Kaitlin Rainwater-Lovett

Viremic relapse after HIV-1 remission in a perinatally infected child

Recently the “Mississippi Child” was reported as having a prolonged clearance of HIV viremia after the initiation of antiretroviral therapy shortly after birth. Further follow-up of this case is now reported.

Very early combination antiretroviral therapy in infants: prospects for cure.

Purpose of reviewA single case of sustained HIV control in the absence of antiretroviral therapy or HIV-specific immune responses ensued following 18 months of combination antiretroviral therapy initiated at 30 h of age in a perinatally HIV-infected child (the Mississippi child). This case provides proof-of-concept that delay in HIV viremic rebound may ensue following very early treatment (VET) in perinatal infection, likely through marked reduction of latent replication-competent HIV reservoirs. Recent findingsThe latent HIV reservoir remains the critical barrier to remission. Several studies indicate that the earlier effective combination antiretroviral therapy is initiated, the smaller the size of the HIV reservoir. The unique ability of perinatally infected neonates to initiate VET at the time of birth maximizes the potential benefits of limiting latent reservoir size and permitting reservoir decay, likely lengthening the duration of remission and limiting the capacity for re-establishment of viremia. SummaryThis article covers the rationale and feasibility of VET to achieve sustained virologic remission in perinatal infection. Recent studies highlighting the effects of VET on biomarkers of HIV persistence in perinatal HIV infection are reviewed as well as implications and challenges for cure research in pediatric populations.

Variation in dengue virus plaque reduction neutralization testing: systematic review and pooled analysis

BackgroundThe plaque reduction neutralization test (PRNT) remains the gold standard for the detection of serologic immune responses to dengue virus (DENV). While the basic concept of the PRNT remains constant, this test has evolved in multiple laboratories, introducing variation in materials and methods. Despite the importance of laboratory-to-laboratory comparability in DENV vaccine development, the effects of differing PRNT techniques on assay results, particularly the use of different dengue strains within a serotype, have not been fully characterized.MethodsWe conducted a systematic review and pooled analysis of published literature reporting individual-level PRNT titers to identify factors associated with heterogeneity in PRNT results and compared variation between strains within DENV serotypes and between articles using hierarchical models.ResultsThe literature search and selection criteria identified 8 vaccine trials and 25 natural exposure studies reporting 4,411 titers from 605 individuals using 4 different neutralization percentages, 3 cell lines, 12 virus concentrations and 51 strains. Of 1,057 titers from primary DENV exposure, titers to the exposure serotype were consistently higher than titers to non-exposure serotypes. In contrast, titers from secondary DENV exposures (n = 628) demonstrated high titers to exposure and non-exposure serotypes. Additionally, PRNT titers from different strains within a serotype varied substantially. A pooled analysis of 1,689 titers demonstrated strain choice accounted for 8.04% (90% credible interval [CrI]: 3.05%, 15.7%) of between-titer variation after adjusting for secondary exposure, time since DENV exposure, vaccination and neutralization percentage. Differences between articles (a proxy for inter-laboratory differences) accounted for 50.7% (90% CrI: 30.8%, 71.6%) of between-titer variance.ConclusionsAs promising vaccine candidates arise, the lack of standardized assays among diagnostic and research laboratories make unbiased inferences about vaccine-induced protection difficult. Clearly defined, widely accessible reference reagents, proficiency testing or algorithms to adjust for protocol differences would be a useful first step in improving dengue PRNT comparability and quality assurance.

Influenza outbreak control practices and the effectiveness of interventions in long-term care facilities: a systematic review

Evaluation of influenza control measures frequently focuses on the efficacy of chemoprophylaxis and vaccination, while the effectiveness of non‐pharmaceutical interventions (NPI) receives less emphasis. While influenza control measures are frequently reported for individual outbreaks, there have been few efforts to characterize the real‐world effectiveness of these interventions across outbreaks.

Variability in dengue titer estimates from plaque reduction neutralization tests poses a challenge to epidemiological studies and vaccine development.

