Co-infection of Manduca sexta larvae with polydnavirus from Cotesia congregata increases susceptibility to fatal infection by Autographa californica M Nucleopolyhedrovirus

Abstract

We investigated pathogenesis of Autographa californica M Nucleopolyhedrovirus in the semipermissive host, Manduca sexta, using a lacZ recombinant virus (AcMNPV-hsp70/lacZ) to track the temporal progression of infection. Results from time course studies monitoring infections initiated orally in fourth instars demonstrated that primary infection of midgut columnar cells began at 3 h post inoculation (hpi). We observed secondary infections in midgut-associated tracheae as early as 9 hpi, showing that the early events of pathogenesis in M. sexta are similar to those of permissive noctuid larvae. In M. sexta, however, unlike in permissive hosts, hemocytes rapidly surrounded infected tracheal cells and formed capsules. Subsequently, baculovirus infections failed to spread and ultimately were cleared, suggesting that a cellular immune response had been triggered. To assess the effects of immunosuppression on baculovirus-induced disease, we compared the outcome of infections in immunocompetent hosts with those that were immunocompromised either by parasitization with the braconid, Cotesia congregata, or by injection of the parasitoid's polydnavirus. During the first 9 days after inoculation, parasitized and polydnavirus-inoculated M. sexta larvae died more quickly and at higher levels than nonparasitized and sham-injected controls, suggesting that the cellular immune response was a factor in conferring resistance to fatal infection by AcMNPV-hsp70/lacZ.

Journal

Title: Journal of Insect Physiology

Abbreviated Title: Journal of Insect Physiology

Publisher: Elsevier BV

ISSN (Print): 00221910

Publication date Created: February 2000

Publication date (Print): February 2000

Volume: 46

Issue: 2

Pages: 179-190

Article

DOI: 10.1016/S0022-1910(99)00115-8

PubMed ID: 12770250

SO-VID: 1743bec4-5a2a-4de2-b4a4-aed557caaa2d

Copyright statement: © 2000

License:

https://www.elsevier.com/tdm/userlicense/1.0/

Product

Self URI (article page): https://linkinghub.elsevier.com/retrieve/pii/S0022191099001158