Comparison of ortho respiratory syncytial virus enzyme-linked immunosorbent assay and HEp-2 cell culture

Respiratory syncytial virus infections in malnourished children

The prevalence of respiratory syncytial virus (RSV) infection among severely malnourished children was studied at the University of Benin Teaching Hospital, Benin City, Nigeria at a time when the infection was known to be prevalent in the community. Nasopharyngeal washings were obtained from subjects on admission and thereafter every 4 days until discharge. RSV was detected by ELISA technique. Of 20 well nourished children who served as controls, 11 were ELISA-positive for RSV (55%). Eight (16%) of the 51 patients who were malnourished were ELISA-positive, four of whom (8%) had nosocomial infection. Fever and rhinitis were the most common presenting features in the RSV-infected malnourished children. None of the children showed any clinical or radiological signs of lower respiratory tract infection. Malnourished children appear not to be at increased risk of RSV infection, and those who contract the infection usually do not manifest severe disease.

Rapid diagnosis of respiratory viral infections by using a shell vial assay and monoclonal antibody pool

We compared the detection of seven respiratory viruses by using a commercially available monoclonal antibody pool in a 2-day shell vial assay with that by using standard cell culture with respiratory syncytial virus (RSV) enzyme-linked immunosorbent assay (ELISA)-negative nasal secretions from hospitalized children. We found 179 respiratory virus isolates by either method in 675 specimens. Overall, the shell vial assay detected 147 of 179 (79%) of the positives after 2 days; cell culture detected 148 of 179 (80%) after a mean incubation period of 7.6 days (range, 1 to 14 days). The sensitivity of the shell vial assay was 78% for RSV, 94% for influenza B virus, 83% for adenovirus, and 80% for parainfluenza viruses. The sensitivity of the cell culture was 70% for RSV, 79% for influenza B virus, 90% for adenovirus, and 89% for parainfluenza viruses. The 2-day shell vial assay allowed the detection of respiratory viruses in a clinically relevant time frame and rapidly detected RSV in specimens lacking RSV antigen by ELISA.

Nosocomial respiratory syncytial virus infection in a newborn nursery

The nosocomial spread of respiratory syncytial virus (RSV) was studied in a newborn nursery in Benin City, Nigeria at a time the virus was known to be highly prevalent in the community. Nasopharyngeal washings were obtained from babies on admission and, thereafter, every 4 days until discharged. Questionnaires were administered to medical personnel with upper respiratory tract infection (URTI). RSV was detected by an ELISA technique. A total of 56 babies were studied, made up of 33 preterm and 23 full term babies. Fourteen of the 56 babies (25%) developed RSV infection. Eleven babies (20.8%) acquired the infection nosocomially. The infected babies were all symptomatic and some had significant morbidity. One preterm baby died following acquisition of RSV. The study demonstrated that medical personnel working in our newborn nursery were a major contributor to the spread of nosocomial RSV infection. Babies hospitalized for more than 4 weeks were more likely to acquire RSV infection. Control measures are outlined for the reduction of nosocomial spread of RSV infection in our newborn nursery.

Comparison of two rapid methods for detection of respiratory syncytial virus (RSV) (Testpack RSV and ortho RSV ELISA) with direct immunofluorescence and virus isolation for the diagnosis of pediatric RSV infection

The ability of two commercial immunoassays to detect respiratory syncytial virus (RSV) in respiratory specimens was evaluated as follows: 152 specimens were tested by TestPack RSV (Abbott), and 72 were tested by Ortho RSV ELISA (Ortho). Test outcomes were compared with those of virus isolation alone, direct immunofluorescence assay (DFA) alone, or virus isolation and/or DFA. TestPack RSV versus virus isolation showed 91% sensitivity, 96% specificity, 93% positive predictive value (PPV), and 95% negative predictive value (NPV). TestPack RSV versus DFA showed 89% sensitivity, 97% specificity, 96% PPV, and 93% NPV. When TestPack RSV performance was compared with that of virus isolation and DFA, the sensitivity was 87% and the specificity was 100%. Ortho RSV ELISA versus virus isolation showed 88% sensitivity, 87% specificity, 79% PPV, and 93% NPV. Ortho RSV ELISA versus DFA showed 91% sensitivity, 88% specificity, 81% PPV and 95% NPV. When Ortho RSV ELISA performance was compared with that of virus isolation and DFA, the sensitivity was 86%, the specificity was 89%, the PPV was 86%, and the NPV was 89%. The accuracy of the TestPack RSV in combination with ease of performance and no need for specialized equipment or special skills make it an attractive alternative to DFA for rapid direct detection of RSV.

