Diagnosis of respiratory syncytial virus infection in children: Comparison of viral antigen detection and serology

Direct detection of viral antigen in nasopharyngeal secretion by radioimmunoassay was compared with serology by IgG antibody enzyme immunoassay for diagnostic efficacy in 77 children with clinically suspected respiratory syncytial virus (RSV) infections. Antigen detection gave a positive diagnosis in 26 of 33 (79%) children in whom RSV infection was diagnosed by any of the two methods. The diagnostic efficacy of antigen detection was dependent upon the interval after onset at which specimens were collected; 88% of specimens taken during the first 5 days and 50% of specimens taken 6–10 days after onset of illness were positive. It was also dependent on the age of the patients, the diagnostic efficacy being 88 and 76% in children under and over 6 months of age, respectively.     

Prospective evaluation of a dot-blot enzyme immunoassay (Directigen RSV) for the antigenic detection of respiratory syncytial virus from nasopharyngeal aspirates of paediatric patients

This study investigated the efficacy of a commercial enzyme immunoassay (Directigen RSV, ColorPAC) in comparison with the shell vial culture method (using Hep-2 cells) for the detection of respiratory syncytial virus (RSV) in nasopharyngeal aspirates from children with bronchiolitis. During the period 1995-2002, 4950 samples were examined. RSV was detected in 1660 (33.5%) samples, with a sensitivity of 80.9%, a specificity of 97.5%, a positive predictive value of 93.8%, a negative predictive value of 91.6%, and a testing efficiency value of 92.2% compared with shell vial culture. In 83 (5%) samples, the ColorPAC was positive and the shell vial assay was negative. Of these, 71 (85.6%) were false-negative by cell culture. The true false-positive results obtained by ColorPAC represented only 0.7% of all RSV-positive samples. In general, no statistically significant differences were detected between the different months and epidemic periods studied. Compared with ColorPAC, the shell vial culture method displayed a sensitivity of 95.8% and a specificity of 100%. Overall, the ColorPAC assay was an acceptable, simple and rapid method for the antigenic detection of RSV in paediatric respiratory samples.     

Evaluation of clinical specimens for the presence of respiratory syncytial virus antigens using an enzyme immunoassay

An enzyme-linked immunoassay (EIA) was developed for the detection of respiratory syncytial virus (RSV) antigen in nasopharyngeal secretions. This assay, which employs goat and rabbit anti-RSV as the capture and detector antibodies respectively, was used in a retrospective evaluation of frozen clinical specimens from children. The EIA results were compared with those of virus isolation in cell culture and direct fluorescent antibody staining performed at the time of specimen collection. The sensitivity of the RSV EIA compared to cell culture was 91.3% (63/69) with a specificity of 96.8% (93/96). The predictive value of a positive EIA result was 95.4% and for a negative EIA result, 93.9%. The sensitivity of the RSV-EIA compared to direct FA was 91.5% (43/47) with a specificity of 96.5% (83/86). These data represent the preclinical evaluation of the Abbott RSV-EIA. This assay could prove to be a useful alternative to virus isolation or direct FA for the diagnosis of RSV infection.     

Evaluation of a peptide-based enzyme immunoassay for anti-SARS coronavirus IgG antibody

High throughput assays for anti-SARS-CoV IgG antibody detection are need for large-scale epidemiologic studies. The performance of a microplate enzyme immunoassay, DETECT-SARS was evaluated for the detection of anti-SARS-CoV IgG antibody. This assay is based on synthetic peptides derived from the nucleocapsid and spike proteins. The results showed that the assay provided a high degree of sensitivity (95.9%) for convalescent serum samples. The level of specificity was close to 90%, and did not show significant variation among different control groups. The high degree of sensitivity together with the high-throughput nature makes it advantageous as a screening assay for studies where handling of a large number of specimens is required.     

Shedding of infectious virus and virus antigen during acute infection with respiratory syncytial virus.

Shedding of respiratory syncytial virus (RSV) in nasopharyngeal aspirates (NPA) of hospitalized children with acute respiratory infection was studied using direct antigen detection by time-resolved fluoroimmunoassay, rapid identification of infectious virus in centrifugally inoculated cell cultures by immunoperoxidase staining and conventional virus culture. Sequential NPAs, in which also local RSV-specific IgA response was measured, were collected from children with proven RSV infection. The shedding pattern was similar for both infectious virus and viral antigen. The overall agreement of the three methods was good (81%) in diagnostic specimens collected on admission, but markedly reduced (46%) in follow-up specimens. Secretory IgA was abundant in specimens giving discrepant or negative results only. The proportion of patients who shed RSV was high (> or = 87%) in the first week after onset of symptoms, and decreased sharply in the second week. An opposite temporal pattern was found in the proportion of patients with detectable RSV-IgA in their secretions. Sequentially isolated strains were antigenically stable as determined by their reactivity with a large panel of monoclonal antibodies. The findings suggest that RSV shedding should be monitored by using more than one method for virus detection.     

