Rapid diagnosis of primary dengue fever by the immunochromatographic test and by electron microscopy - a case report

A 21-year-old woman presented with an acute febrile illness after a two-week holiday in Jamaica. Her symptoms started two days after return, with sudden onset of continuous high fever (> 39 degrees C), dizziness and nausea. Three days later she developed a generalized macular rash, which led to the tentative diagnosis "acute dengue fever." Laboratory confirmation was achieved by demonstrating anti-dengue IgM and IgG antibodies in paired sera; in addition, flavivirus particles were directly visualized by electron microscopy. (AU)

The development and use of an antibody capture radioimmunoassay for specific IgM to a human parvovirus-like agent

An IgM-antibody capture radioimmunoassay (MACRIA) was developed for detection of IgM antibody specific for the human parvovirus-like agent B19. Diagnosis of infection with this agent by either antigen detection or antibody seroconversion had been made by counter-current immunoelectrophoresis (CIE) in 18 cases of aplastic crisis occurring in children with homozygous sickle-cell desease. The MACRIA described here gave positive results in 17 of 18 cases; in the remaining case only an acute specimen taken from the patient during viraemia and late convalescent specimens taken 184 and 247 days after onset of illness were avaliable. The test was used to investigate 20 further cases of aplastic crisis in which neither viral antigen nor antibody seroconversion could be detected by CIE. Detection of virus-specific IgM permitted diagnosis of infection with this parvovirus-like agent in 17 of these cases. In the remaining three cases only single serum specimens taken late in convalescence, 82, days or more after the onset of symptoms, were available. In addition to these 34 cases of aplastic crisis in which primary infection with this agent was diagnosed by MACRIA, seven cases of apparent 'silent' infection detected by CIE were investigated. The test permitted the discrimination between primary infection and re-exposure to the virus in six of these patients. The use of this assay has added a considerable weight of evidence implicating primary infection with this parvovirus-like agent as an important cause of aplasic crisis in children with sickle-cell disease. Furthermore, MACRIA permits diagnosis of infection when only single serum specimens taken up to ten weeks after infection are available. Thus the use of this test will significantly facilitate the investigation of other clinical syndromes of presumptive infective infectious aetiology (AU)

Mapping of antigenic sites on human haemoglobin by means of monoclonal antibodies and haemoglobin variants

Monoclonal antibodies specific for human globin chains have been prepared and the following strategy has been applied in delimiting the antigenic sites involved in antibody binding. The structural sites of the human globin subunit that might be recognised by the monoclonal antibody were deduced from comparisons of the primary structures of mamalian globin chains that did or did not react with the antibody. The involvement of individual residues at these specific sites was subsequently tested by reacting the antibody with abnormal human haemoglobins in which there was either a substitution or a structural site recognised by monoclonal antibody HuHb á 3-2 (an antibody that reacts with the adult haemoglobins from man and macaque monkey, but not with those from baboon and mouse) includes the aspartic acid residue at position 52 of the á-globin subunit.(AU)