Gail J. Demmler-Harrison

Antigenic and Genetic Characteristics of Swine-Origin 2009 A(H1N1) Influenza Viruses Circulating in Humans

Generation of Swine Flu As the newly emerged influenza virus starts its journey to infect the worlds human population, the genetic secrets of the 2009 outbreak of swine influenza A(H1N1) are being revealed. In extensive phylogenetic analyses, Garten et al. (p. 197, published online 22 May) confirm that of the eight elements of the virus, the basic components encoded by the hemagglutinin, nucleoprotein, and nonstructural genes originated in birds and transferred to pigs in 1918. Subsequently, these formed a triple reassortant with the RNA polymerase PB1 that transferred from birds in 1968 to humans and then to pigs in 1998, coupled with RNA polymerases PA and PB2 that transferred from birds to pigs in 1998. The neuraminidase and matrix protein genes that complete the virus came from birds and entered pigs in 1979. The analysis offers insights into drug susceptibility and virulence, as well as raising the possibility of hitherto unknown factors determining host specificity. A significant question is, what is the potential for the H1 component of the current seasonal flu vaccine to act as a booster? Apart from the need for ongoing sequencing to monitor for the emergence of new reassortants, future pig populations need to be closely monitored for emerging influenza viruses. Evolutionary analysis suggests a triple reassortant avian-to-pig origin for the 2009 influenza A(H1N1) outbreak. Since its identification in April 2009, an A(H1N1) virus containing a unique combination of gene segments from both North American and Eurasian swine lineages has continued to circulate in humans. The lack of similarity between the 2009 A(H1N1) virus and its nearest relatives indicates that its gene segments have been circulating undetected for an extended period. Its low genetic diversity suggests that the introduction into humans was a single event or multiple events of similar viruses. Molecular markers predictive of adaptation to humans are not currently present in 2009 A(H1N1) viruses, suggesting that previously unrecognized molecular determinants could be responsible for the transmission among humans. Antigenically the viruses are homogeneous and similar to North American swine A(H1N1) viruses but distinct from seasonal human A(H1N1).

Derivation of human T-lymphocytes from cord blood and peripheral blood with antiviral and antileukemic specificity from a single culture as protection against infection and relapse after stem cell transplantation

Viral infections and leukemic relapse account for the majority of treatment failures in patients with B-cell acute lymphoblastic leukemia (B-ALL) receiving allogeneic hematopoietic stem cell (HSC) or cord blood (CB) transplants. Adoptive transfer of virus-specific cytotoxic T lymphocytes (CTLs) provides protection against common viruses causing serious infections after HSC transplantation without concomitant graft-versus-host disease. We have now generated CTL lines from peripheral blood (PB) or CB units that recognize multiple common viruses and provide antileukemic activity by transgenic expression of a chimeric antigen receptor (CAR) targeting CD19 expressed on B-ALL. PB-derived CAR(+) CTLs produced interferon-gamma (IFNgamma) in response to cytomegalovirus-pp65, adenovirus-hexon, and Epstein-Barr virus pepmixes (from 205 +/- 104 to 1034 +/- 304 spot-forming cells [SFCs]/10(5) T cells) and lysed primary B-ALL blasts in (51)Cr-release assays (mean, 66% +/- 5% specific lysis; effector-target [E/T] ratio, 40:1) and the CD19(+) Raji cell line (mean, 78% +/- 17%) in contrast to nontransduced controls (8% +/- 8% and 3% +/- 2%). CB-derived CAR(+) CTLs showed similar antiviral and antitumor function and both PB and CB CAR(+) CTLs completely eliminated B-ALL blasts over 5 days of coculture. This approach may prove beneficial for patients with high-risk B-ALL who have recently received an HSC or CB transplant and are at risk of infection and relapse.

