Zymogram patterns of Naegleria spp isolated from natural water sources in Taling Chan district, Bangkok.

A genetic approach was cited for species detection of the ameba genus Naegleria using allozyme electrophoresis to characterize the trophozoite stage of three strains of Naegleria fowleri isolated from patients with primary amebic meningoencephalitis, five thermophilic (45 degrees C) Naegleria spp isolated from natural water sources in the Taling Chan district, and a reference control strain, Naegleria fowleri CDC VO 3081. Isoenzymes of ameba whole-cell extracts were analyzed by vertical polyacrylamide slab gel electrophoresis to determine whether there was any correlation between different strains of the ameba. The results showed that five out of fifteen enzymes; aldehyde oxidase (ALDOX), aldolase (ALD), a-glycerophosphate dehydrogenase (a-GPDH), xanthine dehydrogenase (XDH), and glutamate oxaloacetate transaminase (GOT), were undetectable in the pathogenic strains, while the other enzymes; esterase (EST), fumerase (FUM), glucose-6-phosphate dehydrogenase (G-6-PDH), glucose phosphate isomerase (GPI), isocitate dehydrogenase (IDH), lactate dehydrogenase (LDH), leucine aminopeptidase (LAP), malic enzyme (ME), glucose phosphomutase (GPM), and malate dehydrogenase (MDH), were detected. Naegleria fowleri strains were biochemically the most homogeneous. They showed intraspecific isoenzyme variation that allowed them to be grouped. In contrast, the allozyme patterns (EST 1-7, IDH) of Naegleria spp isolated from the environment showed interspecific isoenzyme variations from the pathogenic Naegleria strain. In conclusion, this study recognized the zymograms of the Naegleria fowleri strains were heterogenically different from the thermophilic 45 degrees C Naegleria spp isolated from the environment.

Vaccine potential of 56-66 kDa protease secreted by Entamoeba histolytica.

Excretory/secretory (ES) antigens and sub-cellular fractions of E. histolytica (HM1:IMSS strain) were tested for the presence of common proteases using substrate gel electrophoresis. We obtained two E. histolytica proteases (56-66 kDa and 29 kDa) from ES material, soluble components and plasma membrane. Protease 56-66 kDa from ES antigen was selected for immunizing hamsters because it gave a consistent broad band. We observed 62.5 per cent protection in immunized animals, compared to 0 per cent in unimmunized controls. Although all vaccinated golden hamsters showed high antibody response, there was no correlation between antibody titres and protection. 56-66 kDa ES protease could thus prevent disease and could be a candidate molecular vaccine against amoebiasis.