Analysis of the Contribution of 6-mer Seed Toxicity to HIV-1-Induced Cytopathicity.

HIV-1 (HIV) infects CD4+ T cells, the gradual depletion of which can lead to AIDS in the absence of antiretroviral therapy (ART). Some cells, however, survive HIV infection and persist as part of the latently infected reservoir that causes recurrent viremia after ART cessation. Improved understanding of the mechanisms of HIV-mediated cell death could lead to a way to clear the latent reservoir. Death induced by survival gene elimination (DISE), an RNA interference (RNAi)-based mechanism, kills cells through short RNAs (sRNAs) with toxic 6-mer seeds (positions 2 to 7 of sRNA). These toxic seeds target the 3' untranslated region (UTR) of mRNAs, decreasing the expression of hundreds of genes critical for cell survival. In most cells under normal conditions, highly expressed cell-encoded nontoxic microRNAs (miRNAs) block access of toxic sRNAs to the RNA-induced silencing complex (RISC) that mediates RNAi, promoting cell survival. HIV has been shown to inhibit the biogenesis of host miRNAs in multiple ways. We now report that HIV infection of cells deficient in miRNA expression or function results in enhanced RISC loading of an HIV-encoded miRNA HIV-miR-TAR-3p, which can kill cells by DISE through a noncanonical (positions 3 to 8) 6-mer seed. In addition, cellular RISC-bound sRNAs shift to lower seed viability. This also occurs after latent HIV provirus reactivation in J-Lat cells, suggesting independence of permissiveness of cells to viral infection. More precise targeting of the balance between protective and cytotoxic sRNAs could provide new avenues to explore novel cell death mechanisms that could be used to kill latent HIV. IMPORTANCE Several mechanisms by which initial HIV infection is cytotoxic to infected cells have been reported and involve various forms of cell death. Characterizing the mechanisms underlying the long-term survival of certain T cells that become persistent provirus reservoirs is critical to developing a cure. We recently discovered death induced by survival gene elimination (DISE), an RNAi-based mechanism of cell death whereby toxic short RNAs (sRNAs) containing 6-mer seed sequences (exerting 6-mer seed toxicity) targeting essential survival genes are loaded into RNA-induced silencing complex (RISC) complexes, resulting in inescapable cell death. We now report that HIV infection in cells with low miRNA expression causes a shift of mostly cellular RISC-bound sRNAs to more toxic seeds. This could prime cells to DISE and is further enhanced by the viral microRNA (miRNA) HIV-miR-TAR-3p, which carries a toxic noncanonical 6-mer seed. Our data provide multiple new avenues to explore novel cell death mechanisms that could be used to kill latent HIV.

COVID-19 mRNA Vaccination Generates Greater Immunoglobulin G Levels in Women Compared to Men.

We investigated whether the antibody response to coronavirus disease 2019 (COVID-19) mRNA vaccination is similar in women and men. In a community cohort without prior COVID-19, first vaccine dose produced higher immunoglobulin G (IgG) levels and percent inhibition of spike-ACE2 receptor binding, a surrogate measure of virus neutralization, in women compared to men (7.0 µg/mL, 51.6% vs 3.3 µg/mL, 36.4%). After 2 doses, IgG levels remained significantly higher for women (30.4 µg/mL) compared to men (20.6 µg/mL), while percent inhibition was similar (98.4% vs 97.7%). Sex-specific antibody response to mRNA vaccination informs future efforts to understand vaccine protection and side effects.

Traumatic events and mental health: The amplifying effects of pre-trauma systemic inflammation.

