Brad Karalius

Renal Injury Is a Consistent Finding in Dutch Belted Rabbits Experimentally Infected with Enterohemorrhagic Escherichia coli

Enterohemorrhagic Escherichia coli (EHEC) produces Shiga toxin (Stx) and causes renal disease in humans. Dutch Belted (DB) rabbits naturally infected with EHEC O153 develop hemolytic-uremic syndrome-like disease. The aims of this study were to experimentally reproduce O153-induced renal disease in DB rabbits and investigate bacterial and host factors involved in pathogenesis. The pathogenicity of E. coli O157:H7 was also investigated in rabbits. The stx1AB region of O153 was sequenced. By use of liquid chromatography-tandem mass spectrometry, we identified homologs of the Stx receptor, globotriaosylceramide (Gb3), in rabbit kidney extracts. Infected rabbits developed clinical signs and intestinal and kidney lesions. Renal pathological changes consisted of intimal swelling, perivascular edema, erythrocyte fragmentation, capillary thickening, luminal constriction, leukocytic infiltration, mesangial deposits, and changes in Bowmans capsule and space. Sequence analysis of a approximately 7-kb region of the O153 chromosome indicated homology to the Stx1-producing bacteriophage H19B. Our findings indicate that DB rabbits are suitable for the study of the renal manifestations of EHEC infection in humans.

Influence of Age at Virologic Control on Peripheral Blood Human Immunodeficiency Virus Reservoir Size and Serostatus in Perinatally Infected Adolescents

IMPORTANCE Combination antiretroviral therapy initiated within several weeks of human immunodeficiency virus (HIV) infection in adults limits proviral reservoirs that preclude HIV cure. Biomarkers of restricted proviral reservoirs may aid in the monitoring of HIV remission or cure. OBJECTIVES To quantify peripheral blood proviral reservoir size in perinatally HIV-infected (PHIV+) adolescents and to identify correlates of limited proviral reservoirs. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional study including 144 PHIV+ youths (median age, 14.3 years) enrolled in the United States-based Pediatric HIV/AIDS Cohort Study and receiving durable (median duration, 10.2 years) combination antiretroviral therapy, stratified by age at virologic control. MAIN OUTCOMES AND MEASURES The primary end point was peripheral blood mononuclear cell (PBMC) proviral load after virologic control at different ages. Correlations between proviral load and markers of active HIV production (ie, HIV-specific antibodies, 2-long terminal repeat circles) and markers of immune activation and inflammation were also assessed. RESULTS Proviral reservoir size was markedly reduced in the PHIV+ youth who achieved virologic control before 1 year of age (4.2 [interquartile range, 2.6-8.6] copies per 1 million PBMCs) compared with those who achieved virologic control at 1 to 5 years of age (19.4 [interquartile range, 5.5-99.8] copies per 1 million PBMCs) or after 5 years of age (70.7 [interquartile range, 23.2-209.4] copies per 1 million PBMCs; P < .001). A proviral burden of less than 10 copies per 1 million PBMCs in PHIV+ youth was measured in 11 (79%), 20 (40%), and 13 (18%) participants with virologic control before 1 year, at 1 to 5 years, and after 5 years of age, respectively (P < .001). Lower proviral load was associated with undetectable 2-long terminal repeat circles (P < .001) and HIV-negative or indeterminate serostatus (P < .001) but not with concentrations of soluble immune activation markers CD14 and CD163. CONCLUSIONS AND RELEVANCE Early effective combination antiretroviral therapy with prolonged virologic suppression after perinatal HIV infection leads to negligible peripheral blood proviral reservoirs in adolescence and is associated with negative or indeterminate HIV serostatus. These findings highlight the long-term effect of early effective control of HIV replication on biomarkers of HIV persistence in perinatal infection and the utility of HIV serostatus as a biomarker for small proviral reservoir size, although not necessarily for cure.

