SYNOPSIS A moderately sensitive, rapid, and economical test scheme for the detection of infantile gastroenteritis virus (IGV) in stool or antibody in serum has been developed and evaluated. The test scheme with minor modifications was an adaptation of a counter-immunoelectro-osmophoresis system we once used for the detection of hepatitis B antigen. Large numbers of stool samples may be screened during half a working day for the presence of IGV using reference antiserum to IGV prepared in guinea-pigs. Serological studies of a diagnostic but not epidemiological nature may also be performed with equal facility by this same test scheme using highly purified IGV antigen derived from stool.A specific virus variously called orbi, reo-like, rota, or duovirus has now been found throughout the world (Kapikian et al, 1975). This virus is a major cause of gastroenteritis in infants and young children during colder months in temperate climes (Middleton et al, 1974;Davidson et al, 1975). Until further morphological studies (Martin et al, 1975) and the results of characterization tests have been published we prefer to employ the term and label the agent by the more descriptive name infantile gastroenteritis virus (IGV).Our interest in IGV arose in the course of providing a clinical virology service to a large paediatric hospital. We have found that one electron microscopist and one electron microscope could handle approximately 20 samples per day. Since our service demands often exceeded this capability in gastroenteritis stool samples alone, it became imperative that we explore alternative yet equally rapid diagnostic methods. During the first four months of 1975 our service identified 190 IGV infections by negative contrast staining electron microscopy using non-purified unconcentrated stool samples. Five more identifications were made following stool or rectal swab eluate ultracentrifugation. Two additional and fatal cases were identified by indirect immunofluorescence of small bowel mucosa in this same time span.Complement fixation as a means of providing a rapid diagnosis based on antigen detection was Received for publication 13 August 1975 discarded after a pilot study had shown that crude stool suspensions were often anticomplementary. From experience gathered in work on serum hepatitis, the technique of counter-immunoelectro-osmophoresis (CIEOP) suggested several advantages. By adopting a CIEOP system the anticomplementary problem might be avoided, large numbers of stool samples could be screened during one working day, and the volume of reactants used in the test system would be considerably less than those employed even in a conventional microcomplement fixation test. Moreover, crude stool suspensions might well contain a quantity of subvirion antigen which could migrate towards the anode under the influence of an electric field and produce precipitation lines with reference antibody. Material and Methods CLINICAL SPECIMENSStool specimens were collected from patients admitted to the Hospital for Sick Children, To...
Streptokinase (SK) is a bacterial protein used clinically as a thrombolytic agent in humans. Administration of SK causes a rapid increase in the frequency of anti-SK T cells and the titre of specific anti-SK antibodies that, on subsequent administration of SK, may neutralize the activity of the drug or elicit allergic-type reactions. By locating and modifying the immunogenic T-cell epitopes within the SK protein, it is possible that an agent with reduced immunogenicity but equal efficacy may be produced. We have investigated the T-cell epitopes within SK using nine non-overlapping, recombinant peptide fragments of SK. We investigated the proliferative T-cell response of peripheral blood mononuclear cells obtained from patients before and 6 days after administration of SK for myocardial infarction. We also examined the response of cultured anti-SK T-cell lines derived from patients 6 days after treatment with SK. Before administration of SK, peripheral blood mononuclear cells from six of nine patients showed a proliferative response to SK. The response was significantly higher 6 days after administration of SK (P = 0.0004). Cultured T-cell lines showed similar proliferative responses to clinical-grade SK and recombinant SK. Marked differences in T-cell responses were apparent in response to each recombinant SK fragment (P = 0.04). The mean proliferative response exceeded background to only two peptides, peptide 2 (P = 0.04) and peptide 3 (P = 0.009). Peptide 3, representing amino acids 100-150 of mature SK, was recognized preferentially in the majority of assays. Marked variation in the T-cell response to SK following treatment with this agent was observed between subjects. Despite these differences, peptides 2 and 3 induced T-cell proliferation at a level significantly above background in the majority of subjects. These epitopes may represent a region of enhanced immunogenicity within SK.
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