Confirmed Respiratory Syncytial Virus Infection Research Articles

1841 A Four-Year Retrospective Study of the Safety and Efficacy of Palivizumab in High Risk Infants

AimA four year retrospective review of safety and efficacy of Palivizumab in the prophylaxis of respiratory syncytial virus (RSV) in high risk infants.BackgroundRSV is the leading viral pathogen responsible for...

ACUTE CHEST SYNDROME with RESPIRATORY Syncytial VIRUS and SEASONAL INFLUENZA In CHILDREN with SICKLE CELL DISEASE

Abstract 4845 Background:Respiratory syncytial virus (RSV) has been recognized as a cause of acute chest syndrome (ACS) in children with sickle cell disease (SCD). However, the proportion of children with RSV and SCD that are admitted to hospital or develop ACS is unknown. In studies of young children without SCD, RSV has traditionally been associated with more hospitalizations in the first three years of life then influenza has. To compare the relative severity of RSV vs. seasonal influenza in children with SCD, we compared the clinical characteristics and complications associated with these infections at a single tertiary care hospital. Methods:We defined a case as laboratory-confirmed RSV infection in a patient <18 years with SCD who was evaluated at Johns Hopkins Hospital from 1 September 1993 to June 30 2008. Through July 2006, we searched the discharge and billing databases for Johns Hopkins Hospital to identify those with SCD and laboratory testing for respiratory infections. Thereafter, we prospectively identified cases through divisional records. We confirmed the diagnosis of RSV by review of microbiology results in each patient’s paper and/or electronic medical record. We used Fisher’s exact test to compare proportions, Student’s t-test or Wilcoxon rank-sum test to compare continuous variables, and logistic regression to evaluate associations. Results:We identified 47 patients with SCD and RSV and 76 with influenza during the study period. Clinical symptoms, such as reported fever (83% vs. 89%), cough (98% vs. 93%), and rhinorrhea (90% vs. 80%), were similar for RSV and influenza as were complications, including acute chest syndrome (Table). Treatments given for RSV and influenza including antibacterials (100% vs. 97%), transfusions (7% vs. 11%), and invasive ventilation (4% vs. 0%, p=0.15),with possibly more bronchodilator use for RSV (50% vs. 33%, p=0.055). In a multivariable logistic regression model, older age (OR 1.3 per year, 95% CI 1.04 –1.5, P=.02) and increased white blood cell count (WBC) at presentation (OR 1.2 per 1000/ul increase, 95% CI 1.03 – 1.4, P=0.02) were independently associated with increased risk of ACS in children with RSV. Discussion:Laboratory confirmed RSV infection was predominantly identified in infants and toddlers, while influenza infection was identified in children of all ages. This parallels RSV hospitalizations in the general population, where children are most likely to be hospitalized in the first few years of life. Both older age and high WBC at presentation may be a risk factor for more severe disease. This is unlikely to reflect referral bias (with only the sickest older children being referred for tertiary pediatric care) as a similar pattern was not seen for influenza infection. We conclude that RSV infection is often associated with ACS and similar in severity to influenza infection in children with SCD. An episode of ACS in the first three years of life was associated with more frequent ACS episodes later in childhood in the Dallas Newborn cohort. Since a significant proportion of patients with RSV develop ACS at a young age, RSV infection may represent a modifiable risk factor for recurrent ACS. An area for further study would be the efficacy or cost effectiveness of prevention of RSV-related hospitalizations. Palivizumab, a monoclonal antibody to RSV, has been shown to prevent complications related to RSV in other high risk groups and could be considered as an intervention in SCD that may decrease morbidity.Table:Characteristics of Children with Respiratory Syncytial Virus (RSV) and Sickle Cell Disease (SCD), Johns Hopkins Hospital 1993–2008VariableRSV n=47Influenza n=76P-ValueAge (years)1.5 (0.7 − 3.4)4.3 (1.7 – 10.9)0.0001Male62%53%0.34HbSS79%84%0.57Acute chest syndrome22% (9/41)12% (8/69)0.15Hospital admission100%88%0.02Intensive Care4%3%0.64RBC Transfusion7%11%0.66Length of stay (days)2 (1 – 3)2 (1−3)0.11Hospital Charges ($)4676 (3350-6348)4569 (3008-6419)0.53IQR, interquartile range; HbSS, sickle cell anemia; RBC, red blood cells; Disclosures:No relevant conflicts of interest to declare.

