Enzyme immunoassay for direct detection of influenza type A and adenovirus antigens in clinical specimens.

Detection of viral antigens in specimens without prior cultivation in cell culture provides the most rapid method for specific viral diagnosis. A solid-phase, double-antibody enzyme immunoassay was developed for this purpose and tested with clinical specimens containing influenza type A and adenovirus. Polystyrene microtiter wells were the solid phase and were coated with virus-specific guinea pig immunoglobulins. Specimens were added, and bound viral antigens were detected by addition of virus-specific rabbit immunoglobulins followed by enzyme-labeled goat antirabbit immunoglobulin G. Two methods of labeling goat anti-rabbit immunoglobulin G with horseradish peroxidase were investigated: covalent attachment and a noncovalent, immunological binding of antibody to enzyme, the peroxidase-antiperoxidase method. Both methods of labeling resulted in assays that could detect 10(3.5) 50% tissue culture infectious doses of influenza type A and 10(3.8) 50% tissue culture infectious doses of adenovirus. Equal sensitivity was noted with alkaline phosphatase-labeled goat anti-rabbit immunoglobulin G. An increase in sensitivity of three- to sixfold was achieved when virus-specific rabbit immunoglobulins and conjugate were diluted in 1% gelatin. The solid-phase, double-antibody enzyme immunoassay detected influenza type A and adenovirus in isolation-positive clinical specimens with 53% (21/40) and 62% (13/21) efficiency, respectively. The solid-phase, double-antibody enzyme immunoassay has considerable potential as a practical and rapid method for detection of respiratory viral antigens in nasal wash and throat swab specimens. For optimal value, however, greater sensitivity than was provided by the present methods is desirable.     

Comparison of direct immunofluorescent staining of clinical specimens for respiratory virus antigens with conventional isolation techniques.

Staining of clinical respiratory specimens obtained by nasopharyngeal and throat swabs with direct fluorescein isothiocyanate-conjugated antisera to para-influenza virus types 1, 2, and 3, influenza A virus, respiratory syncytial virus, adenovirus, mumps virus, and measles virus was compared with isolation procedures in routine tissue culture systems. Direct staining of clinical specimens with the commercially available conjugated offered a rapid means of diagnosing respiratory infections on a routine clinical basis when used in conjunction with isolation in tissue culture systems. Of 292 patients who were culture positive for these viruses, 259 were diagnosed by detection of the viral antigen in clinical specimens by direct immunofluorescence. No specimens that subsequently yielded a different respiratory virus by culture were positive by the direct immunofluorescence method. Use of selected antisera based on clinical history of the patient reduced the cost of rapid viral diagnosis.     

Detection of Meningococcal Carriage by Culture and PCR of Throat Swabs and Mouth Gargles

The standard method for detecting meningococcal carriage is culture of throat swabs on selective media, but the levels of carriage determined depend heavily on the skills of the individuals taking the swab and interpreting the cultures. This study aimed to determine the most sensitive detection method for meningococcal carriage. Throat swabs and saline mouth gargles, obtained from 89 university students, were processed in parallel by conventional culture and TaqMan ctrA PCR. Carriage of meningococci, as detected by the combined methods, was 20%. The sensitivities of throat swab culture, throat swab PCR, gargle culture, and gargle PCR were 72, 56, 56, and 50%, respectively, and the probabilities that these techniques would correctly identify the absence of carriage (negative predictive value [NPV]) were 93.4, 89.9, 89.9, and 88.8%. Culturing both throat swabs and gargles increased the NPV to 98.6%. The further addition of throat swab PCR increased this to 100%. Testing gargles by both culture and PCR was as sensitive as testing throat swabs by both methods, suggesting that gargles may be a suitable alternative for large-scale screening studies when throat swabs are difficult to obtain, although they required more lengthy laboratory processing. PCR was a useful adjunct to culture for detecting nasopharyngeal carriage, but it failed to detect some nongroupable strains. For maximum sensitivity, a combination of techniques was required. This study indicates the confidence with which health care professionals involved in meningococcal screening can regard laboratory results.     

Detection of influenza B virus in throat swabs using the polymerase chain reaction.

An assay protocol based on exploiting the polymerase chain reaction (PCR) for the direct detection of influenza B virus in throat swabs is described. By the use of PCR with nested primers, it was possible to detect the virus in throat swabs. Dilution experiments showed that as little as 1 plaque forming unit of virus was sufficient for detecting the HA gene by the PCR. All throat swab samples from which influenza B virus had been isolated by conventional methods were also positive by the PCR method.     

