Characterization of the viral protein tyrosine phosphatase-H2 and the metabolic consequences of Microplitis demolitor bracoviral infection in Pseudoplusia includens
Bottjen, Rachel Christine
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The Microplitis demolitor bracovirus (MdBV) genome contains a large protein tyrosine phosphatase (PTP) gene family that encodes four enzymes with intact catalytic domains, including ptp-H2. Here we report expression of PTP-H2 in Escherichia coli cells as non-fusion or thioredoxin fusion proteins. Expressed protein was localized to hemocytes, and the purified nonfusion form of PTP-H2 exhibited classical Michaelis-Menten kinetics. Overall, our results indicate that PTP-H2 is a functional protein, specifically expressed in MdBV-infected hemocytes. Like many PDV-carrying wasps, Microplitis demolitor inhibits development of its host, Pseudoplusia includens. Here I report that MdBV infection caused a persistent state of hypertrehalosemia, but reduced nutrient stores at a slower rate than starved larvae. Hemolymph trehalase activity was reduced during infection, and feeding cessation was not related to trypsin activity nor hypertrehalosemia. Overall, my results suggest MdBV causes alterations in metabolism apart from starvation, which prevent the host from achieving critical weight.