In vitro host range of five baculoviruses in lepidopteran cell lines

Area of Science:

• Virology
• Insect Pathology
• Cell Biology

Background:

• Nuclear polyhedrosis viruses (NPVs) are significant pathogens of lepidopteran insects.
• Understanding the in vitro host range of NPVs is crucial for developing effective biocontrol strategies.
• Previous studies have indicated variability in NPV host specificity.

Purpose of the Study:

• To determine the in vitro host range of five different NPVs across five lepidopteran cell lines from three genera.
• To compare the replication efficiency of multiple-enveloped and single-enveloped NPVs in various cell lines.
• To investigate the cellular entry mechanisms of NPVs in susceptible and non-susceptible cell lines.

Main Methods:

• In vitro replication assays using five lepidopteran cell lines.
• Titration of viral progeny using TCID50 (50% tissue culture infectious dose).
• Detection of viral replication using a sensitive tritiated thymidine incorporation technique.
• Electron microscopy to observe viral particle entry and localization.

Main Results:

• Multiple-enveloped NPVs (ACMNPV, TNMNPV, GMMNPV) replicated in *T. ni*, *S. frugiperda*, and *H. virescens* cells (approx. 10^7 TCID50/ml).
• Single-enveloped HZSNPV replicated only in *H. zea* and *H. virescens* cells.
• *S. frugiperda* NPV (SFMNPV) replicated exclusively in *S. frugiperda* cells.
• ACMNPV showed limited replication in *H. zea* and *H. virescens*, confirmed by tritiated thymidine assays and electron microscopy showing cellular entry.

Conclusions:

• The in vitro host range of NPVs is virus- and cell line-specific.
• Multiple-enveloped NPVs generally exhibit a broader host range in vitro compared to single-enveloped NPVs.
• Cellular entry mechanisms, as observed with ACMNPV, play a role in determining NPV host range.