Expression of S protein in insect larvae
R. nu larvae were from AgIdea (Pergamino, Argentina). They were reared in trays at 23–25 °C in a 70% humidified chamber, with a 16:8 light:dark photoperiod, and fed a high wheat-germ diet until they reached their fifth instar (20 days of age) prepared by AgIdea (Pergamino, Argentina). For all the experiments, batches of 500 fifth-instar larvae were injected with 50 µL of the recombinant baculovirus stock (diluted to 1×107 PFU mL−1) near the third prolegs, as shown in Figure 2. To characterize and quantify the recombinant protein produced, larvae that were alive and fluorescent under UV light were harvested at day 4 post-infection and frozen immediately at −80 °C until they were processed for analysis. Larvae infected with a non-related recombinant baculovirus were included as the control.