Continuous culture of Vairimorpha sp. NIS M12 (microsporida: Protozoa) in insect cell lines

Spores of Vairimorpha sp. NIS M12 were primed in 0.1 N KOH solution at 27°C for 40 min and were mixed with insect cells suspended in Rinaldini's solution. As host cells 4 lepidopteran cell lines (Antheraea eucalypti, Bombyx mori SES-BoMo-15A, Spodoptera exigua Se3FH and Spodoptera frugiperda IPLB-Sf21AE II) were used. Low osmolarity of Rinaldini's solution caused a rapid decrease of cell population 24 hr post-inoculation, and the initial level of cell infection rate was about 7% when a moderate spore/cell ratio of 1:30 was employed. Growth and development of the Vairimorpha sp. showed similar patterns in A. eucalypti and S. exigua Se3FH cell cultures. In B. mori SES-BoMo-15A and S. frugiperda IPLB-Sf21AE II cell cultures, the growth rates of the Vairimorpha sp. were lower than those in A. eucalypti and S. exigua Se3FH cell cultures. After several passages of the infected cell cultures at 27°C, the persistent infection of the Vairimorpha sp. was maintained only in the S. frugiperda IPLB-Sf21AE II cell line.