Serological studies on possible causes of intra-uterine infections in Thai infants.

Serological tests for toxoplasmosis, rubella, cytomegalovirus (CMV), Herpesvirus hominis (HVH) infections syphilis (TORCHES) were carried out in 49 infants with showed signs of possible intrauterine infections and in 212 mothers and their newborn infants. The tests employed were ELISA for rubella and CMV infections, indirect haemagglutination for HVH infection and toxoplasmosis and RPR Macro-vue card test for syphilis. The immunoglobulin class of the antibody was also determined, and only infants with IgM antibody was considered indicative of intrauterine infection. It was found that 36.7% and 10.2% of infants with signs of intrauterine infections were positive for rubella and CMV antibodies and 19% had mixed infections of rubella, CMV, toxoplasma, syphilis and HVH. In contrast, only 6.1% of normal newborn infants had rubella antibody, 6% had HVH antibody and less than 1% had toxoplasma antibody, and none of them had CMV and treponema antibodies. Higher rate of seropositivities were found in their mothers, the percentage seropositivities for rubella, HVH, CMV infections, syphilis and toxoplasmosis were 19%, 12%, 2% and 1% respectively.

Purification of the antigen specific for amoebiasis.

Two methods used for the purification of specific antigen for amoebiasis were affinity chromatography and agarose gel electrophoresis. The IgG fraction of the serum from a patient with amoebic liver abscess showing a specific band in the IEP test was coupled to CNBr-activated Sepharose 4B. After passage through the immunoadsorbent column of the crude or partially purified extract of Entamoeba histolytica, followed by acid dissociation, specific antigen was obtained. This antigen gave only one band in the IEP test against the serum which gave multiple bands upon testing with the crude antigen. With the agarose gel electrophoresis, fraction 2 from the slit was found to contain specific antigen. Rabbits immunized with the excised agarose strip of this fraction produced antibodies giving 2 precipitating bands in the IEP test, one of which was specific for amoebiasis.

Total serum IgE level in patients with amoebic liver abscess and other parasitic infections.

Total serum IgE level was determined by the radioactive single radial diffusion technique in blood donors, nurse-aid students with the stool positive and negative for parasites, and in patients with helminthic infections. A geometric mean of 445.1 IU/ml in the sera from blood donors was found. Patients with helminthic infections had significantly higher levels than the blood donors and the nurse-aid students with the stool negative for parasites. Intestinal protozoal infections did not cause an increase in IgE level.

Antigenicity of sub-cellular components of Entamoeba histolytica.

Antigencity of the sub-cellular components of axenic Entamoeba histolytica trophozoites was studied. The cells were disrupted by means of a glass-teflon homogeniser and sub-cellular components were prepared by stepwise differential centrifugation. Four fractions were obtained, namely the 350 g, 6500 g, and 100,500 g fractions and the cell sap. Components of the sedimented fractions were examined by phase contrast and electron microscopy. The antigenicity of each fraction was studied by two different methods:-(1) By extraction with 0.5% sodium deoxycholate followed by testing against the reference sera; (2) By demonstration of the loss of immunological activity of the reference sera after absorption with fractionated components. It was found that all 4 fractions had varying antigenic activities as measured in the indirect hemagglutination (IHA), the complement fixation (CF) and the immunoelectrophoresis (IEP) tests. With the extraction technique, the following results were obtained:- The highest IHA activity was found in the cell sap, whereas this activity in other fractions clustered at lower levels. In the CF test, the activities associated with all 4 fractions were similar. In the IEP test, the highest activity was found in the cell sap and the least activity in the 100,500 g fraction. With the absorption technique, slightly different results were obtained. Whilst in the IHA and the IEP test, the results were in concordance with the extraction technique, the CF activity was slightly different, since it was highest in the cell sap and least in the 100,500 g fraction.