Enhancement In Activity Of Syngrapha Falcifera Multiple Nuclear Polyhedrosis Virus By Selected Optical Brighteners

The studies-were reported on the enhancement in activity of the Syngrapha falcifera multiple nuclear polyhedrosis virus (SfaMNPV), polyhedra derived virions (PDVs) that were released from OBs by alkaline treatment and the extracellular phenotype of the virus (ECV) by the selected optical brighteners Tinopal LPW, Tinopal UNPA-GX, VBL and CBS-X in this thesis. The results showed that these brighteners greatly enhanced the virulence of SfaMNPV OB, PDV and ECV.Studies were designed to determine the effect of the selected optical brighteners Tinopal LPW, VBL and CBS-X on the infectivity of the Syngrapha falcifera multiple nuclear polyhedrosis virus (SfaMNPV) . The viral preparations were diluted in either water or the optical brighteners (1%) and applied to the surface of artificial diet. The early third instar larvae of Helicover pa armigera were held individually on the treated diet for the duration of the assays (10 days).The addition of these optical brighteners to the virus in the bioassay greatly enhanced infectivity of the SfaMNPV. Addition of Tinopal LPW (1%) to the SfaMNPV reduced the LC50 values from 2.4x106 polyhedral inclusion bodies (PIB) per ml (1.2xl06-5.6xl06PIBs/ml , 95%CL) to l.lxlO4 PIBs/ml (4.8xl03-2.5xl04PIBs/ml, 95%CL) , and at the highest virus concentration (5.6xl07 PIBs/ml) , the LT50 values was reduced from 5.0d to 3.6d . Added with VBL, CBS-X (1%) , the LC50 values of SfaMNPV ranged from 2.58x106PIBs/ml (l.lxl06-5.1xl06PIBs/ml, 95% CL) to 8.03x104PIBs/ml(1.8xl04~2.2xl05PIBs/ml,95%CL) and to 9.82xl04PIBs/ml(2.2x104-2.6xl05PIBs/ml, 95%CL), and at the highest virus concentration 1.15xl08PIBs/ml, the LT50 values was reduced from 5.20d to 4.30d and to 4.52d, suggesting that the larvae of Helicover pa armigera died more quikly whenbrighteners were added to the virus.The optical brighteners both VBL and CBS-X also enhanced the activity of polyhedra derived virions (PDVs) that were released from OBs by alkaline treatment. When the virions after OB dissolution followed by dilution in water infected the early third Helicover pa armigera, the infectivity was very low or even no infectivity below 1.56xl05OBE/ml was detected. Only 36.17% larvae died at the highest concentration of 1.56xl09OBE/ml and no LC50 values could be obtained. Some activity was regained when these brighteners were added to these virions.The LC50 values was 7.72xl07OBE/ml when 1% VBL was added to the PDV and 5.56xl07OBE/ml when 1% CBS-X added.Additionally, the optical brighteners enhanced the virulence of the extracellular phenotype of the virus (ECV) in vitro when TCID50 values were tested. When ECV infected 5B1 cells , the TCID50 values of the ECV was 10~7314, whereas it was 10-8.375 when 5ug/ml VBL was added to the ECV and 1(T7906 when CBS-X added and 10-8.65J when Tinopal UNPA-GX added. The result of the TCID50 values showed that the selected optical brighteners greatly increased the ECV titers.