Comparative study of nasopharyngeal aspirate and nasal swab specimens for diagnosis of acute viral respiratory infection

Paired nasopharyngeal aspirate (NPA) and nasal swab (NS) samples from 475 children hospitalized for acute respiratory infection were studied for the detection of influenza virus, parainfluenza virus, respiratory syncytial virus, and adenovirus by immunofluorescence test, viral culture, and multiplex PCR assay. The overall sensitivity of viral detection with NPA specimens was higher than that obtained with NS specimens.     

Evaluation of a commercial monoclonal antibody-based enzyme immunoassay for detection of adenovirus types 40 and 41 in stool specimens.

A commercial monoclonal antibody-based enzyme immunoassay (Adenoscreen; Mercia Diagnostics Ltd., Guildford, United Kingdom) for the detection of adenovirus types 40 and 41 in stool specimens was evaluated. Two assay modes were tested. In the first, 177 stool samples were screened for the presence of adenovirus type 40 or 41 (assay mode 1). Virus was detected in 79 of 82 specimens positive for adenovirus type 40 or 41 by a polyclonal antibody-based immune electron microscope test, giving a sensitivity of 96.3%. The enzyme immunoassay was negative in 91 of 95 stool samples which contained either other adenovirus serotypes or other viruses or were virus negative. The specificity was thus 95.8%. The positive and negative predictive values of this assay against immune electron microscopy were 95.2 and 96.8%, respectively, and the diagnostic accuracy was 96.0%. Viruses from the three false-negative enzyme immunoassay stool samples were verified as adenovirus type 40 or 41 by restriction enzyme analysis, monoclonal antibody-based immune electron microscopy, or both. Two of the three false-negative stool samples were subsequently concentrated by ultracentrifugation, and one of the two stool samples was then positive by enzyme immunoassay. The third false-negative virus was typed as adenovirus type 41 in the second (serotyping) enzyme immunoassay mode. The four enzyme immunoassay false-positive stool samples all contained other adenovirus serotypes (two were type 2, and two were type 5), but no cross-reactivity was seen with other strains of these serotypes and the results probably reflected simultaneous excretion of adenovirus type 40 or 41 with other adenovirus serotypes. In the second assay mode viruses from 15 stool samples were serotyped. The results by enzyme immunoassay (4 were type 40 and 11 were type 41) correlated completely with previous results from restriction endonuclease analyses. The commercial enzyme immunoassay system showed excellent sensitivity and specificity for the detection of adenovirus types 40 and 41 in stool specimens and will make an important contribution to the accurate diagnosis of adenovirus gastroenteritis.     

New human adenovirus isolated from a renal transplant recipient: description and characterization of candiate adenovirus type 34.

An antigenically distinct adenovirus is described which was isolated in March 1972 from the urine of a 17-year-old Caucasian male who was experiencing fever after receiving a kidney transplant from a cadaver in February. The adenovirus could not be isolated in April from a pharyngeal swab which yielded cytomegalovirus. Complement-fixation, hemagglutination-inhibition, and/or serum-neutralization tests on sequential serum specimens from the patient confirmed that the adenovirus infection occurred during March and showed that infections with cytomegalovirus and respiratory syncytial virus also occurred during late March and April. The patient's persistent fever, for which other causes could not be found, may have been associated with one or more of these infections. Upper respiratory symptoms and lung involvement were not found during this period. Mild liver dysfunction during this time could not be clearly related to adenovirus infection because of the presence of multiple other causes. The adenovirus may have been latent in the donor kidney and become active in the new host as a consequence of immunological impairment. The adenovirus, purified by terminal dilution and plaque procedures, has antigenic, morphological, biophysical, host susceptibility, and hemagglutinating properties characteristic of adenovirus group IA. Buoyant densities in CsCl are 1.340 g/ml for the virion, 1.304 g/ml for the group CF antigen (hexon), 1.295 g/ml for the major soluble complete hemagglutinin (dodecon), and 1.206 g/ml for the minor soluble complete hemagglutinin (tentatively, fiber dimer). The virus does not cross-react in reciprocal hemagglutination-inhibition and serum-neutralization tests with antisera to adenovirus types 1 to 33. We propose this virus as candidate adenovirus type 34 (Compton).     