BACKGROUND: Traumatic experiences are strongly predictive of adverse mental health outcomes. Experimental studies have demonstrated that systemic inflammation can increase reactivity to threatening stimuli. It is not known whether naturally occurring inflammation amplifies the impact of traumatic experiences on mental health. Here we test whether incident traumatic events are more predictive of adverse mental health outcomes for individuals with greater pre-trauma systemic inflammation in a racially and ethnically diverse cohort study of youth assigned male at birth who identify as sexual or gender minorities (ages 16-29, n = 518), a group at high risk for trauma exposure. METHODS: Measures of inflammation, depression symptom severity, and perceived stress were measured at baseline. One year later, depression symptom severity and perceived stress were measured again, and participants reported the traumatic events they had experienced in the intervening year. RESULTS: In a model adjusted for baseline depression symptom severity and other key covariates, we found that higher baseline levels of interleukin-1ß amplified the effect of incident trauma exposure on depression symptom severity at follow-up (ß = 0.234, SE = 0.080, P = 0.004). In a model adjusted for baseline perceived stress and other key covariates, we found that higher baseline scores on a multi-marker inflammatory index amplified the effect of incident trauma exposure on perceived stress at follow-up (ß = 0.243, SE = 0.083, P = 0.003). CONCLUSIONS: These findings suggest that greater pre-trauma inflammation may predict poorer mental health following trauma exposure. Understanding how inflammation interacts with trauma to shape mental health may generate novel insights for preventing and treating the debilitating psychological consequences of trauma.

Differential Inhibition of APOBEC3 DNA-Mutator Isozymes by Fluoro- and Non-Fluoro-Substituted 2'-Deoxyzebularine Embedded in Single-Stranded DNA.

The APOBEC3 (APOBEC3A-H) enzyme family is part of the human innate immune system that restricts pathogens by scrambling pathogenic single-stranded (ss) DNA by deamination of cytosines to produce uracil residues. However, APOBEC3-mediated mutagenesis of viral and cancer DNA promotes its evolution, thus enabling disease progression and the development of drug resistance. Therefore, APOBEC3 inhibition offers a new strategy to complement existing antiviral and anticancer therapies by making such therapies effective for longer periods of time, thereby preventing the emergence of drug resistance. Here, we have synthesised 2'-deoxynucleoside forms of several known inhibitors of cytidine deaminase (CDA), incorporated them into oligodeoxynucleotides (oligos) in place of 2'-deoxycytidine in the preferred substrates of APOBEC3A, APOBEC3B, and APOBEC3G, and evaluated their inhibitory potential against these enzymes. An oligo containing a 5-fluoro-2'-deoxyzebularine (5FdZ) motif exhibited an inhibition constant against APOBEC3B 3.5 times better than that of the comparable 2'-deoxyzebularine-containing (dZ-containing) oligo. A similar inhibition trend was observed for wild-type APOBEC3A. In contrast, use of the 5FdZ motif in an oligo designed for APOBEC3G inhibition resulted in an inhibitor that was less potent than the dZ-containing oligo both in the case of APOBEC3GCTD and in that of full-length wild-type APOBEC3G.

Very High HIV Incidence and Associated Risk Factors in a Longitudinal Cohort Study of Diverse Adolescent and Young Adult Men Who Have Sex with Men and Transgender Women.

To report HIV incidence and associated factors among young men who have sex with men (YMSM) and transgender women (TW). Data were collected February 2015 to July 2018 in the RADAR longitudinal cohort study of YMSM/TW aged 16-29 years (N = 1093). Data included tests for HIV and rectal STIs and self-reported sexual behaviors and networks characteristics. HIV incidence rates were 2.91 per 100 person years (44 seroconversions among 1513 person years). Incidence was significantly higher in Black participants than white (IRR 8.81; 95% CI 2.72-45.26) and Latinx (IRR 3.15; 1.49-7.28) participants, but no significant differences by gender identity were found. Testing positive for rectal STIs (HR 2.50; 95% CI 1.27-4.92) and sex with a partner from a high HIV incidence community area (HR 2.46; 95% CI 1.19-5.07) were associated with higher incidence. HIV incidence was very high and Black YMSM/TW experienced higher HIV incidence attributable to partner race and geographic residence. Rectal STIs were associated with increased HIV incidence.

