ancestral viruses for the two genera. BV has likely evolved from a nudivirus, specifically a betanudivirus, ~. IV has a less clear origin: although earlier reports finds a protein p44/p53 with structural similarities to ascovirus, the link was not confirmed in later studies. As a result, the current opinion is that IV originated from a yet-unidentified novel viral family, with weak link to the NCLDVs. In either case, both genera were formed through a single integration event in their respective wasp lineages. The two groups of viruses in the family are not in fact phylogenetically related suggesting that this taxon may need revision. Effect on host immunity In the host, several mechanisms of the insect immune system can be triggered when the wasp lays its eggs and when the parasitic wasp is developing. When a large body (wasp egg or small particle used experimentally) is introduced into an insect's body, the classic immune reaction is the encapsulation by the hematocytes. An encapsulated body can also be melanised in order to asphyxiate it, thanks to another type of hemocyte, which uses the phenoloxidase pathway to produce melanin. Small particles can be phagocytosed, and macrophage cells can then be also melanised in a nodule. Finally, insects can also respond with production of antiviral peptides. PolyDNAvirus protect the hymenopteran larvae from the host immune system, acting at different levels. First they can disable or destroy hematocytes. The polyDNAvirus associated with Cotesia rubecula, code for a protein CrV1 that denatures actin filaments in hematocytes, so those cells become less able to move and adhere to the larvae. Microplitis demolitor Bracovirus (MdBV) induce apoptosis of hematocytes, thanks to its gene PTP-H2. It also decreases the adhesion capacity of hematocytes, thanks to its gene Glc1.8. The gene also inhibits phagocytosis. PolyDNAvirus can also act on melanisation, MdBV interferes with the production of phenoloxidase. Finally, polyDNAvirus can also produce viral ankyrins, that interfere with production of antiviral peptides. In some Ichnoviruses, Vankyrin can also prevent apoptosis, the extreme reaction of a cell to block viral propagation. The Ichnoviruses produce some proteins called vinnexins which have been recognized as homologous to the innexins of insects. They are responsible for the encoding of the structural units of the gap-junctions. These proteins may alter the intercellular communication which could explain the disruption of the encapsidation process. Virus-like particles Another strategy used by parasitoid Hymenoptera to protect their offspring is production