The Silver Lining in a

Black CloudRecurrent Domestication by Lepidoptera of Genes

from their parasites mediated by Bracoviruses

What is a bracovirus?- Mutualistic Virus associated with 1000’s of parasitic wasps- Produced in the wasp ovaries & injected into the host

larvae

- Integrate into Lepidopteran host cell DNA via HGT & act as gene transfer agent

- A specific bracovirus is associated with a particular species of parasitic wasp

Why is this interesting?1.HGT is being recognized as an important source of a species

acquiring a new novel trait from another species.

2.Integration of these viral genomes into host caterpillar DNA strongly suggests integration can randomly occur in germline leading to future lineages harboring the bracovirus sequences.

How could living Lepidoptera have Bracoviruses in them?

1.Parasitoid wasps also target non-host species, thus failing to interfere with their development.

2.Immune defense and integration of wasp viral circles into Lepitoptera germ cells and possibly genomes

Background Info→ Domestication of Bracoviruses

-Cotestia Congregata Bracovirus (CcBV)

a. Compared DNA sequences with 4 non-host Lepidoptera & 1 regular host Manduca Sexta

b. All 4 non hosts contained insertions with long nucleotide sequences with 90% matching identity to those of bracoviruses

Results: Proves that Bracoviruses have been a recurrent source of genes for Lepidoptera and functional analysis suggests that they might be conserved in their genome

Analysis of Danaus Plexippus genome ( Monarch)

What is a Ben gene?

a.Ben gene family, of 14 genes, is the 2nd most abundant insertion in CcBV.

b.The largest bracovirus proteins with lengths up to 1200 Amino Acids.

Analysis of Spodoptera Exigua genomes (Moth)

1.BV2-5: Member of a bracovirus-specific BV gene family ( BV-2) comprising 8 genes in CcBV

a. 7 sequences found in S. exigua with up to 90% nucleotide matching identity with bracovirus CcBV.

b. One of the most highly expressed genes in the haemocytes of regular host Manduca Sexta

2.Se-BLL2: “S. exigua Bracovirus-like lectin genes” a. Bracovirus genes encoding C type lectins originated from the wasp gene and

demonstrates a bracovirus mediated gene flux between Hymenoptera and Lepidoptera.

b. Moths give stronger evidence of HGT

Purpose of the fixation of Bracoviral genes?Hypothesis: Both could modify some features of the lepidopteran immune response resulting in an impact on other pathogens.

What is a Baculovirus?-Common and deadly pathogen in the insect (invertebrate) world that turns host into a liquid→ Biopesticide

-Typically caught when susceptible host feeds on contaminated plants

-Larval forms of moths are the most common hosts

-Transcription and Replication occur in the nucleus

-Actin Filaments mediate transport to the nucleus

Hypothesis 1: BV2-5 interferes with baculovirus motility in the cells and replication

Hypothesis #2: BV2-5 expression can impair multiplication of virus

Hypothesis#3: Se-BLL2 blocks baculovirus infection

Purpose of the fixation of Bracoviral genes?

Purpose of the fixation of Bracoviral genes?

In Conclusion….1.Bracovirus mediated gene flux has allowed for the Lepidoptera to

acquire these 2 genes: Se-BLL2 and BV2-5 that increase their immunity against the baculovirus

2.They are conserved in the Lepidopteran genome because of their survival advantages

References1.Gasmi L, Boulain H, Gauthier J, Hua-Van A, Musset C, Jakubowska A,

et al. (2015) Recurrent Domestication by Lepidoptera of Genes from Their Parasites Mediated by Bracoviruses PLoS Genet 11(9) :e1005470.doi:10.1371/journal.pgen.1005470

2.Thermo Fisher Scientific net. Actin Staining Protocol online.c2006.https://www.thermofisher.com/us/en/home/references/protocols/cell-and-tissue-analysis/microscopy-protocol/actin-staining-protocol.html#prot4

Any Questions?