PrEP Use and Sexually Transmitted Infections Are Not Associated Longitudinally in a Cohort Study of Young Men Who Have Sex with Men and Transgender Women in Chicago.

Our goal was to understand whether PrEP users are at increased risk for STIs, a key target in prevention efforts aimed at disrupting the spread of STIs and likely downstream HIV infection risk. Data were collected as part of RADAR, a cohort study of young men who have sex with men and transgender women (YMSM/TW) (aged 16-29) in Chicago. Longitudinal lagged regression models were utilized to assess the relationship between PrEP use and odds of rectal STI acquisition. Mediation models were also utilized to consider the potential pathway between PrEP use, condomless anal sex (CAS), and rectal STI. One hundred eighty-seven (16.2%) participants had a rectal STI at baseline. In both cross-sectional and longitudinal models, no significant association was observed between PrEP use and STI. In mediation models, PrEP use was significantly associated with increased CAS, however, CAS was not associated with STI status. We demonstrated that, overall, PrEP use was not associated with STIs among YMSM/TW but did observe that PrEP users were more likely to report increased participation in CAS at the subsequent study visit.

Transgender Women's Concerns and Preferences on Potential Future Long-Acting Biomedical HIV Prevention Strategies: The Case of Injections and Implanted Medication Delivery Devices (IMDDs).

There are several long-acting biomedical HIV prevention products in the development pipeline, including injections and implanted medication delivery devices (IMDDs). It is critical to understand concerns and preferences on the use of these products in populations that shoulder a disproportionate burden of the HIV epidemic, such as transgender women. This will allow researchers and public health professionals to construct interventions tailored to the needs of these women to promote optimal use of these tools. In studies of other biomedical HIV prevention products (e.g., oral PrEP) it is clear that transgender women have unique concerns related to the use of these strategies. This may have an impact on this group's uptake and sustained use of longacting HIV prevention products. This study conducted four focus groups with N = 18 transgender women in New York City to understand their concerns and preferences on long-acting PrEP injections and IMDDs. Findings showed that participants were overwhelmingly positive about long-acting HIV prevention strategies, though they had some apprehensions. Overall, participants felt that injections and IMDDs could help address adherence challenges, and that transgender-specific needs should be addressed during clinical trials. Also, there were concerns related to injection or IMDD logistics, concerns about injections' or IMDDs' presence in the body, and familiarity with these products affected participants' opinions on them. Findings from this work can be used to inform protocols, measures, materials, and adherence interventions in future initiatives for transgender women using PrEP injections or IMDDs.

Understanding the Acceptability of Subdermal Implants as a Possible New HIV Prevention Method: Multi-Stage Mixed Methods Study.

