Comparison of the Raji cell line fluorescent antibody to membrane antigen test and the enzyme-linked immunosorbent assay for determination of immunity to varicella-zoster virus.

A prospective study was performed comparing the fluorescent antibody to membrane antigen (FAMA) test and the enzyme-linked immunosorbent assay (ELISA) for identifying susceptibility and seroconversion to varicella-zoster virus (VZV) infection. A total of 75 sera were collected from index cases and from sibling and parent contacts in 10 families. Varicella-zoster virus-infected human diploid embryonic fibroblasts and continuous lymphoblastoid cells (Raji cells) were compared as indicator cells in the FAMA test. Equivalent results were obtained with both types of cell. Results of the FAMA test and the ELISA were identical in two ways. (i) The same 11 individuals were initally defined as susceptible (seronegative), and 9 of them (82%) developed fourfold rises in antibody titers, clinical varicella, or both. (ii) Of 21 immune (seropositive) individuals, 4 developed fourfold antibody rises by FAMA tests, and 3 of these 4 responded by ELISA. Infection was asymptomatic in these individuals. The geometric mean titer by ELISA was significantly higher than by the FAMA test. The results indicated that the ELISA and the FAMA test have similar capacities to define susceptibility to varicella-zoster virus and that subclinical infection with varicella-zoster virus may be common.

Persistent Varicella-Zoster virus infection in a human rhabdomyosarcoma cell line and recovery of a plaque variant.

Varicella-zoster virus (VZV) has been found to persistently infect the human rhabdomyosarcoma cell line A204. Infectious center assays and fluorescent antibody staining demonstrated continuous production of infectious VZV and viral antigen. The level of infection determined by fluorescent antibody staining was variable, and usually only a small percentage of the cells were capable of producing plaques in permissive fibroblasts. The extent of infection was similar in cell cultures passaged at split ratios of 1:2 or 1:10 and grown at 33 or 37 degrees C. VZV recovered from A204 cells several months after establishment of the persistent infection had markedly increased syncytia-forming activity as compared with the parental VZV grown in human diploid fibroblast cells and the three monkey kidney-derived cell lines Vero, CV-1, and MA104. The expression of this altered phenotype continued after serial passage of the cell-associated virus in human diploid fibroblast and Vero cells. Consequently, we designated the reisolated VZV as plaque variant A. The buoyant densities of VZV plaque variant A and VZV DNAs in CsCl gradients were indistinguishable.

Coronavirus antibodies in sera from patients with multiple sclerosis and matched controls.

Sera from patients with multiple sclerosis and carefully matched controls were tested for antibodies to three strains of coronavirus. There was no significant difference in the levels of antibody in the patients vs the controls. We conclude that unless the strains of coronaviruses recently reported to have been isolated from patients with multiple sclerosis express important serological differences from those used in these studies, coronaviruses are not associated with the cause of multiple sclerosis.

Evaluation of commercially available diagnostic test kits for rubella.

Three standard hemagglutination-inhibition (HAI) methods were compared with 11 commercially available diagnostic test kits for determination of immunity and serologic diagnosis of rubella using a panel of 100 sera. The three standard HAI methods involved removal of serum inhibitors with kaolin, heparin-MnCl2, or dextran sulfate-CaCl2. The HAI kaolin (Flow Laboratories, McLean, Virginia) and Rubelisa (Microbiological Associates Bioproducts, Walkersville, Maryland) kits gave the best specificity as judged by the absence of false-positive results. Rubacell (Abbott Laboratories, Chicago, Illinois), Rubindex (Ortho Diagnostics, Raritan, New Jersey), Fiax (International Diagnostic Technology, Santa Clara, California), and Rubesure (Calbiochem-Behring, La Jolla, California) gave the best sensitivity as judged by the absence of false-negative results. The kits with the highest degree of both specificity and sensitivity were HAI kaolin (Flow), HAI heparin-MnCl2 (Flow), Rubacell (Abbott), and Rubindex (Ortho). In paired sera from five patients with clinical rubella, seroconversions were shown by seven of the kits. One of the kits, Cordia R (Cordis Laboratories, Miami, Florida), showed no significant rise in antibody titer with one pair of sera. Antibody titers in the same serum varied widely between the different kits.

Measles and canine distemper antibody. Presence in sera from patients with multiple sclerosis and matched control subjects.

Antibody to measles virus and canine distemper virus (CDV) was demonstrated in sera from patients with multiple sclerosis (MS) and from carefully matched control subjects. Elevated measles and CDV antibody titers were found in patients with MS when compared with the matched control subjects. The correlation between the measles and CDV antibody titers was quite high, suggesting that the antibody levels between the two viruses are very closely related. Based on the results of our study and a review of the literature, our conclusion is that the CDV antibody levels in patients with MS and matched control subjects are associated with occurrence of measles virus antibodies.

Antigenic relationship of two strains of simian hemorrhagic fever virus.

Serological comparison of the prototype and an epizootic (Corbell) strain of simian hemorrhagic fever virus revealed that the two viruses were serologically similar. The prototype strain differs from the Corbell strain in that the latter cannot be cultivated in vitro. Serological comparison of the prototype virus grown in tissue culture and its homologous antibody and the prototype and Corbell viruses recovered from rhesus monkey serum and their homologous antibodies showed differences and suggest that a complex relationship exists which has not yet been defined.

Multiple sclerosis: cellular and humoral immune responses to several viruses.

One hundred and eight multiple sclerosis (MS) patients and 108 matched controls were studied for antibody levels and cellular immune responses to several viruses. There were significant increases in the mean titers of complement fixation (CF) or hemagglutination inhibition (HI), and complement-mediated cytotoxicity (CMC) tests for measles antibodies in MS patients; there was no increase in antibody titers to herpesviruses 1 and 2, or cytomegalovirus (CMV). The direct migration inhibition (DMI) tests showed no difference between MS patients and controls for measles, CMV, herpesviruses 1 and 2, or vaccinia virus antigens. Lymphocyte-mediated cytotoxicity (LMC) tests showed no difference between patients and controls, using cultures infected with measles and CMV viruses. In a study of stimulation or blocking of the LMC response by serum or cerebrospinal fluid (CSF), no effect was found. Therefore, increased levels of measles antibody in serum were again demonstrated in MS patients, but there was no difference in these patients' cellular immunity to measles virus versus that of the controls, and there was no abnormality of cellular immunity against the other viruses tested.

Comparison of the enzyme-linked immunosorbent assay and the indirect hemagglutination test for detection of antibody to cytomegalovirus.

Thirty samples of serum were tested for antibody to cytomegalovirus by enzyme-linked immunosorbent assay (ELISA) and indirect hemagglutination (IHA). The two tests were in extremely close agreement. Of the 30 sera evaluated by ELISA, 16 were considered to be positive and 14 were considered negative. In all 16 positive samples, the titers by ELISA were at least twofold to 10-fold higher than the indirect hemagglutination titers. Two of the 14 sera evaluated as negative by the ELISA test had low indirect hemagglutination titers (1:8 and 1:4). They were not detectable at the initial dilution (1:50) of the ELISA test. These two sera might have been classified as positive if the initial dilution in ELISA had been lower than 1:50.