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Sensitivity of Polyvoltine Thai Strains of Bombyx mori to a BmNPV Isolate From Mahasarakham
Siripuk Suraporn1, Olle Terenius2
1Department of Biology, Mahasarakham University, Thailand.
Abstract:
Virus infection by the Bombyx mori nucleopolyhedrovirus (BmNPV) is the most severe disease in Thai sericultural practice of polyvoltine silkworms. Here, we characterized a newly isolated BmNPV isolated from the Mahasarakham province in Thailand (BmNPV-MSU). The purity and morphology of BmNPV-MSU were examined using light microscopy and scanning electron microscopy. The polyhedral inclusion bodies (PIBs) of BmNPV-MSU appeared in tetragonal, hexagonal, octagonal, and globular forms. The virions were both single and multiple embedded as observed by transmission electron microscopy. We also determined the virulence of BmNPV-MSU for six different Thai polyvoltine strains by LC50 and time to death after infection. The LC50 values of Nang Lai, NK04, and Sam Rong strains were 5.05-1.52 × 107 PIBs per ml and mortality peaked 7- to 8-d after inoculation. For Nang Noi, SP2, and RE05 strains the LC50 values were 7.91-1.82 × 106 PIBs/ml and mortality peaked 4-5 d after inoculation, thus having lower chance of survival to infection by BmNPV-MSU.
Insights
A new Bombyx mori nucleopolyhedrovirus (BmNPV) strain from Thailand, BmNPV-MSU, was characterized. Different Thai silkworm strains showed varying susceptibility, with some experiencing higher mortality rates.
Area of Science:
- Virology
- Entomology
- Sericulture
Background:
- Bombyx mori nucleopolyhedrovirus (BmNPV) causes severe disease in Thai polyvoltine silkworms.
- Sericulture is economically important in Thailand, making silkworm disease management crucial.
Purpose of the Study:
- To characterize a newly isolated BmNPV strain (BmNPV-MSU) from Thailand.
- To determine the virulence of BmNPV-MSU against different Thai polyvoltine silkworm strains.
Main Methods:
- Isolation and characterization of BmNPV-MSU using light, scanning electron, and transmission electron microscopy.
- Determination of LC50 values and time to death for six Thai polyvoltine silkworm strains after BmNPV-MSU infection.
Main Results:
- BmNPV-MSU polyhedral inclusion bodies (PIBs) exhibited diverse morphological forms (tetragonal, hexagonal, octagonal, globular).
- Virions were observed as single and multiple embedded.
- Thai silkworm strains Nang Lai, NK04, and Sam Rong had LC50 values of 5.05-1.52 × 107 PIBs/ml, with mortality peaking 7-8 days post-inoculation.
- Strains Nang Noi, SP2, and RE05 showed lower LC50 values (7.91-1.82 × 106 PIBs/ml) and higher mortality rates (4-5 days post-inoculation), indicating reduced survival.
Conclusions:
- The characterized BmNPV-MSU strain exhibits virulence against Thai polyvoltine silkworms.
- Significant differences in susceptibility exist among Thai silkworm strains, impacting survival rates.
- Understanding strain-specific virulence is vital for managing BmNPV in Thai sericulture.