BACKGROUND: A long-acting implant for HIV pre-exposure prophylaxis (PrEP) is in development in the Sustained Long-Action Prevention Against HIV (SLAP-HIV) trial. This could provide an alternative to oral PrEP. OBJECTIVE: Our mixed methods study aimed to understand (1) users' experiences with a similar subdermal implant for contraception and (2) factors influencing the likelihood that gay and bisexual men (GBM) would use a proposed PrEP implant. METHODS: Work was completed in 4 stages. In stage 1, we conducted a scientific literature review on existing subdermal implants, focusing on users' experiences with implant devices. In stage 2, we reviewed videos on YouTube, focusing on the experiences of current or former contraceptive implant users (as these implants are similar to those in development in SLAP-HIV). In stage 3, individuals who indicated use of a subdermal implant for contraception in the last 5 years were recruited via a web-based questionnaire. Eligible participants (n=12 individuals who liked implants a lot and n=12 individuals who disliked implants a lot) completed in-depth phone interviews (IDIs) about their experiences. In stage 4, results from IDIs were used to develop a web-based survey for HIV-negative GBM to rate their likelihood of using a PrEP implant on a scale (1=very unlikely and 5=very likely) based on likely device characteristics and implant concerns identified in the IDIs. RESULTS: In the scientific literature review (stage 1), concerns about contraceptive implants that could apply to the PrEP implants in development included potential side effects (eg, headache), anticipated high cost of the device, misconceptions about PrEP implants (eg, specific contraindications), and difficulty accessing PrEP implants. In the stage 2 YouTube review, individuals who had used contraceptive implants reported mild side effects related to their device. In stage 3, implant users reported that devices were comfortable, unintrusive, and presented only minor discomfort (eg, bruising) before or after insertion and removal. They mainly reported removing or disliking the device due to contraceptive-related side effects (eg, prolonged menstruation). Participants in the stage 4 quantitative survey (N=304) were mainly gay (204/238, 85.7%), white (125/238, 52.5%), cisgender men (231/238, 97.1%), and 42.0% (73/174) of them were on oral PrEP. Not having to take a daily pill increased the likelihood of using PrEP implants (mean 4.13). Requiring >1 device to achieve 1 year of protection (mean range 1.79-2.94) mildly discouraged PrEP implant use. Participants did not mind moderate bruising, a small scar, tenderness, or bleeding after insertion or removal, and an implant with a size slightly larger than a matchstick (mean ratings 3.18-3.69). CONCLUSIONS: PrEP implants are promising among GBM. Implant features and insertion or removal-related concerns do not seem to discourage potential users. To ensure acceptability, PrEP implants should require the fewest possible implants for the greatest protection duration.

Discordance of Self-report and Laboratory Measures of HIV Viral Load Among Young Men Who Have Sex with Men and Transgender Women in Chicago: Implications for Epidemiology, Care, and Prevention.

Suppressing HIV viral load through daily antiretroviral therapy (ART) substantially reduces the risk of HIV transmission, however, the potential population impact of treatment as prevention (TasP) is mitigated due to challenges with sustained care engagement and ART adherence. For an undetectable viral load (VL) to inform decision making about transmission risk, individuals must be able to accurately classify their VL as detectable or undetectable. Participants were 205 HIV-infected young men who have sex with men (YMSM) and transgender women (TGW) from a large cohort study in the Chicago area. Analyses examined correspondence among self-reported undetectable VL, study-specific VL, and most recent medical record VL. Among HIV-positive YMSM/TGW, 54% had an undetectable VL (< 200 copies/mL) via study-specific laboratory testing. Concordance between self-report and medical record VL values was 80% and between self-report and study-specific laboratory testing was 73%; 34% of participants with a detectable study-specific VL self-reported an undetectable VL at last medical visit, and another 28% reported not knowing their VL status. Periods of lapsed viral suppression between medical visits may represent a particular risk for the TasP strategy among YMSM/TGW. Strategies for frequent viral load monitoring, that are not burdensome to patients, may be necessary to optimize TasP.

Barriers and Facilitators to Oral PrEP Use Among Transgender Women in New York City.

Transgender women may face a disparate risk for HIV/AIDS compared to other groups. In 2012, Truvada was approved for daily use as HIV pre-exposure prophylaxis (PrEP). However, there is a dearth of research about barriers and facilitators to PrEP in transgender women. This paper will shed light on transgender women living in New York City's perceived and actual challenges to using PrEP and potential strategies to overcome them. After completing an initial screening process, four 90-min focus groups were completed with n = 18 transgender women. Participants were asked what they like and dislike about PrEP. Participants identified the following barriers: uncomfortable side effects, difficulty taking pills, stigma, exclusion of transgender women in advertising, and lack of research on transgender women and PrEP. Facilitators included: reducing pill size, increasing the types of available HIV prevention products, and conducting scientific studies to evaluate PrEP in transgender women.

Phospholipase D1 Couples CD4+ T Cell Activation to c-Myc-Dependent Deoxyribonucleotide Pool Expansion and HIV-1 Replication.

