On the role of baculovirus photolyases in DNA repair upon UV damage of occlusion bodies

The use of baculoviruses in insect biocontrol is hampered by their sensitivity to ultraviolet (UV) light. This irradiation induces cyclobutane pyrimidine dimers (CPDs) in DNA. CPD-photolyases repair CPDs using visible light. Plusiine baculoviruses encode photolyases, which could potentially repair UV-damage prior to infection of larvae. Whether the photolyases encoded by Chrysodeixis chalcites nucleoplyhedrovirus are involved in UV damage repair was tested by infecting larvae with UV-irradiated viral occlusion bodies (OBs) that were subsequently treated with visible light or kept in the dark. The observed mortality was the same for both treatments. We postulate that photolyases are not active as DNA repair enzymes in OBs, but may play a role in other aspects of baculovirus pathogenesis.