Background Accurate determination of neutralization antibody titers supports epidemiological studies of dengue virus transmission and vaccine trials. Neutralization titers measured using the plaque reduction neutralization test (PRNT) are believed to provide a key measure of immunity to dengue viruses, however, the assays variability is poorly understood, making it difficult to interpret the significance of any assay reading. In addition there is limited standardization of the neutralization evaluation point or statistical model used to estimate titers across laboratories, with little understanding of the optimum approach. Methodology/Principal Findings We used repeated assays on the same two pools of serum using five different viruses (2,319 assays) to characterize the variability in the technique under identical experimental conditions. We also assessed the performance of multiple statistical models to interpolate continuous values of neutralization titer from discrete measurements from serial dilutions. We found that the variance in plaque reductions for individual dilutions was 0.016, equivalent to a 95% confidence interval of 0.45–0.95 for an observed plaque reduction of 0.7. We identified PRNT75 as the optimum evaluation point with a variance of 0.025 (log10 scale), indicating a titer reading of 1∶500 had 95% confidence intervals of 1∶240–1∶1000 (2.70±0.31 on a log10 scale). The choice of statistical model was not important for the calculation of relative titers, however, cloglog regression out-performed alternatives where absolute titers are of interest. Finally, we estimated that only 0.7% of assays would falsely detect a four-fold difference in titers between acute and convalescent sera where no true difference exists. Conclusions Estimating and reporting assay uncertainty will aid the interpretation of individual titers. Laboratories should perform a small number of repeat assays to generate their own variability estimates. These could be used to calculate confidence intervals for all reported titers and allow benchmarking of assay performance.

Cell-Associated HIV-1 DNA and RNA Decay Dynamics During Early Combination Antiretroviral Therapy in HIV-1-Infected Infants

BACKGROUND The decay of human immunodeficiency virus type 1 (HIV-1)-infected cells during early combination antiretroviral therapy (cART) in infected infants is not defined. METHODS HIV-1 DNA, including 2-long terminal repeat (2-LTR) circles, and multiply spliced (ms-) and unspliced (us-) HIV-1 RNA concentrations were measured at 0, 24, 48, and 96 weeks of cART in infants from the IMPAACT P1030 trial receiving lopinavir-ritonavir-based cART. The ratio of HIV-1 DNA concentrations to replication-competent genomes was also estimated. Linear mixed effects models with random intercept and linear splines were used to estimate patient-specific decay kinetics of HIV-1 DNA. RESULTS The median HIV-1 DNA concentration before cART at a median age of 2 months was 3.2 log10 copies per million PBMC. With cART, the average estimated patient-specific change in HIV-1 DNA concentrations was -0.040 log10/week (95% confidence interval [CI], -.05, -.03) between 0 and 24 weeks and -0.017 log10/week between 24 and 48 weeks (95% CI, -.024, -.01). 2-LTR circles decreased with cART but remained detectable through 96 weeks. Pre-cART HIV-1 DNA concentration was correlated with time to undetectable plasma viral load and post-cART HIV-1 DNA at 96 weeks; although HIV-1 DNA concentrations exceeded replication-competent HIV-1 genomes by 148-fold. Almost all infants had ms- and usRNA detected pre-cART, with 75% having usRNA through 96 weeks of cART. CONCLUSIONS By 2 months of age, a large pool of HIV-1-infected cells is established in perinatal infection, which influences time to undetectable viral load and reservoir size. This has implications for informing novel approaches aimed at early restriction of HIV-1 reservoirs to enable virologic remission and cure.

Changes in Measles Serostatus Among HIV-Infected Zambian Children Initiating Antiretroviral Therapy Before and After the 2010 Measles Outbreak and Supplemental Immunization Activities

BACKGROUND In 2010, Zambia had a large measles outbreak, providing an opportunity to measure changes in measles serostatus following highly active antiretroviral therapy (HAART), exposure to measles virus, and revaccination among children infected with human immunodeficiency virus (HIV). METHODS A prospective cohort study of 169 HIV-infected Zambian children aged 9-60 months with a history of measles vaccination was conducted to characterize the effects of HAART and revaccination on measles immunoglobulin G (IgG) serostatus by enzyme immunoassay. RESULTS Prior to the measles outbreak, only 23% of HIV-infected children were measles IgG seropositive at HAART initiation. After adjusting for 6-month changes in baseline age and 5% changes in nadir CD4(+) T-cell percentage, HAART was not associated with measles IgG seroconversion. However, 18 of 19 children seroconverted after revaccination. Eight children seroconverted during the outbreak without revaccination and were likely exposed to wild-type measles virus, but none were reported to have had clinical measles. CONCLUSIONS Immune reconstitution after HAART initiation did not restore protective levels of measles IgG antibodies, but almost all children developed protective antibody levels after revaccination. Some previously vaccinated HIV-infected children had serological evidence of exposure to wild-type measles virus without a reported history of measles.

