Isolation and characterization of a potentially virulent species Entamoeba nuttalli from captive Japanese macaques

H. Tachibana, T. Yanagi, A. Akatsuka, S. Kobayashi, H. Kanbara, V. Tsutsumi

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


We have recently proposed revival of the name Entamoeba nuttalliCastellani, 1908 for a virulent amoeba (P19-061405 strain) isolated from a rhesus monkey (Macaca mulatta) and located phylogenetically between E. histolytica and E. dispar. In this study, E. nuttalli was isolated from feces of captive Japanese macaques (M. fuscata) in an open-air corral in Japan. The sequence of the 18S rRNA gene in the isolates differed from the P19-061405 strain in 2 nucleotide positions, but was identical to the EHMfas1 strain isolated previously from a cynomolgus monkey (M. fascicularis). One of the E. nuttalli isolates from Japanese macaques, named the NASA6 strain, was axenized and cloned. In isoenzyme analysis, the mobilities of hexokinase and phosphate glucose isomerase in the NASA6 strain were identical to those in the P19-061405 and EHMfas1 strains, but the mobility of phosphoglucomutase was different. These results were supported by gene analyses of these enzymes. Inoculation of NASA6 strain trophozoites into the liver of hamsters led to formation of an amoebic liver abscess. The liver lesions were characterized by extensive necrosis associated with inflammatory reactions. These results demonstrate that the NASA6 strain is potentially virulent and that E. nuttalli should be recognized as a common parasite in macaques.

Original languageEnglish
Pages (from-to)1169-1177
Number of pages9
Issue number10
Publication statusPublished - 2009 Sept
Externally publishedYes


  • 18S rRNA gene
  • Entamoeba nuttalli
  • Japanese macaque
  • Virulency
  • Zymodeme

ASJC Scopus subject areas

  • Parasitology
  • Animal Science and Zoology
  • Infectious Diseases


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