lineage detected at day 50 post-ART. All RMs starting ART on days 5 and 6 rebounded between 14- and 50-days post-ART with 1-2 rebounding variants each. RMs starting ART on days 7, 9, and 12 had similar time-to-measurable plasma rebound kinetics despite multiple log differences in pre-ART plasma viral load (pVL), with all RMs rebounding between 7- and 16-days post-ART with 3-28 rebounding lineages. Calculated reactivation rates per pre-ART pVL were highest for RMs starting ART on days 5, 6, and 7 after which the rate of accumulation of the RCVR markedly decreased for RMs treated on days 9 and 12, consistent with multiphasic establishment and near saturation of the RCVR within 2 weeks post infection. Taken together, these data highlight the heterogeneity of the RCVR between RMs, the stochastic establishment of the very early RCVR, and the saturability of the RCVR prior to peak viral infection.

10 Prism adaptation testing in children to improve surgical outcomes in esotropia surgery

The aim of strabismus surgery is to improve alignment and ideally restore binocular vision. Prism adaptation (PAT) in esotropia is known to improve post-operative outcomes by allowing choice of target angle in line with pre-operative fusion potential. Reaching a successful end-point in PAT requires co-operation, which is not a given in the paediatric population. The purpose of this study is to describe the successful use of prism adaptation in children in planning target angles for esotropia surgery.Retrospective review of 29 cases from a tertiary centre was conducted, including cases who underwent PAT prior to esotropia surgery over a 6-year period (Jan 2016- Jan 2023). Data was collected from the electronic patient record including patient age, diagnosis, measurements of presenting and prism adapted angles, surgery performed and surgical outcomes.Successful prism adaptation was carried out in children of ages 3-16 . The average presenting angle of esodeviation was 20.9 PD in the distance and 27.3 PD at near. The average maximum prism adapted angle, which was the target angle used for surgery, was 35.3 PD (range 25-50PD). All patients underwent bimedial recessions except one, a re-do who underwent LR re-advancement. 3 patients had one LR resection in addition (3/28). 89.7% of patients achieved binocular vision with stereopsis, 3.4% achieved binocular vision with simultaneous perception. 2 patients had no demonstrable BV, neither were overcorrected post-operatively.Pre-operative PAT is an effective tool in pre-operative assessment of paediatric esotropia patients with binocular potential and can be used to optimise surgical planning and outcomes.

Correction: Tracking the Luminal Exposure and Lymphatic Drainage Pathways of Intravaginal and Intrarectal Inocula Used in Nonhuman Primate Models of HIV Transmission

[This corrects the article DOI: 10.1371/journal.pone.0092830.].

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

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

Effects of Early Antiretroviral Therapy on the Composition and Diversity of the Fecal Microbiome of SIV-infected Rhesus Macaques (Macaca mulatta)

HIV-infected people develop reproducible disruptions in their gastrointestinal microbiota. Despite the suppression of HIV viremia via long-term antiretroviral therapy (ART), alterations still occur in gut microbial diversity and the commensal microbiota. Mounting evidence suggests these microbial changes lead to the development of gut dysbiosis-persistent inflammation that damages the gut mucosa-and correlate with various immune defects. In this study, we examined how early ART intervention influences microbial diversity in SIV-infected rhesus macaques. Using 16S rRNA sequencing, we defined the fecal microbiome in macaques given daily ART beginning on either 3 or 7 d after SIV infection (dpi) and characterized changes in composition, α diversity, and β diversity from before infection through 112 dpi. The dominant phyla in the fecal samples before infection were Bacteroidetes, Firmicutes, Spirochaetes, and Proteobacteria. After SIV infection and ART, the relative abundance of Firmicutes and Bacteroidetes did not change significantly. Significant reductions in α diversity occurred across time when ART was initiated at 3 dpi but not at 7 dpi. Principal coordinate analysis of samples revealed a divergence in β diversity in both treatment groups after SIV infection, with significant differences depending on the timing of ART administration. These results indicate that although administration of ART at 3 or 7 dpi did not substantially alter fecal microbial composition, the timing of early ART measurably altered phylogenetic diversity.

Cytomegalovirus-vaccine-induced unconventional T cell priming and control of SIV replication is conserved between primate species

Strain 68-1 rhesus cytomegalovirus expressing simian immunodeficiency virus (SIV) antigens (RhCMV/SIV) primes MHC-E-restricted CD8+ T cells that control SIV replication in 50%-60% of the vaccinated rhesus macaques. Whether this unconventional SIV-specific immunity and protection is unique to rhesus macaques or RhCMV or is intrinsic to CMV remains unknown. Here, using cynomolgus CMV vectors expressing SIV antigens (CyCMV/SIV) and Mauritian cynomolgus macaques, we demonstrate that the induction of MHC-E-restricted CD8+ T cells requires matching CMV to its host species. RhCMV does not elicit MHC-E-restricted CD8+ T cells in cynomolgus macaques. However, cynomolgus macaques vaccinated with species-matched 68-1-like CyCMV/SIV mounted MHC-E-restricted CD8+ T cells, and half of the vaccinees stringently controlled SIV post-challenge. Protected animals manifested a vaccine-induced IL-15 transcriptomic signature that is associated with efficacy in rhesus macaques. These findings demonstrate that the ability of species-matched CMV vectors to elicit MHC-E-restricted CD8+ T cells that are required for anti-SIV efficacy is conserved in nonhuman primates, and these data support the development of HCMV/HIV for a prophylactic HIV vaccine.

Myeloid cell tropism enables MHC-E-restricted CD8+ T cell priming and vaccine efficacy by the RhCMV/SIV vaccine

The strain 68-1 rhesus cytomegalovirus (RhCMV)-based vaccine for simian immunodeficiency virus (SIV) can stringently protect rhesus macaques (RMs) from SIV challenge by arresting viral replication early in primary infection. This vaccine elicits unconventional SIV-specific CD8+ T cells that recognize epitopes presented by major histocompatibility complex (MHC)-II and MHC-E instead of MHC-Ia. Although RhCMV/SIV vaccines based on strains that only elicit MHC-II- and/or MHC-Ia-restricted CD8+ T cells do not protect against SIV, it remains unclear whether MHC-E-restricted T cells are directly responsible for protection and whether these responses can be separated from the MHC-II-restricted component. Using host microRNA (miR)-mediated vector tropism restriction, we show that the priming of MHC-II and MHC-E epitope-targeted responses depended on vector infection of different nonoverlapping cell types in RMs. Selective inhibition of RhCMV infection in myeloid cells with miR-142-mediated tropism restriction eliminated MHC-E epitope-targeted CD8+ T cell priming, yielding an exclusively MHC-II epitope-targeted response. Inhibition with the endothelial cell-selective miR-126 eliminated MHC-II epitope-targeted CD8+ T cell priming, yielding an exclusively MHC-E epitope-targeted response. Dual miR-142 + miR-126-mediated tropism restriction reverted CD8+ T cell responses back to conventional MHC-Ia epitope targeting. Although the magnitude and differentiation state of these CD8+ T cell responses were generally similar, only the vectors programmed to elicit MHC-E-restricted CD8+ T cell responses provided protection against SIV challenge, directly demonstrating the essential role of these responses in RhCMV/SIV vaccine efficacy.

Developing and testing a case-management intervention to support the return to work of health care workers with common mental health disorders

BACKGROUND

To assess the feasibility and acceptability of conducting a trial of the clinical effectiveness and cost-effectiveness of a new case-management intervention to facilitate the return to work of health care workers, on sick leave, having a common mental disorder (CMD).

METHODS

A mixed methods feasibility study.