Time-resolved fluoroimmunoassay with monoclonal antibodies for rapid diagnosis of influenza infections

Monoclonal antibodies that are broadly reactive with either influenza A or influenza B viruses were used to develop a 2- to 3-h antigen capture time-resolved fluoroimmunoassay (TR FIA) for detecting influenza viral antigens in both original nasopharyngeal aspirate specimens and in tissue cultures inoculated with nose or throat swab specimens. The lower limit of sensitivity of the assay was about 10 pg of protein as determined with purified influenza A nucleoprotein expressed by recombinant DNA. When the TR FIA was performed with 96 nasopharyngeal aspirate specimens collected during outbreaks of influenza A (H3N2) virus and the results were compared with serodiagnosis results with paired sera, the specificity and sensitivity of TR FIA for the demonstration of influenza A infections were 95 and 85%, respectively. In culture confirmation assays, more than 80% of the swab specimens that grew influenza A or B virus within 7 days could be identified by the TR FIA within 48 h of the inoculation of cells. The results are consistent with those previously reported for respiratory syncytial virus and extend the applicability of monoclonal antibody-based TR FIA for the rapid diagnosis of acute respiratory viral infections.     

Replication of human adenoviruses in guinea pig embryo cells: an ultrastructural study

Summary Guinea pig embryo (GPE) cells showed different degrees of susceptibility to human adenovirus types as determined by virus infectivity assay and electron microscopic examination. Adenovirus 2 and 5 induced extensive cellular changes and produced high titers of infectious virus in GPE cells as in human cells. Mature progeny virus and protein crystals were observed in both cell types. Adenovirus 7 induced some cellular changes in GPE cells but only a small number of cells yielded progeny virus as determined by electron microscopy. Adenovirus 3, 8 and 31 induced some cellular changes but no progeny virus was found under electron microscopic examination. Characteristic fibers were observed in nuclei of adenovirus 31 infected cells. The ability of human adenovirus 2 and 5 to replicate in GPE cells is an example of an unusual cross-species biological property of certain adenovirus types. This property may be useful as a biological marker for these virus types.With 8 Figures     

Possible Spread of adenovirus type 3 from poultry to humans: indirect evidence from an outbreak in China

Objective:To explore the epidemiology and etiology for an outbreak of acute respiratory tract infection that occurred in one county of Jiangsu Province, China 2004. Methods: Only cases meeting the case definition were included in the study. We reviewed the medical records of the cases who were admitted to the local hospitals, interviewed cases by a standard questionnaire, and then described the epidemiotogic features and analyzed risk factors by means of a case-control study. We collected pharyngeal swab specimens and sent them to different laboratories for isolation and culture. The laboratory used different detection methods such as DIP, PCR, electron microscope examination and microneutralization assay, to identify and then type the positive specimens. Results:A total of 871 cases were reported during the period from April 18 to July 4,2004. The distribution of onset times presented two peaks, one in late May and another in middle June. The epidemic occurred mainly in the elementary and junior high schools in ten townships of one county, and the mean age of the cases was 12 years (range 7 months to 18 years). The course of the disease was acute, and was characterized by fever accompanied with sore throat and tonsillitis. The WBC count of cases was normal or elevated. The mean duration of illness was 5 days (range 2 to 12 days). No fatalities from illness were reported. A case-control study indicated that the possible risk factors were close contact with a case and/or poultry before onset and sharing of towels among members of the family. The typical CPE was observed through inoculating pharyngeal swab specimens into the HEP-2 cell cultures in different laboratories. An infection of adenovirus type 3 was verified by detecting positive specimens in different methods. Conclusion:This investigation demonstrated that the acute respiratory infection in cases was caused by adenovirus type 3. Cases occurred in over 70 schools in ten townships in 2004, and the route of transmission was possibly close contact with cases or droplet transmission.     

Comparison of direct electron microscopy, immune electron microscopy, and rotavirus enzyme-linked immunosorbent assay for detection of gastroenteritis viruses in children.

