Since insects vector many diseases of humans and animals, understanding the interactions between parasites and their insect hosts is an important area of study. The insect immune system plays an essential role in defending insects against invading organisms, and in large measure defines whether a given species is a suitable host for a given parasite or pathogen. Insect blood cells (hemocytes) often eliminate unicellular pathogens like bacteria by phagocytosis while multicellular, metazoan parasites are killed by encapsulation. Reciprocally, some pathogens and parasites avoid elimination by disrupting hemocyte function. Our previous studies revealed that the parasite Microplitis demolitor disrupts the encapsulation response of its host, Pseudoplusia includens, through the actions of a symbiotic virus called M. demolitor polydnavirus (MdPDV). MdPDV induces the apoptosis of one class of hemocytes in P. includens while rendering another class of blood cells incapable of adhering to the parasite. Based on these observations, we propose to identify the viral genes responsible for inducing these alterations in host hemocytes, and to characterize how the host immune system responds to viral infection.
Specific aims for this proposal are to characterize: 1) the MdPDV genes involved in induction of apoptosis and disruption of hemocyte adhesion; 2) how MdPDV interacts with the apoptotic pathway of host cells; 3) how MdPDV affects mediators of hemocyte adhesion, and; 4) how host hemocyte populations respond to parasitism and viral infection. Hemocyte effector functions are conserved across invertebrate taxa. What we learn in this study will provide important comparative information on the factors regulating anti-parasitic and anti-viral defenses in arthropods.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG5-TMP (01))
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Aultman, Kathryn S
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University of Wisconsin Madison
Schools of Earth Sciences/Natur
United States
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Harvey, Jeffrey A; Gols, Rieta; Strand, Michael R (2009) Intrinsic competition and its effects on the survival and development of three species of endoparasitoid wasps. Entomol Exp Appl 130:238-248
Kadash, K; Harvey, J A; Strand, M R (2003) Cross-protection experiments with parasitoids in the genus Microplitis (Hymenoptera: Braconidae) suggest a high level of specificity in their associated bracoviruses. J Insect Physiol 49:473-82
Lavine, M D; Strand, M R (2002) Insect hemocytes and their role in immunity. Insect Biochem Mol Biol 32:1295-309
Trudeau, D; Witherell, R A; Strand, M R (2000) Characterization of two novel Microplitis demolitor polydnavirus mRNAs expressed in Pseudoplusia includens haemocytes. J Gen Virol 81:3049-58
Strand, M R; Witherell, R A; Trudeau, D (1997) Two Microplitis demolitor polydnavirus mRNAs expressed in hemocytes of Pseudoplusia includens contain a common cysteine-rich domain. J Virol 71:2146-56
Strand, M R; Pech, L L (1995) Immunological basis for compatibility in parasitoid-host relationships. Annu Rev Entomol 40:31-56
Strand, M R; Pech, L L (1995) Microplitis demolitor polydnavirus induces apoptosis of a specific haemocyte morphotype in Pseudoplusia includens. J Gen Virol 76 ( Pt 2):283-91
Strand, M R; Johnson, J A; Noda, T et al. (1994) Development and partial characterization of monoclonal antibodies to venom of the parasitoid Microplitis demolitor. Arch Insect Biochem Physiol 26:123-36
Pech, L L; Trudeau, D; Strand, M R (1994) Separation and behavior in vitro of hemocytes from the moth, Pseudoplusia includens. Cell Tissue Res 277:159-67
Strand, M R (1994) Microplitis demolitor polydnavirus infects and expresses in specific morphotypes of Pseudoplusia includens haemocytes. J Gen Virol 75 ( Pt 11):3007-20