Insect Viruses and Immune Responses to Venom Proteins

27 Jul 2011

Dr. Sassan Asgari, in the School of Biological Sciences at the University of Queensland is studying insect viruses and their uses in biological control, as well as the function of venom proteins from parasitoid wasps and how they affect insect immune systems.

There are a variety of viruses that cause fatal diseases in insects. These viruses can potentially be used as biological control agents against insect pests. For example, baculoviruses are commercially produced and used in the field against a variety of pests (e.g. the cotton bollworm). Sassan Asgari’s main research focus is investigating the interaction of these pathogenic viruses with their host insects. How do these viruses replicate in their insect hosts? What factors (genes) from the viruses are responsible for the pathogenicity in insects? Do insects defend themselves against these viral infections and can we break these defence mechanisms by genetically modifying the viruses to be more efficient in destroying the pests? Discoveries made by one of his PhD students, Mazhar Hussain, indicate the role of very small molecules (ribonucleic acids in origin) produced both by viruses and host cells in host-virus interactions, e.g. host cell’s defence against viral infection.

Parasitoid wasps introduce a variety of components into the body of their host insect during oviposition, which guarantee successful development of the wasp progeny inside the host. Another aspect of Asgari’s research is exploring the function of venom proteins from parasitoid wasps in host-parasite interactions. His research in the past few years has shown that venom components can interfere with insect host immune responses. This means that the parasitoid egg can escape host immune defence responses. Recently, one of his PhD students, Pune Thomas, generated a genetically modified fruit fly, Drosophila melanogaster, that produces a venom protein from a parasitoid wasp. His investigations on the flies showed that the genetically modified flies have a reduced immune system and are more susceptible to fungal pathogens. Studying these parasitoid factors may help us to understand how immune system in insects works and how we may be able to manipulate their immune system to make them vulnerable to biological control agents.