Clinical characteristics of respiratory syncytial virus infection in neonates and young infants

Infection with respiratory syncytial virus (RSV) occurs during the first year of life in 50% of children and 20%-40% of them have signs of lower respiratory tract infection (bronchiolitis or pneumonia). There is an increased risk for complicated course and death from RSV infection in premature infants, especially those with bronchopulmonary dysplasia (BPD) or congenital heart disease. The aim of our study was to analyze clinical characteristics of laboratory confirmed RSV infection in order to evaluate the need for preventive measures in neonates and young infants. The prospective study included children under age of 12 months admitted to our hospital in the period November 2008-March 2009 who were positive for RSV by enzyme immunoassay membrane test. The course of disease was assessed by clinical score and radiographic findings. Infection with RSV was confirmed in 91 patients: 21 (23.0%) were under the age of 30 days, 37 (40.7%) were between 31-60 days, and 33 patients (36.3%) were older than 60 days (p > 0.05). The highest hospitalization rate was in January--33 patients (36.3%; p < 0.01). Disease severity score in these age groups (AG) were: 8.4 +/- 0.4 (AG 0-30 days); 9.0 +/- 0.3 (AG 31-60 days) and 8.3 +/- 0.3 (AG > 60 days), without statistically significant difference among the groups (p > 0.05). Clinical scores in patients with and without risk factors were 10.5 +/- 0.5 and 8.3 +/- 0.2, respectively (p < 0.01). Pathological radiographic findings were observed in 72 (79.1%) and complications (apnea, significant atelectasis, encephalopathy) occured in 15 (16.5%) patients. The average length of hospital stay in complicated and uncomplicated course of the disease was 9 days and 6 days, respectively (p < 0.01). Therapy in 85 (93.4%) patients included bronchodilators, while systemic glucocorticoids and oxygen therapy were used in 51 (56.0%) and 44 (48.4%) patients, respectively. Death occured in 2 (2.2%) patients, both from a high risk group (the patient with BPD and the other one with congenital heart disease and Down syndrome). Infection with RSV in our settings showed marked seasonal characteristics with highest hospitalization rate in January. Although the course and outcome of the disease were favorable in the majority of our patients, the need for hospitalization and administration of therapy with possible side effects warrants that general measures for prevention of respiratory infections are followed especially in the first year of life. Severe disease and death are more probable in neonates and infants with risk factors. In these children passive immunisation with specific monoclonal antibody (e.g. palivizumab) during RSV season should be considered.

Cytokine responses in cord blood predict the severity of later respiratory syncytial virus infection

It has been claimed that an early respiratory syncytial virus (RSV) infection can induce asthma and recurrent wheezing. We addressed the question of whether infants contracting an early RSV infection differ from healthy children in their cytokine production at birth. In a prospective cohort study cord blood samples were collected from 1084 newborns during autumn 2001. Of 47 of these newborns with subsequent virologically confirmed RSV infection before 6 months of age, 24 had enough cells for stimulation in cord blood samples (14 of those were hospitalized). Twenty-eight children had other respiratory virus infections (16 with enough cells), and samples from 48 healthy children of the 1084 total served as control specimens. Stimulated cytokine production of mononuclear cells was measured. The responses in the groups were evaluated by means of factor analysis. The infants hospitalized for RSV infection had higher LPS-stimulated combined IL-6 and IL-8 responses than the infants treated as outpatients (P = .005) or the healthy control subjects (P = .02). The hospitalized patients with RSV showed lower IL-1beta, IL-2, IL-4, IL-5, and IL-10 responses than those treated as outpatients (P = .02). High IL-6 and IL-8 responsiveness predicted a severe RSV infection (odds ratio, 2.20; 95% CI, 1.17-4.14; P = .01). The unstimulated cytokine responses at birth did not differ between the patients and healthy control subjects. The results suggest that natural differences in innate immunity predispose children to severe RSV infection rather than the infection modifying immune responses in childhood.