Advances and hope for perinatal HIV remission and cure in children and adolescents.

Purpose of review The known timing of HIV infection in perinatal transmission, combined with the capacity for early antiretroviral therapy (ART) initiation and immune reconstitution, can provide unique insights into HIV persistence. The scientific basis for a pediatric-specific research agenda aimed at HIV remission and cure is discussed. Recent findings Accumulating evidence supports a favorable biomarker profile for immunotherapeutic interventions in early treated, perinatally infected individuals. HIV DNA concentrations in infected cells of early treated infants decrease over the first few years of life and, after more than 10 years of ART, the overwhelming majority of noninduced proviral genomes are replication-deficient. With early ART initiation, approximately half of perinatally infected individuals become seronegative. Studies of untreated infants and vaccine trials indicate that infected infants can generate HIV-specific humoral responses. Taken together, this evidence suggests that early treatment results in low levels of replication-competent provirus, an absence of HIV-specific immunity, and the capacity to generate immune responses to potential immunotherapeutic interventions. Summary Perinatally HIV-infected individuals require lifelong ART because of the prompt establishment of viral latency in long-lived resting memory CD4+ T cells that rekindle viremia upon treatment cessation. However, intense research efforts are ongoing to perturb HIV latency toward reservoir clearance for virologic remission and cure in which perinatally infected individuals can discontinue ART.

Changes in cellular immune activation and memory T-cell subsets in HIV-infected Zambian children receiving HAART.

Background:Increased exposure to a broad array of pathogens in children residing in sub-Saharan Africa may lead to heightened immune activation and increased proportions of memory T cells. Changes in the size of these cellular subsets have implications for restoration of normal immune function after treatment with highly active antiretroviral therapy (HAART) and are not well characterized in young sub-Saharan African children. Methods:CD4+ and CD8+ T-cell subsets were measured by flow cytometry in 157 HIV-infected Zambian children before and at 3-month intervals during HAART for up to 30 months and in 34 control children at a single study visit. Results:Before HAART, HIV-infected children had higher levels of activated and effector memory (EM) CD4+ and CD8+ T cells, and lower levels of naive T cells and CD8+ T cells expressing IL-7R&agr;, compared with control children. The median duration of follow-up was 14.9 months (interquartile range, 6.4–23.2) among 120 HIV-infected children with at least 1 study follow-up visit. Levels of immune activation and EM CD4+ T cells declined within 6 months of HAART, but the percentages of EM CD4+ T cells and effector CD8+ T cells remained elevated through 30 months of HAART. IL-7R&agr;-expressing CD8+ T cells increased with HAART, suggesting expansion of memory capacity. Conclusions:HAART significantly reduced levels of immune activation and EM CD4+ T cells, and promoted reconstitution of naive T cells and IL-7R&agr;-expressing CD8+ T cells. However, persistently high levels of EM CD4+ T cells in HIV-infected children may reflect chronic perturbations in T-cell subset composition.

Human G3P[9] rotavirus strains possessing an identical genotype constellation to AU-1 isolated at high prevalence in Brazil, 1997–1999

Rotavirus (RV) A is a very common cause of acute diarrhoea in infants and young children worldwide. Most human strains are classified into two major Wa-like and DS-1-like genotype constellations, whilst a minor third strain, AU-1, was described in 1989 among human RV isolates from Japan. AU-1 demonstrates a high degree of homology to a feline RV, FRV-1, which suggests interspecies transmission of feline RV. However, there has been no subsequent report of RVs possessing the AU-1 genotype throughout all 11 genes of the genome. Between March 1997 and December 1999, 157 RV-positive stool samples were collected from Brazilian children, and 16 of the RVs (10.2 %) were P[9] genotype. We analysed eight strains by almost full-genome sequencing. These eight strains were divided into two groups: five AU-1-like and three Wa-like strains. Four of the five AU-1-like strains had the AU-1-like genotype constellation throughout the 11 genes. The remaining AU-1-like strain was considered to be a reassortant strain comprosed of nine, two and one genes from the AU-1-like, Wa-like and G9 strains, respectively. The three Wa-like strains were considered to be reassortants comprising seven to eight genes and three to four genes from Wa-like and non-Wa-like strains, respectively. This report of human G3P[9] RV strains possessing the AU-1 genotype constellation throughout all genes demonstrates the stability and infectivity of the AU-1-like strain with its original genotype over distance and time.