CONTINUOUS-CULTURE OF NOSEMA-MESNILI NM-HC-A8801 (MICROSPORIDA, NOSEMATIDAE) IN 4 LEPIDOPTERAN CELL-LINES

Spores of Nosema mesnili NM-HC-A8801 primed with 0.1 N KOH solution we re inoculated into four lepidopteran cell lines (Antheraea eucalypti, Spodoptera frugiperda SF21AEII, Bombyx mori BmN-4, and Trichoplusia ni hi5), and the microsporidian growth and spread of infection were inve stigated. Ar a ratio of 30 spores per cell, 3% to 5% of host cells wer e infected initially with sporoplasms at 1 h postinoculation. The numb er of the parasites in an infected cell started to increase at 24 h po st-inoculation, depending on the merogony of N. mesnili NM-HC-A8801. A t 48 h post-inoculation, when secondary infective forms appeared, rapi d increases were observed in the number of parasitized cells. The perc entage of infected cells at 120 h post-inoculation in the A. eucalypti , S. frugiperda SF21AEII, and B. mori BmN-4 cell lines reached approxi mately 90%, 60%, and 20%, respectively. Persistent infections of N. me snili NM-HC-A8801 could be maintained through several passages of thes e cell cultures. In particular, the A. eucalypti and S. frugiperda SF2 1AEII cell lines showed high compatibility with this microsporidium. O n the other hand, only 4% of T. ni hi5 cells were infected at 120 h po st-inoculation, and infected cells disappeared after the second passag e.