Evaluation of combined commercial enzyme-linked immunosorbent assay for detection of rota and adenoviruses for automation

219 stools were examined by direct electron microscopy (EM), culture and 'combined' commercial enzyme-linked immunosorbent assay kits (CELISA). The specificity of the combined ELISA for rotavirus was 100% as compared with EM, and 100% for adenovirus when both culture in addition to EM were carried out. ELISA appeared to be more sensitive than EM for both viruses. There was no cross-reaction between the 2 'combined' antisera. This technique may be useful for automation of viral diagnosis with ELISA using a 'panel' of selected viruses for a variety of specimens.

Comparison of three techniques for detection of respiratory viruses in nasopharyngeal aspirates from children with lower acute respiratory infections

A comparison of immunofluorescence (IF), enzyme-linked immunosorbent assay (ELISA), and isolation in tissue culture (TC) for detection of respiratory viruses was performed on 496 nasopharyngeal aspirates from children under 5 years of age with lower acute respiratory infections who were receiving attention at three hospitals in Buenos Aires, Argentina. All samples were tested by the three methods for respiratory syncytial virus (RSV), influenza A and B, adenovirus, and parainfluenza 1 and 3. Viral diagnosis was made in 167 samples (33.7%); of these, 124 (74.3%) were isolated in TC, whereas 120 (71.8%) were detected by ELISA and 127 (76%) by IF. RSV was detected in 121 samples, mainly by ELISA and IF. The sensitivity and specificity of each rapid technique as compared with isolation in TC were similar, reaching 98% and 92%, respectively. When ELISA was compared with IF, the sensitivity was 95%, and the specificity was 98%. Adenovirus was detected in 18 patients by TC. For this virus, rapid techniques sensitivity as compared with TC was low (almost 22%). Parainfluenza 3 was readily detected by IF and TC; influenza A, B and parainfluenza 1 were detected in few samples; and tissue culture proved more efficient than rapid techniques. The results indicate that both rapid techniques are good tools for the detection of most respiratory viruses except for adenovirus, for which TC cannot be omitted.

Nasopharyngeal swabs and nasopharyngeal aspirates equally effective for the diagnosis of viral respiratory disease in hospitalized children

Paired nasopharyngeal swab and nasopharyngeal aspirate specimens from 125 patients were compared for viral diagnosis. The viral isolation rates were comparable for the two types of specimens. There was a high level of agreement between the two specimens in overall positivity rate by immunofluorescence and positivity in culture-confirmed patients.

Evaluation of the Abbott TESTPACK RSV enzyme immunoassay for detection of respiratory syncytial virus in nasopharyngeal swab specimens

The Abbott TESTPACK RSV assay (Abbott Laboratories, North Chicago, Ill.), a rapid (20-min) enzyme immunoassay, was compared with culture and direct immunofluorescence (DFA) of nasopharyngeal cells for the detection of respiratory syncytial virus (RSV) in nasopharyngeal swab specimens. Nasopharyngeal swab specimens, collected from 234 infants, were placed in viral transport medium. Portions of specimen in transport medium were used for each test. Of 234 specimens, 70 (30%) were culture positive, 103 (44%) were DFA positive, 107 (46%) were culture or DFA positive, and 112 (48%) were TESTPACK RSV positive. Of 19 specimens positive by TESTPACK RSV but negative by culture or DFA, 15 were positive by the blocking assay. A total of 122 specimens were culture, DFA, or blocking assay positive; TESTPACK RSV detected 108 specimens (sensitivity, 89%). The specificity, positive predictive value, and negative predictive value of TESTPACK RSV as compared with those of culture, DFA, and the blocking assay were 96, 96, and 89%, respectively. By comparison, the sensitivity, specificity, positive predictive value, and negative predictive value of combined culture and DFA were 88, 100, 100, and 88%, respectively. TESTPACK RSV is a rapid and reliable enzyme immunoassay for the direct detection of RSV antigen in nasopharyngeal swab specimens.