RESULTS

Systematic review examined 40 articles and 2 guidelines. Forty-nine National Health Service Occupational Health (OH) providers completed a usual care survey. We trained six OH nurses as case managers and established six recruitment sites. Forty-two out of 1938 staff on sick leave with a CMD were screened for eligibility, and 24 participants were recruited. Out of them, 94% were female. Eleven participants received the intervention and 13 received usual care. Engagement with most intervention components was excellent. Return-to-work self-efficacy improved more in the intervention group than in the usual care group. Qualitative feedback showed the intervention was acceptable.

CONCLUSIONS

The intervention was acceptable, feasible and low cost to deliver, but it was not considered feasible to recommend a large-scale effectiveness trial unless an effective method could be devised to improve the early OH referral of staff sick with CMD. Alternatively, the intervention could be trialled as a new stand-alone OH intervention initiated at the time of usual OH referral.

Use of diamond sensors for a high-flux, high-rate X-ray pass-through diagnostic

X-ray free-electron lasers (XFELs) deliver pulses of coherent X-rays on the femtosecond time scale, with potentially high repetition rates. While XFELs provide high peak intensities, both the intensity and the centroid of the beam fluctuate strongly on a pulse-to-pulse basis, motivating high-rate beam diagnostics that operate over a large dynamic range. The fast drift velocity, low X-ray absorption and high radiation tolerance properties of chemical vapour deposition diamonds make these crystals a promising candidate material for developing a fast (multi-GHz) pass-through diagnostic for the next generation of XFELs. A new approach to the design of a diamond sensor signal path is presented, along with associated characterization studies performed in the XPP endstation of the LINAC Coherent Light Source (LCLS) at SLAC. Qualitative charge collection profiles (collected charge versus time) are presented and compared with those from a commercially available detector. Quantitative results on the charge collection efficiency and signal collection times are presented over a range of approximately four orders of magnitude in the generated electron-hole plasma density.

RhCMV/SIV tropism modulation programs unconventional CD8+ T cell priming and vaccine efficacy

Strain 68-1 rhesus cytomegalovirus (RhCMV) vectors expressing simian immunodeficiency virus (SIV) antigens demonstrate a vaccine efficacy where 50–60% of vaccinated rhesus macaques are protected from SIV challenge. Intriguingly, RhCMV/SIV vectors elicit CD8+ T cells recognizing epitopes presented by MHC-II and MHC-E instead of MHC-Ia. We are studying how these unconventional T cell responses are elicited and contribute to the efficacy against SIV challenge. Here we utilize host microRNA (miRNA)-mediated vector tropism restriction to show that MHC-II- and MHC-E-restricted responses are primed by directly infected, non-overlapping cell types in rhesus macaques. Targeting essential RhCMV genes with myeloid cell-selective miR-142-3p eliminated MHC-E-restricted CD8+ T cell priming, yielding an exclusively MHC-II-restricted response, whereas endothelial cell-selective miR-126-3p targeting eliminated MHC-II-restricted CD8+ T cell priming, yielding an exclusively MHC-E-restricted response. Incorporation of both restriction elements reverts CD8+ T cell responses back to conventional MHC-Ia restriction. Using these otherwise isogenic vectors we show that although they demonstrate similar overall immunogenicity, only the vectors programmed to elicit MHC-E-restricted CD8+ T cell responses provided protection against SIV challenge. The MHC-E-only RhCMV/SIV vaccine efficacy did not exceed that of the parental 68-1 RhCMV/SIV vectors (that elicits both MHC-II and MHC-E responses) indicating that while the MHC-II-restricted CD8+ T cell responses are neutral to overall vaccine efficacy, an additional component of 68-1 RhCMV/SIV-induced immunity contributes to overall vaccine efficacy.

This work was supported by the National Institute of Allergy and Infectious Diseases (NIAID) grants UM1 AI124377 and U19 AI128741 to LJP; the Oregon National Primate Research Center Core grant from the National Institutes of Health, Office of the Director (P51 OD011092); contracts from the National Cancer Institute (# HHSN261200800001E) to JDL; and the Bill and Melinda Gates Foundation grant OPP1107409.

Liver Biopsies Reveal Temporal Changes in Pathology and Macrophage Function following SIV Infection of Rhesus Macaques

Non-alcoholic fatty liver disease (NAFLD) contributes to morbidity and mortality in HIV-infected individuals. To evaluate liver immune changes during SIV infection of macaques, we obtained liver biopsies laparoscopically at 2, 6, and 16 weeks post-infection as well as at necropsy (32 weeks). SIV infection was associated with liver dysfunction that included elevated liver enzymes during acute infection, higher liver weight at necropsy, and histologic changes within the liver lobule (functional unit of the liver) including sinusoidal dilatation near central veins and portal expansion. The type-1 interferon (IFN-1) response (MX1 expression) increased over time post-SIV infection, initially being observed in macrophages (week 2) with a switch to a mixed hepatocyte/monocyte/macrophage response by 16–32 weeks. Over the course of SIV infection, macrophage frequencies also increased – both infiltrating (CD68+CD163+CD206-) and resident (CD68+CD163+CD206+) tissue macrophages – and these macrophages were found more near central veins over time. In contrast, CD68+CD163-CD206− trafficking myeloid cells/monocytes were detected predominantly in the periportal zone of the lobule and associated with elevated MX1 expression in that zone. Our findings identify pathologic changes within the livers of SIV infected macaques as early as 2 weeks post-infection, IFN-1 responses that are initially observed in liver macrophages, and an accumulation of macrophages associated with signs of inflammation by week 32. These studies offer quantitative and spatial insights to inform macrophage-targeted therapeutic approaches that may improve liver function during HIV infection.

Supported by grants from NIH (R01AI134630)

Rapamycin limits CD4+ T cell proliferation in simian immunodeficiency virus-infected rhesus macaques on antiretroviral therapy

Proliferation of latently infected CD4⁺ T cells with replication-competent proviruses is an important mechanism contributing to HIV persistence during antiretroviral therapy (ART). One approach to targeting this latent cell expansion is to inhibit mTOR, a regulatory kinase involved with cell growth, metabolism, and proliferation. Here, we determined the effects of chronic mTOR inhibition with rapamycin with or without T cell activation in SIV-infected rhesus macaques (RMs) on ART. Rapamycin perturbed the expression of multiple genes and signaling pathways important for cellular proliferation and substantially decreased the frequency of proliferating CD4⁺ memory T cells (TM cells) in blood and tissues. However, levels of cell-associated SIV DNA and SIV RNA were not markedly different between rapamycin-treated RMs and controls during ART. T cell activation with an anti-CD3LALA antibody induced increases in SIV RNA in plasma of RMs on rapamycin, consistent with SIV production. However, upon ART cessation, both rapamycin and CD3LALA–treated and control-treated RMs rebounded in less than 12 days, with no difference in the time to viral rebound or post-ART viral load set points. These results indicate that, while rapamycin can decrease the proliferation of CD4⁺ TM cells, chronic mTOR inhibition alone or in combination with T cell activation was not sufficient to disrupt the stability of the SIV reservoir.

Suppression of human and simian immunodeficiency virus replication with the CCR5-specific antibody Leronlimab in two species

The CCR5-specific antibody Leronlimab is being investigated as a novel immunotherapy that can suppress HIV replication with minimal side effects. Here we studied the virological and immunological consequences of Leronlimab in chronically CCR5-tropic HIV-1 infected humans (n = 5) on suppressive antiretroviral therapy (ART) and in ART-naïve acutely CCR5-tropic SHIV infected rhesus macaques (n = 4). All five human participants transitioned from daily combination ART to self-administered weekly subcutaneous (SC) injections of 350 mg or 700 mg Leronlimab and to date all participants have sustained virologic suppression for over seven years. In all participants, Leronlimab fully occupied CCR5 receptors on peripheral blood CD4+ T cells and monocytes. In ART-naïve rhesus macaques acutely infected with CCR5-tropic SHIV, weekly SC injections of 50 mg/kg Leronlimab fully suppressed plasma viremia in half of the macaques. CCR5 receptor occupancy by Leronlimab occurred concomitant with rebound of CD4+ CCR5+ T-cells in peripheral blood, and full CCR5 receptor occupancy was found in multiple anatomical compartments. Our results demonstrate that weekly, self-administered Leronlimab was safe, well-tolerated, and efficacious for long-term virologic suppression and should be included in the arsenal of safe, easily administered, longer-acting antiretroviral treatments for people living with HIV-1.