CMV-specific T cells generated from naïve T cells recognize atypical epitopes and may be protective in vivo

CMV-specific T cells, derived from the naïve population, recognize different epitopes of CMV than do memory-derived T cells and may be functional and protective in vivo. Sourcing CMV immunotherapy Immunotherapy—such as adoptive T cell therapy—is making headway in treating cancer, autoimmunity, and infectious disease. Indeed, adoptive transfer of cytomegalovirus (CMV)–specific T cells can restore immunity to the virus. However, these cells have been primarily derived from memory cells from CMV-seropositive individuals, which limits the donor pool. Now, Hanley et al. demonstrate that CMV-specific T cells can be derived from naïve T cells taken from CMV-seronegative people. These cells react to different epitopes than the memory cell–derived T cells but with similar avidity. What’s more, these cells were associated with periods of CMV-free survival when transplanted into patients. These data support expanded trials of adoptive therapy of CMV-restricted T cells from seronegative donors. Adoptive transfer of cytomegalovirus (CMV)–specific T cells derived from adult seropositive donors can effectively restore antiviral immunity after transplantation. However, CMV-seronegative donors lack CMV-specific memory T cells, which restricts the availability of virus-specific T cells for immunoprophylaxis. We demonstrate the feasibility of deriving CMV-specific T cells from naïve cells for T cell therapy. Naïve T cells primed to recognize CMV were restricted to different, atypical epitopes than T cells derived from CMV-seropositive individuals; however, these two cell populations had similar avidities. CMV-seropositive individuals also had T cells recognizing these atypical epitopes, but these cells had a lower avidity than those derived from the seronegative subjects, which suggests that high-avidity T cells to these epitopes may be lost over time. Indeed, recipients of cord blood (CB) grafts who did not develop CMV were found by clonotypic analysis to have T cells recognizing atypical CMVpp65 epitopes. Therefore, we examined unmanipulated CB units and found that T cells with T cell receptors restricted by atypical epitopes were the most common, which may explain why these T cells expanded. When infused to recipients, naïve donor–derived virus-specific T cells that recognized atypical epitopes were associated with prolonged periods of CMV-free survival and complete remission. These data suggest that naïve-derived T cells from seronegative patients may be an additional source of cells for CMV immunoprophylaxis.

Congenital cytomegalovirus: Public health action towards awareness, prevention, and treatment

Key awareness issues surrounding congenital CMV infection are outlined and discussed to provide inspirational motivation for many diverse groups who may have the same goal of reducing congenital CMV disease. To this end, steps for public health action towards awareness, prevention and treatment are outlined. These steps include recommendations for universal screening for all newborns for congenital CMV infection at birth to further define the public health impact and facilitate early diagnosis and treatment of newborns, routine prenatal screening of all pregnant women for the presence of CMV antibody to identify women at risk who may benefit most from preventive behavioral interventions as well as to facilitate prenatal diagnosis and therapies, and grass roots efforts to promote CMV awareness in the community.

Expansion of T cells targeting multiple antigens of cytomegalovirus, Epstein–Barr virus and adenovirus to provide broad antiviral specificity after stem cell transplantation

BACKGROUND AIMS Hematopoietic stem cell transplant (HSCT) is the treatment of choice for a proportion of patients with hematologic malignancies as well as for non-malignant diseases. However, viral infections, particularly Epstein-Barr virus (EBV), cytomegalovirus (CMV) and adenovirus (Ad), remain problematic after transplant despite the use of antiviral drugs. We have shown that cytotoxic T lymphocytes (CTL) generated against CMV-pp65, EBV and Ad antigens in a single culture are capable of controlling infections with all three viruses after HSCT. Although pp65-specific CTL have proved efficacious for the control of CMV infection, several reports highlight the importance of targeting additional CMV antigens. METHODS To expand multivirus-specific T cells with activity against both CMV-pp65 and CMV-IE-1, peripheral blood mononuclear cells (PBMC) were transduced with the adenoviral vector (Ad5f35-IE-1-I-pp65). After 9-12 days the CTL were restimulated with autologous EBV-transformed B cells transduced with the same Ad vector. RESULTS After 18 days in culture nine CTL lines expanded from less than 1.5 × 10(7) PBMC to a mean of 6.1 × 10(7) T cells that recognized CMV antigens pp65 [median 273 spot-forming cells (SFC), range 47-995] and IE-1 (median 154 SFC, range 11-505), the Ad antigens hexon (median 153 SFC, range 26-465) and penton (median 37 SFC, range 1-353), as well as EBV lymphoblastoid cell lines (median 55 SFC, range 9-301). Importantly, the T cells recognized at least two antigens per virus and lysed virus peptide-pulsed targets. CONCLUSIONS CTL that target at least two antigens each of CMV, EBV and Ad should have clinical benefit with broad coverage of all three viruses and enhanced control of CMV infections compared with current protocols.

