Detection of Entamoeba histolytica in experimentally induced amoebic liver abscess:comparison of three staining methods

Objective:To compare the efficacy of three different tissue stains,namely haematoxylin and eosin(H&E),periodic-acid Schiff(PAS)and immunohistochemical(1HC)stains for detection of Entamoeba histolytica(E.histolytica)trophozoites in abscessed liver tissues of hamster.Methods:Amoebic liver abscess was experimentally induced in a hamster by injecting 1×10~6of axenically cultured virulent E.histolytica trophozoites(HM1-IMSS strain)into the portal vein.After a week post-inoculation,the hamster was sacrificed and the liver tissue sections were stained with H&E,PAS and IHC stains to delect the amoebic trophozoite.Results:The three stains revealed tissue necrosis and amoebic trophozoites,but with varying clarity.H&E and PAS stained the trophozoites pink and magenta,respectively,however it was difficult to differentiate the stained trophozoites from the macrophages because of their similarity in size and morphology.On the other hand,IHC stain revealed distinct brown appearance of the trophozoites in the infected liver tissues.Conclusions:It can be concluded that out of the three stains.IHC is the best for identification of E.histolytica trophozoites in tissue sections.

Entamoeba histolytica acetyl-CoA synthetase:biomarker of acute amoebic liver abscess

Objective:To characterize the Entamoeba histolytica(E.histolytica)antigen(s)recognized by moribound amoebic liver abscess hamsters.Methods:Crude soluble antigen of E.histolytica was probed with sera of moribund hamsters in 1D-and 2D-Westem blot analyses.The antigenic protein was then sent for tandem mass spectrometry analysis.The corresponding gene was cloned and expressed in Escherichia coli BL21-AI to produce the recombinant E.histolytica ADP-forming acetyl-CoA synthetase(EhACS)protein.A customised ELISA was developed to evaluate the sensitivity and specificity of the recombinant protein.Results:A^75 kDa protein band with a pl value of 5.91-6.5 was found to be antigenic;and not detected by sera of hamsters in the control group.Tandem mass spectrometry analysis revealed the protein to be the 77 kDa E.histolytica ADP-forming acetyl-CoA synthetase(EhACS).The customised ELISA results revealed 100%sensitivity and 100%specificity when tested against infected(n=31)and control group hamsters(n=5)serum samples,respectively.Conclusions:This rinding suggested the significant role of EhACS as a biomarker for moribund hamsters with acute amoebic liver abscess(ALA)infection.It is deemed pertinent that future studies explore the potential roles of EhACS in better understanding the pathogenesis of ALA;and in the development of vaccine and diagnostic tests to control ALA in human populations.