Trial Registration: ClinicalTrials.gov Identifiers: NCT02175680 and NCT02355184.

With approximately 37 million people living with HIV, stopping the HIV epidemic remains a top global health priority. While daily oral antiretroviral therapy limits HIV replication, its use is a lifelong requirement and increases the likelihood for the development of drug-resistant variants. Indeed, the global prevalence of HIV drug resistance has exponentially increased in recent years, leading to a need for new drug targets. CCR5 is an ideal drug target as HIV uses this molecule to gain entry into target cells. As an example of the importance of CCR5, individuals that lack CCR5 expression due to a natural genetic mutation are naturally resistant to HIV infection. Here, we report that weekly injections of Leronlimab, an anti-CCR5 antibody that blocks the binding of HIV to CCR5, suppressed HIV replication in five HIV+ participants for over seven years. When used to treat acutely infected rhesus macaques, we found that the average amount of virus in the blood of Leronlimab-treated macaques was 10,000 times lower than in untreated macaques. These data suggest that Leronlimab is a safe and effective anti-HIV therapeutic drug.

The ingenol-based protein kinase C agonist GSK445A is a potent inducer of HIV and SIV RNA transcription

Activation of the NF-κB signaling pathway by Protein Kinase C (PKC) agonists is a potent mechanism for human immunodeficiency virus (HIV) latency disruption in vitro. However, significant toxicity risks and the lack of evidence supporting their activity in vivo have limited further evaluation of PKC agonists as HIV latency-reversing agents (LRA) in cure strategies. Here we evaluated whether GSK445A, a stabilized ingenol-B derivative, can induce HIV/simian immunodeficiency virus (SIV) transcription and virus production in vitro and demonstrate pharmacological activity in nonhuman primates (NHP). CD4⁺ T cells from people living with HIV and from SIV⁺ rhesus macaques (RM) on antiretroviral therapy (ART) exposed in vitro to 25 nM of GSK445A produced cell-associated viral transcripts as well as viral particles at levels similar to those induced by PMA/Ionomycin, indicating that GSK445A can potently reverse HIV/SIV latency. Importantly, these concentrations of GSK445A did not impair the proliferation or survival of HIV-specific CD8⁺ T cells, but instead, increased their numbers and enhanced IFN-γ production in response to HIV peptides. In vivo, GSK445A tolerability was established in SIV-naïve RM at 15 μg/kg although tolerability was reduced in SIV-infected RM on ART. Increases in plasma viremia following GSK445A administration were suggestive of increased SIV transcription in vivo. Collectively, these results indicate that GSK445A is a potent HIV/SIV LRA in vitro and has a tolerable safety profile amenable for further evaluation in vivo in NHP models of HIV cure/remission.

Antiretroviral therapy (ART) is not a definitive cure for HIV infection, in part, because the virus is able to integrate its genetic material in the host cell and remain in a dormant but fully replication-competent form during ART. These latently-infected cells can persist for long periods of time and remain hidden from the host’s immune system. If ART is stopped, the virus can reactivate from this pool of infected cells and resume HIV replication and disease progression. As such, finding and eliminating cells with latent HIV infection is priority for HIV cure research. One approach is to use compounds referred to as latency-reversing agents, that can induce HIV reactivation during ART. The goal of this approach is to facilitate elimination of infected cells by the virus itself once it reactivates or by the host’s immune system, once virus induction renders the cells detectable by the immune system, while also preventing the virus from infecting new cells due to the continued presence of ART. In this study we report on the activity of a novel latency-reversing agent called GSK445A, a potent activator of the enzyme protein kinase C (PKC). We show that GSK445A can induce HIV and simian immunodeficiency virus (SIV) latency reversal in vitro and has a tolerable saftey profile in nonhuman primates that should permit further testing of this PKC-agonist in strategies to cure HIV.

Liver Bacterial Dysbiosis With Non-Tuberculosis Mycobacteria Occurs in SIV-Infected Macaques and Persists During Antiretroviral Therapy

Liver disease is a significant contributor to morbidity and mortality in HIV-infected individuals, even during successful viral suppression with combination antiretroviral therapy (cART). Similar to HIV infection, SIV infection of rhesus macaques is associated with gut microbiome dysbiosis and microbial translocation that can be detected systemically in the blood. As microbes leaving the intestines must first pass through the liver via the portal vein, we evaluated the livers of both SIV-infected (SIV+) and SIV-infected cART treated (SIV+cART) rhesus macaques for evidence of microbial changes compared to uninfected macaques. Dysbiosis was observed in both the SIV+ and SIV+cART macaques, encompassing changes in the relative abundance of several genera, including a reduction in the levels of Lactobacillus and Staphylococcus. Most strikingly, we found an increase in the relative abundance and absolute quantity of bacteria within the Mycobacterium genus in both SIV+ and SIV+cART macaques. Multi-gene sequencing identified a species of atypical mycobacteria similar to the opportunistic pathogen M. smegmatis. Phosphatidyl inositol lipoarabinomannan (PILAM) (a glycolipid cell wall component found in atypical mycobacteria) stimulation in primary human hepatocytes resulted in an upregulation of inflammatory transcriptional responses, including an increase in the chemokines associated with neutrophil recruitment (CXCL1, CXCL5, and CXCL6). These studies provide key insights into SIV associated changes in hepatic microbial composition and indicate a link between microbial components and immune cell recruitment in SIV+ and SIV+cART treated macaques.

CCR5 Receptor Occupancy Analysis Reveals Increased Peripheral Blood CCR5+CD4+ T Cells Following Treatment With the Anti-CCR5 Antibody Leronlimab

CCR5 plays a central role in infectious disease, host defense, and cancer progression, thereby making it an ideal target for therapeutic development. Notably, CCR5 is the major HIV entry co-receptor, where its surface density correlates with HIV plasma viremia. The level of CCR5 receptor occupancy (RO) achieved by a CCR5-targeting therapeutic is therefore a critical predictor of its efficacy. However, current methods to measure CCR5 RO lack sensitivity, resulting in high background and overcalculation. Here, we report on two independent, flow cytometric methods of calculating CCR5 RO using the anti-CCR5 antibody, Leronlimab. We show that both methods led to comparable CCR5 RO values, with low background on untreated CCR5+CD4+ T cells and sensitive measurements of occupancy on both blood and tissue-resident CD4+ T cells that correlated longitudinally with plasma concentrations in Leronlimab-treated macaques. Using these assays, we found that Leronlimab stabilized cell surface CCR5, leading to an increase in the levels of circulating and tissue-resident CCR5+CD4+ T cells in vivo in Leronlimab-treated macaques. Weekly Leronlimab treatment in a chronically SIV-infected macaque led to increased CCR5+CD4+ T cells levels and fully suppressed plasma viremia, both concomitant with full CCR5 RO on peripheral blood CD4+ T cells, demonstrating that CCR5+CD4+ T cells were protected from viral replication by Leronlimab binding. Finally, we extended these results to Leronlimab-treated humans and found that weekly 700 mg Leronlimab led to complete CCR5 RO on peripheral blood CD4+ T cells and a statistically significant increase in CCR5+CD4+ T cells in peripheral blood. Collectively, these results establish two RO calculation methods for longitudinal monitoring of anti-CCR5 therapeutic antibody blockade efficacy in both macaques and humans, demonstrate that CCR5+CD4+ T cell levels temporarily increase with Leronlimab treatment, and facilitate future detailed investigations into the immunological impacts of CCR5 inhibition in multiple pathophysiological processes.