The Association Between Respiratory Syncytial Virus Infection and the Development of Childhood Asthma

The relation between early respiratory syncytial virus (RSV) infection and later emergence of episodes of wheezing/asthma remains a subject of debate. We carried out a systematic review of studies of the association between RSV infection in the first 36 months of life and the subsequent development of asthma/bronchial hyperreactivity. A literature search for original studies on RSV respiratory infection published in English or Spanish over the last 21 years was conducted in the bibliographic databases Medline, Embase, and Indice Médico Español, and in the Cochrane library. Articles were included if they described original studies of confirmed RSV infection in children under 3 years of age, and had defined outcome variables. The methodologic quality of articles included in the review was evaluated according to the Hadorn criteria. The review included 12 original articles that respond to the research question. The studies evaluated showed that RSV lower respiratory tract infection is associated with an increased risk for subsequent development of asthma/recurrent wheezing, and that this association becomes progressively smaller with increasing age. On the basis of this systematic review of the literature, it can be concluded that a significant association exists between RSV infection in childhood and the long-term development of subsequent episodes of recurrent wheezing or asthma. However, the methodologic quality of the articles evaluated is limited, and hence additional studies are needed, ideally, with specific therapeutic interventions aimed at reducing RSV replication.

Palivizumab prophylaxis of respiratory syncytial virus disease from 1998 to 2002: results from four years of palivizumab usage.

In 1998 the Food and Drug Administration approved palivizumab (Synagis) for the prevention of severe lower respiratory tract infection secondary to respiratory syncytial virus (RSV) in pediatric patients at high risk for developing disease that required hospitalization. In the immediate aftermath of that approval, two retrospective reviews were conducted on 4669 medical records of patients who received at least 1 dose of palivizumab during the 1998 to 1999 and 1999 to 2000 RSV seasons, respectively. These analyses captured data on rates of RSV hospitalization, length of hospital stay, intensive care unit admission and compliance with palivizumab administration. Two prospective US multicenter registry trials followed, during the RSV seasons of 2000 to 2001 and 2001 to 2002. The registries characterized the demographics and outcomes of a total of 7207 high risk infants and children who received prophylaxis for RSV, the risk factors for RSV hospitalization and the patterns and scope of palivizumab usage across 63 and 116 US health care sites, respectively. 1998 TO 1999 PALIVIZUMAB FIRST SEASON OF GENERAL USE: Nine US study sites engaged in a retrospective chart review of infants and children with a gestational age of < or =35 weeks and a chronologic age of <2 years at the time of their first palivizumab injection and who had received at least one dose between September 1998 and May 1999. Of the 1839 prophylaxed children with evaluable data, only 42 (2.3%) were hospitalized with confirmed RSV disease. Of those admitted with confirmed gestational ages, all were premature; the majority were either < 28 weeks gestational age (WGA; 43%) or between 28 and 32 WGA (34%). 1999 TO 2000 PALIVIZUMAB SECOND SEASON OF GENERAL USE: During the 1999 to 2000 RSV season, 12 hospitals and university medical centers, representing a cross-section of US health care facilities, contributed to the second Palivizumab Study Group. The sites collected retrospective data from the charts of 2830 children, all of whom had received at least 1 injection of palivizumab between September 1999 and May 2000. Analysis of 2830 medical records revealed an admission rate of 2.4% (68 of 2830) for confirmed RSV infection, consistent with the overall hospitalization rate of 2.3% from the previous season. 2000 to 2001: Sixty-three sites representing pediatric offices, freestanding clinics and hospital-based clinics participated in a prospective, multicenter, observational study to evaluate the scope of palivizumab usage in a cross-section of US infants. The centers collected outcomes data on RSV-related hospital admissions, injection history and adherence to a standardized palivizumab administration protocol. Of the 2116 infants enrolled 47% were born at < 32 weeks gestation. Patients between 32 and 35 weeks gestational age accounted for another 45% of enrollees. Approximately 8% had a gestational age of >35 weeks. For the 2049 subjects with available follow-up data, the overall confirmed RSV hospitalization rate was 2.9%. 2001 to 2002: Between June 1, 2001 and May 15, 2002, 116 health care centers across the US enrolled 5091 infants in the second prospective Palivizumab Outcomes Registry. As its primary outcome the study measured the occurrence of RSV hospitalization with secondary variables of risk factors for RSV bronchiolitis and compliance with the projected number of palivizumab injections based on month of initial dose. Forty-nine percent (n = 2,501) of the infants were born between 32 and 35 weeks gestational age, 40% (n = 2020) were born at a gestational age of <32 weeks and 11% (n = 570) were born at >35 weeks gestational age. Nineteen percent (n = 964) of these children were deemed at sufficient risk to warrant palivizumab prophylaxis for a second season. Seventy-six of 5084 enrolled subjects experienced a total of 78 RSV-related hospital admissions, for an overall hospitalization rate of 1.5%. Four years of retrospective and prospective data on the use of palivizumab in clinical practice has accumulated a wealth of "real life" information on the clinical effectiveness of RSV immunoprophylaxis in a large cohort of high risk infants from geographically diverse pediatric offices and clinics throughout the United States.