Performance of a Rapid Influenza Test in Children During the H1N1 2009 Influenza A Outbreak

OBJECTIVE: To evaluate the performance of a rapid influenza diagnostic test (RIDT) in detecting H1N1 2009 influenza A virus in respiratory samples from pediatric patients in comparison to that of real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) and viral culture. Methodology. This was a cross-sectional diagnostic-accuracy study conducted at a tertiary care childrens hospital. Patients for whom the RIDT (BinaxNOW [Binax, Inc, Portland, ME]), viral culture, and rRT-PCR results were known were included. Sensitivity, specificity, and likelihood ratios (LRs) were calculated. RESULTS: A total of 3030 specimens had RIDT results paired with both rRT-PCR and viral culture results. With rRT-PCR as the reference, overall test sensitivity was 45% (95% confidence interval [CI]: 43.3%–46.3%) and specificity was 98.6% (95% CI: 98.1%–99%). Positive and negative LRs were 32.9 (95% CI: 22.9–45.4) and 0.56 (95% CI: 0.54–0.58), respectively. RIDT sensitivity was significantly higher in young infants and children younger than 2 years than in older children. Using viral culture as the reference standard, RIDT sensitivity was 55.5% (95% CI: 51.9%–95.6%) and specificity was 95.6% (95% CI: 95%–96.1%). The positive and negative LRs were 12.6 and 0.47, respectively. CONCLUSIONS: The RIDT had relatively poor sensitivity but excellent specificity in this consecutive series of respiratory specimens obtained from pediatric patients. Although a positive RIDT result was highly accurate in predicting infection with influenza type A H1N1 2009 in children, a negative RIDT result did not preclude a child having H1N1. Therefore, for children at high risk with influenza-like illnesses during high-prevalence periods of influenza, empiric initiation of antiviral therapy should be considered for patients with a negative RIDT result.

Outside the Box and Into Thick Air: Implementation of an Exterior Mobile Pediatric Emergency Response Team for North American H1N1 (Swine) Influenza Virus in Houston, Texas

Study objective We describe the implementation of a mobile pediatric emergency response team for mildly ill children with influenza-like illnesses during the H1N1 swine influenza outbreak. Methods This was a descriptive quality improvement study conducted in the Texas Childrens Hospital (Houston, TX) pediatric emergency department (ED), covered, open-air parking lot from May 1, 2009, to May 7, 2009. Children aged 18 years or younger were screened for viral respiratory symptoms and sent to designated areas of the ED according to level of acuity, possibility of influenza-like illness, and the anticipated need for laboratory evaluation. Results The mobile pediatric emergency response team experienced 18% of the total ED volume, or a median of 48 patients daily, peaking at 83 patients treated on May 3, 2009. Although few children had positive rapid influenza assay results and the morbidity of disease in the community appeared to be minimal for the majority of children, anxiety about pandemic influenza drove a large number of ED visits, necessitating an increase in surge capacity. Surge capacity was augmented both through utilization of existing institutional resources and by creating a novel area in which to treat patients with potential airborne pathogens. Infection control procedures and patient safety were also maximized through patient cohorting and adaptation of social distancing measures to the ED setting. Conclusion The mobile pediatric emergency response team and screening and triage algorithms were able to safely and effectively identify a group of low-acuity patients who could be rapidly evaluated and discharged, alleviating ED volume and potentially preventing transmission of H1N1 influenza.

Global gene expression profiling in infants with acute respiratory syncytial virus broncholitis demonstrates systemic activation of interferon signaling networks.