Protection of Newborn Macaques by Plant-Derived HIV Broadly Neutralizing Antibodies: a Model for Passive Immunotherapy during Breastfeeding

Preventing human immunodeficiency virus (HIV) infection in newborns by vertical transmission remains an important unmet medical need in resource-poor areas where antiretroviral therapy (ART) is not available and mothers and infants cannot be treated prepartum or during the breastfeeding period. In the present study, the protective efficacy of the potent HIV-neutralizing antibodies PGT121 and VRC07-523, both produced in plants, were assessed in a multiple-SHIV (simian-human immunodeficiency virus)-challenge breastfeeding macaque model. Newborn macaques received either six weekly subcutaneous injections with PGT121 alone or as a cocktail of PGT121-LS plus VRC07-523-LS injected three times every 2 weeks. Viral challenge with SHIVSF162P3 was twice weekly over 5.5 weeks using 11 exposures. Despite the transient presence of plasma viral RNA either immediately after the first challenge or as single-point blips, the antibodies prevented a productive infection in all babies with no sustained plasma viremia, compared to viral loads ranging from 103 to 5 × 108 virions/ml in four untreated controls. No virus was detected in peripheral blood mononuclear cells (PBMCs), and only 3 of 159 tissue samples were weakly positive in the treated babies. Newborn macaques proved to be immunocompetent, producing transient anti-Env antibodies and anti-drug antibody (ADA), which were maintained in the circulation after passive broadly neutralizing antibody clearance. ADA responses were directed to the IgG1 Fc CH2-CH3 domains, which has not been observed to date in adult monkeys passively treated with PGT121 or VRC01. In addition, high levels of VRC07-523 anti-idiotypic antibodies in the circulation of one newborn was concomitant with the rapid elimination of VRC07. Plant-expressed antibodies show promise as passive immunoprophylaxis in a breastfeeding model in newborns. IMPORTANCE Plant-produced human neutralizing antibody prophylaxis is highly effective in preventing infection in newborn monkeys during repeated oral exposure, modeling virus in breastmilk, and offers advantages in cost of production and safety. These findings raise the possibility that anti-Env antibodies may contribute to the control of viral replication in this newborn model and that the observed immune responsiveness may be driven by the long-lived presence of immune complexes.

Antibody-based CCR5 blockade protects Macaques from mucosal SHIV transmission

In the absence of a prophylactic vaccine, the use of antiretroviral therapy (ART) as pre-exposure prophylaxis (PrEP) to prevent HIV acquisition by uninfected individuals is a promising approach to slowing the epidemic, but its efficacy is hampered by incomplete patient adherence and ART-resistant variants. Here, we report that competitive inhibition of HIV Env-CCR5 binding via the CCR5-specific antibody Leronlimab protects rhesus macaques against infection following repeated intrarectal challenges of CCR5-tropic SHIVSF162P3. Injection of Leronlimab weekly at 10 mg/kg provides significant but partial protection, while biweekly 50 mg/kg provides complete protection from SHIV acquisition. Tissue biopsies from protected macaques post challenge show complete CCR5 receptor occupancy and an absence of viral nucleic acids. After Leronlimab washout, protected macaques remain aviremic, and adoptive transfer of hematologic cells into naïve macaques does not transmit viral infection. These data identify CCR5 blockade with Leronlimab as a promising approach to HIV prophylaxis and support initiation of clinical trials.

CD8+ T cells fail to limit SIV reactivation following ART withdrawal until after viral amplification

To define the contribution of CD8+ T cell responses to control of SIV reactivation during and following antiretroviral therapy (ART), we determined the effect of long-term CD8+ T cell depletion using a rhesusized anti-CD8β monoclonal antibody on barcoded SIVmac239 dynamics on stable ART and after ART cessation in rhesus macaques (RMs). Among the RMs with full CD8+ T cell depletion in both blood and tissue, there were no significant differences in the frequency of viral blips in plasma, the number of SIV RNA+ cells and the average number of RNA copies/infected cell in tissue, and levels of cell-associated SIV RNA and DNA in blood and tissue relative to control-treated RMs during ART. Upon ART cessation, both CD8+ T cell-depleted and control RMs rebounded in fewer than 12 days, with no difference in the time to viral rebound or in either the number or growth rate of rebounding SIVmac239M barcode clonotypes. However, effectively CD8+ T cell-depleted RMs showed a stable, approximately 2-log increase in post-ART plasma viremia relative to controls. These results indicate that while potent antiviral CD8+ T cell responses can develop during ART-suppressed SIV infection, these responses effectively intercept post-ART SIV rebound only after systemic viral replication, too late to limit reactivation frequency or the early spread of reactivating SIV reservoirs.

In vitro and in vivo characterization of a recombinant rhesus cytomegalovirus containing a complete genome

Cytomegaloviruses (CMVs) are highly adapted to their host species resulting in strict species specificity. Hence, in vivo examination of all aspects of CMV biology employs animal models using host-specific CMVs. Infection of rhesus macaques (RM) with rhesus CMV (RhCMV) has been established as a representative model for infection of humans with HCMV due to the close evolutionary relationships of both host and virus. However, the only available RhCMV clone that permits genetic modifications is based on the 68-1 strain which has been passaged in fibroblasts for decades resulting in multiple genomic changes due to tissue culture adaptations. As a result, 68-1 displays reduced viremia in RhCMV-naïve animals and limited shedding compared to non-clonal, low passage isolates. To overcome this limitation, we used sequence information from primary RhCMV isolates to construct a full-length (FL) RhCMV by repairing all mutations affecting open reading frames (ORFs) in the 68-1 bacterial artificial chromosome (BAC). Inoculation of adult, immunocompetent, RhCMV-naïve RM with the reconstituted virus resulted in significant viremia in the blood similar to primary isolates of RhCMV and furthermore led to high viral genome copy numbers in many tissues at day 14 post infection. In contrast, viral dissemination was greatly reduced upon deletion of genes also lacking in 68-1. Transcriptome analysis of infected tissues further revealed that chemokine-like genes deleted in 68-1 are among the most highly expressed viral transcripts both in vitro and in vivo consistent with an important immunomodulatory function of the respective proteins. We conclude that FL-RhCMV displays in vitro and in vivo characteristics of a wildtype virus while being amenable to genetic modifications through BAC recombineering techniques.

Terumo spectra optia leukapheresis of cynomolgus macaques for hematopoietic stem cell and T cell collection

Macaques are physiologically relevant animal models of human immunology and infectious disease that have provided key insights and advanced clinical treatment in transplantation, vaccinology, and HIV/AIDS. However, the small size of macaques is a stumbling block for studies requiring large numbers of cells, such as hematopoietic stem cells (HSCs) for transplantation, antigen-specific lymphocytes for in-depth immunological analysis, and latently-infected CD4+ T-cells for HIV cure studies. Here, we provide a detailed protocol for collection of large numbers of HSCs and T-cells from cynomolgus macaques as small as 3 kg using the Terumo Spectra Optia apheresis system, yielding an average of 5.0 × 10⁹ total nucleated cells from mobilized animals and 1.2 × 10⁹ total nucleated cells from nonmobilized animals per procedure. This report provides sufficient detail to adapt this apheresis technique at other institutions, which will facilitate more efficient and detailed analysis of HSCs and their progeny blood cells.