Fabry Disease in Mice Protects against Lethal Disease Caused by Shiga Toxin–Expressing Enterohemorrhagic Escherichia coli

Fabry disease is an X-linked recessive disorder in which affected persons lack alpha-galactosidase A (alpha -GalA), which leads to excess glycosphingolipids in tissues, mainly globotriaosylceramide (Gb3). Gb3 is the cellular receptor for Shiga toxin (Stx), the primary virulence factor of enterohemorrhagic Escherichia coli. alpha-GalA-knockout mice were significantly protected against lethal intraperitoneal doses of Stx2 or oral doses of Stx2-expressing bacteria, compared with wild-type (wt) control mice. Kidneys of moribund wt mice revealed tubular necrosis, but no histopathologic changes were observed in Gb3-overexpressing mice. Reducing Gb3 levels in alpha-GalA-knockout mice by the intravenous injection of recombinant human alpha-GalA restored the susceptibility of knockout mice to lethal doses of Stx2. These results suggest that excess amounts of Gb3 in alpha-GalA-deficient mice may impair toxin delivery to susceptible tissues.

Immunity to Measles, Mumps, and Rubella in US Children With Perinatal HIV Infection or Perinatal HIV Exposure Without Infection

BACKGROUND Children with perinatal human immunodeficiency virus (HIV) infection (PHIV) may not be protected against measles, mumps, and rubella (MMR) because of impaired initial vaccine response or waning immunity. Our objectives were to estimate seroimmunity in PHIV-infected and perinatally HIV-exposed but uninfected (HEU) children and identify predictors of immunity in the PHIV cohort. METHODS PHIV and HEU children were enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS) at ages 7-15 years from 2007 to 2009. At annual visits, demographic, laboratory, immunization, and clinical data were abstracted and serologic specimens collected. Most recent serologic specimen was used to determine measles seroprotection by plaque reduction neutralization assay and rubella seroprotection and mumps seropositivity by enzyme immunoassay. Sustained combination antiretroviral therapy (cART) was defined as taking cART for at least 3 months. RESULTS Among 428 PHIV and 221 HEU PHACS participants, the prevalence was significantly lower in PHIV children for measles seroprotection (57% [95% confidence interval {CI}, 52%-62%] vs 99% [95% CI, 96%-100%]), rubella seroprotection (65% [95% CI, 60%-70%] vs 98% [95% CI, 95%-100%]), and mumps seropositivity (59% [95% CI, 55%-64%] vs 97% [95% CI, 94%-99%]). On multivariable analysis, greater number of vaccine doses while receiving sustained cART and higher nadir CD4 percentage between last vaccine dose and serologic testing independently improved the cumulative prediction of measles seroprotection in PHIV. Predictors of rubella seroprotection and mumps seropositivity were similar. CONCLUSIONS High proportions of PHIV-infected children, but not HEU children, lack serologic evidence of immunity to MMR, despite documented immunization and current cART. Effective cART before immunization is a strong predictor of current seroimmunity.

Antiretroviral Drug Resistance Among Children and Youth in the United States With Perinatal HIV

Among 234 US youths with perinatal human immunodeficiency virus, 75% had antiretroviral resistance, substantially higher than that of the reference laboratory overall (36%-44%). Resistance to newer antiretrovirals and to all antiretrovirals in a class was uncommon. The only factor independently associated with future resistance was a higher peak viral load.

CD4+ and viral load outcomes of antiretroviral therapy switch strategies after virologic failure of combination antiretroviral therapy in perinatally HIV-infected youth in the United States

