Center for Infectious Disease and Vector Research

Events Calendar

CEPCEB Seminars BPSC 252

Brian A. Federici

Friday, May 24, 2013
Noon1 p.m.


Genomics Building , Genomics Auditorium 1102A
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Brian A. Federici
Department of Entomology and IIGB
University of California, Riverside


"Wasp/Viral Genome Integration Yields Novel Immunosuppressive
Organelles in Insects"


Endoparasitic wasps inject particles into their lepidopteran hosts that enable these parasitoids to evade or directly suppress their hosts’ innate immune response, especially encapsulation by hemocytes. For decades, these particles have been considered virions produced by DNA viruses known as polydnaviruses (family Polydnaviridae). Structurally, there are two main types of particles, those resembling, respectively, virions of baculoviruses or ascoviruses. These particles contain double-stranded DNA in the form of multiple small circular molecules that are transcribed but not replicated in cells of the lepidopteran hosts. Instead, particle DNA is replicated from the wasp genome and selectively amplified for packaging into the particles in the reproductive tract of female wasps. Once assembled and secreted, the particles become mixed with eggs, and injected into caterpillars during wasp oviposition. Particle DNA, referred to as the “viral genome,” has now been sequenced for several polydnaviruses. Annotation shows that most of this DNA consists of non-coding DNA or wasp genes, not viral genes. More significantly,recent studies have shown that particle structural proteins are of viral origin, but are coded for by the wasp genome, not by the putative “virion” genome. Together, these findings provide strong evidence that these particles originated from viruses, but through symbiogenesis (genome integration to form new organisms) followed by gene deletion and acquisition evolved into transducing organelles that shuttle wasp immunosuppressive genes into their hosts, thereby enhancing the survival of wasp progeny and species radiation.

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Institute for Integrative Genome Biology

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