Quiescent CD4+ T cells restrict human immunodeficiency virus type 1 (HIV-1) infection at early steps of virus replication. Low levels of both deoxyribonucleotide triphosphates (dNTPs) and the biosynthetic enzymes required for their de novo synthesis provide one barrier to infection. CD4+ T cell activation induces metabolic reprogramming that reverses this block and facilitates HIV-1 replication. Here, we show that phospholipase D1 (PLD1) links T cell activation signals to increased HIV-1 permissivity by triggering a c-Myc-dependent transcriptional program that coordinates glucose uptake and nucleotide biosynthesis. Decreasing PLD1 activity pharmacologically or by RNA interference diminished c-Myc-dependent expression during T cell activation at the RNA and protein levels. PLD1 inhibition of HIV-1 infection was partially rescued by adding exogenous deoxyribonucleosides that bypass the need for de novo dNTP synthesis. Moreover, the data indicate that low dNTP levels that impact HIV-1 restriction involve decreased synthesis, and not only increased catabolism of these nucleotides. These findings uncover a unique mechanism of action for PLD1 inhibitors and support their further development as part of a therapeutic combination for HIV-1 and other viral infections dependent on host nucleotide biosynthesis.

Preferences for Long-Acting Pre-exposure Prophylaxis (PrEP), Daily Oral PrEP, or Condoms for HIV Prevention Among U.S. Men Who Have Sex with Men.

HIV prevention method preferences were evaluated among 512 U.S. men who have sex with men (MSM; median age: 22 years). Approximately 90 % consistently preferred one option across pairwise comparisons of condoms, daily oral pre-exposure prophylaxis (PrEP), and long-acting PrEP delivered via either an injectable or one of two types of PrEP implants differing in visibility. Condoms were most frequently preferred (33.8 %), followed by non-visible implants (21.5 %), and oral PrEP (17.0 %); HIV risk was reported by more choosing implants. In a follow-up question comparing the four PrEP options only, daily oral pills and non-visible implants were most frequently preferred (35.5 and 34.3 %, respectively), followed by injections (25.2 %) and visible implants (4.3 %). An inductive, open-coding approach determined that convenience, duration of protection, and privacy were the most commonly cited reasons for a PrEP method choice, and associated with self-report of HIV risk. Tailoring PrEP product development to privacy and other concerns important to those at highest HIV risk may improve HIV prevention.

Genetic analysis of the localization of APOBEC3F to human immunodeficiency virus type 1 virion cores.

UNLABELLED: Members of the APOBEC3 family of cytidine deaminases vary in their proportions of a virion-incorporated enzyme that is localized to mature retrovirus cores. We reported previously that APOBEC3F (A3F) was highly localized into mature human immunodeficiency virus type 1 (HIV-1) cores and identified that L306 in the C-terminal cytidine deaminase (CD) domain contributed to its core localization (C. Song, L. Sutton, M. Johnson, R. D'Aquila, J. Donahue, J Biol Chem 287:16965-16974, 2012, http://dx.doi.org/10.1074/jbc.M111.310839). We have now determined an additional genetic determinant(s) for A3F localization to HIV-1 cores. We found that one pair of leucines in each of A3F's C-terminal and N-terminal CD domains jointly determined the degree of localization of A3F into HIV-1 virion cores. These are A3F L306/L368 (C-terminal domain) and A3F L122/L184 (N-terminal domain). Alterations to one of these specific leucine residues in either of the two A3F CD domains (A3F L368A, L122A, and L184A) decreased core localization and diminished HIV restriction without changing virion packaging. Furthermore, double mutants in these leucine residues in each of A3F's two CD domains (A3F L368A plus L184A or A3F L368A plus L122A) still were packaged into virions but completely lost core localization and anti-HIV activity. HIV virion core localization of A3F is genetically separable from its virion packaging, and anti-HIV activity requires some core localization. IMPORTANCE: Specific leucine-leucine interactions are identified as necessary for A3F's core localization and anti-HIV activity but not for its packaging into virions. Understanding these signals may lead to novel strategies to enhance core localization that may augment effects of A3F against HIV and perhaps of other A3s against retroviruses, parvoviruses, and hepatitis B virus.

