Comparison of anticomplement immunofluorescence and fluorescent antibody-to-membrane antigen tests for determination of immunity status to varicella-zoster virus and for serodifferentiation of varicella-zoster and herpes simplex virus infections

Evaluation of a multiplex bead immunoassay for determination of immune status to varicella-zoster virus in medical center students and employees

This study evaluated an enzyme immunoassay, a multiplex bead immunoassay (MBIA), and the anticomplement immunofluorescence (ACIF) test for detecting varicella-zoster virus IgG antibodies in sera from medical center students and employees. The agreement between methods was ≥95%. The MBIA was less sensitive than was the ACIF test, with a negative predictive value of 66.7%.

Seroepidemiology of varicella-zoster virus in Korean adolescents and adults using fluorescent antibody to membrane antigen test

We conducted a cross-sectional seroepidemiological study in 2012–2013 to determine the seroprevalence of varicella-zoster virus (VZV) in adolescents and adults living in Korea, where varicella vaccination has been recommended universally at age 12–15 months since 2005. Residual serum samples were collected from 1196 healthy adults and adolescents aged ⩾10 years between November 2012 and March 2013. The fluorescent antibody to membrane antigen (FAMA) test and enzyme-linked immunosorbent assay (ELISA) were performed to determine the seroprevalence of VZV. The seroprevalences of VZV were compared between six age groups: 10–19, 20–29, 30–39, 40–49, 50–59, and ⩾60 years. The seroprevalence of VZV in the entire study cohort was 99·1% according to the FAMA test and 93·1% as determined by ELISA. The seroprevalences of the six age groups were as follows: 96·0%, 99·5%, 99·5%, 99·5%, 100%, and 100%, respectively, by the FAMA test, and 83·3%, 93·0%, 93·0%, 97·5%, 94·5%, and 97·5%, respectively, by ELISA. Seroprevalence increased significantly with age (P < 0·001); moreover, the seroprevalence in subjects aged 10–19 years was significantly lower than in other age groups (P < 0·001), as measured by both the FAMA test and ELISA. Thus, strategies to increase protective immunity against VZV in teenagers are necessary.

Comparison of indirect immunofluorescence and membrane fluorescence assays for the differentiation of antibodies to human immunodeficiency virus types 1 and 2

Serum samples from 20 human immunodeficiency virus type 1 (HIV-1)- and 30 HIV-2-infected and 7 dually infected individuals were reacted by using the indirect immunofluorescence assay (IFA) and membrane fluorescence assay in order to determine whether these methods were useful for typing HIV-1 and HIV-2 antibodies. Although 41 of 50 (82%) of the HIV-1- and HIV-2-positive specimens cross-reacted to some extent with the heterologous antigen in the IFA, the antigen with the higher titer correlated completely with the infecting type. The IFA could not distinguish single from dual infections, however. In contrast, only 4 of the 50 (8%) serum samples cross-reacted in the membrane fluorescence test. All seven of the specimens from patients with mixed infections reacted with both antigens. The membrane fluorescence test appears to be reliable for serodifferentiation of HIV-1 and HIV-2 infections and may be useful for laboratories with low-volume typing requirements.

Comparison of fluorescent-antibody-to-membrane-antigen test, indirect immunofluorescence assay, and a commercial enzyme-linked immunosorbent assay for determination of antibody to varicella-zoster virus

The demand for sensitive and specific assays to determine immune status to varicella can be expected to increase with the anticipated availability of a varicella-zoster virus vaccine for use in nonimmune adults, especially health care personnel, and in immunosuppressed children. Although the fluorescent-antibody-to-membrane-antigen (FAMA) test remains the reference standard to which other tests are compared, simpler alternative assays are needed. In this study, the FAMA was compared with a simple indirect immunofluorescence assay (IFA) and a commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of antibody to varicella-zoster virus. One hundred and twelve serum samples were screened by the FAMA test and IFA at a 1:5 dilution, and 100% agreement was found. Of these samples, 101 were available for testing by ELISA, and identical results were obtained with 97 samples (96% agreement). When the samples were screened at a 1:2 dilution, 99 of 101 results agreed. In addition, 31 spinal fluid samples were tested by all three methods. When screening was at a 1:2 dilution, there was 96.8% agreement between the FAMA test and IFA. When the cutoff value established for sera was used for the spinal fluid samples, there was 90.3% agreement between the ELISA and the FAMA test. Thus, both IFA and ELISA can be considered sensitive and specific alternatives to the FAMA test, and in addition, both use commercially available reagents.