An approximate 10% suspension in water of the first available stool sample from 411 infants and young children with acute gastroenteritis was examined by electron microscopy (EM) after 2 min of negative staining. This procedure enabled the detection of 88% of the 199 rotavirus infections, all of the 22 adenovirus infections, and 47% of the 15 approximately 27-nm virus infections ultimately detected by a combination of techniques, including immune electron microscopy (IEM) and rotavirus enzyme-linked immunosorbent assay (ELISA). Of the 204 infections detected by direct EM of stools, 76% were detected within 2 min of viewing, and 94% were detected within 6 min of viewing. Type 1 and type 2 rotavirus particles were visualized with approximately equal efficiency, although type 2 rotavirus infections were more common. Rectal swab preparations were clearly inferior to stool preparations for the detection of virus infection by direct EM. IEM examination was required for efficient visualization of viruses in rectal swab specimens. ELISA was the most sensitive method for the detection of rotaviruses; with this method, all infections in which rotavirus particles were visualized by EM or IEM were detected. However, 73% of the 1,834 specimens which were presumptively positive for rotavirus by conventional indirect ELISA proved to be falsely positive on the basis of EM, IEM, blocking ELISA, confirmatory ELISA, or a combination of these methods. False-positive rotavirus ELISA reactions apparently were eliminated when fecal specimens were tested in a modified confirmatory ELISA with a lower dilution of rotavirus-negative (pre-immunization) than rotavirus-positive (post-immunization) capture antibody from the same animal.     

Adsorption of influenza viruses to nitrocellulose membrane filters by filtration and their quantitative densitometric determination

Influenza viruses concentrated and adsorbed onto nitrocellulose membrane filters by filtration are detected rapidly and sensitively by sequential incubation with the primary antibody and the secondary antibody conjugated with peroxidase. The bound enzyme is detected by incubation with a substrate which is converted to an insoluble colored product. A dual-wavelength TLC scanner is used for densitometric quantitation. The membrane filtration-blotting enzyme immunoassay provides a method for quantitative analysis and rapid typing of influenza isolates. The method may be also applicable for quantitative detection of influenza viruses in throat swab specimens from patients, as well as in tissue culture fluids.     

四例咽拭子检测阳性发热伴血小板减少综合征重症患者的临床特征分析?

通过疑似发热伴血小板减少综合征（ Severe fever with thrombocytopenia syndrome, SFTS）病例咽拭子的新型布尼亚病毒（SFTSV）检出情况,探讨SFTSV通过呼吸道传播的可能性。按照国家卫生部颁发的《发热伴血小板减少综合征防治指南（2010版）》中疑似病例的纳入标准,于2013年5～9月在SFTS高发区河南信阳的监测哨点医院收集72例疑似 SFTS 病例的血清和咽拭子标本,采用实时 RT?PCR 方法和ELISA方法检测SFTSV。结果显示,在72例疑似SFTS病例中,52（72?2％）例检测是SFTSV阳性,其中46例核酸RT?PCR检测阳性,6例血清ELISA检测阳性。在52例SFTSV阳性病例中,4（7?7％）例咽拭子核酸检测SFTSV阳性;在20例SFTSV阴性病例中,咽拭子核酸均未检测到SFTSV。4例咽拭子SFTSV阳性病例均为重症,同时都伴有咳嗽症状,其病毒载量最高可达108 copies／mL。 SFTSV在患者的咽拭子中可以检测到,咽拭子核酸检测SFTSV阳性检出率远低于血清标本,其作为检测SFTSV的可行性值得商榷。咽拭子检测SFTSV阳性患者体内病毒载量高且伴有咳嗽症状,加大了SFTSV通过呼吸道传播的风险。     

A comparison of direct electron microscopy, virus isolation and a DNA amplification method for the detection of avian infectious laryngotracheitis virus in field material

Seventy-two post-mortem samples of mainly tracheal tissue from commercial chickens from 25 commercial chicken flocks with suspected infectious laryngotracheitis (ILT) were examined for the presence of the virus using direct electron microscopy (EM), virus isolation (VI) in primary chick embryo liver cell culture and a DNA amplification method (polymerase chain reaction; PCR). ILT virus was identified in 22 outbreaks, and in 58 of the 72 specimens. PCR detected virus in 52 of the 72 specimens and VI was positive in 48. In five instances, VI was positive where the other methods were negative and in three, PCR was the only test positive. Direct EM examination detected virus in only 19 of the 58 positive samples and in no case was EM the only method positive. An advantage of PCR was that it could sometimes detect virus in samples that were too heavily contaminated with bacteria for virus to be isolated and on other occasions it was positive for ILT virus when the only virus that could be detected by growth in tissue culture was adenovirus.     

