Neutralization enzyme immunoassay for influenza virus

Abstract

A neutralization enzyme immunoassay (N-EIA) was developed for the detection of antibody titer rises in sera of patients infected with influenza A (H3N2) virus. In this N-EIA, a selected strain of influenza A (H3N2) virus was added to monolayers of LLC-MK2 cells in microtiter plates. After 24 h, the replicated virus could be demonstrated with a virus-specific enzyme-labeled monoclonal antibody. Preincubation of the influenza virus with convalescent-phase sera of patients infected with influenza A (H3N2) virus resulted 1 day later in decreased absorbance values that could be used for calculation of neutralization titers. From use of paired serum samples from 10 patients with a history of flu-like symptoms, the results obtained with N-EIA correlated well (r = 0.83) with those of the standard hemagglutination inhibition test.

Monocytes, but not T or B cells, are the principal target cells for dengue virus (DV) infection among human peripheral blood mononuclear cells

“…Results of staining were analyzed using a flow cytometer (FACS) and the CellQuest software. The percentage of inhibition of viral replication or plaque reduction was calculated based on published methods with modifications Benne et al, 1994;Martin et al, 2006]. Specifically, serum positive for dengue neutralization activity was defined as having more than 50% viral inhibition in the above described FACS-based assay.…”

Pulmonary surfactant protein A binds to Cryptococcus neoformans without promoting phagocytosis

“…The influenza A/DELFT/2696/89 (H3N2) virus strain was kindly provided by Dr J. C. de Jong (Research Laboratory for Infectious Diseases, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands). The virus was grown on the LLC monkey kidney (MK2D) cell line (LLC cells) obtained from ICN International (Irvine, UK) as described previously by Benne et al [22]. The virus preparation contained 8·6 × 10 7 plaque-forming units per mL as determined using the immunoplaque assay described by Harder et al [23] For labelling purposes, 1 mL of influenza virus was mixed with 0·1 mL of 1 mol L -1 sodium carbonate buffer (pH 9·6) containing 1 mg of FITC mL -1 (Isomer I; Sigma) and incubated for 1 h at room temperature.…”

Comparison of Neutralizing and Hemagglutination-Inhibiting Antibody Responses to Influenza A Virus Vaccination of Human Immunodeficiency Virus-Infected Individuals

“…The N-EIA was performed with the influenza virus strains Taiwan H1N1 and Beijing H3N2. Apart from the extra disinfection of the microtiter plates, the N-EIA was performed with the same reagents and by the same procedures described previously (4). In brief, the serum samples were heat inactivated at 56°C for 1 h and diluted 1/3, 1/10, 1/30, 1/100, 1/300, 1/1,000, and 1/3,000.…”