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Open Access Publications from the University of California

Open Access Policy Deposits

This series is automatically populated with publications deposited by UC Riverside School of Medicine Center for Cannabinoid Research researchers in accordance with the University of California’s open access policies. For more information see Open Access Policy Deposits and the UC Publication Management System.

Cover page of Exploring Space‐Time Interactions in Fatal Opioid Overdoses

Exploring Space‐Time Interactions in Fatal Opioid Overdoses

(2025)

ABSTRACT This study investigates fatal opioid overdoses in Riverside County, California, between January 2020 and March 2023, employing advanced spatial‐temporal analysis methods to uncover significant clusters and their underlying contexts. By integrating global and local Knox tests, the research identifies both broad trends and specific hotspots of fatal overdoses. The findings reveal substantial spatial disparities, with higher overdose rates in rural areas and neighborhoods characterized by lower socioeconomic status and larger Hispanic populations. Despite a lower overall overdose risk among Hispanics, their neighborhoods exhibit a higher occurrence of fatal overdoses, highlighting complex interactions between individual and environmental factors. These insights underscore the need for targeted, contextually informed public health interventions and policies to effectively address the opioid crisis.

Cover page of Rapid, sensitive, and species-independent detection of Crimean Congo hemorrhagic fever virus nucleoprotein and GP38 antibodies

Rapid, sensitive, and species-independent detection of Crimean Congo hemorrhagic fever virus nucleoprotein and GP38 antibodies

(2025)

BACKGROUND: Crimean-Congo hemorrhagic fever virus (CCHFV), a zoonotic agent in the Nairoviridae family (genus Orthonairovirus), is a high-priority pathogen. CCHFV infection causes Crimean-Congo hemorrhagic fever (CCHF), a human disease with case fatality rates of up to 40%. Serological surveillance of CCHFV in animals and humans is crucial for ecological studies and public health. METHODS: We developed CCHFV mix-and-read assays utilizing split-NanoLuc technology (NanoBiT) to detect anti-CCHFV antibodies against the nucleoprotein (NP) stalk region and the GP38 glycoprotein. These species- and isotype-agnostic assays provide results in ∼30 min. Using serum samples from RT-PCR-confirmed CCHF cases collected during and after hospitalization, we investigated anti-NP and anti-GP38 antibody development. The performance of the mix-and-read assays was compared to the NP-based IDScreen® CCHF commercial assay using human sera, and cross-reactivity potential was evaluated using a diverse panel of anti-orthonairovirus antisera raised in mice. FINDINGS: In human convalescent cases (n = 21), mix-and-read assay concordance between anti-GP38 and anti-NP antibody detection was 100%. Both mix-and-read assays and IDScreen® CCHF demonstrated identical sensitivity of 95.2% in convalescent patients. The specificity of the NP assay was 98.9%, and that of GP38 was 99.7%, both comparable to IDScreen® CCHF (specificity: 99.7%). Cross-reactivity against CCHF NP and GP38, regardless of assay type, was primarily observed in antisera raised against other orthonairoviruses within the Nairobi sheep disease genogroup. INTERPRETATION: The simplicity and robust performance of the CCHFV mix-and-read assays make them ideal tools for supporting serological surveillance in humans and animals. Furthermore, the inclusion of the GP38 antigen alongside NP enhances the precise identification of retrospective CCHF cases, further strengthening broad surveillance efforts. FUNDING: CDC Emerging Infectious Disease Research Core Funds, funding for reagent, CDC personal, travel. Defence Threat Reduction Agency (HDTRA12210007): E.K. salary. Oak Ridge Institute for Science and Education (ORISE): E.K. salary and travel. National Institute of Allergy and Infectious Diseases (1R01AI180125-01A1): sample acquisition. Funding sources did not have a role in the writing or decision to submit the publication.