儿童呼吸道感染者肺炎支原体及肺炎衣原体特异性抗体检测临床意义

目的 探究儿童呼吸道感染者肺炎支原体及肺炎衣原体特异性抗体检测临床意义。方法 选择我院2018年1月~8月收治的85例呼吸道感染患儿设为研究组,另选择同期在我院进行健康体检的85例儿童设为对照组,对照组采用ELISA法检测肺炎支原体及衣原体,研究组在此基础上行咽拭子培养法检测,比较两组肺炎支原体、衣原体抗体检出率,ELISA法与咽拭子培养法对肺炎支原体、衣原体抗体的阳性检出率,分析研究组呼吸道感染性疾病中肺炎支原体、衣原体抗体阳性分布情况。结果 研究组患儿肺炎支原体抗体MP-IgM抗体、MP-IgA抗体、MP-IgG抗体及肺炎衣原体特异性抗体CP-IgM抗体、CP-IgG抗体的检出率均高于对照组儿童,差异有统计学意义（P＜0.05）;ELISA法对肺炎支原体特异性抗体阳性的检出率为54.12%高于咽拭子培养法的36.47%,组间对比具有统计学意义（P＜0.05）;ELISA法对肺炎衣原体特异性抗体阳性的检出率为58.82%高于咽拭子培养法的37.65%,差异有统计学意义（P＜0.05）;肺炎支原体、肺炎衣原体抗体阳性在各种儿童呼吸道感染性疾病中均有表现,其中,肺炎和支气管肺炎的阳性检出率较咽炎、扁桃体炎均较高。结论 肺炎支原体、肺炎衣原体是引发肺炎和支气管肺炎感染的主要病原菌。     

Detection of adenovirus types 40 and 41 in stool specimens by immune electron microscopy

An immune electron microscope (IEM) test was developed that allowed the direct detection of adenovirus type 40 (ad 40) or ad 41 in stools specimens. The polyclonal rabbit antisera used differentiated ad 40 and 41 from other ad serotypes but not from each other. The method was evaluated in a 13 month prospective study of stools from children with gastroenteritis. Seventy-two specimens found to contain ad by conventional electron microscope screening were retested by IEM. Results were typically obtained within 2 hr and showed that 55 (76%) viruses typed as ad 40/41. No ads were recovered from conventional virus isolation attempts on these specimens. Additionally, 39 of these 55 viruses were tested by restriction endonuclease analysis (REA) after growth in 293 cells, and results showed that all produced digest patterns typical of ad 40 (seven cases) or ad 41 (32 cases). Twenty-four percent (17/72) of viruses could not be typed by IEM; 9/17 (53%) yielded ads [ad 1 (1), ad 2 (4), ad 5 (1), ad 6 (1), ad 7 (2)] in routine culture, whereas REA identified the other eight as ad 2 (6), ad 1 (1), and ad 41 (1). The concordance between IEM and the reference methods was therefore 100% specificity and 97.5% sensitivity. The method described allows the clinically useful diagnosis of ad 40/41 infection to be rapidly made and will be a particularly useful technique in laboratories screening faeces by electron microscopy.     

Surveillance of respiratory viral infections among pediatric outpatients in northern Taiwan.

BACKGROUND: Viruses are a frequent cause of upper respiratory tract infections in children. Like Taiwan, there were few virological surveillance systems for respiratory viral infections among children in developing countries. MATERIALS AND METHODS: During August 1995 and July 1997, 6-10 throat swab specimens per week were taken from pediatric outpatients with acute, febrile upper respiratory tract infections (URTI). The specimens were randomly obtained by two pediatricians at Chang Gung Children's Hospital and sent for virus isolation and identification. RESULTS: A total of 910 specimens were collected and 365 specimens (40%) were positive for at least 1 virus and included 81 enterovirus, 73 adenovirus, 58 influenza B virus, 54 influenza A virus, 48 cytomegalovirus (CMV), 25 herpes simplex virus-1 (HSV-1), 7 parainfluenza virus, 3 respiratory syncytial virus (RSV) and 16 mixed viruses. Adenovirus and enterovirus were identified throughout the study period. No seasonal variation was noted for adenovirus while enterovirus peaked between May and July and also during September and November. Influenza viruses, both A and B, were identified during two periods, respectively and altogether, influenza viruses could be detected almost throughout the year. An association between the virus type identified and the mean age of patients was found (P-value = 0.0001 by ANOVA test). The mean age of patients infected with influenza viruses, either A or B, was significantly higher than those of patients infected with adenovirus, HSV-1, CMV and enterovirus. CONCLUSION: The results of this study demonstrate that adenovirus and enterovirus are the two most common viruses isolated from pediatric outpatients with acute, febrile URTIs and can be identified throughout the year in northern Taiwan. Influenza viruses also can be identified throughout the year and during the epidemic, a child older than 5 years of age with acute febrile URTI is likely to be a case of influenza.