Factors associated with mortality among persistently viraemic triple-antiretroviral-class-experienced patients receiving antiretroviral therapy in the HIV Outpatient Study (HOPS).

BACKGROUND: Identifying factors associated with mortality for HIV-infected patients with persistent viraemia despite antiretroviral (ARV) therapy may inform diagnostic and treatment strategies. METHODS: We analysed data from viraemic triple-ARV-class-experienced HIV Outpatient Study patients seen during 1 January 1999 to 31 December 2012 who, despite treatment that included ARVs from three major drug classes [nucleoside analogue reverse transcriptase inhibitors, non-nucleoside analogue reverse transcriptase inhibitors and protease inhibitors (PIs)], had plasma HIV RNA levels [viral load (VL)] >1000 copies/mL ['triple ARV class failure' (TCF)]. The baseline was defined as the date of meeting the TCF criteria during 1999-2008. We identified factors associated with mortality using Cox regression. RESULTS: Of 597 patients who met the TCF criteria (median follow-up after baseline 4.9 years), 115 (19.3%) died. Baseline factors associated with mortality were age per 10 years [hazard ratio (HR) 1.61, 95% CI 1.28-2.02], risk of HIV from use of injection drugs (HR 1.81, 95% CI 1.10-2.98), CD4+ T cell count <200 cells/mm(3) (HR 3.68, 95% CI 2.41-5.62), VL ≥5.0 log10 copies/mL (HR 2.91, 95% CI 1.88-4.49) and receiving a first combination ARV therapy regimen that was PI-based (HR 2.44, 95% CI 1.47-4.06); receiving a novel ARV agent during follow-up (HR 0.45, 95% CI 0.22-0.93) was protective. Genotypic resistance testing results were available for 274 (45.9%) of the TCF patients, of whom 47 (17.2%) died. In this group, factors associated with death were increasing age (HR 1.94, 95% CI 1.36-2.78, per 10 year increment), risk of HIV from use of injection drugs (HR 2.71, 95% CI 1.37-5.39), baseline VL ≥5.0 log10 copies/mL (HR 5.35, 95% CI 2.82-10.1) and receiving PI-based first combination ARV therapy regimen (HR 3.20, 95% CI 1.25-8.17). No HIV mutations or combinations of mutations were significantly associated with survival. CONCLUSIONS: Factors significantly associated with mortality risk among TCF patients who received ongoing ARV therapy included traditional clinical predictors but not the presence, type or number of HIV genetic mutations. The use of novel ARV drugs by these ARV therapy-experienced patients was associated with an improved survival.

The Global Impact of Diversifying PrEP Options: Results of an International Discrete Choice Experiment of Existing and Potential PrEP Strategies with Gay and Bisexual Men and Physicians.

To improve current and future use of existing (oral, injectable) and potential future (implants, douches) pre-exposure prophylaxis (PrEP) products, we must understand product preferences relative to one another, among gay and bisexual men (GBM), and physicians who prescribe PrEP. We completed an online discrete choice experiment (DCE) with separate groups of GBM and/or physicians from the United States, South Africa, Spain, and Thailand. Participants were presented information on PrEP products, including daily pills, event-driven pills (2-1-1 regimen), injections, subdermal implants (dissolvable, removable), and rectal douches. Next, they completed a choice exercise in which they were shown 10 screens, each presenting 3 of the aforementioned products at a time with 11 attributes for physicians and 10 attributes for GBM. For the attributes that were not constant, one level was shown per screen for each product. Participants selected the product they preferred most and rated their likelihood to select (GBM) or recommend (physicians) that product. Data were modeled using hierarchical Bayes estimation; resulting model coefficients were used to develop attribute importance measures and product preferences. For GBM across all countries, if all aforementioned PrEP products were on the market at the same time, over 90% of GBM would use some form of PrEP; 100% of physicians would recommend at least one of the PrEP products. There were variations in product preference by country. GBM in the United States and Thailand preferred the injection (21.7%, 22.9%, respectively), while the dissolvable implant was preferred in South Africa and Spain (19.9%, 19.8%, respectively). In the United States, South Africa, and Spain (where physician data were available), physicians were most likely to recommend the dissolvable implant (37.2%, 40.6%, 38.3%, respectively).

