Balamuthia mandrillaris: Staining Properties of Cysts and Trophozoites and the Effect of 2,6‐Dichlorobenzonitrile and Calcofluor White on Encystment

Abstract

Here, we determined the staining properties of Balamuthia mandrillaris cysts, and assessed the effect of 2, 6-dichlorobenzonitrile (DCB), a cellulose synthesis inhibitor, and calcofluor white, a brightening agent, on its encystment. Periodic acid-Schiff reagent stained the inner wall intensely and middle and outer walls weakly suggesting that the cyst wall of B. mandrillaris may contain glycans. Furthermore, cysts, but not trophozoites, fluoresced when stained with calcofluor white. Calcofluor white and DCB, a cellulose synthesis inhibitor, inhibited B. mandrillaris encystment. This is the first report suggesting possible glycan biosynthesis in B. mandrillaris encystment, and this pathwaymay provide a potentially useful drug target and help improve treatment.

Killing the Dead: Chemotherapeutic Strategies Against Free‐Living Cyst‐Forming Protists (Acanthamoeba sp. and Balamuthia mandrillaris)

“…In agreement with this, Periodic acid‐Schiff reagent stained the inner and outer walls, suggesting that the cyst wall of A. castellanii and B. mandrillaris contains glycans (Siddiqui et al. a). Furthermore, cysts of both protists fluoresced when stained with Calcofluor white.…”

“…; Siddiqui et al. a). Studies using lectins identified N ‐acetylglucosamine, mannose/glucose as major carbohydrate residues expressed on the surface of A. castellanii cysts (Elloway et al.…”

“…The linkage analysis showed B. mandrillaris cyst wall carbohydrates with apparently linear and branching saccharides (Table ) (Siddiqui et al. b). There was an interesting lack of amino sugars compared with G. intestinalis or Entamoeba invadens (Eichinger ; Gerwig et al.…”

“…) and B. mandrillaris (Siddiqui et al. b). Enzymes for the synthesis and breakdown of cellulose have been identified in A. castellanii (Anderson et al.…”

Potential Value of Cellulose Synthesis Inhibitors Combined With PHMB in the Treatment of Acanthamoeba Keratitis

“…12 Encystment of Balamuthia mandrillaris is inhibited by 2,6-dichlorobenzonitrile (DCB), a cellulose synthesis inhibitor used in numerous studies. 13 DCB also blocks encystation of Acanthamoeba and enhances the effect of the antiamebic drug pentamidine isethionate on Acanthamoeba keratitis (AK) isolates. 14 Isoxaben has previously been used in Arabidopsis thaliana for transcriptional profiling in response to inhibition of cellulose synthesis.…”