Vairimorpha necatrix: Infectivity for and development in a lepidopteran cell line

Timothy J. Kurtti, Ulrike G. Munderloh, Hiroaki Noda

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17 Scopus citations


Vairimorpha necatrix infected and replicated in the Heliothis zea cell line HZBCIRLAM1. Spores were purified from caterpillars by Percoll density gradient centrifugation. After priming with 0.01 n KOH in 0.17 m KCl, the spores were mixed with H. zea cells suspended in Tris-HCl (pH 8) containing 0.17 m KCl, and EDTA as a chelator. Infected cells were cultured at 28°C in L-15B medium with 5% serum. Sporoplasms and early stages were noted in cells stained with Giemsa's solution within the first 24 hr post-infection (pi). The sporoplasms developed into bipolar meronts but did not divide during this time. Using 5 to 10 spores per cell, we initially infected 23.64 ± 4.27% of the cells in three duplicate studies. Three-fourths of the infected cells harbored a single sporoplasm, and the remainder were infected with two to four parasites each. The proportion of infected cells rose to 36.03 ± 7.02% during the first 2 to 4 days, and after 1 week, meronts were rarely seen. Between day 1 and 3 pi V. necatrix multiplied with a doubling time of 8 to 12 hr. Three to 4 days pi, V. necatrix sporonts were seen and by 6 days pi mature spores developed. Within the first 4 days of culture, large multinucleated syncytia formed by cell fusion. The number of host cell nuclei in syncytia correlated with the number of V. necatrix; those with 3 to 5 H. zea nuclei and 20 to 40 V. necatrix were most common. There was considerable asynchrony in parasite development and variability in the number of V. necatrix per host cell.

Original languageEnglish (US)
Pages (from-to)61-68
Number of pages8
JournalJournal of Invertebrate Pathology
Issue number1
StatePublished - Jan 1990

Bibliographical note

Funding Information:
This is paper number 16,732, Scientific Journal Series, Minnesota Agricultural Experiment Station, St. Paul, Minnesota. This work was supported in part by a grant from the Legislative Commission on Minnesota Resources, the Minnesota Agricultural Experiment Station, and by “Special Coordination Funds for Promoting Science and Technology” granted to H.N. by the Japanese Government.


  • Heliothis zea
  • Lepidoptera
  • Microsporida
  • Noctuidae
  • Nosematidae
  • Vairimorpha necatrix
  • cell fusion
  • cell line
  • corn ear worm
  • gradient purification
  • in vitro replication


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