Acta pathologica et microbiologica Scandinavica. Section B, Microbiology最新文献

Antibodies measured in enzyme-linked immunosorbent assay (ELISA) had a slower rate of increase and were equally persistent as those measured in the dye test. Hence it was possible to correlate a quotient of the two antibody levels to the acuteness of a Toxoplasma infection.

A preliminary report on a simplified procedure for the preparation of nasopharyngeal suction specimens making direct smears of aspirated material is presented. The smears were examined by the indirect immunofluorescence (IF) technique for the presence of respiratory syncytial (RS) virus antigens. Specimens form 99 children with acute respiratory tract illnesses were collected during the winter season 1978-79, and RS virus was identified in samples from 45 of these patients. Serological investigations run in parallel showed fairly good correlation with the IF examinations of the smears. This simplified procedure for the preparation of nasopharyngeal suction specimens may be recommended when the conventional preparation cannot readily be performed.

LLC-MK2, GMK AH-1, BSC-1, and Vero cells were compared in titrations of recent isolates and laboratory strains of influenza A and B and parainfluenza types 1, 2, and 3 viruses. About the same titres, as determined by haemadsorption in cell cultures, were obtained in LLC-MK2, GMK AH-1, and BSC-1 cells when trypsin had been added to the medium, whereas the Vero cells were less sensitive to the influenza virus strains tested. Virus titres were usually low in the absence of trypsin. A laboratory strain of parainfluenza 2 virus reached about the same titres in medium without as in medium with trypsin, possibly owing to prior adaptation by passages in Vero cells. Comparative titrations of influenza A, and parainfluenza 1 and 3 viruses suggested the same susceptibility of LLC-MK2 cells with trypsin as of primary monkey kidney cells. Re-isolation experiments from 38 clinical specimens showed LLC-MK2 cells to be as efficient as primary monkey kidney cells for isolation of influenza and parainfluenza viruses, whereas the susceptibility of the other cell lines to clinical material has not yet been tested on a larger scale. It is concluded that a continuous line of monkey kidney cell culture may be acceptable as an alternative to primary monkey kidney cells for the isolation of influenza and parainfluenza viruses from patients.

Bordetella pertussis microorganisms were treated with several extracting agents followed by ultracentrifugation to remove particulate matter. Analysis of the resulting supernatants by SDS gel electrophoresis showed one major component after simple salt extraction, and much more complex, although consistent pattern following detergent treatment. The yield of the solubilized protein in detergent extracts exceeded by far the values recorded for salt extracts. In order to prevent irreversible precipitation of the solubilized proteins upon removal of the denaturing agent, a novel procedure was developed. After extraction with urea-salt, the solubilized material was absorbed on a mineral carrier prior to the separation of the denaturing agent. The resulting absorbed vaccine was highly potent in the mouse-protection test, whereas the toxic reactions, elicited upon injection into experimental animals, were reduced in the comparison to the starting material. This diminished reactogenic potential was accompanied by the partial loss of the leukocytosis-promiting factor, whose activity was greatly diminished by urea-salt at alkaline pH-values. The procedure described may be applied to large-scale processing of Bordetella persussis microorganisms. Clinical trials now in progress should confirm or rebut the thesis that increased tolerability of the product, inferred from animal experiments, is reflected by fewer adverse reactions in humans. In the former case, the detergent extract vaccine may constitute a realistic alternative to conventional whole-cell vaccines against whooping-cough.

Two new media were developed, containing only the dialyzable components of Todd Hewitt broth (TH) with (medium II) or without (medium IV) inactivated horse serum. The two media were used to detect activity of the competence factor (CF) and the competence factor inactivator (CGI) of Streptococcus sanguis, and in preliminary experiments of CF isolation. Because all the dissolved substances with molecular weight (mol. wt.) less than 12,000 can be removed from these media by dialysis, leaving the CF and possible other high mol. wt. substances formed by growth in the dialysis tube, the use of these media should facilitate the isolation of CF and other high mol. wt. substances involved in genetic transformation of S. sanguis. Dialysis experiments suggest a mol. wt. greater than 12,000 of the CFs of the strains Challis and 13b. The CF of strain 13b was further isolated by Sephadex gel filtration and was eluted in the fractions of low mol. wt. compounds.