Objective:This study compared 12-month CD4+ and viral load outcomes in HIV-infected children and adolescents with virological failure, managed with four treatment switch strategies. Design:This observational study included perinatally HIV-infected (PHIV) children in the Pediatric HIV/AIDS Cohort Study (PHACS) and Pediatric AIDS Clinical Trials (PACTG) Protocol 219C. Methods:Treatment strategies among children with virologic failure were compared: continue failing combination antiretroviral therapy (cART); switch to new cART; switch to drug-sparing regimen; and discontinue all ART. Mean changes in CD4+% and viral load from baseline (time of virologic failure) to 12 months follow-up in each group were evaluated using weighted linear regression models. Results:Virologic failure occurred in 939 out of 2373 (40%) children. At 12 months, children switching to new cART (16%) had a nonsignificant increase in CD4+% from baseline, 0.59 percentage points [95% confidence interval (95% CI) −1.01 to 2.19], not different than those who continued failing cART (71%) (−0.64 percentage points, P = 0.15) or switched to a drug-sparing regimen (5%) (1.40 percentage points, P = 0.64). Children discontinuing all ART (7%) experienced significant CD4+% decline −3.18 percentage points (95% CI −5.25 to −1.11) compared with those initiating new cART (P = 0.04). All treatment strategies except discontinuing ART yielded significant mean decreases in log10VL by 12 months, the new cART group having the largest drop (−1.15 log10VL). Conclusion:In PHIV children with virologic failure, switching to new cART was associated with the best virological response, while stopping all ART resulted in the worst immunologic and virologic outcomes and should be avoided. Drug-sparing regimens and continuing failing regimens may be considered with careful monitoring.

Association of Risk of Viremia, Immunosuppression, Serious Clinical Events, and Mortality With Increasing Age in Perinatally Human Immunodeficiency Virus–Infected Youth

Importance As perinatally human immunodeficiency virus–infected youth (PHIVY) in the United States grow older and more treatment experienced, clinicians need updated information about the association of age, CD4 cell count, viral load (VL), and antiretroviral (ARV) drug use with risk of opportunistic infections, key clinical events, and mortality to understand patient risks and improve care. Objective To examine the incidence or first occurrence during follow-up of key clinical events (including Centers for Disease Control and Prevention stage B [CDC-B] and stage C [CDC-C] events) and mortality among PHIVY stratified by age, CD4 cell count, and VL and ARV status. Design, Setting, and Participants Combining data from the Pediatric HIV/AIDS Cohort Study (PHACS) Adolescent Master Protocol and International Maternal Pediatric Adolescent AIDS Clinical Trials (IMPAACT) P1074 multicenter cohort studies (March 2007 through April 2015), we estimated event rates during person-time spent in key strata of age (7-12, 13-17, and 18-30 years), CD4 cell count (<200, 200-499, and ≥500/&mgr;L), and a combined measure of VL and ARV status (VL <400 or ≥400 copies/mL; ARV therapy or no ARV therapy). A total of 1562 participants in the PHACS Adolescent Master Protocol and IMPAACT P1074 were eligible, and 1446 PHIVY from 41 ambulatory sites in the 12 US states, including Puerto Rico were enrolled. The dates of analysis were March 2015 through January 2017. Main Outcomes and Measures Clinical event rates stratified by person-time in age, CD4 cell count, and VL and ARV categories. Results A total of 1446 PHIVY participated in the study (mean [SD] age, 14.6 [4.6] years; 759 female [52.5%]; 953 black [65.9%]). During a mean (SD) follow-up of 4.9 (1.3) years, higher incidences of CDC-B events, CDC-C events, and mortality were observed as participants aged. Older PHIVY (aged 13-17 and 18-30 years) spent more time with a VL of 400 copies/mL or more and with a CD4 cell count of less than 200/µL compared with 7- to 12-year-old participants (30% and 44% vs 22% of person-time with a VL≥400 copies/mL; 5% and 18% vs 2% of person-time with CD4 cell count <200/µL; P < .001 for each comparison). We observed higher rates of CDC-B events, CDC-C events, bacterial infections, and mortality at lower CD4 cell counts, as expected. The mortality rate among older PHIVY was 6 to 12 times that among the general US population. Higher rates of sexually transmitted infections were also observed at lower CD4 cell counts after adjusting for age. Conclusions and Relevance Older PHIVY were at increased risk of viremia, immunosuppression, CDC-B events, CDC-C events, and mortality. Interventions to improve ARV therapy adherence and optimize models of care for PHIVY as they age are urgently needed to improve long-term outcomes among PHIVY.

