Structural and serological studies of the O-antigen of the bacterium Proteus mirabilis OXK (serogroup O3) used in the Weil-Felix test

Sugar analysis and 1H- and 13C-NMR spectroscopic studies showed that various strains of Proteus mirabilis OXK used as antigens in the Weil-Felix test for serodiagnosis of rickettsiosis (scrub typhus) produce lipopolysaccharides (LPSs) with the same O-specific polysaccharide chain having the following structure: [formula: see text] where GlcA and GalA are glucuronic and galacturonic acids, respectively. This polysaccharide which defines the O3 specificity of Proteus and has been found earlier in an unclassified P. mirabilis strain S1959, contains an amide of D-galacturonic acid with L-lysine which plays an important role in manifesting the immunospecificity. A cross-reaction was observed in ELISA between sera from patients with scrub typhus, caused by the bacterium Orientia (Rickettsia) tsutsugamushi, and purified LPS of P. mirabilis OXK, thus suggesting that the common epitope involved in the Weil-Felix test is located on P. mirabilis OXK LPS. Rabbit anti-P. mirabilis OXK antibodies did not cross-react with LPS-lacking O. tsutsugamushi strain Gilliam in dot-blotting and Western blotting, and the nature of the rickettsial antigen responsible for the Weil-Felix reaction remains unknown.

Comparison of serological reactions of Rickettsiae-infected patients and rabbit anti-Proteus OX antibodies with Proteus OX2, OX19 and OXK lipopolysaccharides

The reactivity of anti-Rickettsiae human antibodies with Proteus OX cells is used as a presumptive rickettsial diseases diagnostic test Weil-Felix reaction. In presented studies we compare the reactivity of human anti-Rickettsiae and rabbit anti-Proteus antibodies with series of Proteus OX2, OX19 and OXK lipopolysaccharides (LPS). Polyclonal rabbit anti-OX2, anti-OX19 and anti-OXK sera reacted only with the homologous LPS--OX2, OX19 and OXK, respectively. The antibodies of Japanese spotted fever patients were less specific and reacted with OX2 as well as OX19 LPS. The antibodies of scrub typhus patients recognized Proteus OXK LPS, only. The serological reactions of O-antigen of P. mirabilis S1959 indicated that this, previously serologically not classified, strain may belong to the OXK group. Bacteria, used in the studies, came from the American, Japanese and European strain collections. The series of OX2, OX19 and OXK LPS, isolated from these Proteus strains, presented pattern of electrophoretic mobility and serological reactivities specific for each of OX-group types.

Serological studies of the antigenic similarity between typhus group rickettsiae and Weil-Felix test antigens

The sera from two patients with murine typhus reacted with whole cells of Rickettsia prowazekii, R. typhi, and Proteus vulgaris OX19, and with lipopolysaccharides (LPS) from the spotted fever group rickettsia strain TT-118 and P. vulgaris OX19 in the enzyme-linked immunosorbent assay. Sera from these patients reacted with ladder-like bands of LPS from R. prowazekii and R. typhi in the immunoblot, whereas the reactivity of these sera with LPS from P. vulgaris OX19 differed from each other. These results indicate that LPS from the typhus group rickettsiae and P. vulgaris OX19 contain similar epitopes.

[Comparison by SES-PAGE of molecular weights of lipopolysaccharides from Campylobacter jejuni Lior serotype reference strains and clinical isolates]

To compare the molecular weights (MWs) of lipopolysaccharides (LPSs) from 30 Lior serotype reference strains and 17 clinical isolates of Campylobacter jejuni, we analyzed their migration rates by SDS-PAGE and the silver staining of the gel. LPSs from the serotype strains showed one band in the low-molecular-weight region of the gel as did those from R mutants of enterobacteria. Based on those from Salmonella minnesota R mutants, MWs of LPSs from C. jejuni strains were calculated to fall within a range of 3900 to 5300. Furthermore, in comparison of MWs of LPSs from the clinical isolates with those from the same serotype reference strains, six out of eight serotypes did not coincide each other. These results indicate that the Lior method is unrelated with the Penner method in the serotyping of C. jejuni.

[The evaluation of serum estradiol, progesterone, testosterone concentrations and urinary estrogen excretion level for the monitoring indices of follicular maturation]

We have evaluated serum estradiol, progesterone, testosterone, and urinary estrogen excretion in 24 hour urine samples to monitor indices of follicular maturation. The serum steroid levels were determined with the direct radioimmunoassay kit. The urinary estrogen level was measured with the estrogen micrometering kit using hemagglutination inhibition reaction. Moreover, relationships between these steroid levels and the follicular size measured with ultrasound were analyzed. The serum estradiol concentration and the estrogen excretion in 24 hour urine samples mostly showed a continuous increase during the late follicular phase, and had a positive correlation to the maximum follicular diameter of the leading follicle (MxFD) and to the total of the maximum diameter of the follicles (TFD). The serum progesterone concentration showed a remarkable increase especially on the day of the LH surge onset in many cases, and had a significant (p less than 0.01) correlation to MxFD but not to TFD. The serum testosterone concentration, however, showed neither a specific tendency on its daily change nor a correlation with the follicular size. These results indicated that the serum estradiol and progesterone, and the urinary estrogen excretion can be utilized as indices of follicular maturation.