Establishment, Growth kinetics, and Susceptibility to AcMNPV of Heat Tolerant Lepidopteran Cell Lines

Lepidopteran heat-tolerant (ht) cell lines have been obtained with sf-9, sf-21 and several Bombyx cells. They have a distinct karyotype, membrane lipid composition, morphology and growth kinetics from the parental cell lines. In this paper, we report the development of ht cell lines from other insect species and examination of their growth characteristics and virus susceptibility. Adaptation of cell lines sf-9, BTI-TN-5B1-4 (High5) and BTI-TN-MG1 (MG1) to 33℃ and 35℃ was carried out by shifting the culture temperature between 28℃ and higher temperatures by a gradual stepwise increase in temperature. The process of adaption to a higher culture temperature was accomplished over a period of 2 months. The cell lines with the temperature adaption were designated as sf9-ht33, sf9-ht35, High5-ht33, High5-ht35, MG1-ht33, MG1-ht35. These cell lines have been subcultured over 70 passages. Adaption to high temperatures was confirmed by a constant population doubling time with individual cell lines. The population doubling time of heat adapted cell lines were 1-4 h less than these of parental cell lines. Cell shapes did not show obvious change, however, the cell size of sf9-ht cells was enlarged and those of High5 and MG1 ht cells were reduced after heat adaption. When the cell lines were infected with Autographa californica nuclear polyhedrosis virus (AcMNPV) at 28℃, 33℃, 35℃ and 37℃, production of budded virus and occlusion bodies in each cell line was optimum at its own adapted temperature.

Generation and characterization of a novel ovariole cell line derived from Spodoptera frugiperda in China with sensitivity to both SfMNPV and AcMNPV

Spodoptera frugiperda multiple nucleopolyhedrovirus(SfMNPV),belonging to the species Alphabaculovirus spofrugiperdae,has been recently registered as an insecticide in China.This virus has a specific effect on the global major agricultural pest Spodoptera frugiperda.To gain insights into viral infection,replication processes,and the complex formation of viral particles,in vitro studies using cell lines are essential tools.Although the IPLB-Sf9 and IPLB-Sf21 cell lines derived from S.frugiperda are widely used for studies on the infection and replication mechanisms of Autographa californica multiple nucleopolyhedrovirus(AcMNPV),their capacity to produce viral polyhedra after SfMNPV infection is not optimal.To address this limitation,a novel cell line named IOZCAS-Sf-1 was developed from a S.frugiperda population in Yunnan,China.The mitochondrial COX1 gene analysis confirmed the species origin of the IOZCAS-Sf-1 cell line.Furthermore,a comparative study was carried out to contrast the COX1 gene sequence of this novel cell line with that of IPLB-Sf9,highlighting the distinctions between the two.Importantly,the IOZCAS-Sf-1 cells exhibited a remarkable ability to generate polyhedra when infected with AcMNPV and SfMNPV,respectively.Consequently,this cellular lineage is considered a promising and valuable resource.It serves not only to investigate the molecular mechanisms of viral replication and its impact on host cells,but also to explore the transfection efficiency of SfMNPV DNA.This exploration further expands into its potential application in recombinant DNA experiments,laying a theoretical groundwork for the advancement of more effective biopesticides and sustainable agricultural practices.