Importance of anticomplement immunofluorescence antibody titration for diagnosing varicella-zoster virus infection in Bell's palsy

Anticomplement Immunofluorescence was used for antibody titration against varicella-zoster virus (VZV) in 43 patients with peripheral facial palsy. Nine of 31 patients (29%) with Bell's palsy and eight of 12 patients (75%) with Ramsey-Hunt syndrome had anticomplement immunofluorescence antibody titres of greater than or equal to 1/10. On the other hand, none of 14 patients with herpes simplex virus (HSV) infection and 51 healthy adults showed anticomplement immunofluorescence antibody titres of greater than or equal to 1/10. The anticomplement immunofluorescence antibody titre in two patients with Ramsey-Hunt syndrome increased later and decreased sooner than the indirect immunofluorescence antibody titre, becoming undetectable at 66 and 104 days, respectively, after onset of the disease. There was no cross reaction between anti-VZV and anti-HSV antibodies in the patients who showed a positive antibody rise for VZV. As the acute stage of VZV infection is obscure in the patients with peripheral facial palsy without herpes the screening of anticomplement immunofluorescence antibody to VZV at titres greater than or equal to 1/10 may be useful for the diagnosis of VZV infection in patients with peripheral facial palsy.

The potency determination of human varicella-zoster immunoglobulin by enzyme-linked immunosorbent assay, complement-fixation test and indirect fluorescent antibody tests

Traditionally, plasma for the production of the human varicella-zoster immunoglobulin (VZIG) has been selected on the basis of the complement-fixing antibody (CFA) titre. Since immune individuals may lack CFA to varicella-zoster virus (VZV), non-CFA may be of importance in protection. In a search for a simple and reliable method for potency determination, 24 VZIG preparations were quantified by enzyme-linked immunosorbent assay (ELISA), the complement-fixation test (CFT), the indirect fluorescent antibody test to acetone-fixed (IF) and viable (FAMA) VZV-infected cells, respectively. The antibody titres obtained by the various methods were compared. Arranged in order of decreasing agreement, the correlation coefficients (r) of the regression equations between the variables were 0.62 for CFT and FAMA, 0.50 for CFT and ELISA and 0.26 for CFT and IF in a log2 plot. There was complete agreement between the titres obtained by the commercially available Enzygnost Varicella/Zoster kits (Behring Institute, Marburg, F.R. Germany) and the ELISA microtitre plates produced at our institute (r = 1). The regression equation lines for ELISA/CFT and FAMA/CFT titres tended to be parallel to each other, while the line for IF/CFT titres had a less steep slope. Similar titration curves were obtained for VZIGs fractionated by two different methods. Furthermore, the titration curves of serum pools from varicella and zoster convalescents, respectively, had a similar shape below delta OD = 0.4. Generally, a steeper slope was observed above delta OD = 0.4. As antibody detectable by ELISA seems to correlate with protection and the method is sensitive, specific, reproduceable, simple to carry out and easily automated, it may be suitable for the potency determination of VZIGs.

Herpes zoster of the larynx after intubational trauma

Multiple or prolonged endotracheal intubations may result in laryngeal trauma. This case illustrates that recrudescence of latent varicella-zoster virus as herpes zoster of the larynx, with subsequent laryngeal paralysis, can complicate intubation. Consequently, physicians should strive to minimize laryngeal injury in this setting. It is advised that careful laryngeal examination follow extubation.

