Bracovirus

The Bracovirus bracovirus is an ancient symbiotic virus contained in parasitic braconoid wasps that evolved off of the nudivirus about 190 million years ago and has been evolving at least 100 million years.^[1] It is one of two genera belonging to the Polydnaviridae family, Ichnovirus being the other genus. The virus is also one of the rare instances where there is a mutual relationship through symbiosis involving a virus and eukaryote. The virus itself is contained within tens of thousands wasps but one example wasps that has been studied is the Cotesia congregata the studies conducted on this species have shown that male wasps do contain proviral sequences of DNA but the females are the ones responsible for the amplification of the DNA so the males do contain the virus only they are used as controls while the females are the ones that actually produce the particles of the virus.^[2]

Virus

The genome of the virus is enveloped with 35 double stranded DNA (dsDNA) all of which are circular.^[3] The replication of the Bracovirus occurs within the ovaries of a parasitic wasps in calyx cells and is maintained by vertical transmission and to go into further detail the packaged genome of dsDNA is replicated inside of the wasp ovaries by development of the sequences of the virus from proviral segments in the tandem arrays in the wasp genome. The development of the sequences of bracovirus shows head-to-head and tail-to-tail sequences, which is unexpected, considering it is a spin-off and has evolved from the nudivirus ^[4] The research conducted on the Cortesia congregata shows that the viral genome contains one to three proviral segments.^[5]

Transmission

The virus is transmitted into and infects and manipulates the physiology of a lepidopteran host (caterpillar) so that it can be used as a living incubator for wasp larvae. When this happens the virus poisons the caterpillars immune system causing paralysis and inhibts the pupating of the host. The arresting of the host aids in the success of developing wasp larva to ensure the survival of the wasp species.^[6]

References