Understanding Opioid Use from Retrospective Accounts of Young Adults in Recovery: Motives, Experiences, and Implications for Prevention

(2025)

Opioid use disorder is a public health problem with disastrous effects for young people and their families. Opioid use shares risk factors with other substances; there may be additional unique motives and experiences associated with opioid use with potential implications for improving prevention. The present study used surveys and interviews to elicit retrospective accounts of 30 young adults (19 female) in recovery from opioid use disorder to examine (1) self-reported motives for opioid use, and (2) experiences and factors that participants associate with opioid use as compared to other substances. Motives reported for past opioid use on surveys were enhancement (i.e., fun or excitement) and coping (i.e., to forget worries or cheer up when in a bad mood), followed by conformity and social motives. Through analysis of interview data, we found that: experiences of opioid use differed from experiences associated with other substances, with effects described in terms of escape and numbing (theme 1); and the ability (early in use) to remain/appear functional (theme 2). Participants reported perceptions of lower risk of harm compared to other substances (theme 3). For some, access was the main factor reported to contribute to opioid use (theme 4). Evidence-based prevention approaches focused on environmental strategies (such as prescription regulation policies) and individual strategies (such as coping skills and prevention education) are relevant for opioid use prevention. Additional supplemental approaches are needed to focus on misperceptions among young people that prescription medications confer lower risk than other substances.

Cover page of Chronic, Low-Dose Methamphetamine Reveals Sexual Dimorphism of Memory Performance, Histopathology, and Gene Expression Affected by HIV-1 Tat Protein in a Transgenic Model of NeuroHIV

Chronic, Low-Dose Methamphetamine Reveals Sexual Dimorphism of Memory Performance, Histopathology, and Gene Expression Affected by HIV-1 Tat Protein in a Transgenic Model of NeuroHIV

(2025)

Methamphetamine (METH) use is frequent among people with HIV (PWH) and appears to increase the risk of neuronal injury and neurocognitive impairment (NCI). This study explored in vivo the effects of a 12 week (long-term), low-dose METH regimen in a transgenic animal model of neuroHIV with inducible expression of HIV-1 transactivator of transcription (Tat). Seven months after transient Tat induction and five months after METH exposure ended, we detected behavioral changes in the Barnes maze (BM) spatial memory task in the Tat and METH groups but not the combined Tat + METH group. The novel object recognition (NOR) task revealed that Tat extinguished discrimination in female animals with and without METH, although METH alone slightly improved NOR. In contrast, in males, Tat, METH, and Tat + METH all compromised NOR. Neuropathological examination detected sex-dependent and brain region-specific changes of pre-synaptic terminals, neurites, and activation of astrocytes and microglia. RNA-sequencing and quantitative reverse transcription polymerase chain reaction indicated that METH and Tat significantly altered gene expression, including factors linked to Alzheimer's disease-like NCI. In summary, chronic low-dose METH exerts long-term effects on behavioral function, neuropathology, and mRNA expression, and modulates the effects of Tat, suggesting sex-dependent and -independent mechanisms may converge in HIV brain injury and NCI.

Cover page of Durable humoral immunity and long-term protection induced by a Crimean-Congo hemorrhagic fever virus replicon particle vaccine in mice

Durable humoral immunity and long-term protection induced by a Crimean-Congo hemorrhagic fever virus replicon particle vaccine in mice

(2025)

A Crimean-Congo hemorrhagic fever virus replicon particle vaccine was evaluated for long-term immunity and efficacy in mice. IgG responses persisted up to 18 months, with similar titers across dosing strategies through 12 months. Protective efficacy reached ≥75% at 6 months (prime-only) and up to 12 months (prime-boost). Booster dosing enhanced antibody avidity, effector function, and improved long-term protection. These findings support durable immunity from single or boosted vaccination.

Cover page of Can a Hybrid Line Break a Selection Limit on Behavioral Evolution in Mice?

Can a Hybrid Line Break a Selection Limit on Behavioral Evolution in Mice?

(2025)

Artificial selection yielded four replicate high runner (HR) lines of mice that reached apparent selection limits (~ threefold increase in wheel revolutions per day vs. four control lines), despite maintenance of additive genetic variance. After 68 generations, we used animal models to test for changes in additive-genetic variances and covariance of the two measured components (average speed and duration) of running distance. We also attempted to break the selection limit by crossing two HR lines, then continuing directional selection on this hybrid line and on the two parental lines for nine generations. The genetic correlation between speed and duration was positive in the base population, but evolved to be negative in the two parental HR lines. Although heritability for both speed and duration (but not distance) increased in the hybrid line, their genetic correlation remained negative. Hybrid F1 mice from generation 68 parents showed heterosis for running distance, which was lost in subsequent generations, and the hybrid line did not exceed the limit. Both male and female hybrids ran faster than parental lines for most generations, but running duration was intermediate or reduced, reflecting their negative genetic correlation. The evolved genetic trade-off between speed and duration may explain the inability for the hybrid line to break the selection limit for distance run, despite renewed additive genetic variance for at least one of its component traits.