Cytokine gene polymorphisms moderate illness severity in infants with respiratory syncytial virus infection

Illness severity and frequency of complications in infants with respiratory syncytial virus (RSV) infection may be influenced by the local elaboration of cytokines. Cytokine gene polymorphisms moderate severity of illness in various inflammatory and infectious diseases. We performed cytokine genotyping on 77 infants hospitalized with confirmed RSV infection to determine whether specific cytokine gene polymorphisms are associated with illness severity or complications. DNA was extracted from buccal brushings and assayed for tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-6 and IL-10, and transforming growth factor (TGF)-β1 genotypes using polymerase chain reaction–sequence-specific primer technology. Clinical outcomes consisted of severity scores of lower respiratory illness, blood oxygen saturation, lengths of oxygen supplementation, and intensive care unit (ICU) and hospital stays, and the presence or absence of pneumonia and otitis media. IFN-γ genotype was related to severity of lower respiratory illness, duration of ICU stay, and frequency of otitis media. Additionally, IL-6 genotype was related to the length of oxygen (O 2) supplementation and hospital stay, IL-10 genotype to the frequency of pneumonia, and TGF-β1 genotype to O 2 saturations at presentation. There were no associations between TNF-α genotype and any of the outcome parameters. These results demonstrate that certain cytokine gene polymorphisms contribute to illness severity and complications during RSV infection in infants. If future prospective studies confirm these observations, cytokine genotyping may be a useful tool for identifying “at risk” infants who may benefit from the selective use of preventive or early intervention treatments for RSV.

Population-based rates of severe respiratory syncytial virus infection in children with and without risk factors, and outcome in a tertiary care setting.

The aim of this study was to make a population-based estimate of the risk of hospitalization and complications during virologically confirmed respiratory syncytial virus (RSV) infection in relation to established risk factors, and an estimation of additional risk factors and outcome as seen in a tertiary care referral centre. During a period of 12 y, all children with virologically confirmed RSV infection were included. Recorded complications were: admission to the intensive care unit, mechanical ventilation, death and later hospitalization for wheezing. In total, 1503 cases were identified, 1354 of which originated from the population defined by the catchment area. There was a biannual seasonal variation with late small outbreaks alternating with early large ones. The hospitalization rates for infants without risk factors were 0.8 and 1.4% during the 2 epidemic types. They were 1.6-3.2% for infants born preterm (<33 gestational wk), 2.9-7.0% for children under 2 y old with chronic lung disease of prematurity and 2.8-6.4% for infants with congenital heart disease. The presence of siblings in the family more than doubled the risk of hospitalization. Later hospitalization for wheezing occurred in 8.4 and 4.9% of children without risk factors over and under the age of 2 mo, respectively (p < 0.001). This study found lower population rates of hospitalization and complications than have previously been reported. The seasonal variation and the presence of siblings in the home influenced these rates by factors of 2.

Population‐based rates of severe respiratory syncytial virus infection in children with and without risk factors, and outcome in a tertiary care setting

The aim of this study was to make a population‐based estimate of the risk of hospitalization and complications during virologically confirmed respiratory syncytial virus (RSV) infection in relation to established risk factors, and an estimation of additional risk factors and outcome as seen in a tertiary care referral centre. During a period of 12 y, all children with virologically confirmed RSV infection were included. Recorded complications were: admission to the intensive care unit, mechanical ventilation, death and later hospitalization for wheezing. In total, 1503 cases were identified, 1354 of which originated from the population defined by the catchment area. There was a biannual seasonal variation with late small outbreaks alternating with early large ones. The hospitalization rates for infants without risk factors were 0.8 and 1.4% during the 2 epidemic types. They were 1.6–3.2% for infants born preterm (&gt;33 gestational wk), 2.9–7.0% for children under 2 y old with chronic lung disease of prematurity and 2.8–6.4% for infants with congenital heart disease. The presence of siblings in the family more than doubled the risk of hospitalization. Later hospitalization for wheezing occurred in 8.4 and 4.9% of children without risk factors over and under the age of 2 mo, respectively (p &gt; 0.001). Conclusion: This study found lower population rates of hospitalization and complications than have previously been reported. The seasonal variation and the presence of siblings in the home influenced these rates by factors of 2.

