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Replication of a Mamestra brassicae nuclear polyhedrosis virus in a newly established Mamestra brassicae cell line
1Institute of Biological Control, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Abstract:
A continuous cell line, designated MbL-3, was newly established from minced neonate larvae of the cabbage armyworm, Mamestra brassicae. This new cell line is heteroploid, containing triploid cells predominantly at the frequency of about 50%. Doubling time of the cell population is 33 hrs. The Akutsu isolate of a Mamestra brassicae nuclear polyhedrosis virus (MbNPV) was examined for replication in 16 continuous cell lines, including the cell line MbL-3, from seven lepidoptera species: Mamestra brassicae, Pseudaletia separata, Spodoptera exigua, Spodoptera frugiperda, Spodoptera littoralis, Spodoptera litura and Plutella xylostella. Of these cell lines, only the MbL-3 cells supported a high replication of the virus. Four other Mamestra cell lines and a P. separata cell line showed a low virus-susceptibility, while the other cell lines were not permissive for the virus infection. Maximum infection rate of MbL-3 cells to the Akutsu isolate was 23.4%. The growth kinetics of this virus isolate in MbL-3 cells showed that the virus was released from infected cells 24 hrs p.i. and reached a maximal titer 96 hrs p.i. The number of polyhedral inclusion bodies (PIBs) reached a maximum of 10(7.5) PIBs/ml 120 hrs p.i.
Insights
A new continuous cell line, MbL-3, derived from Mamestra brassicae, efficiently supports Mamestra brassicae nuclear polyhedrosis virus (MbNPV) replication. This finding is crucial for lepidopteran virus research and pest control strategies.
Area of Science:
- Insect cell culture
- Virology
- Entomology
Background:
- Continuous insect cell lines are vital for studying insect viruses.
- Mamestra brassicae nuclear polyhedrosis virus (MbNPV) is a significant pathogen of lepidopteran pests.
- Evaluating virus replication across different cell lines is essential for understanding host-pathogen interactions.
Purpose of the Study:
- To establish and characterize a new continuous cell line from Mamestra brassicae.
- To assess the susceptibility of this new cell line, MbL-3, to Mamestra brassicae nuclear polyhedrosis virus (MbNPV).
- To compare the replication efficiency of MbNPV in MbL-3 cells with other lepidopteran cell lines.
Main Methods:
- Establishment of a continuous cell line (MbL-3) from Mamestra brassicae neonate larvae.
- Characterization of MbL-3 cell line properties, including ploidy and doubling time.
- Infection of 16 continuous cell lines from seven lepidopteran species with the Akutsu isolate of MbNPV.
- Quantification of virus replication, infection rate, and production of polyhedral inclusion bodies (PIBs).
Main Results:
- The MbL-3 cell line, predominantly triploid, was successfully established with a doubling time of 33 hours.
- MbL-3 cells demonstrated high susceptibility to the Akutsu isolate of MbNPV, supporting significant viral replication.
- Maximum infection rate reached 23.4%, with virus release starting at 24 hours post-infection and maximal titer at 96 hours.
- Peak polyhedral inclusion body (PIB) production reached 10(7.5) PIBs/ml at 120 hours post-infection.
Conclusions:
- The MbL-3 cell line is a highly permissive host for Mamestra brassicae nuclear polyhedrosis virus (MbNPV) replication.
- This cell line provides a valuable tool for studying MbNPV biology and for developing viral biocontrol agents against Mamestra brassicae.
- The differential susceptibility observed among cell lines highlights the importance of specific cell line selection for insect virus research.