PubMed · 4934980
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J Y Lacut. 1971. [Practical data obtained from serodiagnosis].. https://pubmed.ncbi.nlm.nih.gov/4934980/
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The O and R antigenic variants of the Plasmodium falciparum Palo Alto strain present differences in the morphology of the infected red blood cell membrane, in their adhesion properties, surface immunofluorescence, and agglutination specificities and importantly, induce a variant-specific protection after a primary infection in Saimiri sciureus monkeys. To identify potential targets of variant-specific immunity, we have compared the antigenic makeup of both variants by immunoblot. O-specific monkey sera generated similar profiles on both parasite types, while R-specific sera showed a consistent difference on a high-molecular-mass undefined antigen. Distinct antibody specificities were eluted from the surface of O- or R-infected erythrocytes, generating variant-specific agglutination, surface immunofluorescence, and immunoblot profiles. An antiserum raised to Pf60.1, predicted to cross-react with the cytoplasmic domain of PfEMP1, reacted with specific, SDS-soluble antigens in both variants. Antigens associated with the membrane of the infected red blood cells were further investigated using several specific antisera. The 85-kDa HRP1 gene product was more abundant in O than in R parasites, while the reverse was observed for the PfEMP3 protein. These data indicate that O and R parasites differ in the expression of several antigens associated with the membrane of the infected red blood cell.
Antibody titers to Toxoplasma gondii were determined in 16 pigs orally inoculated with 1000 or 10,000 oocysts of one of the four strains (GT-1, ME-49, TS-2, TC-2) of T. gondii. Pigs were euthanized on postinoculation days 103-875 and their tissues were bioassayed for T. gondii. Antibody titers were measured in the modified agglutination test (MAT) using formalin-preserved (test A) or acetone-preserved (test B) tachyzoites, latex agglutination test (LAT), indirect hemagglutination test (IHA), enzyme-linked immunobsorbant assay (ELISA), and the Sabin-Feldman dye test (DT). Toxoplasma gondii was isolated from all but two (one with GT-1 strain and one with TC-2 strain) of the inoculated pigs. Results of the serologic tests varied by test used, by strain of T. gondii and from pig to pig within groups. One pig inoculated with the TC-2 strain was considered not to be infected because it remained seronegative in all tests and T. gondii was not isolated from its tissues by bioassay. The IHA and LAT did not produce consistently positive results with infected pigs and two pigs remained seronegative (< 1:64) in both tests. At the time of necropsy, IHA titers had declined to < 1:64 in five pigs and LAT titers had declined to < 1:64 in four pigs. The MAT (test A) and ELISA detected antibodies in all infected pigs but ELISA did not detect antibody at the time of necropsy in one pig. Antibody titers peaked earliest in the DT. Antibody titers in the MAT (test B) peaked at 2560 in all seropositive pigs by 6 weeks postinoculation (PI) but declined to < 1:160 by 15 weeks PI; this test may be useful in determining recency of T. gondii infection in pigs. Overall, the MAT (test A) gave most consistent results.
We analyzed 127 urine samples for benzodiazepines by a radioreceptor assay and two immunoassays (cloned enzyme donor immunoassay [CEDIA, Boehringer Mannheim, Indianapolis, Ind] and agglutination immunoassay [ONLINE, Roche Diagnostic Systems, Branchburg, NJ]). Sixty samples that were positive by at least one of these assays were submitted to gas chromatography-mass spectrometry, which detected benzodiazepines such as oxazepam, nordiazepam, and lorazepam in 44 samples. Diagnostic sensitivity and specificity of the receptor assay were almost equal or superior to those of the two immunoassays, although discrepant results were obtained in some samples. The discrepancies resulted from differences in the cross-reactivity of these assays. For example, the receptor assay could detect lorazepam, while the two immunoassays could not, and CEDIA was interfered with by a metabolite of sertraline while the others were not. This is the first report showing the utility of a receptor assay for screening benzodiazepines in urine.