Selection And Screening Of Clonal Isolates Of Higher Violence Mythimna Separata Nuclear Polyhedrosis Virus In A Homologous Embryonated Egg Cell Line

This paper reports clonal isolates of higher violence Mythimna separata nuclear polyhedrosis virus in a homologous embryonated egg cefl line (Ms-927311) selected by plaque purification. Two clones C: C4 were selected for further evalution in vivo and in vitro. The corrected mortality of the clones C2. C4 were 85. 72%. 82. 14% by neonate bioassay respectively. They were 1. 2 and 1. 15 times of that of virus in vitro. In the experiment of further neonate bioassay. The clones C2. C4. wild virus and virus in vivo were conducted, the mean lethal concentration for 50% of the test insect (LC50) for them ranged from 2. 301 X i0 PIB/mL 2. 465 X io PIB/mL.. 7. 402 >C io PIB/mL7. 579X io PIB/mL. These figures showed the clones C2.C4 had higher vio- lence for neonates of Mythimna separata. The titer of serial passage of non occluded virus of the clones C2 C4 in Ms-927311 cell line were: C:: 2. 685 X io TCID50/ mL, 3. 162 X io TCID22/mL, 3. 724 X i0 TCID30/mL. C4: 2. 512X105 TCID50/mL.2. 754Xl0s TCIDso/mL2. 371X10 TCID50/ mL. They were all higher than that of the 3rd passage of NOV. The infective concentration of cell of the clones C2..C4 were 51. 68% 49. 87%. They were 1. 05 and 1. 02 times of that of the 3rd passage virus. They yield of polyhedra in- clusion bodies of the clones C2 C4 were 35. 4 PIB/mL. 28. 6 PIB/mL. They were 1. 29 and 1. 04 times of that of the 3rd passage virus. The titer of wild virus was 1. 774 X i0 TCID50/mL but the titer of three serial pas- sages of NOV were 1. 469 X 10 TCIDso/mL~ 1. 585 X i0 TCID5o/mL 1. 932 >1O TCID50/mL. The 3rd passage of NOV were 1. 08 times of that of wild virus. All the above revealed the clones C2 C4 had the advantages of the 3rd passage virus and virus in vivo over titer.LC5o infectivity and yield of polyhedra inclusion bodies. Postgraduate: Wang Yan Major: Entomology Supervisor: Prof. LI Guoxun...