Nathalie J. Schmidt

A Complement-Fixing Antigen for Varicella-Zoster Derived from Infected Cultures of Human Fetal Diploid Cells.

Summary A procedure is described for preparation of complement-fixing antigens for the varicella-zoster (V-Z) virus in human fetal diploid skin and muscle cell strains. These cells are highly susceptible to the cytopathic effect of the V-Z virus, and can be maintained without a fluid change for the entire period required by the virus to produce complete cellular degeneration. Most of the specific antigen elaborated in the cultures was found to be cell-associated, and relatively high-titered antigens (1:32 and 1:64) were prepared by 50-fold concentration of the cellular phase of infected cultures. Antigens were usually free from anticomplementary activity, but when they were not, the activity could be abolished by treatment with inactivated guinea pig complement.

Demonstration of Rubella IgM Antibody by Indirect Fluorescent Antibody Staining, Sucrose Density Gradient Centrifugation and Mercaptoethanol Reduction

Three methods were compared for sensitivity and specificity in detecting rubella IgM antibody in early sera from post-natal infections and in sera from congenital infections. treatment pro-Mercaptoeth

The Complement-Fixing Antigen of Rubella Virus.

Summary A complement-fixing antigen for rubella virus has been produced by concentration of infected RK-13 cell culture fluids 100-fold by dialysis against polyethylene glycol. The antigen was shown to be separable from the intact viral particle by centrifugation (soluble antigen), and could be rendered non-infectious by ether treatment without undergoing a change in specific reactivity. The complement fixation test was found to be comparable to the neutralization test for detecting significant increases in antibody level in rubella virus infections. Individuals showing significant rises in antibody titer to myxo-virus antigens or Mycoplasma pneumoniae did not show antibody rises with the rubella complement-fixing antigen.

Hemagglutination and Hemagglutination-Inhibition with Adenovirus Type 12.

Summary Hemagglutmation has been demonstrated with the prototype Huie strain and two nonprototype strains of adenovirus type 12. This viral type resembles those classified in Group 3 in that hemagglutination occurred with rat cells in the presence of hetero-typic immune serum. Hemagglutination was specifically inhibited by immune serum to adenovirus type 12, but not immune serum to other adenoviruses. The identity of the hemagglutinating virus as adenovirus type 12 was confirmed by both hemagglutination–inhibition and neutralization tests with reference immune sera prepared in other laboratories.

Observations on Antigenic Variants of Echovirus Type 11.

Summary Strains of echovirus type 11 isolated in this laboratory since 1962 appear to have a broader antigenic spectrum than the prototype Gregory strain. The isolates were neutralized to low titer or not at all by immune serum to the Gregory strain, but immune serum to a representative isolate (Silva) neutralized both the prototype and homologous strains, as well as the other isolates. Results of cross hemagglutination inhibition and complement fixation tests, as well as im-munodiffusion tests, confirmed the relationship of these isolates to echovirus type 11. Sera of patients from whom the antigenic variants were recovered showed significant neutralizing antibody responses to both the prototype echovirus type 11 strain and the Silva “prime” strain.

Immunologic identification of Coxsackie A21 virus with Coe virus.

Summary Cross neutralization tests in HeLa cell cultures, using both the monolayer and metabolic-inhibition technics, show the Coe virus, etiologically associated with respiratory disease, to be immunologically indistinguishable from the recently-described Cox-sackie group A, type 21, virus.

Tissue Culture in the Laboratory Diagnosis of Viral Infections

Abstract The use of both rhesus monkey kidney and human fetal diploid cell cultures for attempts to isolate virus from human clinical specimens recovered approximately 30% more isolates from fecal, throat, skin lesion, and tissue specimens than were recovered in a single cell culture system. The sensitivities of the two cell types for isolation of viruses in the major groups infecting man are compared. The use of both BS-C-1 and RK-13 cells yielded approximately 25% more rubella virus isolates than were recovered in a single cell system. Procedures such as the establishment of cell cultures from tissues suspected of harboring viruses, cocultivation of cells from biopsy or autopsy specimens with other cell types, and the use of organ cultures, have in certain situations resulted in greater sensitivity for recovery of viruses. Micro cell culture tests have been devised for virus identification and antibody assays; these are far more economical than conventional tests in terms of reagents, space requirements, and personnel time. Methods have been developed for the production of higher-titered viral serologic antigens in cell culture systems.

Microneutralization Test for the Reoviruses. Application to Detection And Assay of Antibodies in Sera of Laboratory Animals.

Summary The problem of determining the specificity of hemagglutination-inhibiting activity for reovirus type 3 seen in mouse, hamster and rat sera examined as part of a mu-rine virus monitoring program, together with the need for a sensitive and efficient technic for detection of reovirus antibodies in the sera of other laboratory animals, led to the development of a microneutralization technic. The test, conducted in a HeLa cell system in disposable microplates, is a modified metabolic inhibition procedure which permits reading of results colorimetrically. The results obtained in microneutralization tests showed good correlation with those obtained in conventional neutralization tests conducted in tube cultures of monkey kidney cells. The technic was found to be suitable for detection of antibodies to all 3 reovirus types in sera of a variety of species, and it is particularly useful for monitoring rodent colonies for reovirus type 3 infections. HI tests appeared to possess less specificity than neutralization tests for demonstration of reovirus antibodies in animal sera.

Carrier cultures of human fetal diploid cells infected with coxsackievirus type B2

Carrier cultures of coxsackievirus type B2, strain V1-013 were established without the use of “normal” human serum or serum containing viral antibodies, and without frequent changes of medium. Blind passage of virus strain V1-013 in human fetal diploid (HFD) cell cultures on maintenance medium resulted in viral multiplication without apparent CPE. In addition, human fetal diploid cultures infected with the V1-013 virus strain could be subcultivated for over 20 transfers, and infectious virus and antigen demonstrable by immunofluorescent staining were present at each passage level; again, viral multiplication occurred without apparent CPE. Sustained infections were not observed when HFD cells were inoculated with two other (Ohio and Lincoln) B2 coxsackievirus strains; however, the life-span of inoculated cultures was reduced in comparison to that of control cultures.

Demonstration of rubella complement-fixing antigens of two distinct particle sizes by gel filtration on sephadex G-200.

Summary By means of gel nitration on Sephadex G-200, rubella complement-nxing antigens of two distinct particle sizes have been demonstrated in concentrates of fluids from infected BHK-21 cultures. The large-particle antigen elutes from Sephadex columns together with infectious virus, shortly after the void volume is eluted, and is sedimented by centrifugation at 80,000 × g for 3 hours together with the infectious virus. The small-particle antigen elutes after the infectious virus and is not sedimented under conditions of centrifugation which sediment the infectious virus. Sephadex gel nitration was shown to be more effective than direct centrifugation of rubella-infected fluids in separating the two different antigens.