Cover page of PTPN2 Regulates Iron Handling Protein Expression in Inflammatory Bowel Disease Patients and Prevents Iron Deficiency in Mice

PTPN2 Regulates Iron Handling Protein Expression in Inflammatory Bowel Disease Patients and Prevents Iron Deficiency in Mice

(2025)

Anemia is the most common extraintestinal manifestation of inflammatory bowel disease (IBD). Iron deficiency is the most frequent cause of anemia in IBD; however, the mechanisms involved are still poorly understood. Here, we investigated the role of the IBD risk gene, protein tyrosine phosphatase non-receptor type 2 (PTPN2), in regulating iron homeostasis. Proteomic analyses were performed on serum from IBD patients genotyped for the IBD-associated loss-of-function rs1893217 PTPN2 variant. Constitutive Ptpn2 wild type (WT), heterozygous (Het), and knockout (KO) mice were analyzed for iron content, blood parameters, and expression of iron handling proteins. Iron absorption was assessed through radiotracer assays. Serum proteomic analyses revealed that the "iron homeostasis signaling pathway" was the main pathway downregulated in Crohn's disease (CD) patients carrying the PTPN2 risk allele, independent of disease activity. Ptpn2-KO mice showed characteristics of anemia, including reduced hemoglobin concentrations along with serum and tissue iron deficiency and elevated serum hepcidin levels vs. Ptpn2-WT and Het mice. 55Fe absorption via oral gavage was significantly impaired in Ptpn2-KO mice. Correspondingly, Ptpn2-KO mice showed reduced apical membrane expression of the iron transporter DMT1. CD patients with the PTPN2 loss-of-function rs1893217 variant display alterations in serum iron handling proteins. Loss of Ptpn2 in mice caused features of anemia, including iron deficiency associated with reduced apical membrane expression of DMT1. These findings identify an important role for PTPN2 in regulating systemic iron homeostasis.

The I-ACTED study (investigating action civics training through an experimental design): a cluster randomized controlled trial of a school-based action civics education intervention on adolescent wellbeing

(2025)

BackgroundObservational studies have found that youth civic engagement is associated with positive mental health, education, and socioeconomic outcomes. However, access to civic opportunities is not evenly distributed. Many classrooms in the United States of America (USA) do not have access to high-quality civics education. Action civics approaches to civic education prepare students for civic engagement by developing the necessary civic skills, knowledge, and character. Through action civics, classes take action on a real-world issue students choose together. Some evidence suggests that action civics may positively affect participants’ wellbeing through the feelings of civic connection and empowerment. The aim of this study is to investigate, through a randomized controlled trial, the impact of a school-based action civics education intervention on civic and wellbeing outcomes, and the mechanisms of any impact observed, among middle and high school students in the USA.MethodsThis study uses a cluster-randomized trial with a waitlist-control design. We are randomizing at the school level, implementing the intervention at the teacher/classroom level, and measuring outcomes at the student level. We are recruiting social studies, civics, government, and related subject teachers, across both middle and high schools, from across the USA, leveraging network ties and referrals to invite teachers/schools to participate. We aim to recruit a sample of around 1,500 students. Intervention group teachers will receive action civics curricular resources they can incorporate into their regular teaching, while the control group will not receive the curricular resources until 12 months later and will continue with their teaching as planned. Students will fill out surveys at the beginning and end of the semester, and will be invited to complete a survey six months later. Surveys will assess civic, wellbeing, demographic, and other related variables.DiscussionThis study is one of the first randomized controlled trials to assess the impacts of action civics curricular materials on civic and wellbeing outcomes. The study will strengthen our understanding of the impacts of action civics education, with implications for the quality and adoption of civic curricula nationwide.Trial registrationNCT04514133 (date of registration September 25, 2020).

