Identification of influenza A virus by shell vial culture and two commercially available antigen detection methods

BACKGROUND

Effective use of amantidine and rimantidine for treating patients and for reducing transmission requires rapid diagnosis of influenza A. Rapid culture methods require 1-2 days to detect influenza A virus. Direct fluorescent antibody (DFA) staining and enzyme immunoassay (EIA) can detect influenza A antigen within 1-4 h.

OBJECTIVES

We compared DFA staining using the Bartels viral respiratory panel and the Directigen FLU-A EIA with shell vial centrifugation culture.

STUDY DESIGN

Ninety-seven fresh specimens from a variety of respiratory sources and transported from hospitals throughout the USA to our national referral laboratory were tested. A true positive was defined as culture positive or both antigen tests positive.

RESULTS

Fifteen specimens were true positive. Sensitivity with culture was 93%, EIA 67%, and DFA 47%. Specificity was excellent with all three methods: 100%, 98%, 99%. Culture detected additional viruses that can cause respiratory tract disease: herpes simplex, cytomegalovirus, respiratory syncytial, influenza B, and adenovirus. Fourteen (70%) of 20 frozen specimens previously positive for influenza A were positive on retest by EIA. Overall sensitivity of EIA compared with culture using 35 positive specimens was 69%.

CONCLUSIONS

These results suggest that the rapid EIA is useful to screen for influenza A, but that critical antigen-negative specimens should be submitted to a virology laboratory for culture for optimal sensitivity and for recovery of other viruses.

Identification of influenza A virus by shell vial culture and two commercially available antigen detection methods

BACKGROUND

Influenza continues to be a major cause of morbidity and mortality especially in the elderly and persons with underlying disease. Shell vial cell culture and antigen detection techniques may speed up diagnosis and enable better patient treatment and management.

OBJECTIVES

To compare shell vial centrifugation culture with commercially available direct fluorescence and enzyme immunoassay kits using a variety of respiratory specimens.

STUDY DESIGN

To detect influenza A virus, we compared direct fluorescent antibody (DFA) staining using the Bartels Viral Respiratory Panel and the Directigen FLU-A enzyme immunoassay (EIA) with shell vial centrifugation culture. Ninety-seven fresh specimens from a variety of respiratory sources, and transported from hospitals throughout the U.S. to our national referral laboratory, were tested.

RESULTS

Fifteen specimens were true positives: culture positive or both antigen tests positive. Sensitivity with culture was 93%, EIA 67%, and DFA 47%. Specificity was excellent with all three methods: 100%, 98%, 99%. Culture detected additional viruses that can cause respiratory tract disease: herpes simplex, cytomegalovirus, respiratory syncytial, influenza B, and adenovirus. Fourteen (70%) of 20 frozen specimens previously positive for influenza A were positive on retest by EIA. Overall sensitivity of EIA compared with culture using 35 positive specimens was 69%.

CONCLUSIONS

The rapid EIA is useful to screen for influenza A, but critical antigen-negative specimens should be submitted to a virology laboratory for culture. Shell vial cultures can provide a sensitive and universal diagnostic system for influenza A and a variety of other viruses.

Rhabdomyosarcoma cell line can be used for the isolation of soluble acetylcholine receptor and for assaying blocking and modulating autoantibodies

We found that the Rhabdomyosarcoma (RD) cell line expresses human acetylcholine receptor (AChR) based on the following evidences: 1. Soluble AChR can be isolated from RD cells following the isolation procedure for AChR from human muscle; 2. Intact RD cells bind to alpha-bungarotoxin (alpha Butx) in a time-dependent and saturable fashion. The apparent dissociation constant (5.3 x 10(-10) M) is very similar to that reported for TE671 cells, which is known to express AChR; 3. Like fresh muscle culture, RD cells not only bind but also internalize 125I-alpha Butx. Soluble AChR from RD cells can be labeled specifically with 125I-alpha Butx and then used to quantify binding autoantibodies in myasthenic patients. We also demonstrate that blocking antibodies can be detected in sera from patients with myasthenia gravis (MG) using RD cells and the ability of RD cells to internalize alpha Butx. Consequently, RD cells can be used as a reliable source for obtaining soluble AChR and as a replacement for rodent or human muscle cultures in measuring blocking and modulating antibodies.