Oral Immunization with HIV-1 Envelope SOSIP trimers elicits systemic immune responses and cross-reactive anti-V1V2 antibodies in non-human primates

Development of a successful HIV vaccine is dependent upon a determination of the optimum antigen and adjuvant as well as choosing an optimal site for vaccine delivery. The site of delivery is particularly relevant as HIV transmission generally requires that the virus crosses a mucosal membrane to infect a new host. Here we undertake a pilot study comparing three vaccine delivery routes, two to the oral cavity (intraepithelial (iEp) and needle-free (NF-Injex)) as well as intramuscular (IM) delivery. These vaccinations utilized a recombinant HIV-1 Env trimer 10042.05 from an elite neutralizer, subject VC10042, that has previously induced high titers of cross-clade reactive V1V2 antibodies. The 10042.05.SOSIP fused trimer was administered with adjuvants R848 (Resiquimod), MPLA and Alhydrogel to characterize the innate cellular and anti-HIV Envelope (Env) antibody responses following the administration of the vaccine to the oral mucosa. Oral delivery of the 10042.05.SOSIP induced high titers of anti-V1V2 antibodies, which together with previous studies, indicates an immunogenic bias toward the V1V2 regions in 10042-derived Envs. Both types of oral vaccine delivery resulted in immunologic and serologic responses that were comparable to the IM delivery route. Furthermore, induction of anti-V1-V2 specific antibodies was best following iEp delivery of the oral vaccine identifying this as the optimal method to orally deliver this vaccine formulation.

The human IL-15 superagonist N-803 promotes migration of virus-specific CD8+ T and NK cells to B cell follicles but does not reverse latency in ART-suppressed, SHIV-infected macaques

Despite the success of antiretroviral therapy (ART) to halt viral replication and slow disease progression, this treatment is not curative and there remains an urgent need to develop approaches to clear the latent HIV reservoir. The human IL-15 superagonist N-803 (formerly ALT-803) is a promising anti-cancer biologic with potent immunostimulatory properties that has been extended into the field of HIV as a potential “shock and kill” therapeutic for HIV cure. However, the ability of N-803 to reactivate latent virus and modulate anti-viral immunity in vivo under the cover of ART remains undefined. Here, we show that in ART-suppressed, simian-human immunodeficiency virus (SHIV)_SF162P3-infected rhesus macaques, subcutaneous administration of N-803 activates and mobilizes both NK cells and SHIV-specific CD8+ T cells from the peripheral blood to lymph node B cell follicles, a sanctuary site for latent virus that normally excludes such effector cells. We observed minimal activation of memory CD4+ T cells and no increase in viral RNA content in lymph node resident CD4+ T cells post N-803 administration. Accordingly, we found no difference in the number or magnitude of plasma viremia timepoints between treated and untreated animals during the N-803 administration period, and no difference in the size of the viral DNA cell-associated reservoir post N-803 treatment. These results substantiate N-803 as a potent immunotherapeutic candidate capable of activating and directing effector CD8+ T and NK cells to the B cell follicle during full ART suppression, and suggest N-803 must be paired with a bona fide latency reversing agent in vivo to facilitate immune-mediated modulation of the latent viral reservoir.

IL-15 regulates NK and memory T cell homeostasis and is therefore being explored for clinical immunotherapy of chronic diseases like cancer and HIV. To explore the applicability of the clinical grade IL-15 superagonist N-803 to HIV cure strategies we tested the impact of N-803 on host immunity and latent virus in SHIV-infected rhesus macaques. Our results suggest that N-803 beneficially modulates effector NK and CD8+ T cells by expanding the numbers of these cells and redistributing them to lymph node B cell follicles, a site known to harbor persistent latent virus during ART. However, our results further suggest that N-803 does not perturb the viral reservoir present in memory CD4+ T cells and that in order to fully unlock the immunotherapeutic potential of N-803 it must be paired with latency reversal agents.

A behaviour change package to prevent hand dermatitis in nurses working in the National Health Service: results of a cluster randomized controlled trial

BACKGROUND

Occupational hand dermatitis poses a serious risk for nurses.

OBJECTIVES

To evaluate the clinical and cost-effectiveness of a complex intervention in reducing the prevalence of hand dermatitis in nurses METHODS: This was a cluster randomized controlled trial conducted at 35 hospital trusts, health boards or universities in the UK. Participants were (i) first-year student nurses with a history of atopic conditions or (ii) intensive care unit (ICU) nurses. Participants at intervention sites received access to a behavioural change programme plus moisturizing creams. Participants at control sites received usual care. The primary outcome was the change of prevalent dermatitis at follow-up (adjusted for baseline dermatitis) in the intervention vs. the control group. Randomization was blinded to everyone bar the trials unit to ensure allocation concealment. The trial was registered on the ISRCTN registry: ISRCTN53303171.

RESULTS

Fourteen sites were allocated to the intervention arm and 21 to the control arm. In total 2040 (69·5%) nurses consented to participate and were included in the intention-to-treat analysis. The baseline questionnaire was completed by 1727 (84·7%) participants. Overall, 789 (91·6%) ICU nurses and 938 (84·0%) student nurses returned completed questionnaires. Of these, 994 (57·6%) had photographs taken at baseline and follow-up (12-15 months). When adjusted for baseline prevalence of dermatitis and follow-up interval, the odds ratios (95% confidence intervals) for hand dermatitis at follow-up in the intervention group relative to the controls were 0·72 (0·33-1·55) and 0·62 (0·35-1·10) for student and ICU nurses, respectively. No harms were reported.

CONCLUSIONS

There was insufficient evidence to conclude whether our intervention was effective in reducing hand dermatitis in our populations. Linked Comment: Brans. Br J Dermatol 2020; 183:411-412.

Viral opportunistic infections in Mauritian cynomolgus macaques undergoing allogeneic stem cell transplantation mirror human transplant infectious disease complications

Allogeneic hematopoietic stem cell transplantation (HSCT) and xenotransplantation are accompanied by viral reactivations and virus-associated complications resulting from immune deficiency. Here, in a Mauritian cynomolgus macaque model of fully MHC-matched allogeneic HSCT, we report reactivations of cynomolgus polyomavirus, lymphocryptovirus, and cytomegalovirus, macaque viruses analogous to HSCT-associated human counterparts BK virus, Epstein-Barr virus, and human cytomegalovirus. Viral replication in recipient macaques resulted in characteristic disease manifestations observed in HSCT patients, such as polyomavirus-associated hemorrhagic cystitis and tubulointerstitial nephritis or lymphocryptovirus-associated post-transplant lymphoproliferative disorder. However, in most cases, the reconstituted immune system, alone or in combination with short-term pharmacological intervention, exerted control over viral replication, suggesting engraftment of functional donor-derived immunity. Indeed, the donor-derived reconstituted immune systems of two long-term engrafted HSCT recipient macaques responded to live attenuated yellow fever 17D vaccine (YFV 17D) indistinguishably from untransplanted controls, mounting 17D-targeted neutralizing antibody responses and clearing YFV 17D within 14 days. Together, these data demonstrate that this macaque model of allogeneic HSCT recapitulates clinical situations of opportunistic viral infections in transplant patients and provides a pre-clinical model to test novel prophylactic and therapeutic modalities.

Managing common mental health disorders in healthcare workers

BACKGROUND

Approximately a quarter of sickness absence in the UK National Health Service (NHS) is attributed to common mental health disorders (CMHDs). This is costly to the NHS and impacts on patient care and staff morale. Little is known about the occupational health (OH) management of NHS staff who take sick leave for CMHDs.

AIMS

To explore the current OH management of NHS staff on sick leave for CMHDs.

METHODS

We invited providers of NHS OH services identified from the NHS Health at Work Network and Commercial OH Providers Association to complete a survey on the management of employees off work because of CMHDs. Analysis involved descriptive statistics and content analysis.

RESULTS

Forty-nine (39%) of the 126 OH departments approached responded. The majority (98%) had an organizational sickness absence policy that included triggers for referral for staff absent with CMHDs. In 63%, referral occurred 8-28 days after the onset of absence; in 92%, the consultation was completed by an OH nurse or OH physician. Content of the first consultation often included assessment of symptoms and medication for CMHDs. Case management and regular reviews were least commonly used despite evidence on their effectiveness in supporting return to work. All providers offered some support for managers of staff with CMHDs.

