In contrast to HIV infection in humans and SIV in macaques, SIV infection of natural hosts including sooty mangabeys (SM) is non-pathogenic despite robust virus replication. We identified a novel SM CCR5 allele containing a two base pair deletion (Δ2) encoding a truncated molecule that is not expressed on the cell surface and does not support SIV entry in vitro. The allele was present at a 26% frequency in a large SM colony, along with 3% for a CCR5Δ24 deletion allele that also abrogates surface expression. Overall, 8% of animals were homozygous for defective CCR5 alleles and 41% were heterozygous. The mutant allele was also present in wild SM in West Africa. CD8+ and CD4+ T cells displayed a gradient of CCR5 expression across genotype groups, which was highly significant for CD8+ cells. Remarkably, the prevalence of natural SIVsmm infection was not significantly different in animals lacking functional CCR5 compared to heterozygous and homozygous wild-type animals. Furthermore, animals lacking functional CCR5 had robust plasma viral loads, which were only modestly lower than wild-type animals. SIVsmm primary isolates infected both homozygous mutant and wild-type PBMC in a CCR5-independent manner in vitro, and Envs from both CCR5-null and wild-type infected animals used CXCR6, GPR15 and GPR1 in addition to CCR5 in transfected cells. These data clearly indicate that SIVsmm relies on CCR5-independent entry pathways in SM that are homozygous for defective CCR5 alleles and, while the extent of alternative coreceptor use in SM with CCR5 wild type alleles is uncertain, strongly suggest that SIVsmm tropism and host cell targeting in vivo is defined by the distribution and use of alternative entry pathways in addition to CCR5. SIVsmm entry through alternative pathways in vivo raises the possibility of novel CCR5-negative target cells that may be more expendable than CCR5+ cells and enable the virus to replicate efficiently without causing disease in the face of extremely restricted CCR5 expression seen in SM and several other natural host species.

Human immunodeficiency virus type 1 transmission selects for virus variants with genetic characteristics distinct from those of donor quasispecies, but the biological factors favoring their transmission or establishment in new hosts are poorly understood. We compared primary target cell tropisms and entry coreceptor utilizations of donor and recipient subtype C Envs obtained near the time of acute infection from Zambian heterosexual transmission pairs. Both donor and recipient Envs demonstrated only modest macrophage tropism, and there was no overall difference between groups in macrophage or CD4 T-cell infection efficiency. Several individual pairs showed donor/recipient differences in primary cell infection, but these were not consistent between pairs. Envs had surprisingly broad uses of GPR15, CXCR6, and APJ, but little or no use of CCR2b, CCR3, CCR8, GPR1, and CXCR4. Donors overall used GPR15 better than did recipients. However, while several individual pairs showed donor/recipient differences for GPR15 and/or other coreceptors, the direction of the differences was inconsistent, and several pairs had unique alternative coreceptor patterns that were conserved across the transmission barrier. CCR5/CCR2b chimeras revealed that recipients as a group were more sensitive than were donors to replacement of the CCR5 extracellular loops with corresponding regions of CCR2b, but significant differences in this direction were not consistent within pairs. These data show that sexual transmission does not select for enhanced macrophage tropism, nor for preferential use of any alternative coreceptor. Recipient Envs are somewhat more constrained than are donors in flexibility of CCR5 use, but this pattern is not universal for all pairs, indicating that it is not an absolute requirement.A majority of new human immunodeficiency virus type 1 (HIV-1) infections are initiated by only a single genetic species, although in some, several closely related variants are transmitted (19,26,34,44,55). Nevertheless, in all cases, a molecular bottleneck occurs during transmission (8,15,22,33,56). This bottleneck does not appear to be simply a stochastic result of low-efficiency transmission since viral sequences in recipients do not typically reflect the majority sequences in donors, even in genital secretions responsible for transmission (22,56). Identifying the biological factors that favor particular variants in transmission and/or establishment in new hosts is essential both to understanding the mechanisms of transmission and to developing approaches, including vaccines and microbicides, that might interrupt transmission.More than 15 years ago, it was recognized that new infections were nearly always initiated by HIV-1 variants that were macrophage tropic and non-syncytium inducing (NSI) in T-cell lines, even though donors often harbored variants that were syncytium inducing (SI) and non-macrophage tropic (55). The molecular basis for these characteristics was subsequently linked to use of the entry coreceptor CCR5 by macrophagetropic/...