Human Immunodeficiency Virus Type 1 DNA Decay Dynamics With Early, Long-term Virologic Control of Perinatal Infection

Background. Early antiretroviral therapy (ART) limits proviral reservoirs, a goal for human immunodeficiency virus type 1 (HIV-1) remission strategies. Whether this is an immediate or long-term effect of virologic suppression (VS) in perinatal infection is unknown. Methods. We quantified HIV-1 DNA longitudinally for up to 14 years in peripheral blood mononuclear cells (PBMCs) among 61 perinatally HIV-1-infected youths in the Pediatric HIV/AIDS Cohort Study who achieved VS at different ages. Participants in group 1 (n = 13) were <1 year of age and in group 2 (n = 48) from 1 through 5 years of age at VS. Piecewise linear mixed-effects regression models assessed the effect of age at VS on HIV-1 DNA trajectories during VS. Results. In the first 2 years following VS, HIV-1 DNA levels decreased by -0.25 (95% confidence interval [CI], -.36 to -.13) log10 copies/million PBMCs per year and was faster with early VS by age 1 year compared with after age 1 (-0.50 and -0.15 log10 copies/million PBMCs per year, respectively). Between years 2 and 14 from VS, HIV-1 DNA decayed by -0.05 (95% CI, -.06 to -.03) log10 copies/million PBMCs per year and was no longer significantly different between groups. The estimated mean half-life of HIV-1 DNA from VS was 15.9 years and was shorter for group 1 compared to group 2 at 5.9 years and 18.8 years, respectively (P = .09). Adjusting for CD4 cell counts had no effect on decay estimates. Conclusions. Early effective, long-term ART initiated from infancy leads to decay of HIV-1-infected cells to exceedingly low concentrations desired for HIV-1 remission strategies.

Incomplete Immune Reconstitution Despite Virologic Suppression in HIV-1 Infected Children and Adolescents

Objectives:Some perinatally infected children do not regain normal CD4+ T-cell counts despite suppression of HIV-1 plasma viremia by antiretroviral therapy (ART). The frequency, severity and significance of these discordant treatment responses remain unclear. Design:We examined the persistence of CD4+ lymphocytopenia despite virologic suppression in 933 children (≥5 years of age) in the USA, Latin America and the Caribbean. Methods:CD4+ T-cell trajectories were examined and Kaplan–Meier methods used to estimate median time to CD4+ T-cell count at least 500 cells/&mgr;l. Results:After 1 year of virologic suppression, most (99%) children achieved a CD4+ T-cell count of at least 200 cells/&mgr;l, but CD4+ T-cell counts remained below 500 cells/&mgr;l after 1 and 2 years of virologic suppression in 14 and 8% of children, respectively. Median times to first CD4+ T-cell count at least 500 cells/&mgr;l were 1.29, 0.78 and 0.46 years for children with less than 200, 200–349 and 350–499 cells/&mgr;l at the start of virologic suppression. New AIDS-defining events occurred in nine children, including four in the first 6 months of virologic suppression. Other infectious and HIV-related diagnoses occurred more frequently and across a wide range of CD4+ cell counts. Conclusion:ART improved CD4+ cell counts in most children, but the time to CD4+ cell count of at least 500 cells was highly dependent upon baseline immunological status. Some children did not reach a CD4+ T-cell count of 500 cells/&mgr;l despite 2 years of virologic suppression. AIDS-defining events occurred in 1% of the population, including children in whom virologic suppression and improved CD4+ T-cell counts were achieved.

Brief Report: APOL1 Renal Risk Variants Are Associated With Chronic Kidney Disease in Children and Youth With Perinatal HIV Infection.

Abstract:APOL1 renal risk alleles are associated with chronic kidney disease (CKD) in adults, with the strongest effect being for HIV-associated nephropathy. Their role in youth with perinatal HIV-1 infection (PHIV) has not been studied. In a nested case–control study of 451 PHIV participants in the Pediatric HIV/AIDS Cohort Study, we found a 3.5-fold increased odds of CKD in those carrying high-risk APOL1 genotypes using a recessive model [95% confidence interval (CI): 1.2 to 10.0]. We report an unadjusted incidence of 1.2 CKD cases/100 person-years (95% CI: 0.5 to 2.5) in PHIV youth carrying APOL1 high-risk genotypes, with important implications for sub-Saharan Africa.