Maternal antibody and respiratory syncytial virus infection in infancy

One hundred newborn infants were studied prospectively for 1 year for evidence of infection with respiratory syncytial virus (RSV). The indirect membrane fluorescence technique was used to determine specific antibody in sera. Infection was shown in 29 cases. In 31 infants exposed to an RSV epidemic season, there was no evidence of infection. Maternal antenatal sera were also tested, and a wide range of IgG antibody to RSV was found. Mean titre of maternal IgG antibody to RSV was significantly higher (P < 0.001) in those mothers whose babies remained uninfected than in those whose babies had proved RSV infection before 6 months of age. Babies born to mothers with high levels of IgG antibody to respiratory syncytial virus were protected against infection with this virus during the first months of life when the risk of severe disease was greatest.     

Local antibody production and respiratory syncytial virus infection in children with leukaemia

Children undergoing therapy for acute lymphoblastic leukaemia (ALL) are at increased risk of severe viral respiratory infection, and some find it difficult to terminate virus secretion. This increased severity may result from a defect in the mucosal immune response. To test this hypothesis, nasal immunoglobulin secretion and specific antiviral antibody responses to infection with respiratory syncytial (RS) virus in children with ALL have been compared with those in a normal age-matched comparison group. Children with leukaemia secreted normal levels of IgA and slightly raised IgM levels. IgG levels were depressed. Following RS virus infection, the majority of children with leukaemia secreted normal amounts of IgA and IgG nasal antibody and successfully cleared the virus. However, three of the 13 children studied made poor or undetectable nasal antibody responses, which correlated with their inability to clear the virus.     

Experimental respiratory syncytial virus infection of four species of primates.

Four species of nonhuman primates were inoculated intranasally with 10(3.1) to 10(3.7) plaque forming units (pfu) of respiratory syncytial (RS) virus. Adults squirrel monkeys and newborn rhesus monkeys became infected and shed small quantities (peak titer 10(2.0) pfu/ml of nasopharyngeal swab specimen) of virus, but illness did not develop. Infant cebus monkeys aged 2 months became infected, shed 10(2.3) to 10(3.8) pfu/ml of nasopharyngeal swab specimen, but did not become ill. Chimpanzees aged 15 to 18 months shed a large quantity of virus, up to 10(6.0) pfu/ml of nasopharyngeal swab specimen and developed an upper respiratory illness. Chimpanzees are proposed as a possible animal model for future study of the immunopathology of RS virus disease and for in vivo evaluation of attenuated live virus vaccine candidates.     

化学发光酶免疫分析法在乙肝病毒及核心抗体定性检测中的应用分析

目的 通过对比,探讨了化学发光酶免疫分析法在乙肝病毒及核心抗体定性检测中的应用价值.方法 选取2013年5月至2015年5月在我院的疑似乙型肝炎患者80例,抽取空腹血液样本后都分别进行乙肝病毒以及核心抗体的化学发光酶免疫分析法及ELISA法检测,并对其检测结果进行分析.结果 化学发光酶免疫分析法检出乙型肝炎病毒阳性78例,检出率为97.5％;而ELISA检出乙型肝炎病毒阳性76例,检出率为95.0％,两种方法的检出率对比差异无统计学意义(P＞0.05).化学发光酶免疫分析法对于乙肝病毒核心抗体IgM与IgG的检测阳性率分别为80.0％和70.0％,而ELISA法检测两种抗体的阳性率则分别为18.8％和20.0％,化学发光酶免疫分析法对乙肝核心抗体IgM与IgG的检测阳性率明显高于ELISA法(P＜0.05).ELISA法检出HBc-IgM的最低限为0.135 IU/ml,检出HBc-IgM最低限为0.143 IU/ml;化学发光酶免疫分析法检出HBc-IgM最低限为0.032 IU/ml,检出HBc-IgG最低限为0.038 IU/ml.结论 化学发光酶免疫分析法在乙型肝炎检测中具有高的检出率,尤其对乙肝病毒的核心抗体的检测敏感度较高,值得在临床推广应用.     

