Lack of significant association between rosette formation and parasitized erythrocyte adherence to purified CD36.

The ability of Plasmodium falciparum infected erythrocytes from 162 Thai patients with uncomplicated malaria, 82 patients with severe malaria and 19 patients with cerebral malaria to form rosettes in vitro was studied. Of 263 isolates, 62 were evaluated for their adherence to different target molecules. We found that wide variation occurred in isolates from all groups in the level of rosette formation and adherence to CD36, intracellular adhesion molecule-1, thrombospondin and chondroitin sulfate A. No statistically significant correlation between the magnitude of rosette formation and disease severity was found (p > 0.05). In addition, our results from the use of purified CD36 as an adherence receptor showed no association between the degree rosetting and level of cytoadherence (p > 0.05, r = -0.04). Our data provide evidence that rosette formation and cytoadherence involve different molecular mechanisms and both phenomena can occur in all manifestations of the disease.

Production of monoclonal antibody specific to Campylobacter jejuni and its potential in diagnosis of Campylobacter enteritis.

A monoclonal antibody (MAb 3G6) specific for Campylobacter jejuni and Campylobacter coli was produced by immunizing BALB/c mice with a local strain of C.jejuni (28.1). No cross-reactivity was observed with Enterobacteriaceae controls. By immunoprecipitation, MAb 3G6 identified a major protein band of molecular weight 45 kDa and also gave a slight reactivity with 30 and 55 kDa proteins. Using an indirect enzyme-linked immunosorbent assay, MAb 3G6 was able to detect C.jejuni suspended in stool without cross-reactivity to 14 other enteropathogenic bacteria suspended, normal flora in fecal suspension, or fecal debris. In the analysis of fifty clinical specimens, MAb 3G6 detected most positive samples with the exception of one which possessed very low Campylobacter concentration and gave no reactivity to negative samples, demonstrating its high specificity to C. jejuni and C. coli. MAb 3G6 may be suitable as a new tool for the development of diagnostic method for Campylobacter infection.

Molecular cloning and expression of Salmonella typhi flagellin: characterization of 52 kDa specific antigen of S. typhi.

We previously reported monoclonal antibodies (MAbs) specific to S. typhi 52 kDa antigen which do not cross react with related protein antigens from 11 bacteria causing enteric fever and enteric fever-like illness. Using the combination of these specific MAbs and recombinant DNA technology, expression plasmids containing the antigen gene producing substantial amount of the S. typhi protein antigen have been established. Plasmid pSKM-T7 containing the specific 52 kDa antigen gene was cloned and the antigen expressed was detectable by immunoblotting using specific mAbs. The complete nucleotide sequence of this gene was compared with other bacterial sequences and found to be highly homologous with the flagellin gene H1-d of S. muenchen except in the hypervariable region in the central portion. The specific 52 kDa antigen of S. typhi detected by our MAbs is thus a flagellin.