Cover page of Tofacitinib Mitigates the Increased SARS-CoV-2 Infection Susceptibility Caused by an IBD Risk Variant in the PTPN2 Gene

Tofacitinib Mitigates the Increased SARS-CoV-2 Infection Susceptibility Caused by an IBD Risk Variant in the PTPN2 Gene

(2025)

BACKGROUND & AIMS: Coronavirus disease (COVID-19), caused by severe acquired respiratory syndrome-Coronavirus-2 (SARS-CoV-2), triggered a global pandemic with severe medical and socioeconomic consequences. Although fatality rates are higher among the elderly and those with underlying comorbidities, host factors that promote susceptibility to SARS-CoV-2 infection and severe disease are poorly understood. Although individuals with certain autoimmune/inflammatory disorders show increased susceptibility to viral infections, there is incomplete knowledge of SARS-CoV-2 susceptibility in these diseases. The aim of our study was to investigate whether the autoimmunity risk gene, PTPN2, which also confers elevated risk to develop inflammatory bowel disease, affects susceptibility to SARS-CoV-2 viral uptake. METHODS: Using samples from PTPN2 genotyped patients with inflammatory bowel disease, PTPN2-deficient mice, and human intestinal and lung epithelial cell lines, we investigated how PTPN2 affects expression of the SARS-CoV-2 receptor angiotensin converting enzyme 2 (ACE2), and uptake of virus-like particles expressing the SARS-CoV2 spike protein and live SARS-CoV-2 virus. RESULTS: We report that the autoimmune PTPN2 loss-of-function risk variant rs1893217 promotes expression of the SARS-CoV-2 receptor, ACE2, and increases cellular entry of SARS-CoV-2 spike protein and live virus. Elevated ACE2 expression and viral entry were mediated by increased Janus kinase-signal transducers and activators of transcription signaling and were reversed by the Janus kinase inhibitor, tofacitinib. CONCLUSION: Collectively, our findings uncover a novel risk biomarker for increased expression of the SARS-CoV-2 receptor and viral entry, and identify a clinically approved therapeutic agent to mitigate this risk.

Cover page of Inflammation associated with monocyte/macrophage activation and recruitment corresponds with lethal outcome in a mouse model of Crimean-Congo haemorrhagic fever

Inflammation associated with monocyte/macrophage activation and recruitment corresponds with lethal outcome in a mouse model of Crimean-Congo haemorrhagic fever

(2024)

Crimean-Congo haemorrhagic fever virus (CCHFV) causes human disease ranging from subclinical to a fatal haemorrhagic syndrome. Determinants of CCHF pathogenesis are largely unknown and animal models that recapitulate human disease are limited. A recently described mouse model uses a monoclonal antibody (mAb 5A3) targeting the interferon (IFN) alpha/beta receptor to suppress type I IFN responses, making animals transiently susceptible to infection. To advance utility of this model, we investigated effects of challenge route, timing of 5A3 delivery, mouse sex and age, and virus strain on clinical course and outcome. C57BL/6J mice received mAb 5A3 -1, 0, or -1/+1 days post-infection (dpi). Subsets were challenged with CCHFV strain Turkey04 or IbAr10200 subcutaneously or intraperitoneally, and serially euthanized 3- and 7-dpi, when meeting euthanasia criteria or at study completion (14 dpi). CCHFV-IbAr10200-infected mice almost uniformly succumbed to infection, whereas CCHFV-Turkey04-infected mice transiently lost weight but survived. These results were consistent regardless of mAb timing or route of challenge. Viral replication and dissemination were comparable between the two strains at 3 dpi. However, in the plasma and livers of non-survivors, expression of proinflammatory cytokines/chemokines that correspond with macrophage activation and recruitment were significantly elevated. Lethal disease was also associated with elevated levels of macrophage activation marker CD163 in plasma. Further, mouse macrophages were more permissive to IbAr1200 infection in vitro, suggesting tropism for these cells may influence pathogenesis. Our data suggest that early inflammation may be a critical determinant of CCHF outcome and therapeutics to control inflammation may be worthwhile targets for future investigation.