A Method for Identifying the Financial Burden of Hospitalized Infants on Families

Objectives To describe a method for measuring the direct and indirect costs to families of infants hospitalized with respiratory syncytial virus (RSV). Methods After pretesting and revising a questionnaire, a prospective survey was conducted in multiple tertiary-care hospitals with pediatric intensive care units. Eligible patients were infants less than 12 months old who had not received RSV prophylaxis and were hospitalized with a confirmed RSV infection. All English- and Spanish-speaking caregivers of eligible subjects were asked to participate in a face-to-face, structured interview on the day of hospital discharge regarding hospitalization-related direct and indirect costs. Thirty days later, caregivers were re-interviewed by telephone about their RSV-related costs during the elapsed month. The survey was initiated in February 2000 and continued through April 2001. Results In addition to the infants' parents, numerous adults visited 55% of hospitalized infants. In 17% of cases, nonparents missed work to visit the child. Volunteers watched siblings of 26% of the infants. Relying only on closed-ended questions about parents' costs during the hospitalization would have missed important information about child-care volunteers and types of expenses. Follow-up interviews revealed that RSV-related out-of-pocket expenses and missed work continued during the month following discharge. Conclusions Survey instruments should be pretested with potentially eligible subjects. Open-ended questions are needed, because all costs cannot be anticipated. Respondents should be probed for details. This method revealed certain time and financial burdens during and after hospitalization that had not been previously reported in the literature.

Palivizumab, a Humanized Respiratory Syncytial Virus Monoclonal Antibody, Reduces Hospitalization From Respiratory Syncytial Virus Infection in High-risk Infants

Objective. To determine the safety and efficacy of prophylaxis with palivizumab in reducing the incidence of hospitalization because of respiratory syncytial virus (RSV) infection in high-risk infants. Methods. A randomized, double-blind, placebo-controlled trial was conducted at 139 centers in the United States, the United Kingdom, and Canada. During the 1996 to 1997 RSV season, 1502 children with prematurity (</=35 weeks) or bronchopulmonary dysplasia (BPD) were randomized to receive 5 injections of either palivizumab (15 mg/kg) or an equivalent volume of placebo by intramuscular injection every 30 days. The primary endpoint was hospitalization with confirmed RSV infection. Children were followed for 150 days (30 days from the last injection). Those with hospitalization as a result of RSV infection were evaluated for total number of days in the hospital, total days with increased supplemental oxygen, total days with moderate or severe lower respiratory tract illness, and incidence and total days of intensive care and mechanical ventilation. The incidence of hospitalization for respiratory illness not caused by RSV and the incidence of otitis media were also evaluated. The placebo and palivizumab groups were balanced at entry for demographics and RSV risk factors. Ninety-nine percent of children in both groups completed the protocol and ~93% received all five scheduled injections. Results. Palivizumab prophylaxis resulted in a 55% reduction in hospitalization as a result of RSV (10.6% placebo vs 4.8% palivizumab). Children with prematurity but without BPD had a 78% reduction in RSV hospitalization (8.1% vs 1.8%); children with BPD had a 39% reduction (12.8% vs 7.9%). When gender, entry age, entry weight, BPD, and gestational age were included in a logistic regression model, the effect of prophylaxis with palivizumab remained statistically significant. The palivizumab group had proportionally fewer total RSV hospital days, fewer RSV hospital days with increased oxygen, fewer RSV hospital days with a moderate/severe lower respiratory tract illness, and a lower incidence of intensive care unit admission. Palivizumab was safe and well tolerated. No significant differences were observed in reported adverse events between the two groups. Few children discontinued injections for related adverse events (0.3%). Reactions at the site of injection were uncommon (1.8% placebo vs 2.7% palivizumab); the most frequent reaction was mild and transient erythema. Mild or moderate elevations of aspartate aminotransferase occurred in 1.6% of placebo recipients and 3.6% of palivizumab recipients; for alanine aminotransferase these percentages were 2.0% and 2.3%, respectively. Hepatic and renal adverse events related to the study drug were similar in the two groups. Conclusions. Monthly intramuscular administration of palivizumab is safe and effective for prevention of serious RSV illness in premature children and those with BPD.

Local variability in respiratory syncytial virus disease severity

Respiratory syncytial virus (RSV) lower respiratory tract infections are considered to be a serious disease in centres such as the Sophia Children’s Hospital (Rotterdam, the Netherlands), but as more benign...