Class-specific antibody responses to early and late antigens of varicella and herpes simplex viruses

Antibody responses to early antigens of varicella-zoster virus (VZV), simian varicella virus, and herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) were studied in primary, secondary, and latent infections. IgG antibody responses to the early antigens occurred in primary and secondary VZV and HSV infections, and antibodies to early antigens were also demonstrable in healthy individuals with latent VZV and HSV infections, indicating that the presence of antibodies to early antigens cannot be taken as evidence of active infection with the viruses. Patients with current VZV or HSV infections showed heterotypic IgG antibody responses to early antigens of VZV and HSV to the same extent as to late antigens. In all groups of patients, IgG antibody titers to early antigens were similar to those against the corresponding late antigens, and no difference was seen in the reactivity of early antigens produced with four different blocking agents (cytosine arabinoside, bromodeoxyuridine, trisodium phosphonoformate, and cycloheximide). Antibodies of the IgM and IgA classes reacted with both early and late antigens of HSV, but only with late antigens of VZV and simian varicella virus, suggesting that these antibodies may be directed against late proteins that are expressed to a greater extent in HSV-infected cells treated with blocking agents than they are expressed in treated VZV-infected cells. Homologous IgM antibody responses occurred in both primary and secondary VZV infections, but only in primary HSV infections. Heterotypic IgM responses to HSV-2 antigen were noted in a few VZV patients who did not have demonstrable IgG antibody to HSV, suggesting that even in patients without prior experience with HSV, a VZV infection may stimulate the production of IgM antibodies that react with antigens that are shared by VZV and HSV-2. IgA antibodies to late antigens of VZV and HSV were demonstrable in latent, as well as active, infections with these viruses.

Rapid viral diagnosis

There has been much interest and activity in the development of techniques for rapid viral diagnosis which would allow successful intervention in the treatment of patients or their contacts or in the control of viral diseases in the community. The greatest emphasis has been on techniques that permit viral detection directly in the clinical specimen, since these avoid the need to cultivate the agent, are feasible for detection of viruses that cannot be cultivated, and can detect virus in specimens in which the agent is no longer infectious. Direct methods used for viral detection include electron microscopy and various immunoassays which are based on demonstrating reactivity of viral antigen in the specimen with known viral antisera. The use of immunoassays for more rapid identification of viruses isolated in laboratory host systems and for selective detection of viral antigen in inoculated cell cultures even before the agents produce an observable effect has been an important advance in viral diagnosis by the approach of isolation and identification. The reliability of all specific viral identification procedures depends on the use of high quality viral antisera. Some of the problems previously encountered in preparing satisfactory viral immune reagents are being overcome through the availability of highly specific monoclonal antibodies produced by cell hybridization techniques. Virus-specific IgM antibody assays for rapid diagnosis have been improved greatly through the use of a "capture" technique in which antibody to the human mu chain is used in the solid phase to separate IgM from other serum components which might compete with IgM antibody or give nonspecific reactivity, and also through the availability of highly specific monoclonal antibodies to the human mu chain. A variety of simple assays for determination of viral antibody status have been developed, and many are commercially available. The reliability of some of these antibody assays has been improved through the incorporation of more suitable controls and through better definition of interpretations which should be made from test results.

Evaluation of the anticomplement immunofluorescence test for detection of antibody to varicella-zoster virus

The anticomplement immunofluorescence (ACIF) test was compared with complement fixation and fluorescent antibody to membrane antigen procedures for the detection of antibody to varicella-zoster virus. All of 50 sera from pregnant women contained antibody measured by ACIF (titer, greater than or equal to 1:10); only 27 (54%) were positive by complement fixation (P less than 0.01). For 16 paired sera obtained before and after varicella-zoster virus infection and tested by ACIF and fluorescent antibody to membrane antigen, the result agreed in 27 determinations (sensitivity, 94%; specificity, 81%). Of 99 sera submitted for routine determinations of immune status to the virus, 89 showed comparable results for both tests (sensitivity, 92.5%; specificity, 88%). The ACIF test offers a specific and sensitive alternative to the fluorescent antibody to membrane antigen procedure for the detection of antibody to varicella-zoster virus. In addition, the ACIF test is rapid, easy to perform, and uses commercially available reagents.