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A semipermissive nuclear polyhedrosis virus infection: characterization of infection kinetics and morphogenesis

W M Carpenter1, S L Bilimoria

  • 1Department of Biological Sciences, Texas Tech University, Lubbock, Texas 79409, USA.

Virology
|October 15, 1983
PubMed

Insights

A new in vitro system (System II) studied Spodoptera frugiperda multicapsid nucleopolyhedrovirus (SF-MNPV) infection in different cells. SF-MNPV replication was significantly restricted in Trichoplusia ni cells, indicating a block in early virus development.

Area of Science:

  • Virology
  • Cell Biology
  • Insect Pathology

Background:

  • The Spodoptera frugiperda multicapsid nucleopolyhedrovirus (SF-MNPV) is an important insect pathogen.
  • Understanding its host range and replication dynamics is crucial for developing effective biocontrol strategies.
  • Previous studies have indicated variability in SF-MNPV infection efficiency across different insect cell lines.

Purpose of the Study:

  • To establish and characterize an in vitro host-range model system (System II) for SF-MNPV.
  • To investigate the infection kinetics and viral morphogenesis of SF-MNPV in a permissive (S. frugiperda) and a semipermissive (T. ni) cell system.
  • To identify potential restriction points in the SF-MNPV replication cycle within semipermissive cells.

Main Methods:

  • Development of System II using SF-MNPV-infected Spodoptera frugiperda (permissive) and Trichoplusia ni (semipermissive) cells.
  • Infection kinetic studies to quantify infectious virus yield.
  • Electron microscopy to examine viral morphogenesis and cellular alterations.

Main Results:

  • Infection kinetic studies showed a 700-fold lower infectious virus yield in the semipermissive T. ni cells compared to controls.
  • Electron microscopy revealed that the majority of progeny nucleocapsids in T. ni cells were unenveloped.
  • Only 5% of infected T. ni cells contained enveloped virions, while 95% displayed cytopathic effects and virogenic stroma.

Conclusions:

  • System II effectively models SF-MNPV host-range restriction in vitro.
  • SF-MNPV infection in T. ni cells is significantly restricted at or before early stages of virion morphogenesis.
  • The findings suggest a critical block in nucleocapsid envelopment and/or egress in semipermissive cells.

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