CONCLUSION

Variation existed between providers of NHS OH services in the timing of referrals, use of case management and regular reviews for staff with CMHDs. Our findings suggest that current evidence-based guidance on interventions to improve return to work is not being implemented consistently.

Interferon-Gamma test for the detection of Mycobacterium tuberculosis complex infection in Macaca mulatta and other non-human primates

We have formatted an assay to detect Mycobacterium tuberculosis complex infections of non-human primates. Commercially available reagents were used to elicit a specific immune response that was measured by interferon-gamma release. Initial evaluation using blood samples from Rhesus macaques experimentally infected with M tuberculosis distinguished infected versus uninfected animals.

Defining early SIV replication and dissemination dynamics following vaginal transmission

Understanding HIV transmission is critical to guide the development of prophylactic interventions to prevent infection. We used a nonhuman primate (NHP) model with a synthetic swarm of sequence-tagged variants of SIVmac239 ("SIVmac239X") and scheduled necropsy during primary infection (days 3 to 14 after challenge) to study viral dynamics and host responses to the establishment and dissemination of infection following vaginal challenge. We demonstrate that local replication was initiated at multiple sites within the female genital tract (FGT), with each site having multiple viral variants. Local replication and spread in the FGT preceded lymphatic dissemination. Innate viral restriction factors were observed but appeared to follow viral replication and were ineffective at blocking initial viral establishment and dissemination. However, major delays were observed in time to dissemination in animals and among different viral variants within the same animal. It will be important to assess how phenotypic differences affect early viral dynamics.

Mucosal T Helper 17 and T Regulatory Cell Homeostasis Correlate with Acute Simian Immunodeficiency Virus Viremia and Responsiveness to Antiretroviral Therapy in Macaques

Depletion of gut T helper 17 (Th17) cells during HIV infection leads to decreased mucosal integrity and increased disease progression. Conversely, T regulatory (Treg) cells may inhibit antiviral responses or immune activation. In HIV elite controllers, a balanced Th17/Treg ratio is maintained in the blood, suggesting a role for these responses in controlling inflammation and viral replication. HIV-infected individuals exhibit a range in responsiveness to combination antiretroviral therapy (cART). Given the link between the Th17/Treg ratio and HIV disease, we reasoned these responses may play a role in cART responsiveness. In this study, we investigated the relationship between the mucosal Th17/Treg ratio to acute simian immunodeficiency virus (SIV) viremia and the response to cART. Nineteen rhesus macaques were infected with highly pathogenic SIVΔB670 virus and cART was initiated 6 weeks postinfection. Mucosal CD4 T cell subsets were assessed by intracellular cytokine staining in the colon and mesenteric lymph nodes. Higher baseline Th17/Treg ratios corresponded with increased acute SIV viremia. Th17/Treg ratios decreased during acute SIV infection and were not restored during cART, and this corresponded to increased gut immune activation (Ki67⁺), markers of microbial translocation (sCD14), and T cell exhaustion (TIGIT⁺). Animals that maintained a more balanced mucosal Th17/Treg ratio at the time of cART initiation exhibited a better virological response to cART and maintained higher peripheral CD4 counts. These results suggest mucosal Th17 and Treg homeostasis influences acute viremia and the response to cART, a result that suggests therapeutic interventions that improve the Th17/Treg ratio before or during cART may improve treatment of HIV.

Early cellular innate immune responses drive Zika viral persistence and tissue tropism in pigtail macaques

The immunological and virological events that contribute to the establishment of Zika virus (ZIKV) infection in humans are unclear. Here, we show that robust cellular innate immune responses arising early in the blood and tissues in response to ZIKV infection are significantly stronger in males and correlate with increased viral persistence. In particular, early peripheral blood recruitment of plasmacytoid dendritic cells and higher production of monocyte chemoattractant protein (MCP-1) correspond with greater viral persistence and tissue dissemination. We also identify non-classical monocytes as primary in vivo targets of ZIKV infection in the blood and peripheral lymph node. These results demonstrate the potential differences in ZIKV pathogenesis between males and females and a key role for early cellular innate immune responses in the blood in viral dissemination and ZIKV pathogenesis.

Gammaherpesvirus infection and malignant disease in rhesus macaques experimentally infected with SIV or SHIV

Human gammaherpesviruses are associated with malignancies in HIV infected individuals; in macaques used in non-human primate models of HIV infection, gammaherpesvirus infections also occur. Limited data on prevalence and tumorigenicity of macaque gammaherpesviruses, mostly cross-sectional analyses of small series, are available. We comprehensively examine all three-rhesus macaque gammaherpesviruses -Rhesus rhadinovirus (RRV), Rhesus Lymphocryptovirus (RLCV) and Retroperitoneal Fibromatosis Herpesvirus (RFHV) in macaques experimentally infected with Simian Immunodeficiency Virus or Simian Human Immunodeficiency Virus (SIV/SHIV) in studies spanning 15 years at the AIDS and Cancer Virus Program of the Frederick National Laboratory for Cancer Research. We evaluated 18 animals with malignancies (16 lymphomas, one fibrosarcoma and one carcinoma) and 32 controls. We developed real time quantitative PCR assays for each gammaherpesvirus DNA viral load (VL) in malignant and non-tumor tissues; we also characterized the tumors using immunohistochemistry and in situ hybridization. Furthermore, we retrospectively quantified gammaherpesvirus DNA VL and SIV/SHIV RNA VL in longitudinally-collected PBMCs and plasma, respectively. One or more gammaherpesviruses were detected in 17 tumors; generally, one was predominant, and the relevant DNA VL in the tumor was very high compared to surrounding tissues. RLCV was predominant in tumors resembling diffuse large B cell lymphomas; in a Burkitt-like lymphoma, RRV was predominant; and in the fibrosarcoma, RFHV was predominant. Median RRV and RLCV PBMC DNA VL were significantly higher in cases than controls; SIV/SHIV VL and RLCV VL were independently associated with cancer. Local regressions showed that longitudinal VL patterns in cases and controls, from SIV infection to necropsy, differed for each gammaherpesvirus: while RFHV VL increased only slightly in all animals, RLCV and RRV VL increased significantly and continued to increase steeply in cases; in controls, VL flattened. In conclusion, the data suggest that gammaherpesviruses may play a significant role in tumorogenesis in macaques infected with immunodeficiency viruses.

Emerging diagnostic challenges and characteristics of simian betaretrovirus infections in captive macaque colonies

To better understand Simian betaretrovirus (SRV) seropositivity in virus-negative macaques, we transfused blood from SRV-infected or suspect donors into immunosuppressed naive recipients. Our results do not support typical SRV1-5 infection as the cause, but provide evidence for several possibilities including serological artifact, new/different SRV, or an endogenous virus.

Identification of novel simian endogenous retroviruses that are indistinguishable from simian retrovirus (SRV) on current SRV diagnostic assays

Simian betaretroviruses include the well-known exogenous simian retroviruses (SRV-1 through SRV-8), and some closely related simian endogenous retroviruses (SERV). Here, we characterized two new viral genomes, which appear to represent novel SERVs but have characteristics of both SRV and SERV highlighting the need to develop new assays providing molecular and serologic differentiation of SERV and SRV to avoid false positives.