Evaluation of a monoclonal antibody pool for rapid diagnosis of respiratory viral infections

A pool of monoclonal antibodies (MAbP) was evaluated both as a method of cell culture confirmation and as a rapid diagnostic screen for viral infection in respiratory secretions. The MAbP was used in a two-step fluorescent staining procedure on cells harvested from cultures (phase 1) and on exfoliated nasopharyngeal or tracheal cells (phase 2). Antibodies in the MAbP were directed against respiratory syncytial virus, adenoviruses, parainfluenza virus types 1, 2, and 3, and influenza viruses A and B. Individual antiviral antibody stains were used to identify specific viruses from MAbP-positive specimens. In phase 1 (cell culture confirmation only), 241 respiratory specimens were tested. MAbP sensitivity and specificity were 91 and 94%, respectively. In phase 2, 376 respiratory specimens were evaluated by direct staining of exfoliated cells, and these results were compared with results of cell culture isolation. The sensitivity and specificity of the MAbP used in direct specimen testing were 69 and 97%, respectively. These results indicate that the MAbP is highly specific and fairly sensitive for detection of seven different respiratory viruses in one testing procedure. The MAbP is a rapid screening technique for respiratory secretions and is potentially a cost-effective approach to viral detection.

Use of high-speed rolling to detect respiratory syncytial virus in cell culture

We examined the effect of motion on respiratory syncytial virus (RSV) growth in cell culture. Infected cultures were incubated stationary, rolling, or on an orbital shaker. Enzyme immunoassay (EIA) results for cultures infected with high concentrations of a laboratory strain of RSV were similar for all incubation conditions. However, cultures infected with low concentrations of virus and rolled at 96 rpm had a significantly greater mean EIA optical density (1.78 +/- 0.22) than cultures rolled at 2 rpm (1.42 +/- 0.08) (P less than 0.05). The mean EIA optical density of high-speed-rolled cultures was also significantly greater than for cultures on an orbital shaker (1.25 +/- 0.08) or for stationary cultures (0.21 +/- 0.17) (P less than 0.01). The amount of virus measured by EIA from cultures infected with clinical specimens was also found to be significantly greater at 96 rpm than for stationary cultures. Cultures infected with cell culture isolates were detected significantly earlier at 96 rpm than when stationary. We suggest that high-speed-rolling can be used to enhance the detection of RSV in clinical specimens, especially if the virus is present in low concentrations.

Nonculture methods for detection and identification of microorganisms in clinical specimens

The pressures of cost reduction and clinical relevancy that led to the conception and introduction of direct detection tests continue to influence the course of modern microbiology. A significant amount of progress has been made in the past few years in the refinement of these tests. Some of the procedures that have been developed have been disappointing in their true clinical utility. Others seem to be a genuine advance in technique. Unquestionably, these methods will continue to be developed and will have a significant impact on the way laboratory testing is performed and, we hope, the cost of laboratory work and the quality of care given to patients.

Pertussis: the disease and new diagnostic methods

Bordetella pertussis, the causative agent of whooping cough, produces an acute and chronic respiratory infection in infants and young children. B. pertussis is still a major health problem of young children throughout the world even though effective immunization against whooping cough is available. While predominantly a childhood disease, it has been reported also to be a cause of persistent cough in adults. This review discusses the numerous bacterial virulence factors that may play roles in the pathogenesis of pertussis and in immunity to infection. The present problems with pertussis diagnosis, recent advances, and future prospects for new and improved rapid diagnostics tests also are explored.

Detection of respiratory syncytial virus antigen in nasopharyngeal secretions by Abbott Diagnostics enzyme immunoassay

We compared a rapid respiratory syncytial virus (RSV) antigen enzyme immunoassay (EIA) (Abbott Diagnostics, North Chicago, Ill.) with virus culture and with the indirect fluorescent-antibody test (FAT) by using nasopharyngeal washings from children with suspected RSV pneumonia or bronchiolitis. Fresh washings were used in all three tests. Specimens were inoculated into HEp-2 cells and human embryonic lung fibroblasts and observed for cytopathic effect. Cells in the centrifuged sediments of the nasal washes were examined for typical cytoplasmic fluorescence of RSV by FAT. The EIA cutoff was an optical density (OD) at 492 nm that was greater than the mean OD of the negative controls plus 0.1. An OD within +20% of the cutoff was considered borderline, and these specimens were retested. Of 289 specimens, 118 (41%) were positive by culture, 150 (52%) were positive by FAT, and 154 (53%) were positive by EIA. Eight borderline EIAs were all negative when the specimens were retested after storage at -70 degrees C. Of 17 specimens positive by EIA but negative by culture and FAT, 9 were blocked in a competitive EIA, indicating that they were true-positives and that the culture and FAT were falsely negative. The sensitivity, specificity, and predictive value (positive) of the EIA versus culture, FAT, or blocking assay were 90, 94, and 95%, respectively. We conclude that the Abbott RSV antigen EIA is highly sensitive and specific.