Cross contamination of viral specimens related to shell vial caps

A cluster of poliovirus type 3-positive specimens cultured in shell vials led to the discovery of significant cross contamination between vials related to the type of vial cap. Simulated testing with colored media in the shell vials indicated that the most contamination occurred with the plastic snap cap and that the least occurred with the screw cap. Measures to prevent cross contamination in clinical virology laboratories are discussed.

Simultaneous cytomegalovirus and herpes simplex virus pneumonia

A 35-year-old patient who underwent renal transplant developed persistent fever, hypoxemia, and diffuse interstitial pulmonary infiltrates one month after allograft implantation. An open lung biopsy specimen demonstrated simultaneous infection with cytomegalovirus and herpes simplex virus type 1. This initially was unsuspected on routine histology, but was confirmed by the demonstration of both viruses with immunofluorescence, as well as the timely recovery in culture of both. The clinical and pathologic implications of an accurate diagnosis of such a simultaneous infection are discussed.

Rapid detection of herpes simplex virus in clinical specimens by centrifugation and immunoperoxidase staining

The effect of immunoperoxidase staining and centrifugation on the sensitivity and rapidity of herpes simplex virus detection in mink lung cell cultures was determined with 730 clinical specimens. In standard tube cultures, the use of immunoperoxidase staining resulted in detection of 31 (91%) of 34 positive cultures after overnight incubation, compared with 25 (74%) detected without the stain (P less than 0.05). The effect of centrifugation of specimens onto the monolayer followed by overnight incubation and immunoperoxidase staining was studied with 431 specimens. Of 107 positive specimens, 103 (96%) were detected by this method, compared with 91 (85%) detected in standard cell cultures observed for 5 days (P less than 0.02). Standard cell cultures that were examined after overnight incubation detected only 62 (58%) of the 107 positive specimens (P less than 0.001). Centrifugation of clinical specimens onto cell monolayers followed by overnight incubation and immunoperoxidase staining is more rapid and sensitive than are standard cell culture techniques for the laboratory diagnosis of herpes simplex virus infection.

More rapid isolation of herpes simplex virus in a continuous line of mink lung cells than in Vero or human fibroblast cells

Herpes simplex virus (HSV) was isolated from clinical specimens more rapidly in mink lung (ML) cells, a continuous cell line available from a commercial supplier, than in Vero cells or human fibroblast (HF) cells. Stock strains of HSV type 1 (HSV-1) and HSV-2 titered higher in ML cells than in Vero or HF cells. ML cells were equivalent to rabbit kidney (RK) cells in the isolation of HSV in clinical specimens, but titers of stock HSV strains were lower. ML cells could be employed to type strains of HSV-1 and HSV-2, using the technique of differential susceptibility to bromovinyldeoxyuridine (BVDU). ML cells, therefore, are a convenient and useful cell line for the isolation and typing of HSV in diagnostic virology laboratories.

Comparison of cell culture with an immunoperoxidase kit for rapid diagnosis of herpes simplex virus infections

Cell culture technique using continuous mink lung cells was compared to an immunoperoxidase kit for rapidity and sensitivity of herpes simplex virus (HSV) detection. Forty-eight hours after inoculation, 26 (65%) of 40 clinical specimens were positive for HSV by cell culture compared with 19 (48%) by immunoperoxidase staining (p less than 0.001, Fisher's Exact Test).

Epstein-Barr virus infection and antibody synthesis in patients with multiple sclerosis

We studied infectious and immune mechanisms in demyelinating disease. The clinical diagnosis in this study of 313 consecutive cases of multiple sclerosis (MS) was based on the clinical conclusions of two or more neurologists and definite abnormalities in CSF IgG. Measurement of antibodies to six microbial agents was compared in 313 patients with MS and 406 controls in the same age range. Using a standardized immunofluorescent antibody (IFA) technique, we found a significantly higher prevalence of Epstein-Barr virus (EBV) infection and a higher level of serum viral capsid antigen IgG antibody titer in the MS population than in the controls. The MS population had a lower cytomegalovirus (CMV) infection rate and lower CMV complement fixing antibody production than controls. Except for the higher measles infection rate and antibody titer in patients with MS, data on the other viruses did not differ from controls.