Comparison of a lateral-flow immunochromatography assay with real-time reverse transcription-PCR for detection of human metapneumovirus

Comparison of sputum specimens and nasopharyngeal swab specimens for diagnosis of acute human metapneumovirus-related lower respiratory tract infections in adults

BACKGROUND

To detect human metapneumovirus, tests besides reverse transcription-polymerase chain reaction (RT-PCR) on nasopharyngeal swab specimens are less accessible. Immunochromatography assays are rapid and simple without the need of any special equipment but sometimes are insufficiently sensitive. This study describes the usefulness of immunochromatography assays to detect human metapneumovirus in adult patients with human metapneumovirus-related acute lower respiratory tract infection using sputum specimens.

METHODS

This prospective single-center study enrolled adults and adolescents aged ≥16 years with signs and symptoms of an acute respiratory illness who were diagnosed with acute lower respiratory tract infection. The presence of human metapneumovirus infection was confirmed by seroconversion. Immunochromatography assays and real-time RT-PCR were performed to compare the efficacy of nasopharyngeal swab specimens and sputum specimens. Comparative results were obtained via McNemar's test.

RESULTS

Overall, 337 patients were recruited in this study; 63 (18.7%) patients were seroconverted. Sputum specimens showed significantly higher positivity rates than nasopharyngeal swab specimens with both immunochromatography assays (p = 0.0008) and real-time RT-PCR (p = 0.014). Among 29 patients with pneumonia who had concordant positive real-time RT-PCR results for both nasopharyngeal swab specimens and sputum specimens, 21 (72.4%) had a higher viral load in the sputum specimens.

CONCLUSIONS

Sputum specimens are more useful in detecting human metapneumovirus than nasopharyngeal swab specimens in adult patients with acute lower respiratory tract infection.

Human metapneumovirus-associated community-acquired pneumonia in adults during the first wave of COVID-19

Objective: The clinical course of human metapneumovirus (hMPV) infection is similar to that of coronavirus 2019 disease (COVID-19). However, community-acquired hMPV infections in adults have not yet been sufficiently investigated. We examined the detection status of hMPV antigens and the clinical features of positive patients during the first wave of COVID-19, which coincided with the epidemic season of hMPV infection in Japan.

Methods: In this cross-sectional, observational, and single-center study, we recruited consecutive individuals who visited the Japan Agricultural Cooperatives Kochi Hospital due to fever, respiratory symptoms, or close contact with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected persons during the period from January to May 2020.

Results: The positive rate of immunochromatography for hMPV antigens from nasopharyngeal swabs was 9.5% (4/42), and four positive cases were community-acquired pneumonia (CAP) (5.3% of all CAP). The positive rate of hMPV antigens in the CAP group (30.8%, 4/13) was higher than that in the non-pneumonia group (0.0%, 0/19) (p < 0.05). The average age of the four adult patients with CAP was 69.8 years (range 35–93). Mean white blood cell counts and C-reactive protein blood levels were 6,250 cells/μL (3,500–12,180) and 4.30 mg/dL (4.05–7.04), respectively. Chest computed tomography images were diverse and two patients showed dense consolidation. No multi-organ disorder was noted during the clinical course in any of the four cases, and their prognoses were good.

Conclusion: hMPV infection may be considered in the differential diagnosis of COVID-19 and CAP in Japan under the preventive measures for SARS-CoV-2 infection, at least during the epidemic season of hMPV infection.

Unraveling Gardnerella vaginalis Surface Proteins Using Cell Shaving Proteomics

Gardnerella vaginalis is one of the main etiologic agents of bacterial vaginosis (BV). This infection is responsible for a wide range of public health costs and is associated with several adverse outcomes during pregnancy. Improving our understanding of G. vaginalis protein cell surface will assist in BV diagnosis. This study represents the first proteomic approach that has analyzed the exposed proteins on G. vaginalis cell surface using a shaving approach. The 261 G. vaginalis proteins identified using this approach were analyzed with bioinformatic tools to detect characteristic motifs from surface-exposed proteins, such as signal peptides (36 proteins), lipobox domains (17 proteins), LPXTG motifs (5 proteins) and transmembrane alpha-helices (66 proteins). One third of the identified proteins were found to have at least one typical motif of surface-exposed proteins. Furthermore, the subcellular location was examined using two predictors (PSORT and Gpos-mPLoc). These bioinformatic tools classified 17% of the identified proteins as surface-associated proteins. Interestingly, we identified 13 members of the ATP-binding cassette (ABC) superfamily, which were mainly involved in the translocation of various substrates across membranes. To validate the location of the G. vaginalis surface-exposed proteins, an immunofluorescence assay with antibodies against Escherichia coli GroEL was performed to reveal the extracellular location of the moonlighting GroEL. In addition, monoclonal antibodies (mAb) against G. vaginalis Cna protein were produced and used to validate the location of Cna on the surface of the G. vaginalis. These high affinity anti-Cna mAb represent a useful tool for the study of this pathogenic microorganism and the BV.

