Establishment of a Method for Biosynthesizing Rare Vitamin Ds by Overexpressing the Neverland Protein in Silkworm (Bombyx mori) using Baculovirus

Vitamin D is a fat-soluble vitamin with physiological effects that vary depending on differences in its side chains. However, rare forms of vitamin D (D4-D7) are poorly distributed in nature, making them difficult to obtain. This study aimed to evaluate the potential of recombinant baculovirus-injected silkworms to synthesize rare forms of vitamin D. Using the silkworm baculovirus expression vector system (BEVS) to overexpress the Bombyx mori neverland (BmNvd) protein, we detected provitamins D3, D5, and D7 in these silkworms. We assessed the synthesis of vitamin D under two different ultraviolet (UV) exposure conditions and identified the synthesized vitamins D3, D5, and D7 using gas chromatography-mass spectrometry (GC-MS) analysis. Silkworms achieved a maximum of 6910.81 ± 400.98 μg/100 g of vitamin D3, with vitamin D5 and D7 levels of 1653.57 ± 102.98 and 243.22 ± 19.78 μg/100 g, respectively. The results demonstrated the potential of silkworms to synthesize vitamin D3 and other rare forms of vitamin D, offering a new perspective on insects as viable sources of rare vitamin D.