Northwestern University resource and education development initiatives to advance collaborative artificial intelligence across the learning health system.

Introduction: The rapid development of artificial intelligence (AI) in healthcare has exposed the unmet need for growing a multidisciplinary workforce that can collaborate effectively in the learning health systems. Maximizing the synergy among multiple teams is critical for Collaborative AI in Healthcare. Methods: We have developed a series of data, tools, and educational resources for cultivating the next generation of multidisciplinary workforce for Collaborative AI in Healthcare. We built bulk-natural language processing pipelines to extract structured information from clinical notes and stored them in common data models. We developed multimodal AI/machine learning (ML) tools and tutorials to enrich the toolbox of the multidisciplinary workforce to analyze multimodal healthcare data. We have created a fertile ground to cross-pollinate clinicians and AI scientists and train the next generation of AI health workforce to collaborate effectively. Results: Our work has democratized access to unstructured health information, AI/ML tools and resources for healthcare, and collaborative education resources. From 2017 to 2022, this has enabled studies in multiple clinical specialties resulting in 68 peer-reviewed publications. In 2022, our cross-discipline efforts converged and institutionalized into the Center for Collaborative AI in Healthcare. Conclusions: Our Collaborative AI in Healthcare initiatives has created valuable educational and practical resources. They have enabled more clinicians, scientists, and hospital administrators to successfully apply AI methods in their daily research and practice, develop closer collaborations, and advanced the institution-level learning health system.

Signals in APOBEC3F N-terminal and C-terminal deaminase domains each contribute to encapsidation in HIV-1 virions and are both required for HIV-1 restriction.

Human cytidine deaminases APOBEC3F (A3F) and APOBEC3G (A3G) inhibit human immunodeficiency virus type-1 (HIV-1) replication. In the absence of HIV-1 Vif, A3F and/or A3G are incorporated into assembling virions and exert antiviral functions in subsequently infected target cells. Encapsidation of A3F or A3G within the protease-matured virion core following their incorporation into virions is hypothesized to be important for the antiviral function of these proteins. In this report, we demonstrated that A3F was quantitatively encapsidated in the mature virion core. In distinct contrast, A3G was distributed both within and outside of the virion core. Analysis of a series of A3F-A3G chimeras comprised of exchanged N- and C-terminal deaminase domains identified a 14 amino acid segment in the A3F C-terminal deaminase domain that contributed to preferential encapsidation and anti-HIV activity. Amino acid residue L306 in this C-terminal segment was determined to be necessary, but not sufficient, for these effects. Amino acid residue W126 in the N-terminal deaminase domain was determined also to contribute to preferential encapsidation and antiviral activity of A3F. Analysis of the A3F (W126A L306A) double mutant revealed that both residues are required for full anti-HIV function. The results reported here advance our understanding of the mechanisms of A3F virion encapsidation and antiviral function and may lead to innovative strategies to inhibit HIV-1 replication.

Barriers and facilitators to recruitment of underrepresented research participants: Perspectives of clinical research coordinators.

