We have characterized @entity281 and pathogenesis of an @entity20422 californica M nucleopolyhedrovirus recombinant, @entity20422 -hsp70/lacZ, carrying the lacZ reporter gene, in penultimate (fifth) instar Spodoptera frugiperda. Bioassays revealed that while <0.1 p.f.u. of budded virus was required to generate an LD(50) by intrahaemocoelic injection, approximately 6000 occlusions were required orally to achieve the same mortality in newly moulted fifth instar (5(0)) larvae. In pathogenesis experiments, 78 % of the 5(0) larvae inoculated orally with 6000 occlusions of @entity20422 -hsp70/lacZ were LacZ-positive at 8 h post-inoculation (p.i.) and 50 % had LacZ signals in tracheal cells indicating that in these @entity281 had been transmitted from the midgut to secondary target cells. At 24 h p.i., maximum numbers of midgut and midgut-associated tracheal foci were observed (mean of 35 foci per infected larva), and 88 % of the larvae were LacZ-positive. The extremely low foci-per-occlusion ratio (0.006) indicated that successful @entity281 of midgut cells was the primary barrier to fatal @entity281 . A second barrier involved the loss of infected tracheal cells associated with the midgut. At 24 h p.i., 88 % of the inoculated larvae had a @entity281 , but in bioassays only 51 % succumbed to @entity66 . The absence of melanized tracheal cells in the insects throughout the time-course suggested that the larvae that cleared their infections (38 %) did so by a mechanism other than a classical immune response.

Pathogenesis of XXXX californica M nucleopolyhedrovirus in fifth instar Spodoptera frugiperda.

@entity281 :: ('MESH:D007239', 'Disease') :: ['larvae infection', 'infection', 'systemic infection'] @entity66 :: ('MESH:D004194', 'Disease') :: ['polyhedrosis disease'] @entity20422 :: ('46015', 'Species') :: ['AcMNPV', 'Autographa']
@entity20422 :: (46015,Species) :: ['Autographa']