Laparoscopic Technique for Serial Collection of Liver and Mesenteric Lymph Nodes in Macaques

The mesenteric lymph nodes (MLN) and the liver are exposed to microbes and microbial products from the gastrointestinal (GI) tract, making them immunologically unique. The GI tract and associated MLN are sites of early viral replication in human immunodeficiency virus (HIV) infection and the MLN are likely important reservoir sites that harbor latently-infected cells even after prolonged antiretroviral therapy (ART). The liver has been shown to play a significant role in immune responses to lentiviruses and appears to play a significant role in clearance of virus from circulation. Nonhuman primate (NHP) models for HIV and Acquired Immunodeficiency Syndrome (AIDS) closely mimic these aspects of HIV infection and serial longitudinal sampling of primary sites of viral replication and the associated immune responses in this model will help to elucidate critical events in infection, pathogenesis, and the impact of various intervention strategies on these events. Current published techniques to sample liver and MLN together involve major surgery and/or necropsy, which limits the ability to investigate these important sites in a serial fashion in the same animal. We have previously described a laparoscopic technique for collection of MLN. Here, we describe a minimally invasive laparoscopic technique for serial longitudinal sampling of liver and MLN through the same two port locations required for the collection of MLN. The use of the same two ports minimizes the impact to the animals as no additional incisions are required. This technique can be used with increased sampling frequency compared to major abdominal surgery and reduces the potential for surgical complications and associated local and systemic inflammatory responses that could complicate interpretation of results. This procedure has potential to facilitate studies involving NHP models while improving animal welfare.

Ferumoxytol as an intraprostatic MR contrast agent for lymph node mapping of the prostate: a feasibility study in non-human primates

Background A variety of magnetic resonance (MR) lymphographic agents have been proposed for mapping the lymph nodes draining the prostate. Purpose To investigate the feasibility of using ferumoxytol (an FDA-approved iron oxide agent) for lymph node mapping of the prostate on imaging (MRI) in a non-human primate (NHP) Macaque model. Material and Methods Four NHPs weighing 5-13 kg underwent injection of ferumoxytol after a needle was introduced transrectally under MRI guidance into the prostate using a commercially available intrarectal MRI biopsy guide. Ferumoxytol was administered at dosage in the range of 0.15-0.75 mg Fe/kg in a fixed injection volume of 0.2 mL. T1-weighted MRI was performed at 3 T starting immediately and extending at least 45 min post-injection. Two readers evaluated the images in consensus. The NHPs tolerated the ferumoxytol injections at all doses with no evident side effects. Results It was determined that the lowest dose of 0.15 mg Fe/kg produced the best outcome in terms of lymph node visualization and draining nodes were reliably visualized at this dose and volume. Conclusion Thus, MRI with intraprostatic injection of ferumoxytol may be considered an effective T1 contrast agent for prospective mapping of lymph nodes draining the prostate and, thus, for attempted sentinel lymph node identification in prostate cancer. Large clinical trials to determine safety and efficacy are needed.

Adoptive Transfer of Engineered Rhesus Simian Immunodeficiency Virus-Specific CD8+ T Cells Reduces the Number of Transmitted/Founder Viruses Established in Rhesus Macaques

AIDS virus infections are rarely controlled by cell-mediated immunity, in part due to viral immune evasion and immunodeficiency resulting from CD4+ T-cell infection. One likely aspect of this failure is that antiviral cellular immune responses are either absent or present at low levels during the initial establishment of infection. To test whether an extensive, timely, and effective response could reduce the establishment of infection from a high-dose inoculum, we adoptively transferred large numbers of T cells that were molecularly engineered with anti-simian immunodeficiency virus (anti-SIV) activity into rhesus macaques 3 days following an intrarectal SIV inoculation. To measure in vivo antiviral activity, we assessed the number of viruses transmitted using SIVmac239X, a molecularly tagged viral stock containing 10 genotypic variants, at a dose calculated to transmit 12 founder viruses. Single-genome sequencing of plasma virus revealed that the two animals receiving T cells expressing SIV-specific T-cell receptors (TCRs) had significantly fewer viral genotypes than the two control animals receiving non-SIV-specific T cells (means of 4.0 versus 7.5 transmitted viral genotypes; P = 0.044). Accounting for the likelihood of transmission of multiple viruses of a particular genotype, the calculated means of the total number of founder viruses transmitted were 4.5 and 14.5 in the experimental and control groups, respectively (P = 0.021). Thus, a large antiviral T-cell response timed with virus exposure can limit viral transmission. The presence of strong, preexisting T-cell responses, including those induced by vaccines, might help prevent the establishment of infection at the lower-exposure doses in humans that typically transmit only a single virus.

IMPORTANCE

The establishment of AIDS virus infection in an individual is essentially a race between the spreading virus and host immune defenses. Cell-mediated immune responses induced by infection or vaccination are important contributors in limiting viral replication. However, in human immunodeficiency virus (HIV)/SIV infection, the virus usually wins the race, irreversibly crippling the immune system before an effective cellular immune response is developed and active. We found that providing an accelerated response by adoptively transferring large numbers of antiviral T cells shortly after a high-dose mucosal inoculation, while not preventing infection altogether, limited the number of individual viruses transmitted. Thus, the presence of strong, preexisting T-cell responses, including those induced by vaccines, might prevent infection in humans, where the virus exposure is considerably lower.

Transmission of MDR MRSA between primates, their environment and personnel at a United States primate centre

OBJECTIVES

MDR MRSA isolates cultured from primates, their facility and primate personnel from the Washington National Primate Research Center were characterized to determine whether they were epidemiologically related to each other and if they represented common local human-associated MRSA strains.

METHODS

Human and primate nasal and composite environmental samples were collected, enriched and selected on medium supplemented with oxacillin and polymyxin B. Isolates were biochemically verified as Staphylococcus aureus and screened for the mecA gene. Selected isolates were characterized using SCCmec typing, MLST and WGS.

RESULTS

Nasal cultures were performed on 596 primates and 105 (17.6%) were MRSA positive. Two of 79 (2.5%) personnel and two of 56 (3.6%) composite primate environmental facility samples were MRSA positive. Three MRSA isolates from primates, one MRSA from personnel, two environmental MRSA and one primate MSSA were ST188 and were the same strain type by conventional typing methods. ST188 isolates were related to a 2007 ST188 human isolate from Hong Kong. Both MRSA isolates from out-of-state primates had a novel MLST type, ST3268, and an unrelated group. All isolates carried ≥1 other antibiotic resistance gene(s), including tet(38), the only tet gene identified.

CONCLUSIONS

ST188 is very rare in North America and has almost exclusively been identified in people from Pan-Asia, while ST3268 is a newly reported MRSA type. The data suggest that the primate MDR MRSA was unlikely to come from primate centre employees. Captive primates are likely to be an unappreciated source of MRSA.

Laparoscopic Technique for Serial Collection of Para-Colonic, Left Colic, and Inferior Mesenteric Lymph Nodes in Macaques

Unlike peripheral lymph nodes (PLN), the mesenteric lymph nodes (MLN) draining the gastrointestinal (GI) tract are exposed to microbes and microbial products from the intestines and as such, are immunologically distinct. GI draining (MLN) have also been shown to be sites of early viral replication and likely impact early events that determine the course of HIV infection. They also are important reservoir sites that harbor latently-infected cells and from which the virus can emerge even after prolonged combination antiretroviral therapy (cART). Changes in the microbial flora and increased permeability of the GI epithelium associated with lentiviral infection can impact the gut associated lymphoid tissue (GALT) and induce changes to secondary lymphoid organs limiting immune reconstitution with cART. Nonhuman primate models for AIDS closely model HIV infection in humans and serial sampling of the GALT and associated secondary lymphoid organs in this model is crucial to gain a better understanding of the critical early events in infection, pathogenesis, and the role of immune responses or drugs in controlling virus at these sites. However, current techniques to sample GI draining (MLN) involve major surgery and/or necropsy, which have, to date, limited the ability to investigate mechanisms mediating the initiation, persistence and control of infection in this compartment. Here, we describe a minimally invasive laparoscopic technique for serial sampling of these sites that can be used with increased sampling frequency, yields greater cell numbers and immune cell subsets than current non-invasive techniques of the GALT and reduces the potential for surgical complications that could complicate interpretation of the results. This procedure has potential to facilitate studies of pathogenesis and evaluation of preventive and treatment interventions, reducing sampling variables that can influence experimental results, and improving animal welfare.