Background: Insufficient recruitment of groups underrepresented in medical research threatens the generalizability of research findings and compounds inequity in research and medicine. In the present study, we examined barriers and facilitators to recruitment of underrepresented research participants from the perspective of clinical research coordinators (CRCs). Methods: CRCs from one adult and one pediatric academic medical centers completed an online survey in April-May 2022. Survey topics included: participant language and translations, cultural competency training, incentives for research participation, study location, and participant research literacy. CRCs also reported their success in recruiting individuals from various backgrounds and completed an implicit bias measure. Results: Surveys were completed by 220 CRCs. CRCs indicated that recruitment is improved by having translated study materials, providing incentives to compensate participants, and reducing the number of in-person study visits. Most CRCs had completed some form of cultural competency training, but most also felt that the training either had no effect or made them feel less confident in approaching prospective participants from backgrounds different than their own. In general, CRCs reported having greater success in recruiting prospective participants from groups that are not underrepresented in research. Results of the implicit bias measure did not indicate that bias was associated with intentions to approach a prospective participant. Conclusions: CRCs identified several strategies to improve recruitment of underrepresented research participants, and CRC insights aligned with insights from research participants in previous work. Further research is needed to understand the impact of cultural competency training on recruitment of underrepresented research participants.

Filamin A protein interacts with human immunodeficiency virus type 1 Gag protein and contributes to productive particle assembly.

HIV-1 Gag precursor directs virus particle assembly and release. In a search for Gag-interacting proteins that are involved in late stages of the HIV-1 replication cycle, we performed yeast two-hybrid screening against a human cDNA library and identified the non-muscle actin filament cross-linking protein filamin A as a novel Gag binding partner. The 280-kDa filamin A regulates cortical actin network dynamics and participates in the anchoring of membrane proteins to the actin cytoskeleton. Recent studies have shown that filamin A facilitates HIV-1 cell-to-cell transmission by binding to HIV receptors and coreceptors and regulating their clustering on the target cell surface. Here we report a novel role for filamin A in HIV-1 Gag intracellular trafficking. We demonstrate that filamin A interacts with the capsid domain of HIV-1 Gag and that this interaction is involved in particle release in a productive manner. Disruption of this interaction eliminated Gag localization at the plasma membrane and induced Gag accumulation within internal compartments. Moreover, blocking clathrin-dependent endocytic pathways did not relieve the restriction to particle release induced by filamin A depletion. These results suggest that filamin A is involved in the distinct step of the Gag trafficking pathway. The discovery of the Gag-filamin A interaction may provide a new therapeutic target for the treatment of HIV infection.

APOBEC3G complexes decrease human immunodeficiency virus type 1 production.

APOBEC3G (A3G) is packaged into human immunodeficiency virus type 1 (HIV-1) virions unless HIV-1 virion infectivity factor (Vif) counteracts it. Virion A3G restricts HIV-1 reverse transcription and integration in target cells. Some A3G in producer cells colocalizes with specific cytoplasmic structures, in what are called "A3G complexes" here. Functional effects of producer cell A3G complexes on HIV-1 replication were studied. HeLa cells were cotransfected with HIV-1 constructs producing pseudoviruses, as well as either wild-type (WT) A3G or a mutant A3G (C97A, Y124A, W127A, or D128K A3G). Pseudovirus particle production was decreased from cells expressing any of the A3Gs that formed complexes by 24 h after transfection, relative to cells with C97A A3G that did not form detectable A3G complexes by 24 h or A3G-negative cells. The intracellular HIV-1 Gag half-life was shorter in cells containing A3G complexes than in those lacking complexes. HIV-1 virion output was decreased in a single round of replication from a T cell line containing A3G complexes (CEM cells) after infection with Vif-negative HIV-1, compared to Vif-positive HIV-1 that depleted A3G. Levels of production of Vif-negative and Vif-positive virus were similar from cells not containing A3G (CEM-SS cells). Knockdown of the mRNA processing body (P-body) component RCK/p54, eliminated A3G complex formation, and increased HIV-1 production. We conclude that endogenous A3G complexes in producer cells decrease HIV-1 production if not degraded by Vif.