A monoclonal antibody pool for routine immunohistochemical detection of human respiratory syncytial virus antigens in formalin-fixed, paraffin-embedded tissue.

Four monoclonal antibodies (MAbs) with specificities for epitopes on human respiratory syncytial virus (RSV) proteins preserved after formalin fixation and paraffin embedding were identified in fixed and embedded virus-infected HEp-2 cell pellets. The MAbs bound epitopes on the fusion protein, the nucleoprotein, the phosphoprotein, and the M2 protein of the virus. Following high-temperature antigen unmasking, immunohistochemical staining revealed RSV antigens in the lungs of five of seven children who died with confirmed RSV infection and in none of nine children who died for other reasons, with no evidence of RSV infection. Staining was cytoplasmic, granular, and confined to epithelial cells. Intense staining was seen at the apex of ciliated bronchial and bronchiolar epithelial cells in all five positive cases. In one case, of pneumonitis, infected pneumocytes were present in the alveoli and in several cases, CD68-positive, cytokeratin-negative alveolar macrophages stained for viral antigens. These antibodies may prove useful in studies of the pathogenesis of RSV infection.

Frequency of respiratory syncytial virus in hospitalized infants with lower acute respiratory tract infection in Colombia.

In Colombia, health workers obtained a nasopharyngeal wash from 103 infants aged less than 12 months hospitalized for acute lower respiratory infection (ALRI) at the General Hospital of Medellin during April 1994 to April 1995 so researchers could determine the frequency of ALRI caused by respiratory syncytial virus (RSV) in hospitalized children. Immunofluorescence detected RSV infection in 43 (41.7%) patients. The presence of the following signs and symptoms allowed a clinical diagnosis of a viral infection: rhinorrhea, prolonged expiration, expiratory wheezing, interstitial infiltrates, and hyperinflation on chest radiographs as well as negative tests for 3 or 4 acute phase reactants. The physicians initiated antibiotic therapy (for 1-3 days) in 12 cases (27.9%) based on acute phase reactant findings who actually had an RSV infection. When the physicians learned that the laboratory confirmed RSV infection, they stopped antibiotic therapy. Antibiotics were continued in 16 (37.2%) other RSV infected infants, all of whom were less than 2 months old, due to mixed pneumonia (viral and bacterial). 39.4% of RSV-infected children whose clinical findings strongly suggested RSV received no antibiotics. None of these children or other ALRI patients with a viral disease suffered complications. They required less hospitalization time--since no further diagnostic tests were needed--than ALRI patients with a bacterial infection. Admissions for both ALRI and RSV infection peaked during November to January. RSV incidence peaked in January (23.3%). The leading reasons for hospitalization were pneumonia and bronchiolitis. These findings show that RSV diagnosis is useful and it lessens the indiscriminate use of antibiotics.

Invasive monitoring in infants with respiratory syncytial virus infection

OBJECTIVE: Coincident with a change in the physician staff in our pediatric intensive care unit (PICU), the frequency and duration of invasive monitoring were decreased. We examined the impact of this change on outcomes, complications, and hospital charges in infants admitted to the PICU with respiratory syncytial virus (RSV) infection. STUDY DESIGN: We reviewed medical records of all children less than 1 year of age who were admitted to the PICU from January 1989 to July 1993 with confirmed RSV infection. Patient characteristics, therapeutic interventions, outcomes, and hospital charges were extracted and compared. RESULTS: Seventy-eight patients were identified, 38 admitted from January 1989 through July 1991 (group 1) and 40 from July 1991 through July 1993 (group 2). The groups were well matched in age, preexisting disease, and cardiorespiratory status on admission. Group 1 had significantly greater use of invasive monitoring, pharmacologic paralysis, inotropes, blood products, antibiotics, and parenteral nutrition. Outcomes were not different, but group 1 patients had significantly longer stays, more complications, and higher hospital charges. CONCLUSIONS: Routine use of invasive monitoring of PICU patients with RSV disease was associated with increased laboratory testing, overtreatment, and significant increases in costs and morbidity without improvement in outcome. (J P EDIATR 1996;128:357-62)

Stability of respiratory syncytial virus antigen due to buffer treatment for direct detection in nasopharyngeal specimens with enzyme immunoassay

