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Inactivation of Bombyx mori macula-like virus under physical conditions
Kodai Uchiyama1, Hirofumi Fujimoto2, Susumu Katsuma3
1Department of Agrobiology and Bioresources, Faculty of Agriculture, Utsunomiya University, Mine-machi 350, Utsunomiya-shi, Tochigi, 321-8505, Japan.
Abstract:
The Bombyx mori macula-like virus (BmMLV) is a member of the genus Maculavirus, family Tymoviridae, and contains a positive-sense single-stranded RNA genome. Previously, we reported that almost all B. mori-derived cell lines have already been contaminated with BmMLV via an unknown infection route. Since B. mori-derived cell lines are used for the baculovirus expression vector system, the invasion of BmMLV will cause a serious safety risk in the production of recombinant proteins. In this study, to determine the inactivation effectiveness of BmMLV, viruses were treated with various temperatures as well as gamma and ultraviolet (UV) light radiation. After these treatments, the virus solutions were inoculated into BmMLV-free BmVF cells. At 7 days postinoculation, the amount of virus in cells was evaluated by real-time reverse transcription PCR. Regarding heat treatment, conditions under 56°C for 3 h were tolerated, whereas infectivity disappeared after treatment at 75°C for 1 h. Regarding gamma radiation treatment, viruses were relatively stable at 1 kGy; however, their infectivity was entirely eliminated at a dose of 10 kGy. With 254 nm UV-C treatment, viruses were still active at less than 120 mJ/cm(2); however, their infectivity was completely lost at greater than 140 mJ/cm(2) UV-C radiation. These results provide quantitative evidence of the potential for BmMLV inactivation under a variety of physical conditions.
Insights
Bombyx mori macula-like virus (BmMLV) inactivation was studied using heat, gamma, and UV radiation. BmMLV infectivity was eliminated by 75°C for 1 hour, 10 kGy gamma radiation, or >140 mJ/cm² UV-C light.
Area of Science:
- Virology
- Molecular Biology
- Biotechnology
Background:
- Bombyx mori macula-like virus (BmMLV), a Maculavirus, contaminates B. mori cell lines.
- BmMLV contamination poses a significant safety risk to recombinant protein production using baculovirus expression systems.
Purpose of the Study:
- To determine the inactivation effectiveness of BmMLV using physical treatments.
- To establish quantitative parameters for BmMLV inactivation.
Main Methods:
- BmMLV was subjected to various temperatures (up to 75°C), gamma radiation (up to 10 kGy), and UV-C light (254 nm, up to 140 mJ/cm²).
- Inactivation effectiveness was assessed by inoculating treated virus solutions into BmMLV-free BmVF cells.
- Viral load was quantified using real-time reverse transcription PCR at 7 days post-inoculation.
Main Results:
- Heat treatment at 75°C for 1 hour inactivated BmMLV.
- Gamma radiation at 10 kGy completely eliminated BmMLV infectivity.
- UV-C radiation above 140 mJ/cm² was effective in completely inactivating the virus.
Conclusions:
- Physical treatments including heat, gamma radiation, and UV-C light can effectively inactivate Bombyx mori macula-like virus.
- Quantitative data on inactivation parameters are provided, crucial for ensuring safety in biotechnological applications.