Background: Respiratory syncytial virus (RSV) is a leading cause of pediatric lower respiratory tract infections and has a high impact on pediatric emergency department utilization. Variation in host response may influence the pathogenesis and disease severity. We evaluated global gene expression profiles to better understand the systemic host response to acute RSV bronchiolitis in infants and young children. Methods: Patients (age ⩽ 24 months) who were clinically diagnosed with acute bronchiolitis and who had a positive rapid test for RSV assay were recruited from the Texas Children’s Hospital emergency department. Global gene expression of peripheral whole blood cells were analyzed in 21 cases and 37 age-matched healthy controls. Transcripts exhibiting significant upregulation and downregulation as a result of RSV infection were identified and confirmed in a subset of samples using RNA sequencing. The potential pathways affected were analyzed. Results: Blood was obtained from patients with acute RSV bronchiolitis (mean age 6 months). Of these, 43% were admitted to the hospital, 52% were given intravenous fluids and 24% received oxygen. Highly significant expression differences were detected in a discovery cohort of White infants (N = 33) and validated in an independent group of African–American infants (N = 19). Individuals with mild disease (N = 15) could not be distinguished from subjects with clinically moderate disease (N = 5). Pathway enrichment analyses of the differentially expressed genes demonstrated extensive activation of the innate immune response, particularly the interferon signaling network. There was a significant downregulation of transcripts corresponding to antigen presentation.

Hearing Loss in Children With Asymptomatic Congenital Cytomegalovirus Infection

The prevalence, characteristics, and risk of sensorineural hearing loss are assessed in children with asymptomatic congenital cytomegalovirus infection identified through hospital-based newborn screening managed through 18 years of age. OBJECTIVES: To assess the prevalence, characteristics, and risk of sensorineural hearing loss (SNHL) in children with congenital cytomegalovirus infection identified through hospital-based newborn screening who were asymptomatic at birth compared with uninfected children. METHODS: We included 92 case-patients and 51 controls assessed by using auditory brainstem response and behavioral audiometry. We used Kaplan–Meier survival analysis to estimate the prevalence of SNHL, defined as ≥25 dB hearing level at any frequency and Cox proportional hazards regression analyses to compare SNHL risk between groups. RESULTS: At age 18 years, SNHL prevalence was 25% (95% confidence interval [CI]: 17%–36%) among case-patients and 8% (95% CI: 3%–22%) in controls (hazard ratio [HR]: 4.0; 95% CI: 1.2–14.5; P = .02). Among children without SNHL by age 5 years, the risk of delayed-onset SNHL was not significantly greater for case-patients than for controls (HR: 1.6; 95% CI: 0.4–6.1; P = .5). Among case-patients, the risk of delayed-onset SNHL was significantly greater among those with unilateral congenital/early-onset hearing loss than those without (HR: 6.9; 95% CI: 2.5–19.1; P < .01). The prevalence of severe to profound bilateral SNHL among case-patients was 2% (95% CI: 1%–9%). CONCLUSIONS: Delayed-onset and progression of SNHL among children with asymptomatic congenital cytomegalovirus infection continued to occur throughout adolescence. However, the risk of developing SNHL after age 5 years among case-patients was not different than in uninfected children. Overall, 2% of case-patients developed SNHL that was severe enough for them to be candidates for cochlear implantation.

Direct immunofluorescence assay compared to cell culture for the diagnosis of mucocutaneous herpes simplex virus infections in children

BACKGROUND Direct immunofluorescence assay (DFA) is commonly used for the rapid identification of herpes simplex virus (HSV) infection in mucocutaneous lesions, yet little is known about its diagnostic accuracy. OBJECTIVE To determine the diagnostic yield and accuracy of HSV DFA for the diagnosis of mucocutaneous HSV infection in pediatric patients. STUDY DESIGN Retrospective cross-sectional study of all patients who underwent HSV DFA testing by the Texas Childrens Hospital Diagnostic Virology between January 1, 1995 and December 31, 2005. HSV DFA sensitivity, specificity, positive likelihood ratio (LRs), and negative LRs were estimated using viral culture as the reference standard. RESULTS 659 specimens were submitted for HSV DFA with concurrent viral cultures. Viral cultures were positive for HSV type 1 in 158 (24%) and HSV type 2 in 2 (0.3%). There were 433 different patients with a median age of 8.6 years. Types of lesions were as follows: 50% ulcerative, 26% vesicular, 8% erythema or purpura, 5% pustular, and 11% missing. Of the 659 specimens submitted for HSV DFA, 160 (24%) were inconclusive due to inadequate cells. Of the 499 adequate specimens, overall HSV DFA test accuracy was: sensitivity 61%, specificity 99%, LR positive 40, and LR negative 0.39. CONCLUSIONS A quarter of specimens submitted for HSV DFA testing are not adequate for DFA testing. When HSV DFA can be performed, it is specific, but not sensitive, for the identification of mucocutaneous HSV infection in children.