Four serological tests, viz. indirect hemagglutination (IHA), metabolism inhibition (MI), immunofluorescence (IMF), and a modification of the growth-inhibition (GI) test have been compared for the detection of antibodies against Mycoplasma hominis in female grivet monkeys with experimentally induced pelvic inflammatory disease. Moreover, cold hemagglutinins (CHA), and immunoglobulins, M, G, and A have been determined. The IHA test was found to be superior to the other methods used. The antibodies were present in all inoculated monkeys two weeks after the inoculation and a maximum in titre occurred one week later. Antibodies detected by the modified GI test occurred in all monkeys inoculated with the organism together with the IHA antibodies, but the maximum in titre was less marked. The IMF test was less sensitive than the GI test; the antibodies generally occurred later and disappeared faster. Using the MI test, no antibodies could be detected in any of the monkeys during the experimental period and no CHA antibodies were found in any of the sera. IgM rose earlier and declined more rapidly than IgG. It is concluded that the IHA test is most suitable for the measurement of serum antibodies caused by infection with M. hominis in grivet monkeys. The modified GI test, although less sensitive, may also be useful because of its simplicity in performance.

Various auxiliary treatments of L-cells employed for the isolation and cultivation of C. psittaci were investigated in order to develop an improved method for the detection of the agent, in addition to the aid obtained by centrifugation and cycloheximide treatment. Glucocorticoid treatment increased the observed number of inclusions considerably through a preservative effect on host cells and enhanced an spontaneous re-infection. Besides, the hormone made the scanning of cell culture for inclusions more convenient through an altered cell morphology. This method was tested with two extreme species types that differed as regards cytopathogenicity and growth rate. The length of the cultivation period was of great importance for the diagnostic result. Especially the cytopathogenic agent-type influenced the optimal time of cell culture fixation, which was situated around 48 or 88 hours post infection (h p.i.). Owing to the cytotoxicity of field samples (milk secretion), the cell culture technique (48 h p.i.) was less sensitive compared to the conventional isolation method in embryonated eggs. However, a different sampling technique improved the result, and simultaneous use of the secondary multiplication cycle of chlamydia (88 h p.i.) makes the less cumbersome cell culture technic recommendable.

Antigenic variants of influenza A/Hong Kong/1/68 (H3N2) were obtained in vitro by letting virus multiply in the allantosis-on-shell system in the presence of anti-haemagglutinin antibodies, prepared from immune goat serum to purified haemagglutinin antigen, and in vivo by giving mice antibody intraperitoneally one day before challenge with a sublethal dose of live virus. In both systems it was shown that the most narrowly reacting strain-specific antibodies selected antigenic variants at an apparently higher rate than a more cross-reactive preparation of antibodies.

Altogether, 412 strains of Yersinia enterocolitica and Y. enterocolitica-like bacteria from environmental and human sources were examined for their ability to produce enterotoxin at 22 degrees C and 37 degrees C using the infant mouse assay. A total of 73 strains were positive at 22 degrees C, only. Another 28 strains were positive both at 22 degrees C and 37 degrees C. Of these 28 strains, 26 were sucrose and aesculin non-fermenting and all were Voges-Proskauer negative. All of these strains were isolated from non-human sources. All of 13 strains belonging to O-serogroup 28 produced enterotoxin at 37 degrees C. The results indicate that enterotoxin production at 22 degrees C is widespread in Y. enterocolitica with the highest prevalence among human clinical isolates. Enterotoxin production at both 22 degrees C and 37 degrees C seems to be common in Y. kristensenii (sucrose non-fermentors). Enterotoxin production is apparently rare in Y. frederiksenii (rhamnose fermentors) and in Y. intermedia (rhamnose and melibiose fermentors).