Objective Prevention of Clostridium difficile infection (CDI) in acute care hospitals is a priority for hospitals and clinicians. We performed a qualitative systematic review to update the evidence on interventions to prevent CDI published since 2009. Design We searched Ovid, MEDLINE, EMBASE, The Cochrane Library, CINAHL, ISI Web of Knowledge, and grey literature databases from January 1, 2009 to August 1, 2015. Setting We included studies performed in acute care hospitals. Patients or participants We included studies conducted on hospitalized patients that investigated the impact of specific interventions on CDI rates. Interventions We used the QI-Minimum Quality Criteria Set (QI-MQCS) to assess the quality of included studies. Interventions were grouped thematically: environmental disinfection, antimicrobial stewardship, hand hygiene, chlorhexidine bathing, probiotics, bundled approaches, and others. A meta-analysis was performed when possible. Results Of 3236 articles screened, 261 met the criteria for full-text review and 46 studies were ultimately included. The average quality rating was 82% on the QI-MQCS. The most effective interventions, resulting in a 45% to 85% reduction in CDI, included daily to twice daily disinfection of high-touch surfaces (including bed rails) and terminal cleaning of patient rooms with chlorine-based products. Bundled interventions and antimicrobial stewardship showed promise for reducing CDI rates. Chlorhexidine bathing and intensified hand hygiene practices were not effective for reducing CDI rates. Conclusions Daily and terminal cleaning of patient rooms using chlorine-based products were most effective in reducing CDI rates in hospitals. Further studies are needed to identify the components of bundled interventions that reduce CDI rates.

This cohort study examines the association of self-reported postvaccination symptoms with anti–SARS-CoV-2 antibody response among Framingham Heart Study participants contributing to the Collaborative Cohort of Cohorts for COVID-19 Research study.

Background: The pulmonary vasculature is essential for gas exchange and impacts both pulmonary and cardiac function. However, it is difficult to assess and its characteristics in the general population are unknown. We measured pulmonary blood volume (PBV) noninvasively using contrast enhanced, dual-energy computed tomography to evaluate its relationship to age and symptoms among older adults in the community. Methods: The MESA (Multi-Ethnic Study of Atherosclerosis) is an ongoing community-based, multicenter cohort. All participants attending the most recent MESA exam were selected for contrast enhanced dual-energy computed tomography except those with estimated glomerular filtration rate <60 mL/min per 1.73 m 2 . PBV was calculated by material decomposition of dual-energy computed tomography images. Multivariable models included age, sex, race/ethnicity, education, height, weight, smoking status, pack-years, and scanner model. Results: The mean age of the 727 participants was 71 (range 59–94) years, and 55% were male. The race/ethnicity distribution was 41% White, 29% Black, 17% Hispanic, and 13% Asian. The mean±SD PBV in the youngest age quintile was 547±180 versus 433±194 mL in the oldest quintile ( P <0.001), with an approximately linear decrement of 50 mL per 10 years of age ([95% CI, 32–67]; P <0.001). Findings were similar with multivariable adjustment. Lower PBV was associated independently with a greater dyspnea after a 6-minute walk ( P =0.04) and greater composite dyspnea symptom scores ( P =0.02). Greater PBV was also associated with greater height, weight, lung volume, Hispanic race/ethnicity, and nonsmoking history. Conclusions: Pulmonary blood volume was substantially lower with advanced age and was associated independently with greater symptoms scores in the elderly.

Background:Patient navigation (PN) programs can improve cancer screening in underserved populations. PN may advance quality and equity of care by supporting individuals at increased risk of not receiving recommended care.Objective:To evaluate patient satisfaction with medical care and PN for cancer screening.Methods:We conducted a telephone survey of patients enrolled in a randomized control trial evaluating the impact of PN for cancer screening to assess their satisfaction with overall medical care and the PN program. We measured patient satisfaction with medical care using the Patient Satisfaction Questionnaire-18 and evaluated patient satisfaction with PN in the navigated group using the Patient Satisfaction with Interpersonal Relationships with Navigator questionnaire.Key Results:Satisfaction surveys were completed by 114 navigated and 108 non-navigated patients (33% response rate). Patients who received PN had higher satisfaction scores with overall medical care (71.0 vs 66.8; P < .001).Conclusions:Our findings show that patients at high risk of nonadherence with comprehensive cancer screening were satisfied with PN and suggest that PN could positively influence patient satisfaction with overall medical care.

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