Comparison of the Abbott and Ortho enzyme immunoassays and cell culture for the detection of respiratory syncytial virus in nasopharyngeal specimens

A comparison of the Abbott Laboratories and the Ortho Diagnostic Systems Respiratory Syncytial Virus (RSV) Enzyme Immunoassays (EIA) and HEp-2 cell culture for the detection of RSV in 81 nasopharyngeal (NP) specimens from pediatric patients with lower respiratory tract infection was carried out. The sensitivity and specificity of the Abbott test compared to confirmed infection was 92.3% and 100.0%, respectively. The sensitivity and specificity of the Ortho test was 87.5% and 80.3%, respectively. We found the Abbott EIA test to be sensitive, specific, rapid, and easy to perform.

An enzyme-linked immunosorbent assay using monoclonal antibodies for the detection of respiratory syncytial virus in clinical specimens

An enzyme-linked immunosorbent assay (ELISA) has been developed for the detection of respiratory syncytial virus in nasopharyngeal secretions. This assay employed as immunoreagents two monoclonal antibodies directed against two distinct epitopes of the viral nucleocapsid. One of them (RSV 4) was used for antigen capture and the other (NC 4) was labelled with N-hydroxy-succinimide-epsilon-caproil biotin and used for antigen detection. Streptavidin biotin-peroxidase complexes were employed as amplification mode. The immunoassay was performed in 6 hours and was able to detect as little as 1 ng/ml of purified nucleocapsid. When 87 nasopharyngeal secretions were analyzed by an indirect immunofluorescence assay using commercial reagents and by the newly developed ELISA, the sensitivity and the specificity of the two assays were found to be very similar.

Detection of respiratory syncytial virus in clinical specimens by viral culture, direct and indirect immunofluorescence, and enzyme immunoassay

We evaluated prospectively the detection of respiratory syncytial virus (RSV) by culture and by direct antigen detection using an indirect immunofluorescence assay (IFA), a direct monoclonal immunofluorescence assay (DFA), and a monoclonal enzyme immunoassay (EIA). Of 221 specimens, 95 (43%) were culture positive for RSV, 4 (1.8%) contained more than one virus, and 17 (7.6%) contained a virus other than RSV. Overall, HEp-2 and Flow 6000 cells grew significantly more RSV isolates (82 and 72%, respectively) than A549 cells, which grew only 29% of the isolates. The mean time for RSV detection with HEp-2 cells was 2.9 days. This was significantly less than the mean time for RSV detection with either Flow 6000 cells (6.1 days) or A549 cells (6.4 days). Of 221 specimens, 129 were tested simultaneously by culture, IFA, and DFA. Of these 129 specimens, 62 (48%) were positive by culture, 69 (53%) were positive by IFA, and 70 (54%) were positive by DFA. For 92 specimens screened simultaneously by culture, IFA, and EIA, positive results were obtained for 33 (36%) of the specimens by both culture and IFA and for 29 (32%) of the specimens by EIA. Of 126 culture-negative specimens, 21 (17%) were positive for RSV when determined by IFA. Conversely, 14 (15%) of 95 RSV culture-positive specimens were negative by IFA, whereas DFA missed 19% of the culture-positive specimens. Compared with culture, the Kallestad EIA kit had a sensitivity and specificity of 73 and 92% respectively, but missed 9 (27%) of 33 culture-positive specimens. These data demonstrate that isolation by culture continues to be important for viral diagnosis of REV infections and that for valid comparative studies between viral isolations and rapid detection methods, both sensitive host cells and appropriate test conditions are required.

Comparison of cell culture and three enzyme-linked immunosorbent assays for the rapid diagnosis of respiratory syncytial virus from nasopharyngeal aspirate and tracheal secretion specimens

