Folia Parasitologica 55[2] 105-110 (2008) | DOI: 10.14411/fp.2008.014

Differences in viability and reactivity of actinospores of three myxozoan species upon ageing

Dennis Marc Kallert, Mansour El-Matbouli

Clinic for Fish and Reptiles, Faculty of Veterinary Medicine, University of Munich, Kaulbachstraße 37, D-80539 Munich, Germany

Little is known about the viability of myxozoan actinospore stages after harvest from laboratory cultures of infected oligochaete worms. The viability and reactivity of actinospores of three myxozoan species was evaluated after short-term storage at 4°C and 12°C. Two methods of determining actinospore viability were compared: differential fluorescent staining and direct microscopic observation of morphological indicators of spore integrity. Spore reactivity was quantified by measuring polar filament discharge rates in a micro-assay with fish mucus substrate and mechanical stimulation by vibration. The age-dependent viability of the three species showed clear differences. Myxobolus cerebralis actinospores had the shortest effective life span whereas Henneguya nuesslini actinospores survived significantly longer. Storage at lower temperatures yielded higher viability in all species. Myxobolus pseudodispar actinospores were significantly robust up to 12°C when assessed by staining, but showed similar viability characteristics as H. nuesslini when analyzed morphologically. Evaluation of spore viability by fluorescent staining correlated with morphological assessment, although fewer viable actinospores were usually detected microscopically. Polar filament discharge activity of morphologically intact actinospores did not significantly decrease until the third day of storage compared to freshly harvested samples. The results indicate that durability and reactivity trends during storage of actinospores differ among myxozoan species.

Keywords: Myxozoa, Myxobolus cerebralis, Myxobolus pseudodispar, Henneguya nuesslini, viability, polar capsule discharge, actinospore, temperature, age, fluorescent staining

Received: February 13, 2008; Accepted: April 25, 2008; Published: June 1, 2008  Show citation