ARS | Publication request: Characterization of a novel cypovirus isolated from the bilobed looper, Autographa biloba

Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 31, 2012
Publication Date: June 14, 2012
Citation: Breitenbach, J.E., Popham, H.J. 2012. Characterization of a novel cypovirus isolated from the bilobed looper, Autographa biloba [abstract]. American Society for Virology Meeting. p. 113.

Technical Abstract: Cypoviruses are non-enveloped arthropod-specific viruses of the family Reoviridae with a segmented, double-stranded RNA genome and a number have been confirmed to circulate in populations of mosquito and moth species. Cypoviruses complete their replication cycle exclusively in the cellular cytoplasm by extruding mRNA and daughter genomes from conserved “turret” structures in their capsids. A high percentage of field-isolated bilobed loopers (Autographa biloba) from the Rolla, Missouri area of the U.S. that were lethally infected with the baculovirus Anagrapha falcifera multicapsid nucleopolyhedrovirus (AfMNPV) were also found to be co-infected with a novel cypovirus. Occlusion bodies containing polyhedra of both the cypovirus and the baculovirus were recovered from experimentally infected larvae. Chemical liberation of viral capsids from occlusion bodies followed by proteinase K digestion yielded a mixture of DNA and RNA species: a high molecular weight DNA band corresponding to the baculovirus genome and a ten-segmented dsRNA cypovirus genome as determined by RNAse sensitivity and stability in the presence of DNAse I. Further analysis revealed that the ten segments consisted of 0.5 to 4.5k base-pair bands, comprising a total genome size of approximately 22kb. Interestingly, co-infection of larvae infected with a mixture of the baculovirus and cypovirus did not result in extensive differences in mortality compared to infection with analogous preparations containing baculovirus alone. Taken together, these data indicate that co-infection of loopers with baculovirus and cypovirus is a natural occurrence in wild populations inhabiting the subject geographical area. Complete genomic sequencing of this cypovirus and further studies on its interactions with baculoviruses will yield new insights into the pathogen-host interplay in the field and possibly new tools for use in crop protection strategies.