We developed an enzyme immunoassay (direct EIA; Enzygnost RSV[Ag]) for the direct detection of respiratory syncytial virus (RSV) antigen in nasopharyngeal specimens (NPS). The test procedure is the same as our recently described direct EIA for detection of influenza A and B virus antigens in NPS. For practical purposes it is of advantage to differentiate respiratory viruses on the same microtitration plate in the same run. The test shows no limitations by sample consistency, and results are obtained within 4 hr. In contrast to other test systems, sonification is not necessary. This is due to the sample buffer STD. We studied the influence of sample buffer STD on the stability of RSV (strain Long) antigen at different temperatures over a period of 7 days. PBS-BSA-buffer served as control. The treatment and storage of RSV (strain Long) with sample buffer STD at room temperature or at 4 degrees C showed no decrease of antigen detectability. The antigen is very stable in contrast to the storage of RSV (strain Long) in PBS-BSA buffer during the observation period of 7 days. Consequently, when NPS are stored in sample buffer STD, results of direct EIA are independent from the time of transport and temperature within 7 days. Thirty-eight NPS from infants with confirmed RSV infection were investigated. Confirmation was performed by virus isolation (n = 29) or with commercially available enzyme immunoassays or immunofluorescence test (n = 9). The direct EIA showed a specificity of 99.3% (n = 140) and a sensitivity of 95% (n = 38).

Mapping an antibody-binding site and a T-cell-stimulating site on the 1A protein of respiratory syncytial virus

A synthetic peptide modeled on residues 45 to 60 of the 1A protein of respiratory syncytial (RS) virus [1A(45-60)] was constructed and used for immunization of mice and rabbits. The immunoglobulin G fraction of the resulting rabbit antibody, purified on protein A-Sepharose, immunoprecipitated from RS-infected HEp-2 cells a protein with a molecular size of approximately 9.5 kilodaltons, which corresponds to the previously published molecular size of the 1A protein (Y. T. Huang, P. L. Collins, and G. W. Wertz, Virus Res. 2:157-173, 1985). To investigate the T-cell-inducing properties of 1A(45-60), six strains of mice were immunized and their popliteal lymph node cells were tested for proliferation upon restimulation with peptide in vitro. The lymph node cells of all six strains of mice were responsive to restimulation with 1A(45-60) and showed high- and low-responder strain variation. These peptide-primed lymph node cells also proliferated upon in vitro restimulation with RS virus-infected cells. Correlation of proliferation with interleukin 2 production suggested that the responding lymphocytes were T-helper cells. The antibody-binding and T-cell-stimulating sites of 1A were mapped by constructing a series of overlapping synthetic peptides and testing each for ability to react with antiserum prepared by immunization of BALB/C mice with free peptide 1A(45-60) or for ability to restimulate proliferation in 1A(45-60)-primed lymph node cells of BALB/C mice. Human antibody, obtained during confirmed RS virus infection, was similarly tested with the truncated peptides. Antibody-binding activity was reduced after truncation from the carboxy terminus, and a binding site was mapped to residues 51 through 60, the smallest peptide tested. T-cell-stimulating activity in mice was relatively resistant to truncation from the carboxy terminus and sensitive to truncation from the amino terminus. The smallest region which retained significant T-cell-stimulating activity mapped to residues 46 through 56. However, addition of the naturally occurring Cys at residue 45 and extension of the C terminus to residue 62 resulted in maximum T-cell-stimulating activity of the peptide. These data define both a T-cell epitope and a B-cell epitope of the 1A protein of RS virus and suggest that the carboxy terminus of 1A contains a B-cell epitope, involving residues 51 through 60, which is recognized during natural human infection.

Immunofluorescence for routine diagnosis of respiratory syncytial virus infection

A comparison of immunofluorescent tests for the diagnosis of respiratory syncytial (RS) virus infections was carried out on 42 hospitalized cases of respiratory infection in childhood. Respiratory syncytial virus was detected in 22 (52%) cases, the most sensitive method of detection being by indirect immunofluorescence of Bristol HeLa tissue cultures inoculated with nasopharyngeal aspirates. The highest detection rate was in bronchiolitis cases (92%). Detection of antibody rises in paired sera, eight days apart, confirmed RS virus infection in 13 of 16 cases, the most sensitive test being detection of a specific rise in IgG antibody by indirect immunofluorescence. A serodiagnosis was made in all 10 non-bronchiolitis cases. Recommendations are made for the application ofimmunofluorescence to routine diagnosis of RS virus infection.