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Virus-like particles were identified from the plasma of rabbits which developed pleural effusion disease after inoculation with different strains of Treponema pallidum. These particles were considered coronavirus-like on the basis of their size, morphology, and buoyant density. Clinical and pathological manifestations of pleural effusion disease, which is probably the same disease entity as rabbit cardiomyopathy, resembled those of feline infectious peritonitis which is caused by another probable member of the Coronaviridae family. Coronavirus-like particles also were demonstrated in the feces of rabbits which had been inoculated with a 450-nm fecal filtrate of rabbits which died from infectious intestinal disease.
Tecoram, when administered at doses of 0.01, 0.1, 1 or 10 mg per egg in propylene glycol or in saline to chick embryos caused paralysis, shortening of the extremities, muscular atrophy, dwarfing and death. Microscopically there were signs of peripheral neuropathy, mainly confined to the distal parts of the peripheral nerves, and muscular atrophy. This investigation shows that the chick embryo may be a suitable experimental model for study of the neurotoxic effect of dithiocarbamates.
Two independent outbreaks of ectromelia in mice occurred in The Netherlands. In both cases, the causative virus was isolated and identified as ectromelia virus on the basis of serology, demonstration of antigen by indirect immunofluorescence, negative contrast electron microscopy, morphology of lesions on chorioallantoic membranes of embryonated chicken eggs, and cytopathogenicity for mouse cells. Inoculation of the virus into the dermis of rabbits demonstrated a low virulence for this species.
The use of a density gradient procedure for the quantification of intact, inactivated poliovirus particles in vaccine preparations is described. The procedure is both sensitive and highly reproducible and the results correlate with those of potency tests in rats and with D-antigen content as measured by ELISA. Because of the occasional ambiguity observed with D-antigen assays, it is suggested that the density gradient procedure will provide valuable additional information for the in vitro assessment of inactivated poliovirus preparations.
A monoclonal antibody directed against bovine serum albumin (BSA) has been developed and used in an enzyme-linked immunosorbent assay (ELISA) system for the detection of BSA in virus vaccines. The results correlated well with those obtained with a counter current electrophoresis system which has been employed routinely for this purpose. The ELISA was slightly more sensitive and more readily applicable to the screening of large numbers of samples but could not be used in the presence of certain stabilizers.
An enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantification of IgM and IgG serum antibodies to mouse polyomavirus (MPV). To evaluate the potential of this ELISA for the screening of laboratory rodents, serum samples from specific pathogen free (SPF) BALB/c RIVM mice, collected after experimental intraperitoneal infection with MPV, were tested by this assay. The results were compared with those obtained from the same sera in an immunofluorescence assay (IFA) and a haemagglutination inhibition assay (HIA). The ELISA proved to be the most sensitive of the 3 assays, allowing the detection of seropositive animals within 7 days post-infection and giving antibody titres that were about 4 to 8 times higher than those found in the IFA and HIA respectively. More than 5000 serum samples from non-infected specif...
Lymphocyte hybridomas secreting monoclonal antibodies against different strains of polio virus type 1, 2, or 3 have been produced. For this purpose Balb/C mice were immunized with purified and inactivated virus suspensions and their splenocytes were fused with P3X63Ag8 mouse myeloma cells. Screening for antibody production was performed in an enzyme-linked immunosorbent assay (ELISA). Antibodies were produced either in cell culture or in Balb/C mice by passaging the hybridomas as solid or ascitic tumors, after they had been cloned at least three times by limiting dilutions in microtiter plates. Specificities of a number of these monoclonal antibodies were determined in the ELISA and in a neutralization test using different polio virus subtypes. The results indicate that for epidemiological studies monoclonal antibodies may prove to be ...
A panel of 10 monoclonal antibodies raised to 3 different poliovirus type 1 strains was tested in a micro-enzyme-linked immunosorbent assay and in a micro-neutralization test against 87 poliovirus type 1 strains. The results, evaluated in a newly developed system for intratypic strain characterization, were compared with the results obtained with the classical sero-differentiation system by using a small number of strain-specific, cross-absorbed antisera. The new system not only uses results obtained with strain-specific antibody preparations, but also uses the information obtained with monoclonal antibodies reacting with less unique antigenic determinants. In a theoretical pattern fitting computer program, each virus strain could be compared with all the other strains for which serological data were stored in the memory of the compute...
Twenty 5-fluorouracil-induced temperature-sensitive (ts) mutants of mouse hepatitis virus strain A59 were isolated from 1284 virus clones. Mutants were preselected on the basis of their inability to induce syncytia in infected cells at the restrictive temperature (40 degrees) vs the permissive temperature (31 degrees). Of these mutants, only those with a relative plating efficiency 40 degrees/31 degrees of 3 x 10(-3) or smaller were kept. Virus yields at 40 degrees compared to 37 degrees and 31 degrees (leakiness) were determined. Most mutants (16) were RNA-, i.e., unable to synthesize virus-specific RNA at the restrictive temperature. The other four were RNA+. No qualitative differences were detected in the virus-specific RNAs in cells infected with RNA+ ts-mutants, both at 31 degrees and 40 degrees. Virus-specific proteins present in...
Administration in vivo of monoclonal antibodies to humans is challenged by considerations regarding their safety. Contamination with viruses, potentially oncogenic nucleic acids and biologically active components like growth factors and hormones forms a serious point of concern in this respect. We have investigated the potential risk of viral contamination by measuring the reduction of 12 different viruses (after spiking) in the standard downstream purification process of ascitic fluid. Depending on the type of virus added and the purification step employed, the reduction of infectious virus particles varies considerably. The overall reduction ranges from about 10(3), observed for a member of the family of Papovaviridae, to more than 10(12) for members of the families of Herpesviridae and Orthomyxoviridae. Using hybridization analysis ...
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