Short Communication: Comparative Evaluation of Coformulated Injectable Combination Antiretroviral Therapy Regimens in Simian Immunodeficiency Virus-Infected Rhesus Macaques

The use of nonhuman primate (NHP) models to study persistent residual virus and viral eradication strategies in combination antiretroviral therapy (cART)-treated individuals requires regimens that effectively suppress SIV replication to clinically relevant levels in macaques. We developed and evaluated two novel cART regimens in SIVmac239-infected rhesus macaques: (1) a "triple regimen" containing the nucleo(s/t)ide reverse transcriptase inhibitors emtricitabine (FTC) and tenofovir disoproxil fumarate [TDF, prodrug of tenofovir (TFV, PMPA)] with the integrase strand transfer inhibitor dolutegravir (DTG) (n = 3), or (2) a "quad regimen" containing the same three drugs plus the protease inhibitor darunavir (DRV) (n = 3), with each regimen coformulated for convenient administration by a single daily subcutaneous injection. Plasma drug concentrations were consistent across animals within the triple and quad regimen-treated groups, although DTG levels were lower in the quad regimen animals. Time to achieve plasma viral loads stably <30 viral RNA copies/ml ranged from 12 to 20 weeks of treatment between animals, and viral loads <30 viral RNA copies/ml plasma were maintained through 40 weeks of follow-up on cART. Notably, although we show virologic suppression and development of viral resistance in a separate cohort of SIV-infected animals treated with oral DRV monotherapy, the addition of DRV in the quad regimen did not confer an apparent virologic benefit during early treatment, hence the quad regimen-treated animals were switched to the triple regimen after 4 weeks. This coformulated triple cART regimen can be safely, conveniently, and sustainably administered to durably suppress SIV replication to clinically relevant levels in rhesus macaques.

Experimental colitis in SIV-uninfected rhesus macaques recapitulates important features of pathogenic SIV infection

Mucosal damage to the gastrointestinal (GI) tract with resulting microbial translocation is hypothesized to significantly contribute to the heightened and persistent chronic inflammation and immune activation characteristic to HIV infection. Here we employ a non-human primate model of chemically induced colitis in SIV-uninfected rhesus macaques that we developed using dextran sulfate sodium (DSS), to directly test this hypothesis. DSS treatment results in GI barrier damage with associated microbial translocation, inflammation and immune activation. The progression and severity of colitis are longitudinally monitored by a magnetic resonance imaging approach. DSS treatment of SIV-infected African green monkeys, a natural host species for SIV that does not manifest GI tract damage or chronic immune activation during infection, results in colitis with elevated levels of plasma SIV RNA, sCD14, LPS, CRP and mucosal CD4+ T-cell loss. Together these results support the hypothesis that GI tract damage leading to local and systemic microbial translocation, and associated immune activation, are important determinants of AIDS pathogenesis.

HIV-1 infection in humans and SIV infection in rhesus macaques are associated with mucosal damage to the gastrointestinal tract, microbial translocation and chronic immune activation. Here the authors develop a non-human primate DSS colitis model that recapitulates these aspects of the disease in uninfected rhesus macaques.

Selection of unadapted, pathogenic SHIVs encoding newly transmitted HIV-1 envelope proteins

Infection of macaques with chimeric viruses based on SIVMAC but expressing the HIV-1 envelope (Env) glycoproteins (SHIVs) remains the most powerful model for evaluating prevention and therapeutic strategies against AIDS. Unfortunately, only a few SHIVs are currently available. Furthermore, their generation has required extensive adaptation of the HIV-1 Env sequences in macaques so they may not accurately represent HIV-1 Env proteins circulating in humans, potentially limiting their translational utility. We developed a strategy for generating large numbers of SHIV constructs expressing Env proteins from newly transmitted HIV-1 strains. By inoculating macaques with cocktails of multiple SHIV variants, we selected SHIVs that can replicate and cause AIDS-like disease in immunologically intact rhesus macaques without requiring animal-to-animal passage. One of these SHIVs could be transmitted mucosally. We demonstrate the utility of the SHIVs generated by this method for evaluating neutralizing antibody administration as a protection against mucosal SHIV challenge.

Generation and characterization of a SIVmac239 clone corrected at four suboptimal nucleotides

Background

SIVmac239 is a commonly used virus in non-human primate models of HIV transmission and pathogenesis. Previous studies identified four suboptimal nucleotides in the SIVmac239 genome, which putatively inhibit its replicative capacity. Since all four suboptimal changes revert to the optimal nucleotide consensus sequence during viral replication in vitro and in vivo, we sought to eliminate the variability of generating these mutations de novo and increase the overall consistency of viral replication by introducing the optimal nucleotides directly to the infectious molecular clone.

Results

Using site directed mutagenesis of the full-length/nef-open SIVmac239 clone, we reverted all four nucleotides to the consensus/optimal base to generate SIVmac239Opt and subsequently tested its infectivity and replicative capacity in vitro and in vivo. In primary and cell line cultures, we observed that the optimized virus displayed consistent modest but not statistically significant increases in replicative kinetics compared to wild type. In vivo, SIVmac239Opt replicated to high peak titers with an average of 1.2 × 10⁸ viral RNA copies/ml at day 12 following intrarectal challenge, reaching set-point viremia of 1.2 × 10⁶ viral RNA copies/ml by day 28. Although the peak and set point viremia means were not statistically different from the original “wild type” SIVmac239, viral load variation at set point was greater for SIVmac239WT compared to SIVmac239Opt (p = 0.0015) demonstrating a greater consistency of the optimized virus. Synonymous mutations were added to the integrase gene of SIVmac239Opt to generate a molecular tag consisting of ten genetically distinguishable viral variants referred to as SIVmac239OptX (Del Prete et al., J Virol. doi:10.1128/JVI.01026-14, 2014). Replication dynamics in vitro of these optimized clones were not statistically different from the parental clones. Interestingly, the consistently observed rapid reversion of the primer binding site suboptimal nucleotide is not due to viral RT error but is changed post-integration of a mismatched base via host proofreading mechanisms.

Conclusions

Overall, our results demonstrate that SIVmac239Opt is a functional alternative to parental SIVmac239 with marginally faster replication dynamics and with increased replication uniformity providing a more consistent and reproducible infection model in nonhuman primates.

Electronic supplementary material

The online version of this article (doi:10.1186/s12977-015-0175-3) contains supplementary material, which is available to authorized users.

Antifibrotic therapy in simian immunodeficiency virus infection preserves CD4+ T-cell populations and improves immune reconstitution with antiretroviral therapy

Even with prolonged antiretroviral therapy (ART), many human immunodeficiency virus-infected individuals have <500 CD4(+) T cells/µL, and CD4(+) T cells in lymphoid tissues remain severely depleted, due in part to fibrosis of the paracortical T-cell zone (TZ) that impairs homeostatic mechanisms required for T-cell survival. We therefore used antifibrotic therapy in simian immunodeficiency virus-infected rhesus macaques to determine whether decreased TZ fibrosis would improve reconstitution of peripheral and lymphoid CD4(+) T cells. Treatment with the antifibrotic drug pirfenidone preserved TZ architecture and was associated with significantly larger populations of CD4(+) T cells in peripheral blood and lymphoid tissues. Combining pirfenidone with an ART regimen was associated with greater preservation of CD4(+) T cells than ART alone and was also associated with higher pirfenidone concentrations. These data support a potential role for antifibrotic drug treatment as adjunctive therapy with ART to improve immune reconstitution.