PubMed · 10635792
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I Furuta. 1999. [Widal test].. https://pubmed.ncbi.nlm.nih.gov/10635792/
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Fifty avian (chicken) pathogenic Escherichia coli strains (APEC) isolated from individuals suffering from omphalitis, septicaemia and swollen head syndrome, and 30 strains isolated from healthy chickens were studied regarding their biological characteristics such as serogroups, haemolysin, colicin, cytotoxin, toxin and siderophore production, adhesion capacity to in vitro cultivated cells, and absorption of Congo red dye. Serotyping demonstrated that most of the omphalitis and normal strains were untypable, whereas most of the septicaemic strains were either untypable or rough. There was no prevalent serogroup among the pathogenic strains studied. The capacity for adhesion and invasion of in vitro cultured cells (HeLa, HEp-2, KPCC), as well as the agglutination of different types of red blood cells and the LD50 of each strain were also evaluated. No correlation was observed between the biological characteristics and pathogenicity, except that colicin was characteristically produced by swollen head syndrome E. coli strains. No correlation was found between adhesion or haemagglutination patterns and pathogenicity. Only six of the 50 strains revealed invasive capacity and the strain that best invaded the cell lines was the one with the lowest LD50.
The innate immune system in the lung is essential for controlling infections due to inhaled pathogens. Mycobacterium tuberculosis (M.tb) encounters components of the innate immune system when inhaled into the lung, but the consequences of these interactions are poorly understood. Surfactant protein D (SP-D) binds to and agglutinates M.tb bacilli, and reduces the uptake of the bacteria by human macrophages. In the current studies, we utilized a recombinant SP-D variant (CDM) that lacks the collagen domain to further characterize the interaction of SP-D with M.tb, and determine the effects of agglutination on bacterial uptake by human monocyte-derived macrophages. These studies demonstrate that the binding of SP-D and CDM to M.tb is saturable and inhibited by carbohydrate competition and Ca(2+) chelation, implicating the carbohydrate recognition domain in the interaction. Fluorescence microscopy reveals that dodecameric SP-D leads to agglutination of the bacilli, whereas the trimeric CDM does not, demonstrating that the multivalent nature of SP-D is essential for agglutination of M.tb. However, preincubation of M.tb with increasing concentrations of SP-D or CDM leads to a concentration-dependent reduction in the uptake of the bacteria by macrophages, indicating that agglutination does not play a direct role in this observation. Finally, the reduced uptake of M.tb by SP-D is associated with reduced growth of M.tb in monocyte-derived macrophages. These studies provide direct evidence that the inhibition of phagocytosis of M.tb effected by SP-D occurs independently of the aggregation process.
Fifteen gamma-interferon gene knockout mice were each orally inoculated with 5 x 10(3) Sarcocystis sporocysts derived from Virginia opossums (Didelphis virginiana) fed nine-banded armadillo (Dasypus novemcinctus) muscle containing sarcocysts. Three mice were inoculated with similarly obtained homogenates, but in which no sporocysts were detected. Mouse M8 was pregnant when inoculated and gave birth during the trial. Fifteen of 15 (100%) mice inoculated with sporocysts developed neurologic signs and/or died by day 30 d.p.i. One of 3 (33.3%) mice inoculated with homogenates in which no sporocysts were detected developed clinical signs and died at 34 d.p.i. All young of mouse M8 had maternally acquired antibodies to Sarcocystis neurona, but none developed clinical neurologic signs or had protozoal parasites in their tissues. All brains from mice that developed clinical signs contained merozoites that reacted positively to S. neurona antibodies using immunohistochemical techniques. Evidence from this study further supports the nine-banded armadillo being an intermediate host of S. neurona.