Rapid detection of Bacillus anthracis by γ phage amplification and lateral flow immunochromatography

New, rapid point-of-need diagnostic methods for Bacillus anthracis detection can enhance civil and military responses to accidental or deliberate dispersal of anthrax as a biological weapon. Current laboratory-based methods for clinical identification of B. anthracis require 12 to 120h, and are confirmed by plaque assay using the well-characterized γ typing phage, which requires an additional minimum of 24h for bacterial culture. To reduce testing time, the natural specificity of γ phage amplification was investigated in combination with lateral flow immunochromatography (LFI) for rapid, point-of-need B. anthracis detection. Phage-based LFI detection of B. anthracis Sterne was validated over a range of bacterial and phage concentrations with optimal detection achieved in as little as 2h from the onset of amplification with a threshold sensitivity of 2.5×10(4)cfu/mL. The novel use of γ phage amplification detected with a simple, inexpensive LFI assay provides a rapid, sensitive, highly accurate, and field-deployable method for diagnostic ID of B. anthracis in a fraction of the time required by conventional techniques, and without the need for extensive laboratory culture.

Diagnosis of human metapneumovirus in patients hospitalized with acute lower respiratory tract infection using a metal-enhanced fluorescence technique

Human metapneumovirus (hMPV) is a common respiratory tract infection in children. However, conventional immunofluorescence assays (IFAs) for detecting hMPV in respiratory samples have limited reliability with a sensitivity and false-negative predictive value of 58.1% and approximately 17.8%, respectively. In this study, hMPV was measured in 91 clinical respiratory samples (55 sputum and 36 nasopharyngeal aspirate samples), which were obtained from children under three years of age, utilizing our previously developed high-throughput metal-enhanced fluorescence (MEF)-based biosensor (HT-MEFB). The sensitivity of HT-MEFB for hMPV detection in the 91 samples was improved by up to 77.4% compared with that obtained with IFAs, and the specificity of HT-MEFB for hMPV detection was 91.7%. In addition, the specificity and accuracy obtained after the selection of 55 sputum samples as the analyzed specimen reached 92.3% and 90.9%, respectively. Thus, in terms of accuracy, high throughput, and sensitivity, HT-MEFB exhibits considerable potential for hMPV detection in clinical settings.

Performance of a rapid multi-analyte 2-photon excitation assay in children with acute respiratory infection

The purpose of this study is to evaluate the diagnostic performance of the novel 2-photon excitation-based mariPOC© Assay (ArcDia Laboratories, Turku, Finland) for antigen detection of respiratory viruses versus real-time polymerase chain reaction (PCR). The mariPOC Assay and 2 multiplex real-time PCR techniques were performed on nasopharyngeal samples from pediatric patients with suspicion of acute respiratory infection admitted to a children's hospital in Spain during October 2011 to January 2013. A total of 233 samples were studied. Sensitivities and specificities (95% confidence interval) of the mariPOC Assay were for respiratory syncytial virus (RSV), 78.4% (69.7-85.6) and 99.2% (96.3-100.0); influenza virus (IFV) A, 66.7% (26.2-94.0) and 99.6% (97.9-100.0); IFV-B, 63.6% (33.6-87.2) and 100.0% (98.7-100.0); human metapneumovirus (hMPV), 60.0% (34.5-81.9) and 100.0% (98.6-100.0); adenovirus (ADV), 12.5% (0.6-48.0) and 100.0% (98.7-100.0), respectively. The mariPOC Assay is a highly specific method for simultaneous detection of 8 respiratory viruses but has sensitivities that range from moderately high for RSV to moderate for IFV and hMPV and low for ADV.

Evaluation of a new rapid antigen test using immunochromatography for detection of human metapneumovirus in comparison with real-time PCR assay

A new rapid human metapneumovirus (hMPV) detection kit using immunochromatography (SAS hMPV test) was compared to real-time PCR for 224 nasal swab specimens, 96.4% of which were obtained from children of <15 years of age. The overall sensitivity and specificity were 82.3% and 93.8%, respectively, suggesting that this test is useful for pediatricians to diagnose hMPV infection in a clinical setting.

Establishing a surveillance network for severe lower respiratory tract infections in Korean infants and young children

To reduce morbidity and mortality through integrated case management, a pilot study to detect respiratory viruses in patients with acute lower respiratory infections (ALRIs) was designed as part of a nationwide surveillance for this disease in Korea. The study population consisted of hospitalized patients under the age of 5 years with bronchiolitis, pneumonia, croup, or acute respiratory distress syndrome. A prospective 6-month study was performed. Two hundred and ninety-seven nasopharyngeal secretions were collected and multiplex reverse transcriptase polymerase chain reactions (RT-PCR)/polymerase chain reactions (PCR) were performed to detect respiratory viruses. If there were any positive RT-PCR/PCR results, viral cultures were proceeded for confirmation. Respiratory viruses were identified in 49.6% of 296 patients. The detection rates were as follows: respiratory syncytial virus (RSV) was the most commonly detected in 52.7% (87/165), human metapneumovirus (hMPV) in 15.8%, human corona virus (hCoV) in 5.5%, adenovirus in 9.7%, human bocavirus (hBoV) in 5.5%, parainfluenza virus (PIV) in 3.6%, rhinovirus (RV) in 4.2%, and the influenza virus in 3% of the patients with ALRIs. The consistent rate of positive results between RT-PCR and viral culture was 92% (105/114). Using our methods to detect viral causes seemed to be acceptable for the national surveillance of severe acute respiratory infections in infants and children.