Produção in vitro dos baculovírus Anticarsia e Chrysodeixis em células Sf21

Abstract

Soybean [Glycine max (L.) Merril] is one of the most important cultivars for humanity, being responsible for supplying half of the world demand for proteins and vegetable oils. The Brazil is considered the largest soybean exporter in the world, accounting for a third of all its world production. However, soybean cultivation in Brazil is constantly threatened by pests, which jeopardize the productivity of this plant, with insect pests being the main cause of damage. The most common method of pest control used in Brazil is the use of chemical pesticides, however, these chemicals have impacts on human health and the environment, which demonstrates the need to develop alternative and sustainable pest control methods. The insects Anticarsia gemmatalis (Hübner, 1818) (Lepidoptera: Erebidae) and Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae) are the defoliating pests responsible for damage to soybean plantations not only in Brazil, but throughout the western hemisphere, being its control is difficult to perform, especially when considering the caterpillar of C. includens, which is resistant to commonly used chemical insecticides. Faced with this problem, occlusion bodies (OB) of baculoviruses, a family of viruses that specifically infect insects, can be used as an alternative biological control method for these pests, since they are specific to their host insects, not representing risks. to the environment or to humans. This, the present work aimed at the in vitro production of the baculovirus Anticarsia gemmatalis multiple nucleopolyhedrovirus (AgMNPV) and Chrysodeixis includens single nucleopolyhedrovirus (ChinSNPV), using cells from the insect Spodoptera frugiperda, cell line Sf21, which were adapted to suspension culture without fetal bovine serum. For baculovirus production, cells were adapted for suspension culture with SF900II medium, using Erlenmeyer flasks in a shaker under controlled conditions of 120 rpm and 28oC (±2oC), and infected with two different viral phenotypes: extracellular virus (BV) and occlusion-derived virus (ODV) AgMNPV and ChinSNPV, individually and simultaneously. Samples were taken every 24 hours to determine viability, cell concentration and occlusion bodies (OB). Using the BV of AgMNPV (from the second pass) a maximum volumetric production of 1.38x107 OB/mL was obtained at the end of the process. This production was lower when observing the production of OB from ODV (2.8x107OB/mL). It can be inferred that the ODV viral particle extracted from the in vitro process provided a greater supply of OBs, contributing to the production of AgMNPV. With the ChinSNPV BV, the maximum volumetric production of OB was 1.34x107OB/mL. The result obtained from ODV infection of ChinSNPV was a final concentration of 6.01 x 106 OB/mL. Therefore, it is concluded that the two virus phenotypes (BV and ODV) are infective in suspension cultured Sf21 cells.