A total of 211 specimens, including 144 nasopharyngeal aspirates and 67 tracheal secretions, were evaluated for the rapid detection of Respiratory Syncytial Virus (RSV) antigen by three commercial enzyme-linked immunosorbent assays (ELISA; Kallestad Diagnostic, Austin, TX; Ortho Diagnostics, Raritan, NJ, and Abbott Laboratories, North Chicago, IL) and by isolation of RSV in cell culture. Of the 61 RSV culture positive specimens, Kallestad ELISA, Ortho ELISA, and Abbott ELISA detected RSV antigen in 80%, 95%, and 92% of the specimens, respectively. An additional 28 specimens were found to be positive only by one or more RSV ELISA tests. A blocking assay confirmed the specificity of ELISA in 71% (20/28) of the RSV ELISA positive and the culture-negative specimens, and 29% were found to be false positive. Through the use of cell culture, with the resolution of ELISA positive and culture negative specimens by blocking assay, 81 specimens (61 + 20) were considered to be true positive. The sensitivity, specificity, and diagnostic accuracy were, for cell culture, 75%, 100%, and 91%; for Kallestad ELISA, 79%, 98%, and 91%; for Ortho ELISA, 95%, 99%, and 98%; and for Abbott ELISA, 93%, 96%, and 95% respectively. In our study, commercial ELISA tests have been shown to be rapid, reliable tests for the detection of RSV. Ortho ELISA and Abbott ELISA showed better sensitivity than the Kallestad ELISA for RSV detection directly in the clinical specimens.

Respiratory syncytial virus infection: a cause of respiratory distress syndrome and pneumonia in adults

Respiratory syncytial virus (RSV) infection, an important and sometimes lethal disease of infants and children, generally causes a milder and self-limited syndrome of cough, nasal congestion and fever in adults. While some evidence suggests that RSV may be responsible for more serious respiratory illness in the elderly and chronically ill, it has not been shown to cause life-threatening respiratory tract disease in previously healthy adults. This report describes a previously healthy woman who experienced the acute onset of right lower lobe pneumonia which rapidly progressed to the adult respiratory distress syndrome (ARDS). Acute and convalescent serology showed RSV was the cause of the respiratory tract illness. Michigan Department of Public Health records revealed six additional cases of adult bilateral pneumonia with diagnostic antibody titers to RSV, with or without coinfection with a second organism. These data suggest that RSV may be an under-recognized cause of lower respiratory tract disease in adults.

Comparison of three enzyme-linked immunosorbent assays and a direct fluorescent-antibody test for detection of respiratory syncytial virus antigen

We prospectively evaluated three enzyme immunoassays (EIAs) and a direct fluorescent-antibody (DFA) test for respiratory syncytial virus detection. Of 90 specimens, 79% gave the same results in all four tests (30 positive and 41 negative) and 97% were in agreement in three of the four assays. The agreement between the direct fluorescent-antibody test and each enzyme immunoassay was greater than or equal to 86%.

Detection, pathogenesis, and therapy of respiratory syncytial virus infections

Respiratory syncytial virus (RSV) infection is a major cause of serious lower respiratory disease in infancy and early childhood. The unique pathogenesis of lower respiratory illness due to RSV offers some intriguing clues to the role of the human immune system in both protection against and development of respiratory illness. More than any other virus, rapid diagnostic techniques have been especially successful in identifying RSV infection. Many of these techniques could be easily adaptable to diagnosis of influenza virus infection and other agents. Finally, ribavirin therapy of RSV infection represents one of the few instances in which antiviral therapy has been shown to be effective for respiratory illnesses. Fundamental observations in these areas in the case of RSV infection open up new and exciting pathways for investigation of respiratory infection due to other viral, chlamydial, and mycoplasmal agents.

The selection and performance of monoclonal and polyclonal anti-respiratory syncytial virus (RS) antibodies in capture ELISAs for antigen detection

Six monoclonal antibodies directed against fusion protein (F) or nucleoprotein (NP) of respiratory syncytial virus (RS) have been investigated in an antigen capture ELISA for virus detection. The potency, spectrum and pattern of reactivity were investigated with the intention of selecting antibodies reacting with RS-common antigen determinants and with complementary rather than competitive activity. Two anti-F protein antibodies satisfied these criteria and were used with enzyme amplified detection in a two site monoclonal assay (MCA/MCA) or as detectors with a polyclonal antibody as capture (PCA/MCA). Comparative studies were performed with immunofluorescence (FA) as the reference test and nasopharyngeal aspirates processed in different ways. The PCA/MCA assay was superior to that using monoclonal antibodies alone and gave results comparable to the reference method. However, the apparent sensitivity related to FA varied with the type of sample processing used. These results emphasise the need for a critical analysis of the factors which can influence the sensitivity of a particular assay system before judgements on relative sensitivity are made.

