Prevalences of human herpesvirus 6 and human herpesvirus 7 in normal Thai population.

Prevalences of human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7) DNA were investigated in normal Thai population. Peripheral blood mononuclear cells (PBMC) and saliva were collected from 238 healthy adults in five provinces which might be a representative of each part of the country, and 120 normal children in one province. Prevalences of HHV-6 DNA PBMC were 45.5-74.3% in adults and 78.3% in children, and in saliva, very low prevalences were detected; 5.7-8.6% in adults and 15.0% in children, respectively. Additionally, all HHV-6 DNA detected in this study were variant B. Comparingly to those of HHV-7 DNA, the prevalences were significantly higher than those of HHV-6, ie, 82.9-91.4% in PBMC of adults, 85% in PBMC of children, 84.8-89.0% in saliva of adults and 92.5% in saliva of children. HHV-6 and HHV-7 isolation from saliva specimens were also performed. No HHV-6 could be isolated from any samples, whereas, in the present study, HHV-7 could be isolated as 90.0% from children and as 20.0-54.5% from adults.

Specific binding of Burkholderia pseudomallei cells and their cell-surface acid phosphatase to gangliotetraosylceramide (asialo GM1) and gangliotriaosylceramide (asialo GM2).

Specific binding between bacterial cells and host tissue is an early step of the pathogenesis of infection. Burkholderia pseudomallei cells, the causative micro-organisms of melioidosis, were demonstrated to bind specifically to tissue glycolipids (asialo GM1 and asialo GM2) by solid phase binding assay on thin layer chromatograms. The detection limit was around 400 pmol of the glycolipids. Acid phosphatase purified from the culture filtrate of B. pseudomallei was tested for such binding properties, and the same results were obtained. According to our previous studies, the enzyme is a glycoprotein located on the cell surface, and hydrolysed tyrosine phosphate most actively among the substrates so far tested. The mode of binding between the enzyme and the glycolipids was analyzed by comparison of binding levels among three samples different in protein content, sugar content and specific phosphatase activities per protein and sugar residue. The results suggested the possibility of a receptor-ligand relationship between the bacterial enzyme and the host-cell glycolipids (asialo GM).

Affinity and response of Burkholderia pseudomallei and Burkholderia cepacia to insulin.

The cells of Burkholderia pseudomallei, B. cepacia and Pseudomonas aeruginosa grown on agar plates were stained with fluorescently-labeled insulin. The former two species were stained positively indicating insulin binding but P. aeruginosa was not. Insulin exposure reduced phospholipase C and acid phosphatase activities of B. pseudomallei but did not affect those enzymatic activities of B. cepacia in the employed experimental conditions. It is suggested that B. pseudomallei have insulin receptors which may be associated with a signal transfer system involving phospholipase and protein tyrosine phosphatase.

Evolution of cell-surface acid phosphatase of Burkholderia pseudomallei.

Acid phosphatase active fractions were obtained from cell-free extract, outermembrane fraction and culture filtrate of Burkholderia pseudomallei by column chromatography with sepharose 6B and DEAE cellulose. The comparison of the elution patterns of protein, sugar and enzymatic activity among these three components suggested that the enzyme is a glycoprotein evolving from premature proteins through glycosylation and that the enzyme is translocated during glycosylation from the cytoplasm to the outer membrane and finally excreted into the environment. When tunicamycin, a glycosylation inhibitor, was added to the culture, the peaks of sugar and enzymatic activity were lowered concomitantly leaving the protein peak unchanged in the elution pattern of the culture filtrate. The affinity of the bacterial surface to antienzyme sera was demonstrated by immuno-fluorescence microscopy.

Application of indirect immunofluorescence microscopy to colony identification of Pseudomonas pseudomallei.

Indirect immunofluorescence microscopy was used as a colony identification method of Pseudomonas pseudomallei isolates. The antisera against lipopolysaccharide and protein fractions of P. pseudomallei were prepared in guinea pigs and rabbits. With these antisera and fluorescence-labelled anti-guinea pig IgG and anti-rabbit IgG prepared in sheep (goat), indirect immunofluorescence microscopy was conducted on the colonies of P. pseudomallei and other species of bacteria. The overall results indicated that this method is efficient, rapid and specific for identification of P. pseudomallei colonies from clinical specimens.