Immunoprophylaxis and immunotherapy of respiratory syncytial virus infection in the cotton rat

Human convalescent antiserum to respiratory syncytial virus (RSV) administered intraperitoneally to cotton rats prior to RSV challenge provided near-complete protection from pulmonary infection. Antiserum given subsequent to viral challenge reduced pulmonary viral titers 100-fold or greater within 24 h. Sandoglobulin, a preparation of purified human IgG with high titer of anti-RSV neutralizing activity, produced the same effects as convalescent antiserum. Sandoglobulin was absorbed rapidly and produced a significant therapeutic reduction in virus titer within 3 h. The level of virus reduction in pulmonary and nasal tissues was directly proportional to the neutralizing antibody titer in the cotton rat serum, and was always greater in the lungs than the nose. Animals treated therapeutically with Sandoglobulin had a depressed primary antibody response to infection, but were completely resistant to reinfection with RSV. Histologic examination of pulmonary tissues from Sandoglobulin-treated animals showed no pathologic changes.     

Kinetics of antigen-specific IgM/IgG/IgA antibody responses during Zika virus natural infection in two patients

Understanding of kinetics of antibody responses is crucial for developing rapid serological tests and studying the mechanisms of Zika virus (ZIKV) infection. Most of the serological diagnostic assays previously published are based on either IgM or IgG titer, little is known on the level of IgA antibody in saliva and urine. In this study, we investigated the kinetics of IgM/IgG/IgA antibody responses in serum, saliva, and urine obtained from two ZIKV infected individuals from as early as the second day of onset of symptoms to as long as 2 years postinfection. Other than detecting robust early IgM response, long lasting IgG response, we discovered strong early IgA response specific for ZIKV in saliva in both patients. This unique observation provides a novel strategy and scientific basis for the development of noninvasive rapid tests for ZIKV infection.     

Direct enzyme immunoassay for detection of specific IgG antibody to rubella virus by use of labelled antigen

A new solid phase enzyme immunoassay (EIA) for detection of rubella-specific immunoglobulin G (IgG) antibody was developed. The test uses polystyrene microtiter strips coated with rabbit anti-human IgG immunoglobulins as the solid phase and an enzyme-labelled semipurified rubella antigen as indicator. The direct EIA was compared with hemagglutination inhibition (HI), single radial hemolysis (SRH), radioimmunoassay (RIA) and time-resolved fluoroimmunoassay (TR-FIA) using 52 serum specimens from patients with remote rubella infection. The overall agreement of direct EIA with HI was 96.1%, with SRH and RIA 98.1% and with TR-FIA 100%. The linear regression coefficient varied from 0.77 to 0.91, the best being obtained with direct EIA and SRH. The direct EIA was also suitable for diagnosis of acute infections, as a significant increase in antibody levels was detected in all paired specimens tested from patients with acute rubella infection. The sensitivity and were comparable to those of the assays employed. An advantage of the present assay is that the same method and same labelled antigen can be used to test for different classes of antibody using simply a solid phase with capture antibodies of different chain specificity.     

Primary respiratory syncytial virus infection in mice

A mouse model of respiratory syncytial virus (RSV) infection is described. A high-titered, large-volume inoculum results in replication of RSV to a high titer in lungs of BALB/c mice. Mice older than 15 weeks of age are more susceptible to RSV infection. Titers up to 10(6.9) plaque-forming units (pfu)/gram lung can be attained in 32-week-old mice. Older mice experience a clinical illness manifested by ruffled fur, reduced activity, and weight loss. Lung histology of older mice infected with RSV shows bronchiolitis and increased number of lymphocytes and macrophages in alveolar spaces compared with that of mice less than 8 weeks old. This model will serve as the basis for investigating immunodeterminants of recovery and protection from RSV infection.     

Differentiation and immune function of human dendritic cells following infection by respiratory syncytial virus

RSV causes annual epidemics of bronchiolitis in winter months resulting in the hospitalization of many infants and the elderly. Dendritic cells (DCs) play a pivotal role in coordinating immune responses to infection and some viruses skew, or subvert, the immune functions of DCs. RSV infection of DCs could alter their function and this could explain why protection after natural RSV infection is incomplete and of short duration. In this study, this interaction between DCs and RSV was investigated using a human primary culture model. DCs were generated from purified healthy adult volunteer peripheral blood monocytes. Effects of RSV upon DC phenotype with RSV primed DCs was measured using flow cytometry. Changes to viability and proliferation of cocultured DCs and T-cells were determined using microscopy with fluorescent dyes (Hoechst 33342 and propidium iodide). DC maturation was not prevented by the RSV challenge. RSV infected a fraction of DCs (10-30%) but the virus replicated slowly in these cells with only small reduction to cell viability. DCs challenged with RSV stimulated T-cell proliferation less well than lipopolysaccharide. This is the first study to demonstrate RSV infection of human monocyte derived DCs and suggests that the virus does not significantly interfere with the function of these cells and potentially may promote cellular rather than humoral responses.     