Comparison of nasopharyngeal aspirate and nasopharyngeal swab specimens for respiratory syncytial virus diagnosis by cell culture, indirect immunofluorescence assay, and enzyme-linked immunosorbent assay

Paired nasopharyngeal aspirate (NPA) and nasopharyngeal swab (NPS) specimens obtained from each of 32 hospitalized infants with X-ray-confirmed pneumonia (91%) or bronchiolitis were tested for respiratory syncytial virus (RSV) infection by virus culture, the indirect immunofluorescent-antibody (IFA) technique, enzyme-linked immunosorbent assay (ELISA; Ortho Diagnostic Systems, Inc.), and spot hybridization with a human genomic probe to quantitate cellular DNA. RSV was isolated in cell cultures from 72% (23 of 32) of patients by using NPA specimens compared with 47% (15 of 32) by using NPS specimens. With tissue culture positivity as the reference test, the sensitivities of the ELISA on NPA and NPS specimens were found to be 69% (16 of 23) and 61% (14 of 23), respectively, with a specificity and a positive predictive value from both sites of 100%. The sensitivities of the IFA technique compared with the cell culture on NPA and NPS specimens were 61% (14 of 23) and 52% (12 of 23) with specificities of 89 and 78% and positive predictive values of 96 and 92%, respectively. Despite the recovery of significantly more cells (as shown by detection of more cellular DNA by using NPA specimens), virus was detected by the IFA technique or ELISA at similar frequencies in paired specimens. However, virus was recovered more often from NPA than NPS specimens by cell culture, and ELISA optical density readings and the number of RSV-positive fluorescing cells were greater for NPA specimens. NPA specimen collection was less traumatic for the patient, was an easier procedure for the physician to perform, and provided a superior laboratory specimen for RSV diagnosis than the NPS technique.

Comparison of three rapid diagnostic techniques for detection of respiratory syncytial virus from nasal wash specimens

We report results of three rapid tests for respiratory syncytial virus antigen detection. An immunofluorescence assay using commercial antibody and two commercial enzyme immunoassays (Ortho Diagnostics, Inc., Raritan, N.J., and Abbott Laboratories, North Chicago, Ill.) were applied to 199 nasal wash specimens. The Abbott enzyme immunoassay was the most sensitive technique, with a sensitivity of 93.8%. The specificities of the three techniques were comparable and greater than 95%. The availability of reliable rapid diagnostic techniques will allow for better care of infants with severe respiratory syncytial virus infection.

Comparison of HEp-2 cell culture and Abbott respiratory syncytial virus enzyme immunoassay

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection in children. Rapid identification of RSV infections would allow for specific chemotherapy. We evaluated a means of rapid diagnosis, the Abbott enzyme immunoassay (EIA), by using 314 stored nasopharyngeal aspirates. RSV antigens were identified in 62 of 66 RSV culture-positive specimens. An additional 37 specimens from which RSV was not isolated were positive in the EIA. Of these, 29 were confirmed as truly positive by a blocking assay, for a total of 95 (66 + 29) positive specimens. The sensitivity of the EIA for total positive samples was 96% (91/95) versus 69% (66/95) for cell culture. The specificity of the EIA was 96% (211/219). In these stored specimens, Abbott EIA was superior to cell culture for the detection of RSV.

Comparison of two new tests for rapid diagnosis of respiratory syncytial virus infections by enzyme-linked immunosorbent assay and immunofluorescence techniques

The sensitivity and the specificity of two new commercial reagent tests, an indirect fluorescent antibody test (FAT) with a mouse monoclonal antibody (MAb) against respiratory syncytial virus (RSV) and an enzyme-linked immunosorbent assay (ELISA) RSV antigen detection kit, were determined by a comparison of results from these tests with those of tissue culture isolation and an indirect FAT with bovine polyclonal antibody (BPA). Of 251 nasal aspirates from infants with suspected RSV infection, positive results were found for 99 (39%) by the FAT-MAb, 93 (37%) by the FAT-BPA, and 87 (35%) by the ELISA; 69 of 240 (29%) were positive by cultures. The FAT-MAb was a more sensitive technique than cultures, with 87% sensitivity for the FAT-MAb and 84% for the ELISA. It was also more sensitive than the FAT-BPA, with 97% sensitivity for the FAT-MAb and 85% for the ELISA. This could be caused only by the distinctive volume of suspended specimens used in these tests. Of 171 negative culture specimens, positive (but not false-positive) results were found for 18% by the FAT-MAb and for 12% by the ELISA. Inversely, 13% of 69 culture positive specimens were FAT-MAb negative and 16% were ELISA negative, emphasizing the importance of tissue cultures for the maximum recovery of RSV, as well as for detection of other respiratory viruses. The FAT-MAb and ELISA were easy to perform and interpret, thus facilitating wider use.