呼吸道合胞病毒感染的研究进展

呼吸道合胞病毒是在世界范围内引起婴幼儿呼吸道感染的最常见病原微生物,它不仅可以引起呼吸系统的一些常见症状和体征,而且在肺外器官如中枢神经系统、心血管系统、内分泌系统等各器官也可引起一些尚未被人们普遍认识的肺外表现,而这些临床特点的重要性也愈来愈受到人们的重视.     

Prevalence and clinical characteristics of human respiratory syncytial virus in Chinese adults with acute respiratory tract infection

Respiratory syncytial virus (RSV) is a leading cause of respiratory tract illnesses worldwide. Although the prevalence and clinical manifestations of the two subtypes, RSV‐A and RSV‐B, have been studied in some detail in infants and young children, they have not been determined in adults. To evaluate the prevalence of the RSV subtypes and disease severity between RSV‐A and RSV‐B infections in adults, nasal and throat swabs that were collected from patients ≥15 years old who sought medical care for acute respiratory infections at the Fever Clinic of the Peking Union Medical College Hospital in Beijing, China between May 2005 and April 2010. The samples were tested for RSV infection using PCR and sequencing analysis. RSV was detected in 95 (1%) of the adult patients, of whom 53 (55.8%) were positive for RSV‐A and 42 (44.2%) for RSV‐B. The incidence of RSV infections increased with age (χ² = 37.17, P = 1.66E?07). Demographic data and clinical manifestations of RSV‐A were similar to those of RSV‐B. Although RSV‐A and RSV‐B co‐circulated during the 2005–2006 and 2008–2009 seasons, RSV‐A was predominant in the 2006–2008 seasons, whereas RSV‐B was predominant in the 2009–2010 season. Upper respiratory tract infections were diagnosed in most RSV‐infected patients (n = 80, 84.2%), and three patients suffered from pulmonary infection. This is the first study to provide data on the prevalence and clinical manifestations of RSV subgroups among Chinese adults with fever and acute illness, over five successive epidemic seasons. J. Med. Virol. 85:348–353, 2013. © 2012 Wiley Periodicals, Inc.     

静脉注射用丙种球蛋白对呼吸道合胞病毒治疗的作用

目的:研究静脉注射用丙种球蛋白(IVγG)体内外抗呼吸道合胞病毒(RSV)的作用。方法:①采用微量细胞病变抑制法试验(MCIA),检测不同浓度的IVγG抑制RSV的作用。②建立RSV感染的BALB/c小鼠模型,将40只感染RSV的小鼠分为4组,即IVγG治疗组、病毒唑治疗组、Palivizumab治疗组、生理盐水对照组,及10只未感染RSV的小鼠作为正常对照组,每组10只。于治疗后第5及第7天,分2批处死小鼠,分离病毒并观察肺组织的病理积分。结果:①IVγG具有抑制RSV的作用,其治疗指数(TI)为275,较病毒唑高6倍,较Palivizumab低2倍。②IVγG治疗组小鼠肺组织的病理积分较生理盐水对照组明显减低(P<0.01),但其5d的治疗作用低于Palivizumab治疗组(P<0.05)。结论:IVγG在体内外均有一定的抗RSV的作用,但效果均低于Palivizumab。     

Comparison of strain-specific antibody responses during primary and secondary infections with respiratory syncytial virus

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infection in infants. RSV repeatedly reinfects individuals: this may be due in part to the variability of the attachment (G) glycoprotein and changes in this protein have been shown to be under positive selection. Infants experiencing their primary infection show a genotype-specific antibody response with respect to the variable regions of the G protein. A prospective study of RSV infections in a birth cohort in rural Kenya identified infants experiencing repeat infections with RSV. The serum antibody responses of these infants were investigated with respect to their anti-RSV reactions in an enzyme-linked immunosorbent assay (ELISA) and the specificity of the response to a variable region of the G protein by ELISA and immunoblotting using bacterially expressed polypeptides representative of the currently circulating strains of RSV. The results presented here confirm that the primary antibody response to the variable regions of the G protein is generally genotype-specific, but show that the response may become cross-reactive (at least within group A viruses) during secondary infections even where the secondary infection is of the same genotype as the initial infection. Also, some infants who did not mount a detectable antibody response to whole RSV antigens during their primary infection nevertheless showed genotype-specific responses to the G protein. In conclusion, the strain-specific nature of the serum antibody response to the variable regions of the G protein of RSV observed in primary infections can become cross-reactive in subsequent reinfections.